1996.02.23 / J Mainwaring /  Re: WATER
     
Originally-From: mainwarj@boreal.owlnet.rice.edu (Jonah Paul Mainwaring)
Newsgroups: alt.fan.publius,sci.energy,sci.physics,sci.physics.fusion,al
.physics.new-theories
Subject: Re: WATER
Date: 23 Feb 1996 17:39:32 GMT
Organization: Rice University

|> 
|> <All replies of the *learned* SNIPPED>
|> 
|> > I know enough chemistry to agree with what you say but - just as there
|> > is the atomic reaction way of using water -
|> 
|> > I like to believe
|> > there is some other elegantly simple way of harnessing the energy
|> > potential of water. PUBLIUS
|> 
|> And you would not be alone in this belief ...
|> 
|> The natural properties of WATER are "elemental" in a sense which are
|> not now today appreciated by the wonderous disciplinic academies of
|> intelligentia, yet it is this "element" upon which they, their families,
|> their parents and ancestors, and their children's children turn for
|> their *very survival* on each and every day of their lives - as does 
|> most other living beings of this planet, in its binary helical path
|> with the moon - about the central fire.

Maybe we "intelligentia" don't appreciate the "elemental" nature of 
water because it is not an _element_.  Yes, Aristotle called it one, 
but Aristotle's science was not exactly accurate.  We do turn to 
water for survival every single day.  We also turn to: C6H12O6, NaCl, 
HCl, all the amino acids, etc.  Does that make them all elements?  
Every living thing on this planet needs glucose.  Is that proof of the 
"elemental" nature of glucose.  

Very poetic writing.  However, what does the orbit of the Earth, Luna, and Sol
have to do with the energy potntial of water?
 
|> You will be proved correct, and the learned will be left amazed at the
|> natural properties of water - however the question is to be asked:
|> 
|> Supposing indeed that WATER does have some hitherto "hidden & miraculous"
|> potential energy which could be harnessed .... 
|> 
|> To what END would you harness this energy ??????????????????????
|> To what WORK - to what labour - could this energy be applied?

Depends upon what this energy is.  Offhand, I'd say _nothing_.  

|> 
|> Air and water are the two natural "elements" of the terrestrial weather,
|> just as electricity and magnetism are the two natural "aspects" of the
|> cosmic (EMR - solar) weather ...

Actual, the solar weather is highly dependant upon convection currents within
the sun, rates of fusion, etc.  

|> 
|> Generically, the human natural scientist has had over (perhaps) a
|> million years to suss out the nature of the terrestrial weather, and
|> today it is still very much an "unknown art".
|> 

Actually, it isn't that much of an "unknown art." However, uncertainty theory, and/or
chaos theory tells us that it will never be predictable much more
than a week or so in advance.  
The so-called butterfly effect comes into play.

|> Generically, the human natural scientist has had not much more than one
|> or two centuries to revise "belief systems" in accordance to the *new*
|> understanding of the cosmic environment (heliocentric) and to entertain
|> the odd thought that the known earth (and in particular the THEORIES
|> thereon) was *not* the center of all things in the cosmos ....
|> 

actually he's had well over 3 hundred years, but why bother yourself with facts? 

|> Quite clearly, man has a lot to learn - and I would not be surprised,
|> O Publius, if indeed your belief will be proved sound after all is said
|> and done.   ;-)

That makes you one of the few.  Man has a lot to learn, but there
is also much that he knows.  
And he knows that the breaking of water bonds is endothermic, and
no energy source, in any
way shape or form.


|> 
|> Keep the faith
|> 

Science has nothing to do with faith.  I suggest that you stop
trying to confuse your theology
with science.  


-- 
Jonah Mainwaring
"I think that I am a verb."  - Fuller
http://www.owlnet.rice.edu/~mainwarj
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------------------------------
1996.02.24 / Harry Conover /  Re: CETI's Power Cell on ABC!
     
Originally-From: conover@max.tiac.net (Harry H Conover)
Newsgroups: sci.physics.fusion
Subject: Re: CETI's Power Cell on ABC!
Date: 24 Feb 1996 07:17:26 GMT
Organization: The Internet Access Company

gm76k$fkl@news4.digex.net>
Distribution: 

Seth W. (sethw@access5.digex.net) wrote:
: Harry H Conover (conover@max.tiac.net) wrote:
: : Seth W. (sethw@access5.digex.net) wrote:
: : : OK, you really like to slam "cold fusion", and the people who are interested
: : : in pursuing it.  Would you like to explain why you piped up here in response
: : : to a CETI claim?  Since, after all, CETI does not claim to be using "cold
: : : fusion" to produce the results observed with the Patterson cell?
: : 
: : Seth, being new here you're probably unaware that the devices being discussed,
: : including CETI's, are lumped into the generic category of CF engines
: : (preferable to Free Energy, ZPE, or Perpetual Motion devices). This
: : categorization began about a year ago, when nuclear events were pretty
: : much found lacking in the CF 'evidence' whereupon Jed Rothwell proclaimed 
: : that CF is independent of the producing mechanism.  Most other participants
: : in this newsgroup have gone along with this, although it is more than a 
: : little misleading.

: I am aware that the Patterson cell is being lumped together with other
: "cold fusion" experiments or devices.  Since you have conceded that "it is
: more than a little misleading," I will not belabor the point.
:  
: : : For starters, would you tell me of another "cold fusion" experiment of which
: : : you are aware which has used "light water" and has been proven false?
: :
: : For extraordinary claims that violate the entirety of man's accumulated
: : knowledge, the burden for evidence or proof falls upon the claimant.  To
: : date, no one in CF has successfully built a case for excess heat
: : or excess energy that has been able to withstand close critical
: : examination and analysis, or to support professional replication.
: :
: :                                      Harry C.

: My question to you, then, is whether you mean to include the Patterson
: cell there in your criticism of "cold fusion".  If you do, then I think you
: are incorrect, or premature in your conclusion.  Experimentation and
: replication have not invalidated the "case for excess heat or excess
: energy" where the Patterson cell is concerned--yet.

: My concern is that what might be a new approach will be dismissed out of
: hand because people associate it with other experiments that have nothing
: more to do with it than trying to obtain energy from hydrogen in a metal
: lattice.  There are lots of wrong ways to try to do just about anything,
: but they don't invalidate the right way.

: So if you can tell me of another experiment where thin layers of metal
: were used on small beads held in a grid in light water, I'll be content
: to listen to you say, "It's been done.  There's nothing there."  But if
: you don't know of another experiment similar to the Patterson cell having
: been done and previously discredited, then I don't think you should lump
: the Patterson cell with other "cold fusion" efforts simply to discredit
: the approach.

: I think that's only fair.

It's only fair.

Details notwithstanding, it simply one of many amateur experiments
that violates the second law of thermodynamics.  Nothing personal,
but this requires extraordinary evodemce to be taken seriously by any
intelligent creature.  That extraordinary evidence is not obviously
present here.

                                     Harry C.

cudkeys:
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------------------------------
1996.02.23 /  Fam /  Re: Radiation Detecting Wristwatch
     
Originally-From: "Fam.Borm-Mulder" <j3bkjjm@xs4all.nl>
Newsgroups: sci.energy,sci.environment,sci.engr.biomed,sci.engr.safety,s
i.med.dentistry,sci.med.deseases.cancer,sci.med.immunology,sci.med.occup
tional,sci.med.,sci.physics.accelerators,sci.physics.fusion,sci.physics.
article
Subject: Re: Radiation Detecting Wristwatch
Date: Fri, 23 Feb 1996 20:29:32 +0000 (GMT)
Organization: XS4ALL, networking for the masses

In article <4gi0qu$2sou@news.doit.wisc.edu>, Mike Baker
<mailto:baker@nucst11.neep.wisc.edu> wrote:
> 
> In article <ant2121481cbEmcX@j3bkjjm.xs4all.nl> "Fam.Borm-Mulder" <j3bkjj=
m@xs4all.nl> 
> writes:
[snip]
> =09
> =09The only reason I can think of that these would be turned
> =09down by a regulatory body would be that they don't =09
> =09provide an exposure record for long term storage.  Film
> =09badges and TLD "glow curves" can be used to meet that 
> =09function.
> 
> 
It is just the same for TLD's / badges / wristwatches:
If you don't wear them (despite regulations) or if you don't do
your accounting properly you get a mess, whichever device you use.
the same for inappropriate use or outright abuse.

I.e. I remember a problem with filmbadges showing (slightly)
high exposures once. These were clipped on the lab-coats
and left in closet next to a 131-I therapy room over night.

If the right software is used in the wristwatch and ee-roms
used for long term storage, then reliability might even
be better than both TLD and film badges.

If the company does the right tests to give proof of
reliability then there should be no legal objection.

Forget about accuracy of TLD badges or film badges with
a 'one-a-month' readout policy. This ain't a perfect world.

-- 
Judocus J.J.Borm
Email: j3bkjjm@xs4all.nl

cudkeys:
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------------------------------
1996.02.21 / John Logajan /  What's the secret?
     
Originally-From: jlogajan@skypoint.com (John Logajan)
Newsgroups: sci.physics.fusion
Subject: What's the secret?
Date: 21 Feb 1996 08:13:54 GMT
Organization: SkyPoint Communications, Inc.

jonesse@plasma wrote:
: I think there is something else going on -- which we are about
: to test.  If we are correct, then it is understandable why the so-called
: "control" cell at the PowerGen demo gave "excess heat", and why the
: effect is totally uninteresting as an energy source!

Well, if you clue us in, maybe we spf'ers can bat it around and see what
we come up with?

--
 - John Logajan -- jlogajan@skypoint.com  --  612-633-0345 -
 - 4248 Hamline Ave; Arden Hills, Minnesota (MN) 55112 USA -
 -   WWW URL = http://www.skypoint.com/members/jlogajan    -
cudkeys:
cuddy21 cudenjlogajan cudfnJohn cudlnLogajan cudmo2 cudqt1 cudszS cudyr1996 
------------------------------
1996.02.24 / S Inc /  Re: Merriman wrong, there is a protocol
     
Originally-From: sinecto@clark.net (Sinectonalysis Inc.)
Newsgroups: sci.physics.fusion
Subject: Re: Merriman wrong, there is a protocol
Date: 24 Feb 1996 14:54:24 -0500
Organization: Sinectonalysis, Inc. 24 Murray Rd. West Newton, MA 02165

In article <4gld7f$j7i@bang.hal.com>, Howard Landman <landman@hal.COM> wrote:
>In article <BJjbzBANmNHxEwVS@moonrake.demon.co.uk>,
>Alan M. Dunsmuir <alan@moonrake.demon.co.uk> wrote:
>>As I was saying, homeopathy, like CF, is a load of bollocks.
>
>My understanding is that the central idea of homeopathy is that smaller
>amounts of various substances have more, not less, effect than larger
>amounts.  It seems pretty clear that this general principal is horribly
	NO! The principal is not what you stated. The principle of 
homeopathy is to treat a patient with SOME substance that causes the SAME
symptoms as the disease. I guess the idea is to make the immune system to
respond more strongly to the disease. If you have a cold your body will
respond with elevated temperature, homeopathy would suggest ingesting some
substance which would also elevate body temperature, i.e. induce the same
symtoms that your body produces naturally in responce to the sickness. In
some sense it is like a vaccine (a temporary one). Raspberry jam with hot
tea would be good, so would be niacin (vitamin B), etc...

Nothing to do with fusion but I cannot stand it when ignoramuses argue from
supposed position of "authority".

BTW, I do not practice homeopathy either on myself or others, not do I have
anything to say about whether it works or not. Just don't know.

cudkeys:
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------------------------------
1996.02.24 / A Conference /  APC-96 Information
     
Originally-From: American Power Conference <apc@ece.iit.edu>
Newsgroups: sci.energy,alt.engineering.electrical,alt.energy.renewable,s
i.engr.lighting,sci.physics.fusion,sci.physics.electromag
Subject: APC-96 Information
Date: Sat, 24 Feb 1996 11:54:44 -0600
Organization: Illinois Institute of Technology

American Power Conference  (APC)

58th Annual Meeting

April 9,10,11, 1996

Chicago Marriott Downtown Hotel
Chicago, Illinois, USA

Sponsored by the Illinois Institute of Technology

  
 Technology for Competition and Globalization


Over 2600 attendees from all over the world are expected to attend this
long standing interdisciplinary forum for the power industry.

APC-96 features distinguished speakers who are industry leaders.  Over
400 paper and panel presentations in 80 sessions will address available
and emerging technologies.  Topics include Power Marketing, Environment,
Globalization, Impact of FERC MegaNOPR on system operations and
planning, EMF, System Protection, T&D, Generation, Nuclear, and Power
Quality.

Additional information including the conference registration form, hotel
reservation form, and the complete program,  is available from our Web
page:

http://www.ece.iit.edu/~apc/apc.html

(the page is "Netscape-enhanced").

You can download the registration/reservation forms from the Web page in
several formats:  postscript file, MS Word file, or plain text file.

Important dates:

Advance Registration Deadline:  March 29, 1996
Hotel Reservation Deadline:  March 18, 1996

(Please send the hotel reservation request directly to the hotel)

For further information, email us at  apc@ece.iit.edu,

or call (312) 567-3196  , or (312) 567-3406

Fax: (312) 567-3892

Postal address:

American Power Conference, Illinois Institute Of Technology,
10 West 32nd Street, Chicago, Illinois 60616-3793, USA
cudkeys:
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------------------------------
1996.02.21 /  Nick /  Re: Merriman wrong, there is a protocol
     
Originally-From: lineplex@cix.compulink.co.uk ("Nick Horgan")
Newsgroups: sci.physics.fusion
Subject: Re: Merriman wrong, there is a protocol
Date: Wed, 21 Feb 1996 17:17:37 GMT
Organization: LinePlex Ltd

Most qualified doctors don't and don't believe in it at all.
cudkeys:
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------------------------------
1996.02.24 / Mike Baker /  Re: Radiation Detecting Wristwatch
     
Originally-From: baker@nucst11.neep.wisc.edu (Mike Baker)
Newsgroups: sci.energy,sci.environment,sci.engr.biomed,sci.engr.safety,s
i.med.dentistry,sci.med.deseases.cancer,sci.med.immunology,sci.med.occup
tional,sci.med.,sci.physics.accelerators,sci.physics.fusion,sci.physics.
article
Subject: Re: Radiation Detecting Wristwatch
Date: 24 Feb 1996 16:38:30 GMT
Organization: Univ. of Wisconsin-Madison; College of Engineering

>[snip]
>> =09
>> =09The only reason I can think of that these would be turned
>> =09down by a regulatory body would be that they don't =09
>> =09provide an exposure record for long term storage.  Film
>> =09badges and TLD "glow curves" can be used to meet that 
>> =09function.
>> 
>> 
>It is just the same for TLD's / badges / wristwatches:
>If you don't wear them (despite regulations) or if you don't do
>your accounting properly you get a mess, whichever device you use.
>the same for inappropriate use or outright abuse.
>

	I was referring to having a permanent record of exposure
	history.  The information sent to me on these watches 
	didn't say anything about providing this feature.  Therefore
	a technician would still have to record exposures from
	watch readings.

	The TLD readers I am familiar with provide a paper printout
	of the "glow curve" and film provides an obvious record if
	stored properly.

	As far inappropriate use and "forgetting to wear" the dosimeter,
	these are problems uniform to all dosimeters.  A pocket ionization
	chamber can easily be worn on the wrist if that is the location 
	were monitoring is required.  I don't see how this watch offers
	any advantages over currently available equipment for prices
	less than $2500.



-- 
===============================================================================
		Michael Baker ... baker@nucst11.neep.wisc.edu
===============================================================================

cudkeys:
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------------------------------
1996.02.25 / Robert Heeter /  Conventional Fusion FAQ Glossary Part 6/26 (F)
     
Originally-From: Robert F. Heeter <rfheeter@princeton.edu>
Newsgroups: sci.physics.fusion,sci.answers,news.answers
Subject: Conventional Fusion FAQ Glossary Part 6/26 (F)
Date: 25 Feb 1996 13:03:55 GMT
Organization: Princeton University

Archive-name: fusion-faq/glossary/f
Last-modified: 4-Feb-1995
Posting-frequency: More-or-less-quarterly
Disclaimer:  While this section is still evolving, it should
     be useful to many people, and I encourage you to distribute
     it to anyone who might be interested (and willing to help!!!).

===============================================================
Glossary Part 6:  Terms beginning with "F"

FREQUENTLY USED TERMS IN CONVENTIONAL FUSION RESEARCH
AND PLASMA PHYSICS

Edited by Robert F. Heeter, rfheeter@pppl.gov

Guide to Categories:

* = plasma/fusion/energy vocabulary
& = basic physics vocabulary
> = device type or machine name
# = name of a constant or variable
! = scientists
@ = acronym
% = labs & political organizations
$ = unit of measurement

The list of Acknowledgements is in Part 0 (intro).
==================================================================

FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

# F:  Variable typically used for force; sometimes flux.

& F:  Chemical symbol for the element fluorine.

* FLiBe or flibe or FLIBE:  Fluorine-LIthium-BEryllium; see
entry "Flibe" below.

@ FEDC:  Fusion Engineering Design Center; see entry

@ FLR:  Finite Larmor Radius; see entry

@ FPD:  Fusion Power Demonstration facility; see DEMO.

@ FRC:  Field-Reversed Configuration; see entry

@ FY:  Fiscal Year; see entry

& Fabry-Perot Interferometer:  A type of interferometer with
two parallel mirrors (with a variable separation of a
few centimeters) arranged so that incoming light is reflected
between them multiple times before ultimately being transmitted.
Useful in spectroscopy because it gives very good frequency
resolution without losing too much of the incident signal.

* Faraday Rotator:  A device which rotates the plane of
polarization of an optical-light pulse, typically by
using a glass disc suitably doped with a magnetic ion
and placed in a magnetic field.  These devices are used
to isolate (protect) a laser amplifier chain against
back-reflection from the laser target; the Faraday rotator
in this case gives a 90-degree phase change on the round
trip, so that the returning light is rejected by a
polarizer which transmits the outgoing light.

* Fast neutron:  Neutron with energy greater than roughly
100,000 electron volts (100 keV).  Distinguished from slow or
thermal neutrons.  (See appropriation entries.)

* Fertile Material:  In nuclear physics, this refers to a nuclide
which converts to fissile material (see entry) upon neutron
capture and subsequent radioactive decay.  Examples include
Uranium-238 and Thorium-232.

& Field:  In physics, any macroscopic quantity which exists
(and typically varies) througout a region of space.  Standard
examples include Electric and Magnetic fields, velocity flow fields,
gravitational fields, etc.

& Field Lines:  Lines in space along which a field is either
changing or not changing (depends on the field) but which help
to create diagrams which characterize the behavior and effects
of the field.  For instance, electric field lines run in the
direction that the electric field will push charged particles;
the strength of the field is proportional to the density of
the field lines.  On the other hand, the magnetic force pushes
particles in a direction perpendicular to both the particle's
velocity and the direction of the magnetic field line.

> Field-Reversed Configuration:  A compact torus produced in a
theta pinch and having (in principle) no toroidal field.  The
potential advantages for a fusion reactor include a simple (linear)
machine geometry, an average plasma pressure close to the confining
field pressure, and physical separation of formation and burn
chambers.  The are predicted to be violently unstable to tilting, but
this is rarely observed.  See also: compact torus, theta pinch.
(Arthur Carlson, awc@ipp-garching.mpg.de)

* Field Shaping Coils:  Type of poloidal field coils (in a tokamak)
which create magnetic fields which shape and control the plasma.
Used to constrain horizontal and vertical displacements of the plasma,
as well as (in some configurations) produce non-circular plasma
cross sections (poloidal cross-section) and/or create one or more
divertor separatrices.  (See relevant entries.)

* Finite Larmor Radius:  In many plasma theories the size of the
Larmor radius (or gyroradius - see entries) is assumed to be
negligibly small, or infinitesimal.  Different effects occur when
the size of the Larmor radius is finite and needs to be considered.
(Anyone out there with a succint, but more detailed explanation?)

* First Wall:  The first physical boundary that surrounds a plasma.

* Fiscal Year (FY):  Year used to open and close accounting records;
not necessarily the same as the calendar year.  (For instance, the
U.S. government's Fiscal Year begins Oct 1 and ends Sept 30.)

* Fishbones:  Oscillations in soft x-ray emissions which occur
during intense neutral-beam heating; associated with a recurring
m=1 internal kink mode.  Mode was given its name from its
characteristic signal (looked like the bones of a fish, of course).
Fishbones are associated with loss of fast ions from the plasma
and are triggered by exceeding the upper limit on plasma beta.
(see relevant entries)

* Fissile Material:  Material containing a large number of
easily fissionable nuclei which give off multiple neutrons in
the fission process.  Usual meaning is that if a sufficiently
large amount of fissile material is put together, a fission
chain reaction can occur.  Sometimes used synonymously with
"fissionable material," i.e., material that *can* be fissioned
(though often under restricted circumstances, such as only with
thermal (slow) neutrons).  A more restricted meaning use of
fissile material limits the concept to those materials which can
be fissioned by neutrons of all energies (fast & slow).
Examples include Uranium-235 and Plutonium-239.

& Fission (Nuclear): Nuclear decay process whereby a large
nucleus splits into two smaller (typically comparably-sized)
nuclei (which are thus nuclei of lighter elements), with or
without emission of other particles such as neutrons.
When it occurs, fission typically results in a large energy
release.  Fission can occur spontaneously in some nuclei, but
is usually caused by nuclear absorption of gamma rays,
neutrons, or other particles.  See also spallation, radioactivity.

* Fission Bomb:  see atomic bomb, A-bomb.

* Fission Reactor:  (from Herman) A device that can initiate
and control a self-sustaining series of nuclear fissions.

* Flat-top:  Stable period in the middle of a tokamak
discharge, characterized by a flat, stable peak in a plot
of plasma (current, temperature) vs. time.

* Flibe:  Molten salt of Fluorine, Lithium, and Beryllium;
candidate blanket/coolant/breeder material for fusion reactors.

* Flute Instability:  Term used to describe an interchange
instability in which the perturbation is uniform parallel
to the magnetic field. In cyclindrical geometry, the structure
resembles a fluted column (as in classical architecture).
Occurs in some mirror machines.

& Flux:  The total amount of a quantity passing through a given
surface per unit time.  Typical "quantities" include field lines,
particles, heat, energy, mass of fluid, etc.  Common usage in
plasma physics is for "flux" by itself to mean "magnetic field
flux."

& Flux Density:  Total amount of a quantity passing through a
unit surface area in unit time.  See also flux, above.

* Flux freezing:  See frozen-in law.

* Flux surfaces:  See magnetic flux surfaces.

* Flux trapping:  See frozen-in law.

& F-number:  In optics, denotes the ratio of the equivalent focal
length of an objective lens to the diameter of its entrance pupil.

* Fokker-Planck Equation:  An equation that describes the time rate
of change of a particle's velocity as a result of small-angle
collisional deflections.  Applicable when the cumulative effect of
many small-angle collisions is greater than the effect of rarer
large-angle deflections.

& Force:  Rate of change of momentum with time.  Forces are said
to cause accelerations via F = ma (Newton's law).  There are four
primary forces known presently:  the gravitational, electromagnetic,
weak nuclear, and strong nuclear forces.  The gravitational and
electromagnetic forces are long-range (dropping as 1/distance^2),
while the nuclear forces are short range (effective only within
nuclei; distances on the order of 10^-15 meters).  The
electromagnetic force is much stronger than the gravitational force,
but is generally cancelled over large distances because of the
balance of positive and negative charges.  Refer to entries for each
force for more information.  See also momentum.

* Free Electron:  An electron not bound to an atom, molecule, or
other particle via electric forces.

* Free Wave:  A wave (e.g., electromagnetic) travelling in a
homogeneous infinite medium (no boundary conditions).

* Frozen-in Flow Law:  In a perfect conductor, the total magnetic
flux through any surface is a constant.  In a plasma which is nearly
perfectly conducting, the relevant surfaces move with the plasma;
the result is that the plasma is tied to the magnetic field, and
the field is tied to the plasma.  Motion of the plasma thus
deforms the magnetic field, and vice versa.

* Fusion (Nuclear): a nuclear reaction in which light atomic
nuclei combine to form heavier nuclei, typically accompanied
by the release of energy.  (See also Controlled
Thermonuclear Fusion)

% Fusion Engineering Design Center:  Facility managed by
ORNL and staffed mainly by industrial personnel; undertakes
detailed engineering design of planned fusion facilities.
(Is it still in operation?  The reference I have is out of date.)

* Fusion Reactor: Device which creates energy in a controlled
manner through fusion reactions.

> Fusion-Fission Hybrid: Proposed nuclear reactor relying
on both fusion and fission reactions.  A central fusion
chamber would produce neutrons to provoke fission in a
surrounding blanket of fissionable material.
The neutron source could also be used to convert other
materials into additional fissile fuels (breeder hybrid).
Safer than a plain fission reactor because the fission fuel
relies on the fusion neutrons, and therefore won't spontaneously
melt down.  On the other hand, hybrids are more complex because
of the fusion power core, and still generate fission's radioactive
byproducts.  But could be more economical and have easier technical
requirements than a straight fusion reactor.







cudkeys:
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------------------------------
1996.02.25 / Robert Heeter /  Conventional Fusion FAQ Glossary Part 7/26 (G)
     
Originally-From: Robert F. Heeter <rfheeter@princeton.edu>
Newsgroups: sci.physics.fusion,sci.answers,news.answers
Subject: Conventional Fusion FAQ Glossary Part 7/26 (G)
Date: 25 Feb 1996 13:03:57 GMT
Organization: Princeton University

Archive-name: fusion-faq/glossary/g
Last-modified: 4-Feb-1995
Posting-frequency: More-or-less-quarterly
Disclaimer:  While this section is still evolving, it should
     be useful to many people, and I encourage you to distribute
     it to anyone who might be interested (and willing to help!!!).

===============================================================
Glossary Part 7:  Terms beginning with "G"

FREQUENTLY USED TERMS IN CONVENTIONAL FUSION RESEARCH
AND PLASMA PHYSICS

Edited by Robert F. Heeter, rfheeter@pppl.gov

Guide to Categories:

* = plasma/fusion/energy vocabulary
& = basic physics vocabulary
> = device type or machine name
# = name of a constant or variable
! = scientists
@ = acronym
% = labs & political organizations
$ = unit of measurement

The list of Acknowledgements is in Part 0 (intro).
==================================================================

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

$ G:  abbreviation for Gauss; see entry

@ GA:  General Atomic; see entry.

@ GDC:  Glow Discharge Cleaning; see entry.

@ GN2:  Gaseous diatomic Nitrogen (N2)

@ GNP:  Gross National Product; see entry.

@ GW:  Gigawatt; see entry

@ GWe:  Gigawatt - electrical energy; see gigawatt

@ GWt:  Gigawatt - thermal energy; see gigawatt

& Gain:  (Amplification)  Increase in a signal transmitted
from one point to another through an amplifier.

# gamma:  Third letter in the Greek alphabet; variable used for
a number of things in phyics; in plasma physics gamma is often
used as the variable for growth rates of instabilities.

* Gamma Emission:  Nuclear decay process whereby the nucleus goes
from an excited state to a more stable state by emitting a gamma
ray.  (See entry for gamma ray.)

* Gamma Rays:  Electromagnetic radiation (photons) with energies
greater than (roughly) 100 keV (that is, 100,000 electron volts).
Gamma radiation frequently accompanies alpha and beta decays,
and always accompanies fission.  Gamma rays are highly penetrating
and are best shielded against using dense materials, such as
lead or depleted uranium.  (Gamma rays are similar to X-rays, but
are generally higher in energy and nuclear in origin.)  See
relevant entries for more info.

% Garching:  A town in Germany just north of Munich, where the Max
Planck Institute for Plasma Physics (see entry) is located.  "Garching"
in plasma physics frequently refers to the Max Planck Institute.

* Gas Blanket:  A cold, dense volume of gas surrounding a hot
plasma and used to protect a material wall from bombardment
by hot ions (with subsequent sputtering and impurity production).

! Gauss, Carl Friedrich: (1777-1855) German mathmetician, astronomer
and physicist.

$ Gauss - unit of magnetic field strength (CGS units)
10,000 gauss = 1 tesla (see also Tesla)

& Gaussian Units - See CGS Units

% General Atomic:  U.S. corporation involved in fusion research;
operates the DIII-D device in San Diego; see also Doublet III-D.
(Officially known as GA Technologies, I believe; or is that the
name of the parent company???)

& Getters:  Materials which absorb ("get") atoms and can be
used in purifying near-vacuum atmospheres.

$ Gigawatt:  Unit of power equal to 10^9 watts, 1000 megawatts,
or 1 million kilowatts.  See entry for watt.  1 gigawatt is a typical
size for a nuclear fission reactor, and is expected to be the typical
size of a fusion reactor.

* Glow Discharge:  Low-density, low-temperature plasma discharge
(such as in a fluorescent light) which, well, glows.  Sputtering
in glow discharges is useful in plasma processing of materials.
The voltage applied to the plasma must be greater than the
ionization potential of the gas used; most of the plasma voltage
drop is near the cathode, where the majority of ionization occurs.
Discharge is sustained by secondary electrons emitted when ions
or recombination radiation impact on the cathode; electrons are
accelerated away from the cathode and ionize neutral gas in the
discharge.

* Glow Discharge Cleaning:  Cleaning in which impurities are
removed by sputtering in a glow discharge. (?)

* Grad-Shafranov Equation:  Reduced MHD-equilibrium equation for
an axisymmetric, toroidal plasma.  (Similar reduced equations
can be derived for the cases of helical symmetry and for
the straight cylinder.)  Analytic and numerical studies of these
equations are important in exploring potential plasma
configurations.

 -> Additional info Contributed by James Crotinger, with minor
revisions:

The lowest order force balance in the plasma is simply that
the Lorentz force must be balanced by the pressure force.
This balance, combined with Maxwell's equations, determines
the equilibrium configuration of the magnetic field.  When
the toroidal configuration is axisymmetric, and the equilibrium
plasma flow is zero, the magnetic field may be written in
terms of a stream function \psi that satisfies the
Grad-Shafranov equation

            \Delta*\psi = - \mu_0 R^2 p'(\psi) - FF'(\psi).
        Here p is the plasma pressure and F = R B_\phi.
(R is the radial distance from the axis of the machine)

(Alternatively, leaving out the equation):
   In an axisymmetric torus, in the absence of equilibrium plasma
   fluid flows, the magnetic field may be written in
   terms of a scalar potential. When the plasma is in equilibrium
   (forces balance and the plasma is stationary), this scalar
   potential obeys a non-linear elliptic equation known as the
   Grad-Shafranov equation.


& Gradient:  Mathematical term for the operator which determines
the magnitude and direction of the greatest rate-of-change of a
given function with position.  Similarly used to describe such
a rate-of-change.  For instance, at a given point on a hill, the
slope of the hill in the steepest uphill direction is the gradient
of the altitude funtion for the hill.

& Gravitational Force:  Force which attracts two bodies together
based on the product of their masses and the reciprocal of
the square of their distances.  "Gravity" is the force field
created by one massive body (like the earth) which another body
(like you) will experience.

* Gross National Product:  Total value of goods and services
produced in a country; measure of economic strength of a nation.

$ Gray:  A unit of absorbed dose of radiation, equal to one
joule of energy per kilogram of mass.   1 Gray = 100 rads.
Defined relative to the material into which such radiation passed,
which should therefore be specified.

& Group Velocity:  This is derived from the dispersion relation
(see entry) as Vgroup = dw/dk; the group velocity is the rate
at which modulations or information within a wave travel through
a given medium.

* Guiding Center:  Particles placed in a magnetic field will
gyrate in circles around the magnetic field lines, and drift in
various directions.  The guiding center represents the
instantaneous center of the circular motion.  The idea is that
you can think of the guiding center as drifting, and the particle
as orbiting the guiding center.

* Gyrofrequency:  See cyclotron frequency.

* Gyromagnetic Ratio:  Ratio of the magnetic moment to the
angular momentum of a particle.  (see magnetic moment, angular
momentum)

* Gyroradius: radius of charged particle in magnetic field.
Same thing as cyclotron radius, Larmor radius.

* Gyrotron:  A device for producing microwave energy that
utilizes a strong axial magnetic field in a cavity resonator
to produce azimuthal bunching of an electron beam.



cudkeys:
cuddy25 cudenrfheeter cudfnRobert cudlnHeeter cudmo2 cudqt1 cudszL cudyr1996 
------------------------------
1996.02.25 / Robert Heeter /  Conventional Fusion FAQ Glossary Part 8/26 (H)
     
Originally-From: Robert F. Heeter <rfheeter@princeton.edu>
Newsgroups: sci.physics.fusion,sci.answers,news.answers
Subject: Conventional Fusion FAQ Glossary Part 8/26 (H)
Date: 25 Feb 1996 13:04:01 GMT
Organization: Princeton University

Archive-name: fusion-faq/glossary/h
Last-modified: 4-Feb-1995
Posting-frequency: More-or-less-quarterly
Disclaimer:  While this section is still evolving, it should
     be useful to many people, and I encourage you to distribute
     it to anyone who might be interested (and willing to help!!!).

===============================================================
Glossary Part 8:  Terms beginning with "H"

FREQUENTLY USED TERMS IN CONVENTIONAL FUSION RESEARCH
AND PLASMA PHYSICS

Edited by Robert F. Heeter, rfheeter@pppl.gov

Guide to Categories:

* = plasma/fusion/energy vocabulary
& = basic physics vocabulary
> = device type or machine name
# = name of a constant or variable
! = scientists
@ = acronym
% = labs & political organizations
$ = unit of measurement

The list of Acknowledgements is in Part 0 (intro).
==================================================================

HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

# H: chemical symbol for the element hydrogen; see entry

# He: chemical symbol for the element helium; see entry.

@ HIREX: High-REsolution X-ray spectroscopy

@ H-mode:  see high-mode

@ HTO:  (Hydrogen-Tritium-Oxygen)  Water with a tritium atom
replacing a hydrogen.  See entry for tritium.

* Half-life:  For a given quantity of a radioactive isotope,
there is a time period in which half the nuclei will decay to
a different state; this period is called the half-life.  Measured
half-lives range from less than millionths of a second (for very
short-lived isotopes) to billions of years (for isotopes which
are almost stable, but not quite).  The time in which half the
atoms of a particular radioactive isotope disintegrate
to another nuclear form.  By analogy, "half-life" can also be
used to describe similar time-periods for other sorts of
exponential decay phenomena.

* Hall Effect:  Transverse electric field which develops in a
conductor (as a result of the Lorentz Force acting on the charge
carriers) when current is driven across a magnetic field.

* Halo:  The cold, dense plasma formed outside the last closed flux
surface during a vertical displacement event. The large currents
which flow through this plasma stop the displacement and transfer the
force to the vacuum vessel. If care is not taken in design, the halo
currents can be large enough to threaten the structural integrity of
the vacuum vessel or in-vessel components.  Whereas the center of a
tokamak plasma is too hot for material probes to survive, probes
(such as magnetic-field coils) can sometimes be placed in the
halo, and can measure things such as the halo current (see below).
See also entry for vertical instability.

* Halo Current:  Currents in the halo region of a plasma discharge.
See entry for halo above.

* Hamada coordinates:  A particular magnetic-flux coordinate
system useful for MHD calculations.  In this system the current
density and magnetic field lines are straight and the Jacobian
of the coordinate transformation equals one.

& Hamiltonian Function:  Function arising from the Hamiltonian
approach to mechanics which characterizes the total energy of
a system as a function of generalized coordinates and momenta
and can be used to obtain the dynamical equations of motion
of the system.  (Consult an intermediate or advanced mechanics
text for more info.)

> Hard-core pinch device:  plasma pinch-discharge device using a
solid central conductor ("hard-core").  The discharge then occurs
in an annular region about the central conductor.

& Hartree-Fock approximation:  a refinement of the Hartree method
(see entry) in which one uses determinants of single-particle
wave functions rather than products, thereby introducing exchange
terms into the Hamiltonian.

& Hartree method:  An iterative, variational method of finding an
approximate quantum-mechanical wavefunction for a system of many
electrons, in which one attempts to find a product of
single-particle wave functions, each of which is a solution of
the Schrodinger equation with the field deduced from the charge
density distribution due to all the other electrons; also known
as the self-consistent field method.

& Heat exchanger:  device that transfers heat from one fluid
(liquid or gas) to another (or to an external environment).

* Heavy Hydrogen:  somewhat informal alternative name for deuterium.
(see entry for deuterium).

* Heavy Water:  (D2O)  Water with enriched content of deuterium
relative to hydrogen (greater than the natural abundance of 1 D
per 6500 H).  Heavy water is used as a moderator in some fission
reactors (see CANDU entry) because it slows down neutrons effectively
but also has a low collision cross-section for absorption of neutrons.

> Heliac:  A confinement configuration which superimposes an l=1
stellarator-type field upon a tokamak-like poloidal field.  The
resulting plasma configuration is a helix bent around into a loop.

* Helicity: (from John Cobb)  A measurement of the topological
"tangledness" of magnetic field lines. It is formally defined as the
scalar product of the magnetic vector potential with the magnetic
field, K = A dot B. If the plasma is perfectly conducting, then
helicity is a conserved quantity.  (Without resistance, field lines
cannot reconnect, and magnetic topology is conserved, so helicity is
conserved).  (See frozen-in flow).  If the plasma has a small amount
of resistivity, then Helicity is not exactly conserved.  However, the
total helicity inside of a given flux surface is often conserved to a
good approximation. In that case, the dynamics of a plasma can be
analyzed as an evolution toward a minimum energy state subject to the
constraint of a conserved total helicity (See Taylor State, J.B.
Taylor). This is often used in analyzing the equilibrium and
relaxation of RFP's and other toroidal devices.

> Helios Facility:  Los Alamos laser inertial fusion facility.

& Helium: Element whose nuclei all contain two protons.
Stable isotopes are 3He and 4He.  3He is rare on earth (only 1.3
ppm of naturally-occuring He), can be generated from decaying
tritium (half life of about 12 years), and is relatively abundant
in the crust of the moon.  Helium is the second most abundant element
in the universe and in the sun, and occurs at about (I believe)
1 part per million in earth's atmosphere.  Helium is also found
in significant quantities in natural gas deposits.  The nucleus
of the He atom is also known as an alpha particle.  Helium is
chemically inert, behaves nearly as an ideal gas under a wide
range of pressures and temperatures, and can only be liquefied
at 4 Kelvin (at atmospheric pressures).  One mole of He weighs
4 grams.

! Hertz, Heinrich:  19th-century German physicist; first (?)
observed low-frequency electromagnetic waves.

$ Hertz:  Unit of frequency equal to one complete oscillation (cycle)
per second.  Common abbreviation is Hz.

* High-beta plasma:  A plasma in which the beta value (see entry)
is typically 0.1 to 1.

* High-mode or H-mode:  A regime of operation most easily
attained during auxiliary heating of diverted tokamak
plasmas when the injected power is sufficiently high.
A sudden improvement in particle confinement time leads to
increased density and temperature, distinguishing this mode
from the normal "low mode."  However, H-mode has been achieved
without divertors, auxiliary heating, or a tokamak.  (H-modes
have been observed in stellarators.)

& Holography:  A technique for recording and later reconstructing
the amplitude and phase distribution of a wave disturbance.

& Homopolar generator:  A direct-current generator in which the
poles presented to the armature are all of the same polarity,
so that the voltage generated in the active conductors has the
same polarity at all times.  A pure direct current is thus
produced without commutation.

* Hot cells:  Heavily radiation-shielded enclosure in which
radioactive materials can be handled by persons using remote
manipulators and viewing the materials through shielded windows
or periscopes.

* Hybrid diode:  An ion diode that uses a field coil in series
with the ion diode's accelerating gap to generate sufficient
magnetic flux in the diode for electron control.  The diode is
a combination of the Applied-B diode's ion source and the
Ampfion diode's field coil.

* Hybrid reactor:  see fusion-fission hybrid.

* Hybrid resonance:  A resonance in a magnetized plasma which
involves aspects of both bunching of lighter species parallel
to the magnetic field, characterized by the plasma frequency;
and perpendicular particle motions (heavier species) characterized
by the cyclotron frequency.

& Hydrogen: (H) Element whose nuclei all contain only one proton.
Isotopes are protium (p, no neutrons) deuterium (D or d,
one neutron), and tritium (T or t, two neutrons).  Hydrogen is
the lightest and the single most abundant element in the
universe, and in the sun.  Hydrogen is a major element in
organic compounds, water (H2O), and many other substances.
Hydrogen is ordinarily a gas, but can be liquefied at low
temperatures, and even solidified at low temperature and
high pressure.  Hydrogen gas can burn explosively
in the presence of oxygen.

* Hydrogen bomb or H-bomb: (from Herman) An extremely
powerful type of atomic bomb based on nuclear fusion.
The atoms of heavy isotopes of hydrogen (deuterium and
tritium) undergo fusion when subjected to the immense
heat and pressure generated by the explosion of a nuclear
fission unit in the bomb.

* Hydrogen embrittlement:  A decrease in the fracture
strength of metals (embrittlement) due to the incorporation
of hydrogen within the metal lattice.

* Hydromagnetic Instability:  See MHD Instability

* Hydromagnetics:  see magnetohydrodynamics (MHD)





cudkeys:
cuddy25 cudenrfheeter cudfnRobert cudlnHeeter cudmo2 cudqt1 cudszL cudyr1996 
------------------------------
1996.02.25 / Robert Heeter /  Conventional Fusion FAQ Glossary Part 9/26 (I)
     
Originally-From: Robert F. Heeter <rfheeter@princeton.edu>
Newsgroups: sci.physics.fusion,sci.answers,news.answers
Subject: Conventional Fusion FAQ Glossary Part 9/26 (I)
Date: 25 Feb 1996 13:04:05 GMT
Organization: Princeton University

Archive-name: fusion-faq/glossary/i
Last-modified: 4-Feb-1995
Posting-frequency: More-or-less-quarterly
Disclaimer:  While this section is still evolving, it should 
     be useful to many people, and I encourage you to distribute 
     it to anyone who might be interested (and willing to help!!!).

===============================================================
Glossary Part 9:  Terms beginning with "I"

FREQUENTLY USED TERMS IN CONVENTIONAL FUSION RESEARCH 
AND PLASMA PHYSICS

Edited by Robert F. Heeter, rfheeter@pppl.gov

Guide to Categories:
 
* = plasma/fusion/energy vocabulary
& = basic physics vocabulary 
> = device type or machine name
# = name of a constant or variable
! = scientists 
@ = acronym
% = labs & political organizations
$ = unit of measurement

The list of Acknowledgements is in Part 0 (intro).
==================================================================

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

# I:  variable used to indicate total current through a conductor.

@ IAEA:  International Atomic Energy Agency; see entry
 
@ IBHP:  Integrated Biological Hazard Potential; see entry

@ ICE: Ion Cyclotron Emission; see entry

@ ICF:  Inertial Confinement Fusion; see entry

@ ICH:  Ion Cyclotron Heating - see ICRH

@ ICRF:  Ion Cyclotron Range of Frequencies

@ ICRH:  Ion Cyclotron Resonance Heating; see entry

@ IEEE:  Institute of Electrical and Electronic Engineers; see entry

@ INEL:  Idaho National Engineering Laboratory; see entry

@ IPP:  Max Planck Institute for Plasma Physics; see entry

@ IR:  Infrared (region of the electromagnetic spectrum)

@ ITER:  International Thermonuclear Experimental Reactor; see entry

% Idaho National Engineering Laboratory:  U.S. Department of energy
laboratory involved in engineering studies for fusion and fission
reactors, among other things.  Not surprisingly, located in Idaho.

* Ignition:  In fusion, as in an ordinary (chemical) fire,
ignition is the point where the temperature and confinement
of heat in the fuel (plasma in the case of fusion) are 
such that energy released from ongoing reactions is sufficient
to maintain the temperature of the system, and no external
heating is needed.  An ignited fusion plasma produces so 
much energy from fusion reactions that the plasma is fully
heated by fusion reaction products (alpha particles in the
case of D-T fusion), and the plasma no longer needs any 
external source of power to maintain its temperature.
(The plasma may, however, still need something to maintain 
its confinement; this gives us control over the fusion 
reaction and helps prevent fusion reactors from having 
"meltdown" problems like fission reactors.)

* Ignition Temperature:  For given values of density and
energy confinement, the temperature at which ignition occurs.
(see ignition above)

> Impact Fusion:  Fusion approach where a "fuel" projectile
is acclerated and impacted into either a stationary target or
another projectile.  (Valuable for scientific purposes but
not a candidate for a fusion energy source because the
likelihood of fusion occurring in a single collision is 
too low.  Multiple accelerated pellets colliding with spherical
symmetry might be a viable inertial confinement approach, though.)

* Impact fusion drivers:  macroparticle/projectile accelerator
which could be used in inertial confinement fusion.

* Impurities: atoms of unwanted elements in the plasma, 
which tend to degrade plasma performance, and in the case of 
fusion plasmas tends to inhibit fusion ("poisoning the reactor").
See also poisoning.

* Impurity Control:  Processes which reduce or control the level
of impurities in a plasma, and thereby improve its quality;
see also wall conditioning.

* Inboard side:  portion of a tokamak (or other toroidal device)
closest to the central axis.  (As distinguished from "outboard side.")

* Incoherent scattering:  Type of scattering in which the scattering
elements act independently, so that no definite phase relationships
exist among the different parts of the scattered 
beam (particles or photons).

& Index of Refraction:  For a given wavelength, this is the ratio 
of the velocity of light in vacuum (c) to the velocity of light
in a refractive material (e.g., glass, plasma, etc.).

& Inductance:  Characteristic relating the magnetic flux generated
through a loop of wires to the current in the wires; Phi=LI.

& Induction:  A changing magnetic flux through a current loop will
induce an electric field which will drive a current through the loop.
This is the principle behind an AC transformer, where an oscillating
electric voltage in one loop of the transformer creates a current
which generates an oscillating magnetic field, which then induces
a different voltage and current in a second loop.

* Inductive Current Drive:  Method to drive current in a toroidal
plasma by using the torus of conducting plasma as the second coil
in a transformer.  The primary coil usually runs down the center
of the torus; changes in the current driven through the primary
coil create changing magnetic fields which drive current in
the plasma.  The current thus driven can be used to heat the plasma
as well (see also ohmic heating; induction).

* Inertial Confinement Fusion:  Approach to fusion where the plasma
is imploded so quickly that the inertia of the converging particles
is so high that many fuse before they disperse.  This is the method
used in a hydrogen bomb; ICF schemes for power production usually
use small pellets of fuel in an attempt to make "miniature"
h-bomb type explosions.  Methods for imploding the pellet include
bombardment from all sides with high-powered laser and particle
beams, and of course implosion in a fission bomb.  Parts of ICF
fusion research remain classified due to their military 
implications and applications, though much ICF research was recently
declassified.

* Instability:  A state of a plasma (or any other physical system) 
in which a small perturbation amplifies itself to a considerable 
alteration of the state of the system.  In plasmas instabilities
sometimes leads to disruptions (see entry).  Most instabilities are 
associated with waves and other natural modes of oscillation in the plasma, 
which can sometimes grow.  There are (unfortunately!) 
many kinds.   See also:  Flute instability, MHD instability, 
Interchange instability, microinstability, kink instability, 
resistive instability, trapped particle instability, 
two-stream instability, universal instability, and 
velocity-space instability.

% Institute of Electrical and Electronic Engineers:  Professional
society for this branch of engineering.

* Integrated Biological Hazard Potential (IBHP):  Total
biological hazard potential of a collection of radioactive
materials summed over their decay lifetimes.  See also BHP.
One measure of the IBHP is the amount of water one would need
to use to dilute the materials to the point where the water
would be safe to drink.

* Integrated neutron flux:  Sum (integral) of the neutron
flux (neutrons per unit time per unit area, see flux)
over all time; total number of neutrons which passed through
a unit area.  Important figure-of-merit in testing effects of
neutron radiation on materials, and in assessing how long
such materials can survive exposure to neutron sources
(such as fission reactor cores and D-T fusion plasmas).

* Intensity:  This term has different meanings in different
contexts.  Can refer to the amount of power (energy per unit
time) incident on a unit surface area, or flowing through a
unit volume.  Can refer to the number of particles or photons
incident, per unit time, on a unit area, or flowing through 
a unit volume.  Also, for an amount of a radioactive material,
intensity can refer to the number of radioactive disintegrations
per unit time. 

* Interchange Instability:  In the simplest form, if you
place a high-density fluid on top of a low density fluid,
gravity will pull the high density fluid downwards so that
the low-density fluid ends up on top.  The two fluids
therefore interchange places.  More generally, an interchange
instability occurs when two types of fluid are situated with
an external force such that the potential energy is not
a minimum; the two fluids will then interchange locations to
bring the potential energy to a minimum.  In plasmas with 
magnetic fields, the plasma may interchange position with
the magnetic field.  A prime example is the flute instability 
in mirror machines.  (See MHD, instability, flute, mirror.)

* Interference:  When two waves propagate through the same
region of space, they interfere with each other.  Neither
wave is altered, but the amplitudes of the waves add (or
cancel, if they're of opposite sign) to give the total 
effect to the medium at that point.  

* Interferometer:  Device which measures changes in a medium
by looking at effects on the interference of two waves which
are passed through that medium.  See interferometry,
laser interferometer, optical inteferometer, Fabry-Perot 
interferometer, microwave interferometer.

* Interferometry:  Method of gathering information about a
medium by using an interferometer or similar technique.
        Optical - Uses light as the wave to be interfered.
        Microwave - Uses microwaves instead.  Microwave interferometry
   is especially useful in plasma physics for measuring plasma 
   densities.

> Internal ring devices:  Toroidal configurations in which 
current-carrying rings are suspended (either mechanically
or magnetically) inside the plasma chamber.

% International Atomic Energy Agency: (from Herman)  An
autonomous intergovernmental organization established in 1956
with the purpose of advancing peaceful uses of atomic energy,
with headquarters in Vienna.

> International Thermonuclear Experimental Reactor (ITER):
Huge fusion reactor being planned by the EC, US, Japan,
and Russia (former USSR?).  Should generate far more
energy than it consumes.  Research goals include engineering
studies of reactor materials, component designs for steady-state
devices, and testing/proving commercial feasibility.  Discussed
in sections 5 and 9.

* Ioffe Bars:  Special configuration of conductors which, when
added to a conventional magnetic mirror, generate a "magnetic
well" which stabilizes the mirror against MHD instabilities.

& Ion:  An atom (or molecule) which has become charged as a 
result of gaining or losing one or more orbiting electrons.  
A completely ionized atom is one stripped of all its electrons.

* Ion acoustic wave:  a longitudinal compression wave in the
ion density of a plasma, which can occur at high electron
temperatures and low frequencies, caused by a 

* Ion Cyclotron Emission (ICE):  As ions gyrate around in a magnetic
field (see also larmor radius or cyclotron radius), they radiate 
radio-frequency electromagnetic waves.  This is known as ion 
cyclotron emission, and can be measured to help diagnose a plasma.

* Ion Cyclotron Resonance Heating:  Like Electron Cyclotron 
Heating, but heats ions using waves near the ion cyclotron 
frequency.  See Electron Cyclotron Heating.

* Ion diode:  Device for producing and accelerating ion beams
for light ion drivers for inertial confinement fusion.  Ions 
are produced in an anode plasma, extracted as space-charge-limited
ion flow, and accelerated to the cathode, composed of a confined
electron swarm, by an applied electric field.  Millions of 
amperes of current at millions of volts have been produced this way.

* Ion Temperature: the temperature corresponding to the
mean kinetic energy of the ions in a plasma.

& Ionization:  Process by which a neutral atom is converted to an ion 
(or one ion is converted to another of a different type), by 
removal or addition of electrons.

& Ionization Energy:  Generally refers to the amount of energy 
required to strip a particular electron from an atom.  The 
first-ionization-energy is a commonly used quantity in many fields 
of physics and chemistry.  Typically measured in electron-volts.
Equivalent to the atomic binding energy of the electron.

& Ionization Potential:  See ionization energy.

* Ionizing radiation:  Any high-energy radiation which can 
displace electrons from atoms or molecules, thereby producing ions.
Examples:  alpha-particle radiation; beta radiation; x-rays, 
gamma, and hard ultraviolet light; and accelerated ions.
Ionizing radiation in large quantities may cause severe skin 
and tissue damage and adverse effects.  (On the other hand, 
but not to belittle the hazards of radiation, we are 
continuously exposed to a "natural background" of ionizing
radiation too.) 

* Ionosphere:  Ionized region of the upper earth atmosphere, which
behaves like a plasma, including reflection of AM radio waves and
generation of auroral glows.

* Irradiation:  Process of exposure to radiation.

* Isomer, Nuclear:  two nuclei with the same nuclear mass (total
number of protons and neutrons) but different nuclear compostions.
(e.g.: T & 3He are isomers: T has 1p, 2n; 3He has 2p, 1n)

& Isotope: One of several species of the same element, 
possessing different numbers of neutrons but the same number 
of protons in their nuclei.  Most elements have several 
stable isotopes, and also several possible unstable and 
semi-stable isotopes.  The chemical and physical properties
of the different isotopes are generally the same (except for the
slight mass difference and the possibility of radioactivity).
Examples include the hydrogen isotopes protium (ordinary
hydrogen), deuterium, and tritium (two neutrons, one proton); 
also uranium 238, 233, and 235.  The chemistry of an element 
depends only on the number of protons (nuclear charge) and 
is therefore the same for all isotopes of an element, but 
the nuclear properties of different isotopes will be 
different.  There are roughly 300 known stable isotopes,
and over 1000 unstable ones.

& Isotropic:  adjective which describes a medium whose 
physical properties are independent of the direction in
which they are measured.






cudkeys:
cuddy25 cudenrfheeter cudfnRobert cudlnHeeter cudmo2 cudqt1 cudszL cudyr1996 
------------------------------
1996.02.25 / Robert Heeter /  Conventional Fusion FAQ Glossary Part 11/26 (K)
     
Originally-From: Robert F. Heeter <rfheeter@princeton.edu>
Newsgroups: sci.physics.fusion,sci.answers,news.answers
Subject: Conventional Fusion FAQ Glossary Part 11/26 (K)
Date: 25 Feb 1996 13:04:10 GMT
Organization: Princeton University

Archive-name: fusion-faq/glossary/k
Last-modified: 4-Feb-1995
Posting-frequency: More-or-less-quarterly
Disclaimer:  While this section is still evolving, it should 
     be useful to many people, and I encourage you to distribute 
     it to anyone who might be interested (and willing to help!!!).

===============================================================
Glossary Part 11:  Terms beginning with "K"

FREQUENTLY USED TERMS IN CONVENTIONAL FUSION RESEARCH 
AND PLASMA PHYSICS

Edited by Robert F. Heeter, rfheeter@pppl.gov

Guide to Categories:
 
* = plasma/fusion/energy vocabulary
& = basic physics vocabulary 
> = device type or machine name
# = name of a constant or variable
! = scientists 
@ = acronym
% = labs & political organizations
$ = unit of measurement

The list of Acknowledgements is in Part 0 (intro).
==================================================================

KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK

# k: Mathematical symbol usually used for Boltzmann's Constant.
Value is 1.4 x 10^-23 Joules/Kelvin (in SI units), 
or 1.4 x 10^-16 ergs/Kelvin (in cgs units).

$ kA:  KiloAmpere; see kilo, Ampere

@ KDP:  Potassium Dihydrogen Phosphate; crystal used in frequency
conversion of Nd:glass laser light.

$ kW:  KiloWatt (1000 watts); see also kilo, Watt

$ kWh:  kilowatt-hour; see entry

& Kelvin: (K) temperature scale where zero degrees corresponds
to absolute zero (no thermal energy); degrees have same
size as in Celsius/centigrade scale.  273.16 K = zero C;
373.16 = 100 C.

! (Lord) Kelvin:  honorary name given to William Thompson; 19th 
century British physicist (many contributions in many subfields).

* Kerma:  Kinetic Energy (of charged particles) produced by 
ionizing Radiation per unit MAss of irradiated material.  (ergs/gm)

& kilo:  metric prefix used to indicate 1000 times the following
unit.  e.g., a kiloampere is 1000 amperes.

$ kilowatt-hour:  standard unit of electrical energy; equals one
kilowatt of power delivered for one hour.  Equivalent to 3.6
million joules.

* Kinetic Pressure:  Density of kinetic energy (energy in the
thermal motions of the plasma particles).  For an ideal plasma,
pressure is given by p = nkT, that is:

        pressure = (density) * (Boltzmann's constant)* (temperature), 

* Kinetic Temperature:  A measure of the energy of random motion
(kinetic energy) of an assembly of particles in thermodynamic
equilibrium.

* Kinetic Theory:  A theory which attempts to explain the behavior
of physical systems using the assumptions that the systems are
composed of large numbers of atoms/molecules/particles in 
vigorous motion, that energy and momentum are conserved in
collisions of these particles, and that statistical methods can
be applied to deduce the behavior of such systems.

* Kink Instability:  Instability resulting from excessive growth
of a kink mode; see kink mode.

* Kink Mode:  Class of MHD instabilities which sometimes develop
in a thin plasma column carrying a strong axial current.  If a
kink begins to develop in such a column the magnetic forces on 
the inside of the kink become larger than those on the outside,
so that in general it tends to grow in magnitude.  The column
then becomes unstable and can be displaced into the walls of
the discharge chamber, causing a disruption.

& Klystron:  An evacuated electron-beam tube in which electrons
are given initial velocities such that the beam's charge density
is modulated; the passage of a modulated current generates
microwave radiation, some of which is then fed back to modulate the
electrons' velocities.  The result is a microwave amplifier.

* Kruskal Limit:  In tokamaks, a theoretical limiting value for 
plasma current beyond which MHD instabilities are predicted.






cudkeys:
cuddy25 cudenrfheeter cudfnRobert cudlnHeeter cudmo2 cudqt1 cudszL cudyr1996 
------------------------------
1996.02.25 / Robert Heeter /  Conventional Fusion FAQ Glossary Part 12/26 (L)
     
Originally-From: Robert F. Heeter <rfheeter@princeton.edu>
Newsgroups: sci.physics.fusion,sci.answers,news.answers
Subject: Conventional Fusion FAQ Glossary Part 12/26 (L)
Date: 25 Feb 1996 13:04:11 GMT
Organization: Princeton University

Archive-name: fusion-faq/glossary/l
Last-modified: 20-Feb-1995
Posting-frequency: More-or-less-quarterly
Disclaimer:  While this section is still evolving, it should 
     be useful to many people, and I encourage you to distribute 
     it to anyone who might be interested (and willing to help!!!).

===============================================================
Glossary Part 12:  Terms beginning with "L"

FREQUENTLY USED TERMS IN CONVENTIONAL FUSION RESEARCH 
AND PLASMA PHYSICS

Edited by Robert F. Heeter, rfheeter@pppl.gov

Guide to Categories:
 
* = plasma/fusion/energy vocabulary
& = basic physics vocabulary 
> = device type or machine name
# = name of a constant or variable
! = scientists 
@ = acronym
% = labs & political organizations
$ = unit of measurement

The list of Acknowledgements is in Part 0 (intro).
==================================================================

LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL

# L: variable typically used to indicate self-inductance;
see inductance.

# Li: chemical symbol for the element lithium; see entry.

@ L-mode: see low mode.

@ LAMPF: Los Alamos Meson Physics Facility; see entry

@ LANL: Los Alamos National Laboratory; see entry

@ Laser: Light Amplification by Stimulated Emission of Radiation.
     see entry.

@ LBL: Lawrence Berkeley Laboratory; see entry

@ LCFS: Last Closed Flux Surface; see entry

@ LLE: Laboratory for Laser Energetics; see entry

@ LLNL: Lawrence Livermore National Laboratory; see entry

@ LMFBR: Liquid-Metal Fast-Breeder Reactor; see entry

@ LMR: Liquid-Metal Reactor; see entry

@ LN2: Liquid (diatomic) Nitrogen (N2)

@ LOCA: Loss-of-Coolant Accident; see entry

@ LWR: Light-Water Reactor; see entry

% Laboratory for Laser Energetics:  Second-largest (?) inertial
confinement research facility in the United States; located at
the University of Rochester in New York state.  Home of Omega;
future home of Improved-Omega.

& Lagrangian:  The difference between the kinetic energy and the
potential energy of a system of particles, expressed as a
function of generalized coordinates and velocities.  Equations
of motion can be derived from the Lagrangian.  (see an intermediate
or advanced mechanics text for more information.)

* Lagrangian coordinates:  coordinates which follow fluid motion.
(As distinct from Eulerian coordinates; see entry).

* Landau Damping:  Damping of a wave propagating in a hot plasma,
due to the interaction of the wave with particles whose velocity
is close to the phase velocity of the wave.  Depends on the shape
of the velocity-space distribution function at the phase velocity
of the wave.  More info from John Cobb, with modifications:  

The phenomenon is very similar to surfing on water waves at the 
beach.  If a particle's speed is just slightly lower than the wave, 
then the particle can "catch the wave" and surf along at the wave 
speed.  In so doing, the particle will gain some energy, which will 
be at the expense of the wave.  This is called Landau Damping, since 
the loss of energy tends to damp the wave.  At the same time, if a 
particle moves just slightly faster than the wave, then it will also 
be caught on the wave.  However, in this case, it will slow down, 
giving the wave some extra energy.  In this case particles transfer 
energy to the wave; this is called inverse Landau damping.  Which 
effect dominates depends on whether there are more particles moving 
faster than the wave or more particles moving slower.  Thus it 
depends on the derivative of the distribution function with respect 
to velocity, evaluated at the wave's phase velocity.  Landau dmaping 
can lead to the decay of waves.  Inverse Landau damping can be a 
mechanism for some kinetic instabilities.

! Langmuir, Irving (1881-1957): American chemist, won Nobel Prize in 
chemistry in 1932, developed the theory of Langmuir probes (see 
entry).  Numerous inventions for General Electric (lighting).

* Langmuir frequency:  See plasma frequency.

* Langmuir oscillation:  See electrostatic waves.

* Langmuir probe: a small conductive electrode used to measure the
density, temperature, and electric potential (voltage) of a plasma.
Plasma parameters are deduced from the probe's "Characteristic"
current-drawn vs. voltage-applied curve.

& Larmor radius: the radius of the path of a charged particle 
moving in a magnetic field (and transverse to the field lines).
Also known as gyroradius and cyclotron radius.
 
& Laser:  An optical device that amplifies and concentrates light
waves, emitting them in a narrow, intense beam.  Laser light 
radiation is notable for its brightness and to some extent 
for its monochromaticity and spatial and temporal coherence.

> Laser Fusion:  Form of inertial confinement fusion where
laser beams are used to compress and heat the fuel pellet.

* Laser interferometer:  an interferometer which uses a laser
as a light source (see entries).  Because of the monochromatic
nature and high brightness of laser light, laser interferometers
can operate with much longer beam paths and path differences
than conventional interferometers.

* Laser scattering device: See Thomson scattering device.

* Last Closed Flux Surface (LCFS):  [from Art Carlson]  The boundary 
between the interior region of a tokamak (or other device), where the 
field lines close back on themselves, and the scrape-off layer (see 
entry), where the run into a material wall. (See also separatrix.)

% Lawrence Berkeley Laboratory:  Located in Berkeley, CA; Another
large U.S. science laboratory; minor (?) U.S. fusion research center.  

% Lawrence Livermore National Laboratory:  Located in Livermore, CA,
about an hour east of SF in the Bay Area.  Home of the Nova laser 
inertial confinement fusion program; Nova is the largest
laser in the world.  Home of the former mirror projects MFTF 
(Mirror Fusion Test Facility, shut down on the day it became
operational, or thereabouts, due to budget cutting), 
TMX-U (Tandem Mirror eXperiment Upgrade), and the recently 
shut down Microwave Tokamak eXperiment (MTX).  Some notable 
older fusion experiments at Livermore included Table Top, Toy Top,
Baseball (and Baseball-II) and TMX (predecessor to TMX-U).
Livermore is also the site of the Rotating Target Neutron Sources 
(I and II) for testing materials samples in high-intensity 14 MeV
neutron fluxes and the High Field Test Stand for testing neutral
beams.  Workplace of Albert Chou and several other 
sci.physics.fusion participants. :)  

* Lawson Criterion:  Scientific breakeven criterion based on the 
product of energy confinement time and particle density.  Together
with plasma temperature, the Lawson value of a plasma indicates
how close it is to self-sustained (ignited) fusion; see also 
ignition.  

& Lenz's Law:  Electromagnetism law which states that whenever
there is an induced electromotive force (emf) in a conductor,
it is always in such a direction that the current it would induce
would act in opposition to the change which caused the 
induced emf.

> Levitron:  Single-ring multipole device with an additional
current-carrying rod perpendicular to the ring axis.

* Light-ion fusion:  Light-Ion-Beam-Driven Inertial Confinement 
fusion, using beams of light ions driven at implosion targets.  
Pulsed-power driven accelerators are relatively efficient and 
cost-effective, but beam-focusing is a technical hurdle for 
this approach.

> Light-Water Reactor:  Class of fission reactors using ordinary
"light" water as a coolant, rather than liquid metal or heavy
water (water with deuterium instead of hydrogen).

* Limiters:  Structures placed in contact with the edge of 
a confined plasma which are used to define the shape of 
the outermost magnetic surface.  See also: divertor.

* Line-tying:  Connection of field lines from the end of 
an open-ended device (such as a mirror system) to a conducting
plate.  The rigidity of field lines trapped in the plate can
be transferred to the high-field region of the mirror by using
a cold, moderately-dense plasma in between.  Line-tying helps
to stabilize against interchange instabilities (see entry).

* Liquid Metal:  Metal which has been heated past its melting point
and can be used as a working fluid for pumping heat out from a 
powerplant.  Liquid metal used as coolant in a system where 
significant magnetic fields exist, it  behaves differently due 
to MHD effects; these cause pressure which resists fluid 
circulation, suppression of turbulence, and altered flow 
patterns compared to non-magnetic liquid metal systems.

> Liquid-Metal Reactor:  (Fission) reactor which uses liquid metal
as the reactor coolant.

> Liquid-Metal Fast-Breeder Reactor:  (LMFBR) Fission breeder 
reactor concept (see entry for breeder reactor) using 
liquid-metal coolant and breeding additional fuel off fast 
neutrons.

& Lithium: (Li)  Third element in the periodic table, so all isotopes
contain 3 protons.  Pure lithium at room temperature is a soft
silver-white material, the lightest of all metals.  It is 
chemically very reactive, making it hazardous.  Lithium liquefies at
355 degrees Fahrenheit, making it viable as a liquid-metal
coolant.  Lithium nuclei have two stable isotopes: 
Li-6 (7.5% abundance) and Li-7 (92.5%).  Lithium is a candidate 
for breeding tritium (for D-T fusion) from neutrons, via the 
reactions: 

      n + 6Li -> 4He + T + 4.8 MeV 
      n + 7Li -> 4He + T + n - 2.5 MeV.

* Longitudinal Waves:  (by John Cobb, with editing) Waves where the 
variation of the field is partially or totally in the direction of 
propagation (parallel to wavennumber, k [a vector]).  Examples 
include sound waves and Langmuir waves.  Contrasted with transverse 
waves, where the variation is perpendicular to the direction of 
propagation, such as light waves.

* Lorentz dissociation:  dissociation of molecular ions by Lorentz
ionization (see entry).

& Lorentz Force:  Total electromagnetic force on a charged particle
moving in electric & magnetic fields.  F = q(E + (v/c)xB).  See
also force, cross product, charge, velocity, and relevant 
variable symbols.

* Lorentz Gas:  Plasma model in which the electrons are assumed
not to interact with each other, but only with ions (Z -> infinity)
and where the ions are assumed to remain at rest/fixed (M-i -> 
infinity).  Also known as "electron gas."

* Lorentz ionization:  Ionization of neutral atoms (taken generally
at a highly-excited state) obtained by launching them at high
velocity across a strong magnetic field.  The neutral atoms feel
an electric field proportional to their perpendicular velocity
times the magnetic field strength, and if this electric field
is strong enough ionization can occur.

* Lorentz Model - see Lorentz Gas

% Los Alamos Meson Physics Facility (LAMPF):  Physics research
facility at Los Alamos National Lab; major site for U.S. 
muon-catalyzed fusion research in the 1980s.  May be shut down soon.

% Los Alamos National Laboratory (LANL):  Major DOE research 
facility, located in Los Alamos, New Mexico, about an hour west of 
Santa Fe.  Former home of a frozen-deuterium-fiber Z-pinch device,
which was dismantled.  Home to an active theory division, including
the Numerical Tokamak Grand Challenge (being performed on the CM-5
massively-parallel supercomputer).

Also home to former alternative-concepts experimental devices like 
Scyllac, FRX-A, FRX-B, FRX-C/LSM, ZT40, and the aborted CPRF which 
was killed in 1991 when it was almost complete (budget cuts).

Currently there are some small in-house experiments, including one on 
electrostatic confinement as a possible fusion device, and/or a 
compact neutron source. They also do theory and experimental 
collaboration with other labs worldwide.
 
(Information provided by John Cobb and Ed Chao)


* Loss Cone:  (from John Cobb, with modifications and additions) 
In a magnetic mirror machine, particles with a large velocity 
parallel to the magneitc field and a small velocity perpendicular 
to the field will be able to escape past the magnetic mirror 
(see magnetic mirror). In that case the velocity distribution 
function (see distribution function) will be almost zero in the 
region of velocity space that allows particles to escape. The 
shape of that region (in a velocity space diagram with parallel 
velocity and perpendicular velocity as the axes) is a cone. When a 
particle undergoes a collision, its velocity gets somewhat 
randomized. Particles that are scattered into that cone are lost very 
quickly (in one mirror bounce time). Thus it is called a loss cone. 
Because of the loss cone, the theoretical maximum particle 
confinement time of a magnetic mirror machine can be only a few times 
the particle collision time; this is generally seen as a showstopper 
for mirror-based fusion research.

* Loss of Coolant Accident (LOCA):  Powerplant accident where 
the supply of coolant to the hot power-producing core is 
interrupted, or where the coolant drains out for some reason.
Can lead to meldown of a fission reactor core in extreme cases, 
or to small nuclear explosions (e.g., Chernobyl).  Fusion 
reactors are expected to be less vulnerable to LOCAs, but these 
must still be designed for.

* Low-activation materials:  In fission reactors, one is forced
to deal with the radioactive byproducts of the fission process,
but in fusion reactors one generally has a choice of what materials
to expose to neutrons produced by the fusion process.  A major 
problem for fusion reactors is developing materials (such as for
the reactor vacuum vessel structure) which can be exposed to 
high levels of neutron bombardment without becoming permanently
radioactive.  Candidate structural materials which have 
relatively low induced radiactivation (generally relative to 
stainless steel) are known as low-activation materials; these 
include titanium, vanadium, and silicon-carbide.

* Low Aspect Ratio:  (entry from John Cobb, slightly edited)
An aspect ratio for a torus that is small (minor radius is almost as
big as major radius).  There are many fusion devices which are 
designed to have a low aspect ratio.  Such devices look more like 
tractor tires than bicycle tires, as toruses go.  There are reasons
to believe that low aspect ratio devices will offer some advantages 
for a fusion reactor.  Usually, ease of theoretical and/or numerical 
analysis is not one of these advantages :>.

* Low-beta plasma:  a plasma in which the beta value (see entry)
is typically 0 to 0.01.

* Low mode or L-Mode:  (from Herman) The "normal" behavior of 
a tokamak plasma, characterized by poor confinement and a particular
scaling of decreasing confinement with increasing temperature.

* Lower hybrid frequency:  

* Lower Hybrid Heating:  form of RF heating using Lower Hybrid Waves.

* Lower Hybrid Waves:  "Electrostatic ion oscillations at a frequency
intermediate to the electron extraordinary wave (high frequency) and 
the magnetosonic wave (low frequency).  Not waves, strictly speaking,
because they do not propagate (I think)." 
        - Albert Chou, albert@seas.ucla.edu

* Luminescence:  Light emission that cannot be attributed merely
to the temperature of the emitting body, but results from such
causes as chemical reactions at ordinary temperatures, electron
bombardment, electromagnetic radiation, and electric fields.





cudkeys:
cuddy25 cudenrfheeter cudfnRobert cudlnHeeter cudmo2 cudqt1 cudszL cudyr1996 
------------------------------
1996.02.25 / Robert Heeter /  Conventional Fusion FAQ Glossary Part 13/26 (M)
     
Originally-From: Robert F. Heeter <rfheeter@princeton.edu>
Newsgroups: sci.physics.fusion,sci.answers,news.answers
Subject: Conventional Fusion FAQ Glossary Part 13/26 (M)
Date: 25 Feb 1996 13:04:13 GMT
Organization: Princeton University

Archive-name: fusion-faq/glossary/m
Last-modified: 18-Feb-1995
Posting-frequency: More-or-less-quarterly
Disclaimer:  While this section is still evolving, it should 
     be useful to many people, and I encourage you to distribute 
     it to anyone who might be interested (and willing to help!!!).

===============================================================
Glossary Part 13:  Terms beginning with "M"

FREQUENTLY USED TERMS IN CONVENTIONAL FUSION RESEARCH 
AND PLASMA PHYSICS

Edited by Robert F. Heeter, rfheeter@pppl.gov

Guide to Categories:
 
* = plasma/fusion/energy vocabulary
& = basic physics vocabulary 
> = device type or machine name
# = name of a constant or variable
! = scientists 
@ = acronym
% = labs & political organizations
$ = unit of measurement

The list of Acknowledgements is in Part 0 (intro).
==================================================================

MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM

# m, M:  variable typically used for mass.

$ MA:  MegaAmpere or MegAmpere; see Mega, Ampere

$ m:  meters; SI unit of distance

$ M:  metric prefix "mega", meaning million

@ MARS:  Mirror Advanced Reactor Study; see entry

$ MeV:  Millions of electron volts; see mega, electron-volt.

@ MFE:  Magnetic Fusion Energy

@ MFTF-B:  Mirror Fusion Test Facility; see entry

@ MHD:  Magnetohydrodynamics; see entry

@ MHD Instability:  see Magnetohydrodynamic instability.

@ MHTGR:  Modular High-Temperature Gas-Cooled Reactor; see entry.

@ MIT:  Massachusetts Institute of Technology; see entry

@ MITL:  Magnetically Insulated Transmission Line; see entry

@ MIX 1:  see entry under "MIX 1"

@ MKS:  Meters, Kilometers, Seconds - see SI Units

@ MKSA:  Meters, Kilometers, Seconds, Amperes - See SI Units.

@ MMX:  Multiple Mirror eXperiment; see entry

@ MS:  Maryland Spheromak; see entry

@ MTX:  Microwave Tokamak eXperiment; see entry

$ MW:  Megawatt; one million watts; see entry for watts.

* Mach-Zender Interferometer:  This is a variation of the Michelson
interferometer which is used mainly in measuring the spatial variation
in the refractive index of a gas (or plasma).  A Mach-Zender 
interferometer uses two semi-transparent mirrors and two fully
reflective mirrors located at the corners of a rectangle.  The
incoming beam is split in two at the first semi-transparent mirror,
and the two halves of the beam travel along separate paths around
the edge of the rectangle, meeting at the opposite corner.  Typically
one beam is a control, and the other travels through the system
under study.  The two beams meet at the second semi-transparent
mirror, after which they are mixed together and interfere.

% Madison:  See University of Wisconsin-Madison

* Magnetic Axis: This typically refers to the location of the 
innermost flux "surface" in a toroidal device, the one which 
encloses no volume and has therefore degenerated from a flux 
surface into a single field line. Roughly, the circle through 
the middle of the dough of the donut.  Additionally, in systems
with magnetic islands (see entry below), each island has a 
local magnetic axis, distinct from the overall magnetic axis
of the torus.

* Magnetic Bottle:  Colorful term used to describe a magnetic 
field structure which confines a plasma "like in a bottle".

* Magnetic Confinement:  Use of magnetic fields to confine a 
plasma.  (Confinement involves restricting the volume of 
the plasma and/or restricting particle or energy transport
from the center of the plasma to the edge.)

* Magnetic Confinement Fusion:  Method of fusion which uses
magnetic fields / magnetic bottles to confine a hot plasma
until fusion occurs.

* Magnetic Diffusion:

* Magnetic Field:

* Magnetic Field Coil:  Coiled current-carrying wires used to 
generate magnetic fields.

* Magnetic Flux Surfaces:

* Magnetic Force Parameter:  A dimensionless number equal to
[(magnetic permeability squared) * (magnetic field strength squared) * 
electrical conductivity * characteristic length of system in question] / 
[(mass density) * (fluid velocity)].  This measures the strength
of magnetic forces relative to the plasma's inertia.

* Magnetic Island:  A magnetic topology near a "rational surface" 
(see entry) where the flux surface is broken up into tubes which 
are not connected with each other poloidally. Islands may develop
in non-ideal magnetohydrodynamic fluids, where electrical 
resistance becomes important and magnetic field lines are no 
longer "frozen-in" to the fluid.  Then magnetic tearing and
reconnection may allow field lines to link up and form "islands" 
with a local magnetic axis (see entry) in a narrow region near 
a rational surface (see entry).  (See also MHD, frozen-in law).

The development of islands may be caused by a small perturbation, 
whether internal or external, whether deliberate or accidental, 
and is usually associated with enhanced transport (i.e., reduced 
confinement). The centers of the islands are magnetic O-points, 
while the boundaries between islands are marked by X-points (see entries).


* Magnetic Limiter:  See divertor.

* Magnetic Mach Number:  A dimensionless number equal to the
ratio of the velocity of a fluid to the velocity of Alfven
waves in that fluid.  (See also entry for Alfen waves.)
  
> Magnetic Mirror: See mirror effect, mirror device

* Magnetic Moment: (a) A vector associated with a magnet, current
loop, or particle; the cross product of this vector with the
magnetic field is equal to the torque which the field exerts on
the system.  (b) The adiabatic invariant associated with the
rapid gyromotion of a charged particle in a slowly varying
magnetic field.  (The value of the magnetic moment in sense (b)
is the magnitude of the vector in sense (a).)

* Magnetic Number:  A dimensionless number equal to the square
root of the magnetic force parameter.

* Magnetic Pressure:  Pressure which a magnetic field is capable
of exerting on a plasma; equal to the magnetic energy density;
proportional to B^2.  (The proportionality constant 
is 1/(2*mu-o) in SI units, 1/8pi in CGS units).

* Magnetic Probe:  A conducting coil (sometimes insulated and
inserted into the plasma) will have an induced voltage due
to changes in the magnetic flux through the coil, and can therefore
be used to measure changes in magnetic field strength.  Small
coils used to measure the local field strength are known as
probes.  (Other plasma diagnostics using this effect are the
Rogowski coil, the voltage loop, and the diamagnetic loop.)
Magnetic probes placed outside a toroidal plasma which are used 
to measure the poloidal magnetic field are also called Mirnov coils.
 
* Magnetic Pumping:  Form of plasma heating where the plasma is
successively compressed and expanded by means of a fluctuating
external magnetic field.  (See also adiabatic compression, frozen-in
law.)

* Magnetic Reconnection:  (entry by John Cobb, with some 
modifications)  When a plasma has some resistivity, then the 
frozen-in flow requirement is relaxed (see frozen-in flow). In that 
case, the magnetic field can move through the plasma fluid on the 
resistive (magnetic diffusion) time scale.  (Typically slow compared 
to MHD timescales.)  This allows field lines to reconnect with each 
other to change their topology in response to magnetic and other 
forces in the plasma. (see also Helicity, which is not conserved when 
reconnection is significant.)  The predominant theory for solar 
flares is based on the transfer of energy from magnetic fields to 
plasma particles which can occur in reconnection.  Reconnection can 
also be studied in the laboratory. 

* Magnetic Stress Tensor:  A second-rank tensor, proportional
to the dyadic product of the magnetic field (B) with itself.
The divergence of the magnetic stress tensor gives that part 
of the force which a magnetic field exerts on a unit volume of
conducting fluid due to the curvature of the magnetic field lines.

* Magnetic Switching:  The use as switches of saturable inductors for
producing high power pulses without electrical arcs.  This is a 
principal technology for extending single-shot accelerators in
light-ion-beam-driven inertial confinement fusion to repetitively
pulsed devices for possible reactors.  Three terawatt, 200 KJ
magnetic switches have been developed for fusion drivers at
Sandia National Laboratories.  (Info from the 1985 OSTI Glossary
of Fusion Energy; may be out of date.)

* Magnetic Viscosity:  A magnetic field in a conducting fluid will 
damp fluid motions perpendicular to the field lines, similar to 
ordinary viscosity, even in the absence of sizeable mechanical 
forces or electric fields.

* Magnetic Well:  see Minimum-B Configuration.

* Magnetically Insulated Transmission Line (MITL):  Used to 
transport power efficiently in vacuum lines at very high
power densities.  Although the cathode is a space-charge
limited electron emitter, the electron flow is confined
by self-generated or applied magnetic fields.  MITL's are
used extensively in light-ion-driven inertial confinement fusion.

* Magnetohydrodynamics (MHD):  Physical model describing the 
properties of electrically conducting fluids interacting with
magnetic and electric fields.  MHD theory is relevant at 
relatively low frequencies and for distance scales larger than 
the Larmor radius.  Also known as hydromagnetics.

* Magnetohydrodynamic Generator:  A device that extracts
kinetic energy from a jet of plasma and generates electricity.

* Magnetohydrodynamic Instability (MHD instability): 
Class of unstable (growing, not damped) waves and other 
modes of oscillation which are described by MHD theory.

* Magnetohydrodynamic Turbulence:  Motion of a plasma in which
velocities and pressures fluctuate irregularly.

* Magnetohydrodynamic Waves:  Material waves in an electrically
conducting fluid in the presence of a magnetic field, which
are described by magnetohydrodynamics.

* Marx Generator:  A pulsed-power device invented by Erwin Marx.
Capacitors are charged in parallel and then quickly discharged
in series to produce high voltage, high current (and thus 
high power) pulses.  Used in light-ion-driven and some 
laser-driven inertial confinement fusion systems.

> Maryland Spheromak:  A University of Maryland spheromak 
facility, used to investigate the production, equilibrium,
stability, and confinement properties of spheromaks.  
(What happened to it?)

* Mass Defect:  The energy from fusion reactions comes from the
difference in mass between the reactants and the products.  In an
energy-releasing reaction, some mass is converted to energy via
Einsteins famous equation E (energy) = m (mass) * c^2 (speed of
light squared).  The energy released is the difference between
the binding energies of the reactants and the products (see 
entry on binding energy).

% Massachusetts Institute of Technology (MIT):  Located in Cambridge, 
MA (just outside Boston).  Home of the Plasma Fusion Center and the
Alcator series of compact tokmaks.

% Max Planck Institute for Plasma Physics (IPP):  In Garching (near
Munich).  The largest plasma physics institute in Germany.  Presently
home of ASDEX-Upgrade and Wendelstein-7AS. (See entries)

! Maxwell, James Clerk:  19th-century British physicist, responsible 
for the synthesis of the equations of electromagnetism and the 
prediction of electromagnetic waves, among other things.

& Maxwell-Boltzmann Distribution:  Distribution function of particle
velocities (or energies) corresponding to a system in thermal 
equilibrium with a temperature value of T.  See also: distribution 
functions, temperature.

& Maxwellian Distribution: see Maxwell-Boltzmann Distribution

& Maxwell ('s) Equations: The key equations governing
electrical and magnetic phenomena. These are a set of four
vector partial differential equations relating electric and
magnetic fields to each other and to electric charges and
currents.

& Mean Free Path (for a given event, e.g., collisons):  Average 
distance a particle travels between occurrences of the given 
event; e.g., between collisions.  For collisions, the mean free
path is roughly equal to unity divided by the product of the 
collision cross section times the particle density.

& Mega-:  Metric prefix indicating 1,000,000 times a given quantity.
e.g., a megawatt is 1,000,000 watts.

* Meltdown:  In a fission reactor, if there is insufficient coolant
or the fission chain reaction proceeds too rapidly, heat can
build up in the reactor fuel, causing it to melt.  In extreme
cases the whole fission core can melt down to (or even through) the
reactor floor.  Fusion reactors are not vulnerable to this.

& Metastable state:  several types
        Electronic
        Nuclear

& Micro-:  Metric prefix indicating 1/1,000,000th of a given
quantity.  e.g., a microampere is 1/1,000,000th of an ampere.  
        
* Microinstability: Instabilities due to particle / kinetic-
theoretical effects, typically occuring on small scales, as opposed 
to those derivable from fluid models valid on larger scales.
As with other instabilities, these are driven by various types
of available free energy.  (See also kinetic theory.)

* Microwave Interferometer:  See interferometer, interferometry.
A microwave interferometer uses radio waves in the microwave
frequency (or wavelength) range as the electromagnetic signal.
Microwave interferometers are used to measure the line-averaged
density of a plasma along the path through which the microwave 
beam is passed, through phase shifts in the propagated beam.

* Microwave Tokamak eXperiment (MTX): a reincarnation of Alcator C
at LLNL, now shut down.

> Migma devices:  Non-thermal, non-pulsed devices in which fusion 
occurs among the ions of a self-colliding particle beam.

$ mill:  financial unit equal to 0.1 cents or 0.001 dollars;
standard unit which electrical utilities use in charging for
electricity (e.g., 50 mills/kwh = $0.05/kwh).

> Minimum-B Configuration:  Confinement configuration where the
magnetic field strength is a minimum where the plasma is to be
confined, and increases in all directions away from the confinement
region.  Stability is favorable in such a configuration because the
magnetic pressure increases in all directions away from the plasma.

* Mirnov Oscillations:  Fluctuations in the poloidal magnetic
field (of a toroidal magnetic confinement system) which rotate
in the electron diamagnetic drift direction at a speed comparable
to the electron diagmagnetic drift velocity and with frequencies
due to 5-20 kHz.  Mirnov oscillations arise from tearing modes.
Poloidal magnetic probes used to measure the poloidal field in order
to diagnose Mirnov oscillations (and other MHD phenomena) are
often called Mirnov coils or Mirnov loops.  See relevant entries...

> Mirror Advanced Reactor Study (MARS):  This was a collaborative
effort between government, academia, and industry to design a 
commercial-scale tandem mirror fusion power plant.  Participants
included the Department of Energy (LLNL); University of Wisconsin;
TRW, Inc.; General Dynamics; EBASCO Services; Science Applications,
Inc.; and Grumman Aerospace Corp.  System was never actually built.

> Mirror device, mirror machine:  Generally, linear fusion machines 
which confine the plasma using the mirror effect.  Basically there 
is a weak field in the center, and strong fields at the ends.  
Particles are then reflected at the ends by the strong fields,
and are confined in the center of the device.  (Some particles
will have enough velocity along the axis of the device to escape
from the mirror, however.)

* Mirror effect: A charged particle travelling into an increasing
magnetic field will (if the field becomes strong enough) reverse 
direction and be reflected back.  This is a direct result of
the adiabatic invariance (see entry) of the magnetic moment 
(see entry).  Plasmas can be confined by devices which utilize
this effect; see entry above for mirror device.  The effect 
also occurs in some toroidal plasmas, since the toroidal magnetic
field is stronger on the inboard side than on the outboard side;
in this case it gives rise to so-called "neoclassical" effects.
The strength of the mirror is determined by the mirror ratio.
(See relevant entries.  Consult an introductory plasma physics
text for a more technical explanation.)

> Mirror Fusion Test Facility (MFTF):  A large mirror device built 
at LLNL from the late 1970s to the mid-1980s, but mothballed 
for political reasons (decrease in magnetic fusion funding) 
just before it was to begin operation.

* Mirror Ratio:  In a magnetic mirror, the mirror ratio is the ratio
between the strongest value of the magnetic field on the mirror's 
axis, and the value at some other point on the axis.  In 
a mirror confinement device, the "other point" is taken to be
the location of weakest field strength between two confining
mirrors.  The mirror ratio is a key factor in determining 
confinement properties of the system.

> MIX-1:  A small, gun-injected mirror machine at the University
of Maryland; was used to study the drift-cyclotron loss cone
instability (see entries for DCLC, DCLC instability).

* Mobility: The ease with which a charge in a medium (e.g. a plasma)
moves in response to an electric field. Related to diffusivity and to
resistivity.  Measured by the average equilibrium drift velocity 
attained by the charged particle when subjected to acceleration
by a unit electric field and the opposing frictional force of
collisions with other particles.

* Mode Rational Surface:  A magnetic surface on which field
lines resonate with the helicity of a particular perturbation
or instability; see also rational surface.

* Moderator:  Substance used in a fission reactor to slow down
("moderate") energetic fission neutrons so that they are more
easily captured within the reactor and therefore maintain the
fission chain-reaction.

> Modular High-Temperature Gas-Cooled Reactor:  Class of fission
reactors under study in the U.S.; designed to run at higher 
temperatures and use gas cooling to achieve greater efficiency 
of conversion from thermal to electric energy.

& Mole: The amount of given substance such that the mass in grams 
is equal to its [atomic weight, molecular weight, mass number].
The number of particles in a mole of a substance is Avogadro's
Number N = 6.02497 x 10^23 (see entry).  For instance, one mole
of water weighs 18 grams, since water is H2O, the H's weigh
one apiece, and the O weighs 16.  Heavy water, or D2O, weighs
20 grams/mole, because each D weighs 2 instead of 1.

* Molecular ion injection:  Heating concept for magnetic 
confinement fusion in which energetic (accelerated) molecular
ions are injected into the plasma, dissociate, and heat the
plasma while building up the population of trapped high-energy 
ions.  Not widely used (see neutral beam injection).

& Momentum:  Basic physical quantity measuring motion; generally
defined as momentum = mass * velocity.  The total momentum of
all bodies in a system is conserved in all physical processes 
known so far, I believe.  Momentum is related to force in that
force = rate of change of momentum with time.  See also force.

* Motor-Generator:  Device used to store energy by accelerating
a rotating flywheel to high speeds; energy may be rapidly discharged
and converted to shorter-pulse energy.  (Used to power TFTR; the
electric utility would be a little unhappy if TFTR were to suddenly
draw its 30 MW+ of power at random intervals. :)

> Multiple Mirror eXperiment (MMX):  A 10-meter long simple 
mirror facility which was located at the University of California,
Berkeley.  

> Muon-Catalyzed Fusion: Alternative approach to fusion where
muons are introduced to D-T fluid.  The muon is heavy enough that
it binds more strongly to the D or T than an electron would, and
the result is that the D and T nuclei in the molecule are drawn
more tightly together, and fusion results.  More detailed discussion
is given in section 4B.


cudkeys:
cuddy25 cudenrfheeter cudfnRobert cudlnHeeter cudmo2 cudqt1 cudszL cudyr1996 
------------------------------
1996.02.25 / Robert Heeter /  Conventional Fusion FAQ Glossary Part 4/26 (D)
     
Originally-From: Robert F. Heeter <rfheeter@princeton.edu>
Newsgroups: sci.physics.fusion,sci.answers,news.answers
Subject: Conventional Fusion FAQ Glossary Part 4/26 (D)
Date: 25 Feb 1996 13:03:53 GMT
Organization: Princeton University

Archive-name: fusion-faq/glossary/d
Last-modified: 4-Feb-1995
Posting-frequency: More-or-less-quarterly
Disclaimer:  While this section is still evolving, it should
     be useful to many people, and I encourage you to distribute
     it to anyone who might be interested (and willing to help!!!).

===============================================================
Glossary Part 4:  Terms beginning with "D"

FREQUENTLY USED TERMS IN CONVENTIONAL FUSION RESEARCH
AND PLASMA PHYSICS

Edited by Robert F. Heeter, rfheeter@pppl.gov

Guide to Categories:

* = vocabulary specific to plasma/fusion/energy research
& = basic/general physics vocabulary
> = device type or machine name
# = name of a constant or variable
! = scientists
@ = acronym
% = labs & political organizations
$ = unit of measurement

The list of Acknowledgements is in Part 0 (intro).
==================================================================

DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD

@ D: nuclear/chemical symbol for deuterium/deuteron

@ DC, dc:  Direct Current; see entry

@ DCLC:  Drift Cyclotron Loss Cone instabilities; see entry.

@ DT:  Deuterium-Tritium; see entry labeled DT Fuel

@ DIII-D:  not an acronym (anymore); see entry

@ DOE:  Department of Energy (United States); see entry

@ dpa:  Displacements per atom; see entry

@ DPP:  Division of Plasma Physics; see APS-DPP

* D-shaped plasma:  A toroidal plasma whose cross section
(poloidal plane) is a D (instead of a circle).  A D-shape
has a higher beta limit (see entry) than a circular shape.

* Debye Length: The characteristic distance over which charges are
shielded in a plasma.  See also: Debye shielding.
lambda_D = ( epsilon_0 k_B T_e / (n_e e^2) )^(1/2)
lambda_D[m] = (7.434*10^3)*(_e[eV])^(1/2)*n[m^(-3)]^(-1/2)
(Arthur Carlson, awc@ipp-garching.mpg.de)

! Debye, Peter Joseph:  Physical chemist, studied behavior of
conductive solutions (plasmas have some similar behaviors).

* Debye Radius:  See Debye Length.

* Debye Sheath:  The region of strong electric field in front of
a material surface in contact with a plasma.  Its characteristic
thickness is the Debye length, and it is caused by Debye shielding
of the negative surface charge resulting from electrons flowing to
the surface much faster (initially) than the ions.  The lost
electrons leave behind a region of net positive charge which
gradually diminishes the strength of the electric field
over the debye length.  See also: Debye Length, Debye Shielding.
(Arthur Carlson, awc@ipp-garching.mpg.de, with modifications by
John Cobb, johncobb@uts.cc.utexas.edu)

* Debye Shielding:  If a positive (or negative) charge is inserted
into a plasma, it will change the local charge distribution by
attracting (repelling) electrons.  The net result is an additional
negative (positive) charge density which cancels the effect of the
initial charge at distances large compared to the Debye length.
(There is a corresponding effect of shielding by the ions, which,
for various and subtle reasons, usually is less important.)
See also: Debye Length.
(Arthur Carlson, awc@ipp-garching.mpg.de)

* Debye Sphere:  Sphere around a charged test particle whose
radius is equal to the Debye length.

& Decay, Radioactive: See radioactive decay.

* Decay Modes:  Different pathways for decay of radioactive nuclei.
The decay modes for a given unstable state can include beta
emission (negative = electron, positive = positron), electron
capture, alpha emission, fission, and gamma emission.
(Did I miss any?) See entries for each mode for more information.

* Dee-Shaped:  see D-shaped plasma above.

* Degenerate Configuration:  Magnetic field configuration in
which the magnetic lines of force close exactly on themselves
after passing around the configuration a finite number of times.

* Dense Plasma Focus:  See Plasma Focus.  (Densities of up
to 10^26 particles/m^3 have been reported.)

& Density:  amount per unit of volume, or per unit surface area, or
per unit length. (Usually specified or clear from context which
of these is meant).  Several types:
 Charge density   - amount of charge per unit (volume, area, length)
        Current density  - current flow per unit transverse surface area.
        Energy density   - amount of energy per unit volume.
        Flux density     - flux per unit of transverse surface area.
        Mass density     - mass per unit volume.
        Number density   - number of particles per unit volume.
        Particle density - same as number density.

% Department of Energy:  (DOE) Department within the
executive branch of the U.S. government (at the cabinet
level) which has managed and overseen federally-sponsored
energy research.  The DOE was formed in 1977 from ERDA,
the Energy Research and Development Administration,
and (I think) the Atomic Enegy Commission (AEC).

& Deuterium: A heavy isotope of hydrogen whose nucleus
contains both a neutron and a proton.

* Deuteron: A deuterium ion; nucleus consisting of a proton
and a neutron.

* Diagnostics:  (from Herman) Procedures for determining
(diagnosing) the state of a plasma during an experiment;
also refers to the instruments used for diagnosing.

* Diamagnetic Effects:  Application of a magnetic field to a plasma
will tend to create circulating current within the plasma that will
reduce the strength of the magnetic field.

* Diffusion:  The interpenetration of one substance into another
as a result of thermal / random motion of the individual particles.
(e.g., the diffusion of a plasma across a magnetic field as a
result of collisions which cause particles to move along new
field lines.)  See also classical diffusion, neoclassical diffusion,
anomalous diffusion, transport.

* Direct Conversion:  The generation of electricity by direct
recovery of the kinetic energy of the charged fusion reaction
products.

& Direct Current:  Electric current which is unchanging in
time, or at least not oscillating.  Opposite of Alternating Current.

* Direct Drive:  An approach to inertial-confinement fusion
in which the energy of the driver (laser or particle beam)
is directly incident on the (usually spherical) target,
causing compression heating via ablation of the target surface.

* Dispersion Relation:  For a given wave, the dispersion relation
relates the temporal frequency of a wave (w, or omega) to its
wavenumber k and other physical quantities characteristic of
the system.  Dispersion relations can be quite simple
(e.g., w = k * c for light; c being the speed of light),
and they can also be quite complex, with interesting
mathematical structure.  The dispersion relation and its
mathematical structure provide important information
about the wave, including the phase and group velocities.
(See relevant entries.)  Note that the meaning of "dispersion
relation" is different in plasma physics than in other fields.

* Displacements Per Atom: (dpa)  This is a measure of the
amount of radiation damage in neutron-irradiated materials;
e.g., 10 dpa means each atom in the material has been
displaced from its structural lattice site and average of
10 times (due to interactions between the atoms and the
energetic neutrons irradiating the material.)

* Disruption:  Plasma instabilities (usually oscillatory modes)
sometimes grow and cause disruptions of the carefully-engineered
plasma conditions in the reactor.  Major disruptions can cause
an abrupt temperature drop and the termination of the plasma.
Stored energy in the plasma is rapidly dumped into the rest
of the plasma system (vacuum vessel walls, magnet coils, etc.)
and can cause significant damage if precautions are not taken.

* Disruptive Instability:  Instability which causes a disruption;
see entry for disruption.

* Dissociative Recombination:  The combination of an electron
with a positive molecular ion, followed by dissociation of
the molecule in which the resulting atoms/molecules carry
off the excess energy released in the recombination.

& Distribution Function:  Function characterizing the density of
particles located at a given point in phase space (a combination
of either velocity or position coordinates) at a given time.
The velocity-space distribution function gives the number of
particles with a particular velocity; the position-space
distribution function is synonymous with the particle density
in position-space.  Different combinations of position and
spatial coordinates are useful in different problems.

* Divertor: Component of a toroidal fusion device that diverts
charged particles on the outer edge of the plasma into
a separate chamber where they strike a barrier and become
neutralized.  In a reactor, the divertor would incorporate a
system for pumping out the neutralized particles as exhaust
from the machine.  A divertor, like a limiter, prevents the
particles from striking and degrading the chamber walls
and dislodging secondary particles that would cool and
contaminate the plasma.  Whereas a limiter is a material
object used to limit the shape of the plasma, a divertor is a
magnetic-field construction.  The advantage of the divertor
is that it allows the neutralization region to be
removed from the main plasma.  See also: limiter.

* Doppler Broadening:  Frequency spreading which causes
broadening of single-frequency radiation (e.g., spectral
lines) when the radiating bodies (atoms, molecules, etc.)
have different velocities.  Radiation from each individual
radiating body has a different Doppler shift, and
the collection of radiations at different frequencies
broadens the peak of the line in an intensity-vs-frequency
plot.

& Doppler Effect:  Variation in the frequency of a
wave (as measured by an observer) due to relative motion
between the observer and the source of the wave.
(The observed frequency increases if the source is moving
towards the observer.)

& Doppler Shift:  The amount of change in the observed
frequency of a wave due to the Doppler effect; sometimes
called the Doppler frequency.

> DIII-D:  Latest in a series of tokamaks designed
by General Atomics (formerly GA Technologies) in San Diego
making plasmas with noncircular cross sections, including
kidney shapes and D-shapes.

* Doublet Device / Doublet Plasma:  Tokamak-type devices
where the plasma cross-section is kidney-shaped, with
a deep indentation in the middle so that the plasma has
two major rings of current (on top and bottom).

* Drift Cyclotron Loss Cone Instabilities:  (DCLC)
This is an electrostatic microinstability (frequencies
at harmonics of the ion cyclotron frequency) which is of
major concern in small mirror devices.  Mode is driven
by radial gradients in the electron density, and causes
loss of ions due to non-conservation of magnetic moment
(see adiabatic invariant) as they interact with the mode,
and are dispersed in velocity space into the loss cone.
Stabilization is accomplished by increasing the plasma
size and by partially filling the loss cone with a
continuous extermal warm plasma stream.

* Drift Motion:  Ordinarily particles placed in a magnetic
field will simply orbit in circles, but if the magnetic field
is not uniform, or curves, or there is an electrical field
perpendicular to the magnetic field, or another force is applied
perpendicular to the magnetic field, then the "guiding centers"
of the particle orbits will drift (generally perpendicular to
the magnetic field and to the applied force).  There are several
sorts of drifts; refer to a plasma physics text for more
information (see Section 11: Bibliography).  For a good
introduction at the undergraduate physics level, see Chen.

* Drift Pumping:  A process that removes ions trapped in
a thermal barrier using radial transport induced by an
exterally-applied radiofrequency field tuned to resonate
with the azimuthal drift frequency.

* Drift Surface:  Surface on which the guiding center of
a particle is constrained to move, due to the effects of
the laws of adiabatic invariance on its drift motion.

* Drift Velocity:  Characteristic velocity at which the center
of a particle's orbit ("guiding center") drifts when drift motion
(see above) occurs.

* Drift Waves:  Oscillations in a magnetically-confined plasma
arising in the presence of density gradients (such as at the
plasma's surface).  These resemble the waves that propagate
at the interface of two fluids with different density in
a gravitational field.

* DT Fuel:  (Deuterium-Tritium) Easiest fuel mixture to use
in achieving fusion; unless otherwise specified, probably refers
to a 50-50 (by numbers or by moles) mix of deuterium and tritium.

* Duty Factor:  Ratio of the duration of time when a system is
actually operating to the total time for a complete cycle
of the system.  e.g., if a tokamak experiment runs for 5 seconds
and then sits for 500 seconds while the power supplies are
recharged, then the duty factor is 1%.  Similar to capacity
factor for powerplants.

* Dye laser:  A type laser in which the active material
(the material which emits the laser light) is a dye.
These lasers are tunable when the dye has very large
molecules (such as acridine red or esculin) and the laser
action takes place between the first excited and ground
electronic states, because each of these states contains
a broad continuum band of vibrational-rotational levels.


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