Subject: Workshop on Feedback Stabilization
From: kmcguire@pppl.gov (Kevin McGuire)
Date: 22 Nov 1996 17:06:16 -0500
Dear Colleagues:
Information on an upcoming workshop.
Kevin McGuire PPPL
*** Workshop on Feedback Stabilization of MHD Instabilities ***
======== == ======== ============= == === =============
A workshop on Feedback Stabilization of MHD Instabilities will take
place from Wednesday, December 11th, 1996 to Friday, December 13th, 1996 at
the Princeton Plasma Physics Laboratory, Princeton, New Jersey, USA. It is
co-sponsored by Columbia University and the Princeton Plasma Physics
Laboratory.
Purpose of Workshop:
The feedback stabilization of MHD instabilities is an area of
research that is critical for improving the performance and economic
attractiveness of magnetic confinement fusion devices.
The scope of the workshop includes active and passive control of
MHD modes, such as kinks and tearing modes or tilting modes, and includes
the feedback control of plasma profiles in order to prevent the onset of
instabilities.
The workshop is open to scientists investigating tokamak as well as
non-tokamak devices, such as the control of resistive wall modes in RFPs
and in spherical tokamaks.
The workshop will involve extensive discussion and the preparation of a
workshop summary.
Potential topics include:
* Review existing theoretical and experimental results on feedback.
* General requirements for feedback.
* Feedback options under investigation.
* New sensors for feedback systems.
* Experiments currently being planned nationally and internationally.
* Implications for performance on present and future machines.
YOU ARE INVITED TO SUBMIT AN ABSTRACT TO THIS WORKSHOP AND YOU ARE INVITED TO
ATTEND AND PARTICIPATE IN THE DISCUSSIONS DURING THE WORKSHOP.
Please discuss contributions with Michael Mauel at Columbia University
(mauel@columbia.edu) or Kevin McGuire at PPPL (kmcguire@pppl.gov)
Abstracts should be limited to 200 words and submitted to the
Chairman, Program Committee (mauel@columbia.edu) or (kmcguire@pppl.gov)
(address below) as soon as possible, but no later than Friday Dec 6th 1996.
E-mail submission is preferred. If you plan to attend mainly for
information and discussion and not make a presentation, let us know that
also.
Informal presentations of work in progress are encouraged. There
will be a significant fraction of time allocated for discussions.
There will be a banquet on Wednesday evening, the first day of the
Workshop, at Prospect House at Princeton University.
Please contact the Chairmen for further information.
Michael E. Mauel
Chairman, Program Committee
Department of Applied Physics
Columbia University
New York, NY 10027 U.S.A.
Telephone No. 212-854-4455
Fax No. 212-854-8257
email: mauel@columbia.edu
Kevin McGuire
Co-Chairman
Princeton Plasma Physics Lab
P.O. Box 451
Princeton, NJ 08543 USA
Telephone No. 609-243-3187
Fax No. 609-243-2874
email: kmcguire@pppl.gov
The program committee:
R. LaHaye GA
B. Nevins LLNL
S. Prager University of Wisconsin
M. Mauel Columbia University
K. McGuire PPPL
The Program Committee will be responsible of scheduling both invited and
overview talks (approximately 30 minutes in length) and contributed talks
(approximately 15 minutes in length). If you are interested in presenting
an invited or overview talk, please indicate this to the workshop Chairmen
or to members of the Program Committee.
Registration Fee: $30, visitors from outside the US may pay at the workshop.
Please register early, by contacting:
Terry Greenberg, Princeton Plasma Physics Laboratory
P.O. Box 451, Princeton, NJ, 08543,
Fax 609-243-2874 (phone 609-0243-3347).
or
Kevin McGuire, Princeton Plasma Physics Laboratory, P.O. Box 451,
Princeton, NJ 08543,
Fax 609-243-2874 (phone 609-243-3187).
*****************************************************************************
*****************************************************************************
TRAVEL, HOTELS AND AUTHORIZATION FORMS
*****************************************************************************
*****************************************************************************
A hotel list and foreign visitor authorization form to enter PPPL
have been enclosed. Please contact T. Greenberg if you need help with this.
*************************************************************
TO ALL PARTICIPANTS:
Below is a hotel list and an authorization form for non-US
citizens. Further information (such as local maps) will be available at
registration or can be faxed on request.
You are responsible for your own travel and hotel reservation.
*************************************************************
Accommodations and Travel Information:
(for all hotels mention gov. rate & add 6% tax)
Nearby Hotels:
Novotel 100 Independence Way, Princeton, NJ $79 w/full breakfast
3.0 miles
08540, (609) 520-1200, $75 w/o breakfast
Fax (609) 520-0594
We recommend Novotel Hotel where there are some rooms put aside for the
workshop.
Holiday Inn 4355 Rt. 1, Princeton, NJ 08540 $85 w/full breakfast
3.0 miles
(609) 452-2400, Fax (609) 452-2494
Residence Inn 4255 Rt. 1, South, Princeton, NJ 08540 $67 or $77
3.5 miles
(609) 683-0001, Fax (908)-329-8422 (studios)
The Forrestal Princeton Forrestal Center $89
1.5 miles
at Princeton 100 College Road, Princeton, NJ 08540 (can walk to PPL)
(formerly (609) 452-7800, Fax (609) 452-7883
Scanticon)
Nassau Inn Palmer Square, Princeton, NJ 08540 $90.00 4.0 miles
609-921-7500, Fax (609) 921-9385
Directions from Newark Airport to PPPL (1 hour by car, 1.5 hours by bus):
Take the New Jersey Turnpike South to Exit #9. Then use U.S. Route #1
South for about 20 miles to the Princeton area.
Bus Service: There is frequent airport bus service to the Princeton area
from the Newark Airport. Look for the Princeton Airporter booth at the
Ground Transportation area of each terminal (for assistance in scheduling
call 609-587-6600).
Driving to Hotel: If you rent a car at Newark airport, follow Airport exit
signs to the New Jersey Turnpike South (marked NJTP inter-locking letters).
Follow any NJTP South sign to the toll plaza and get a toll card from a
machine or a person; go south on the NJ Turnpike for about 25 miles. Get
off the turnpike at Exit 9 and take the rightmost exit from the toll plaza
to Rt. 18 East. Move left to get onto the middle lane of Rt. 18. Follow
Rt. 18 for only about half a mile to an overpass, and then exit from the
right hand lane after the overpass to Rt. 1 South Princeton. Go south on
Rt. 1 for about 15 miles to the Princeton area. Most of the Hotels are on
or near Rt. 1. To get to the Forrestal at Princeton (formerly Scanticon),
exit Rt. 1 at the large College Road interchange toward the Forrestal
Campus (not Forrestal Center) direction, cross over Rt. 1 and the hotel is
less than 0.5 miles on the right side (their sign is small, so go slowly).
To get to PPPL from a hotel: Take Rt. 1 and get off at the small exit
marked Forrestal Campus/Sayre Drive, between the College Road and Scudders
Mill Road exits. Go in Forrestal Campus direction past open gate and then
left to PPPL. Stop at 2nd gate (guard station) for check-in to PPPL. On
the first day of the meeting, allow 15 minutes for check-in process.
All non-US Citizens:: Please fill out the Visitor Authorization Form
and send it to us as soon as you can ahead of your arrival.
**********************************************************
VISITOR AUTHORIZATION FORM
(for non-US citizens only)
NAME OF VISITOR: __________________________________________
CITIZENSHIP: _________________ PASSPORT#/_________________
EXP. DATE___________________
PLACE/DATE OF BIRTH: ______________________________________
INSTITUTIONAL AFFILIATION: ________________________________
ADDRESS: ___________________________________________________
OFFICIAL DOE EXCHANGE AGREEMENT: ____YES ____NO
ARRIVAL DATE: ________________ DEPARTURE DATE: ___________
PPPL HOST/SUPERVISOR: __Kevin McGuire_________________________
PURPOSE OF VISIT (state specific subjects to be discussed):
_______________________ __________ ____________________
Division Head Date Foreign Visitor Coordinator
______________________ _______________________
Department Head Visitor's Signature
************************************************************************
RETURN COMPLETED FORM TO: Terry Greenberg, P.O. Box 451, Princeton, NJ 08543,
Fax 609-243-2874, (phone 609-0243-3347).
(electronic version is acceptable to tgreenberg@pppl.gov)
or
KEVIN MCGUIRE, Princeton Plasma Physics Laboratory, P.O. Box 451,
Princeton, NJ 08543,
Fax 609-243-2874 (phone 609-243-3187).
_____________________
*This information is required of all visitors who stay more than ten
working days at PPPL or who request a picture badge, with the exception of
those on official DOE exchange agreements.
Subject: Conventional Fusion FAQ Glossary Part 1/26 (A)
From: Robert F. Heeter
Date: 23 Nov 1996 06:14:27 GMT
Archive-name: fusion-faq/glossary/a
Last-modified: 4-Feb-1995
Posting-frequency: More-or-less-monthly
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 1: Terms beginning with "A"
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).
==================================================================
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
# A: symbol used to indicate either area or magnetic
vector potential.
$ A: abbreviation for Amperes; see entry.
@ AAPT: American Assocation of Physics Teachers; see entry
@ AC: Alternating Current; see entry.
@ ACT-I: Advanced Concepts Torus I; see entry.
@ AEC: (US) Atomic Energy Commission; see entry
@ AIC: Alfven Ion Cyclotron Instability; see entry
@ AIP: American Institute of Physics; see entry
@ AJP: American Journal of Physics; see entry
@ ALEX: (see entry "ALEX" below)
@ AMBAL: (see entry "AMBAL" below)
@ ANL: Argonne National Laboratory; see entry
@ ANS: American Nuclear Society; see entry
@ APS: American Physical Society; see entry
@ APS-DPP: American Physical Society - Division of Plasma
Physics; see entry.
# Ar: Chemical symbol for the element Argon
@ ARIES: Advanced Reactor Innovative Engineering Study (?)
See Entry under ARIES
@ ASDEX: Axially Symmetric Divertor EXperiment; see entry
@ ASDEX-U: ASDEX-Upgrade; see entry for ASDEX.
@ ASME: American Society of Mechanical Engineers
@ ATF: Advanced Toroidal Facility; see entry.
* Absolute Instabilities: A class of plasma instabilities
growing exponentially with time at a point in space, in
contrast to convective instabilities (see entry).
* Absorption: In plasma physics, the loss of (electromagnetic)
energy to a medium. For instance, an electromagnetic wave
which propagates through a plasma will set the electrons
into motion. If the electrons make collisions with other
particles, they will absorb net energy from the wave.
* Absorption Coefficient: Measures the degree of wave
absorption (see Absorption above); defined as the fraction
of wave energy lost as the wave travels a unit distance.
& Activation: Activation occurs when a particle interacts
with an atomic nucleus, shifting the nucleus into an
unstable state, and causing it to become radioactive.
In fusion research, where deuterium-tritium is a common
fuel mixture, the neutron released when (D + T) combine
to form (4He + n) can activate the reactor structure.
Sometimes called "radioactivation." See also activation
product, activation analysis.
& Activation Analysis: Method for identifying and measuring
chemical elements in a sample of material. Sample is first
made radioactive by bombardment with neutrons, charged
particles, or gamma rays. Newly formed radioactive atoms
in the sample then give off characteristic radiations
(such as gamma rays) that tell what kinds of atoms are
present, and how many.
* Activation Product: The unstable nucleus formed when
activation occurs. (See activation above.)
& Adiabatic: Not involving an exchange of heat between the
system said to be adiabatic and the rest of the universe.
& Adiabatic Compression: Compression (of a gas, plasma, etc.)
not accompanied by gain or loss of heat from outside the system.
For a plasma in a magnetic field, a compression slow enough that
the magnetic moment (and other adiabatic invariants - see entry)
of the plasma particles may be taken as constant.
* Adiabatic Invariant: Characteristic parameters which do not
change as a physical system slowly evolves; the most commonly
used one in plasma physics is the magnetic moment of a charged
particle spiraling around a magnetic field line.
* Aftercooling: Cooling of a reactor after it has been
shut down.
* Afterglow: Recombination radiation emitted from a cooling
plasma when the source of ionization (heating, etc) is removed.
(See entry for recombination radiation.)
* Advanced Fuels: There are several elements/isotopes which
could be fused together, besides the DT fuel mixture. Many such
fuel combinations would have various advantages over DT, but
it is generally more difficult to achieve fusion with these
advanced fuels than with the DT mix. See fuels section of FAQ
for discussion.
> Advanced Concepts Torus I: (ACT-I) A steady-state toroidal
device built primarily for studies of RF heating (see entry)
and RF current drive (see entry). Operated at PPPL but shut
down several years ago.
> Advanced Toroidal Facility: (ATF) A large stellarator device
developed at Oak Ridge National Lab (ORNL), but recently mothballed.
See Section 5 for more information.
> Alcator: Name given to a set of tokamaks designed and built at MIT;
these machines are distinguished by high magnetic fields with
relatively small diameters. The high magnetic field helps create
plasmas with relatively high current and particle densities.
The current incarnation is Alcator C-mod, and is described further
in Section 5. Alcator C was donated to LLNL for use as the
Microwave Tokamak eXperiment (MTX), now shut down.
> Alcator A: First of the Alcator series of tokamaks at MIT;
was operational from 1969 to 1982.
> Alcator C: Commissioned in 1978; used extensively to study
plasma confinement under strong ohmic heating (see entries).
Also studied high-density plasmas and used frozen fuel pellet
injection. Set record values of Lawson product (density
times confinement time; see entries) of 8 x 10^19 m^3-seconds.
Was donated to Livermore (LLNL; see entry) for use as the
Microwave Tokamak eXperiment (MTX: see entry), now shut down.
> Alcator C-mod: Successor to Alcator C; actually a completely
new device. Currently operational; described in more detail in
Section 5.
> Alcator DCT: Proposed fully-superconducting extension of
the Alcator series; never built.
* Alcator Scaling: A proposed empirical law in which the
energy confinement time is proportional to the product
of the average density and the square of the plasma radius
(see relevant entries).
> ALEX: A single-cell, minimum-B magnetic mirror system
(see entries) in which the magnetic field was generated by a
baseball coil (see entry) wound on a 60 cm sphere. Formerly
operated at the Rensselaer Polytechnic Institute, Troy, New York.
* Alfven Ion Cyclotron instability: (AIC) An electromagnetic
microinstability near the ion cyclotron frequency; driven by
the ion loss cone in a mirror device. (See relevant entries.)
* Alfven velocity: Phase velocity of the Alfven wave;
equal to the speed of light divided by the square root
of (1 plus the ratio of the plasma frequency to the cyclotron
frequency for a given species). i.e.,
Va = c / SQRT(1 + plasma freq. / cyclotron freq.)
(As defined in Stix, _Waves in Plasmas_, 2nd ed. 1992, p. 31)
* Alfven waves: Transverse electromagnetic waves that are
propagated along lines of magnetic force in a plasma. The waves
have frequency significantly less than the ion cyclotron frequency,
and are characterized by the fact that the field lines oscillate
(wiggle) with the plasma. The propagation velocity depends on the
particle density and the strength of the magnetic field. "[Relatively]
Low frequency ion oscillation in the presence of an equilibrium
magnetic field. Also called the transverse hydromagnetic wave along Bo.
The torsional Alfven wave in cylindrical geometry was first measured
in liquid mercury by B. Lehnert. Alfven waves were first generated
and detected in plasma by Allen, Baker, Pyle, and Wilcox in Berkeley
and by Jephcott in England in 1959." (quoting from Chen's book;
see bibliography) - Albert Chou
! Alfven, Hannes Olof: Nobel Prize-Winning Plasma Physicist
and Astronomer who first suggested the possibility of MHD waves
in 1942.
* Alpha Channeling: Term for an idea (so far theoretical)
in magnetic confinement fusion; the idea is that plasma
waves can be used to control the alpha particles produced
in a fusion reactor, to transfer their energy directly to fuel
ions, and to help push them out of the plasma. This could
potentially help to substantially improve the power output
capabilities of fusion plasmas.
* Alpha emission: Form of nuclear decay where the nucleus
emits an alpha particle (see entry below).
* Alpha particle: The nucleus of a Helium-4 atom; is a
typical product of fusion reactions; also released
in various nuclear decay processes. Alpha particles readily
grab electrons from other sources, becoming neutral helium;
even energetic alpha particles are easily stopped by thin
barriers (sheets of paper, dead layers of skin, etc.), so that
as a radiological hazard alpha particles are only dangerous if
they are generated inside one's body (where the skin cannot
protect tissue from damage). Alpha particles are common
products in fusion reactions between light elements.
& Alternating Current: (AC) Electrical Current (see entry) which
alternates in direction with time. (For instance, household
electric current is AC alternating at 60 oscillations/sec
(60 Hertz) in the United States, and 50 Hertz in many other
countries.)
> AMBAL: An ambipolar trap (tandem mirror) located at
Novosibirsk in Russia. (Any additional information would
be welcome.)
* Ambipolar Diffusion: Diffusion process in which buildup
of spatial charge creates electric fields which cause
electrons and ions to leave the plasma at the same rate.
(Such electric fields are self-generated by the plasma
and act to preserve charge neutrality.)
% American Association for the Advancement of Science: (AAAS)
Organization dedicated to promoting science research and
education in the United States. Publishers of _Science_.
% American Association of Physics Teachers: (AAPT) Professional
society of physics teachers in the United States. Organizes
conferences on physics education. Publishers of _American
Journal of Physics_ (AJP)
% American Institute of Physics: (AIP) Organization dedicated
to promoting physics research and the dissemination of physics
knowledge; publishers of many physics books.
% American Nuclear Society: (ANS) Professional society of nuclear
scientists in the United States.
% American Physical Society: (APS) Professional society of physicists
in the United States. Organizes major conferences and publishes
many peer-reviewed journals.
% American Physical Society - Division of Plasma Physics: (APS-DPP)
Branch of the APS for plasma physicists, including fusion scientists.
The Annual Meeting of the APS-DPP is the largest plasma physics
conference in the United States.
$ Ampere, kiloampere, megampere: (from Herman) The standard
unit for measuring the strength of an electric current
representing a flow of one coulomb of electricity per second.
1 kiloampere = 1000 amperes; 1 megampere = 1,000,000 amperes.
Common abbreviations: A, amps, kiloamps, megamps, kA, MA
! Ampere, Andre-Marie (1775-1836): French physicist responsible
for much of what is known about the fundamentals of electromagnetism.
& Ampere's Law: General equation in electromagnetism relating
the magnetic field and the currents generating it.
* Aneutronic Fuels: Advanced fusion fuels which would not
produce fusion neutrons. See fuels section of FAQ for discussion.
$ Angstrom: A unit of distance equal to 10^-10 meters or 10^-8 cm.
& Angular Momentum: Momentum involved in the rotation of a body
about an axis; conserved like ordinary momentum (see momentum).
Angular momentum is defined as the cross product of ordinary momentum
with the position vector running from the axis of rotation to the
body whose angular momentum is being determined. Torque is the
rate of change of angular momentum with time. (see also torque)
& Anisotropy: Term used to describe a medium whose characteristic
properties vary in with direction of travel through the medium.
(e.g., velocity of light transmission, conductivity of heat or
electric current, compressibility, etc.)
* Anomalous Diffusion: Diffusion in most plasma devices,
particularly tokamaks, is higher than what one would predict from
understood causes. The observed, "typical" diffusion is referred to
as "anomalous" because it has not yet been explained. Anomalous
diffusion includes all diffusion which is not due to collisions
and geometric effects. While such effects were not understood
when the term was coined, and most still aren't, diffusion due
to well-understood wave phenomena is still 'anomalous'. "Classical"
diffusion and "Neo-classical" diffusion are the two well-understood
diffusion theories, neither is adequate to fully explain the observed
"anomalous" diffusion. See also: entries for classical and
neoclassical diffusion. (Acknowledgements to Philip Snyder)
* Antares: Laser-target irradiation system (i.e., laser fusion
research device) at Los Alamos National Lab; was operational in
1982. (The author would welcome current information.)
& Aperture: The opening in an optical system which restricts the
size of the bundle of rays incident on a given surface. (Usually
circular and specified by diameter.)
* Applied-B Diode: An ion diode with an applied magnetic field
to prevent electrons flowing from cathode to anode. The applied
magnetic field also regularizes the electron swarm to reduce
beam divergence.
* Arc: A type of electrical discharge between two electrodes;
characterized by high current density. Similar in meaning
to "spark" in common language.
% Argonne National Laboratory: One of the U.S. Department of Energy
basic-research Laboratories, located in Illinois... (need more info!)
> Argus: Two-beam, 5-terawatt Nd-glass laser system used at Livermore
(LLNL) for inertial-confinement fusion research from 1976 to 1981.
* ARIES: Set of four fusion reactor design studies which investigated
the safety, economic, and environmental implications of various
advances in fusion reactor science and technology.
* Ash: Fusion reaction products trapped in a plasma. Ash is
bad because (a) it generally radiates more strongly than the fuel
ions, and thus reduces energy confinement, and (b) it creates
additional plasma pressure and/or reduces pressure available for fuel
ions. (due to beta limits, see beta) Controlling ash is a major
area of fusion research. Ideally one would be able to extract
the ash ions after diverting an appropriate fraction of their
energy to heating the fuel ions, and then convert the remaining ash
energy to electricity. Current research involves using RF waves to
transfer energy from ash ions to fuel ions, and to push the ash into
the scrape-off layer, where it can be collected via divertors.
(See also scrape-off layer, divertors)
* Ash control - see ash, divertors.
* Ash removal - see ash, divertors.
* Aspect Ratio: In toroidal geometry, the ratio of
the major diameter (total width of the torus) to the
minor diameter (width of a slice taken through one side
of the ring). (This would be much better with a picture!)
In inertial-confinement fusion, aspect ratio refers to
the ratio of a fuel pellet's radius to its wall thickness.
& Atom: (from Herman) The smallest unit of an element that
retains the characteristics of that element. At the center
of the atom is the nucleus, made up of neutrons and protons,
around which the electrons orbit. Atoms of ordinary hydrogen,
the lightest element, consists of a nucleus of one proton
orbited by one electron. (Note: distinct from a molecule,
which is the smallest unit of a substance which retains the
characteristics of that substance. It takes far less
energy to break apart a stable molecule into its constituent
atoms than to divide a stable atom into two smaller atoms.)
Note that in solids, atoms are typically two angstroms
(2 x 10^-10 meters) apart; in air the gas molecules are about
30 angstroms apart. A drop of water has on the order
of 10^21 atoms in it. Atoms are generally electrical neutral;
when an atom acquires an electrical charge (by gaining or
losing electrons) it is usually called an ion.
& Atomic Bomb, A-Bomb: (from Herman) A weapon with a large
explosive power due to the sudden release of energy when the
nuclei of heavy atoms such as plutonium-239 or uranium-235
are split. This fission is brought about by the bombardment
of the fuel with neutrons, setting off a chain reaction.
The bomb releases shock, blast, heat, light, and lethal
radiation. The world's first atomic bomb was successfully
tested by the United States on July 16, 1945.
% Atomic Energy Commission: United States governmental
authority for atomic energy; split into ERDA and NRC in 1975.
(may not be 100% correct)
& Atomic Mass: Mass of an atom relative to 1/12th the mass
of a carbon atom. Approximately equal to the sum of the
number of protons and neutrons in the nucleus of the atom.
& Atomic Number (Z): The number of protons in a nucleus; same
as the number of electrons in a neutral atom; determines the
position of an element in the periodic table, and hence its
chemical properties (see also isotope).
* Atomic Temperature: The temperature corresponding to the mean
kinetic energy of the neutral atoms in a plasma. (If there were
no ions or electrons, the atomic temperature would be what we
normally think of as the temperature of a gas, such as the air.)
* Auger effect: Transition of an electron in an atom from a
discrete electronic level to an ionized continuous
level with the same energy; also known as autoionization.
& Avogadro's number: N = 6.02497 x 10^23. Number of particles
in a mole of a substance. Coefficient relating Boltzmann's
constant to the ideal gas constant. This is the number of
atoms per gram-atom. See also: mole
> Axially Symmetric Divertor EXperiment (from Herman)
(ASDEX, Asdex: Garching, Germany) A large tokamak designed
for the study of impurities and their control by a magnetic
divertor. The H mode or high mode of operation with neutral
beam injection was first observed on ASDEX.
> Axially Symmetric Divertor EXperiment (ASDEX, Asdex): "The original
ASDEX, located in Garching, Germany and decommisioned in 1990(?),
would qualify today as a medium-sized tokamak. It was designed for
the study of impurities and their control by a magnetic divertor.
The H mode or high mode of operation with neutral beam injection was
first observed on ASDEX. Its successor ASDEX-Upgrade (a completely
new machine, not really an "upgrade") is larger and more flexible.
It is the first tokamak whose toroidal and poloidal field coils are
not linked, which will be a necessary design factor in a reactor.
It will achieve parameters at the edge which are very similar to
those needed for a power reactor." - Arthur Carlson
* Azimuth: An angle measured clockwise relative to some
reference point on a circle (e.g., "south" or "north").
* Azimuthal: Generally an angle, measured "around" an object.
In spherical geometries, the angle which is *not* the "polar angle".
On the earth, one incarnation of the azimuthal angle is the longitude
of a location relative to the prime meridian through Greenwich,
England. In toroidal geometries, the longitude idea still applies,
but the other angle is the "poloidal" angle, not the "polar" angle.
The azimuthal direction is the "long way" around a torus.
See also: poloidal.
Subject: Conventional Fusion FAQ Glossary Part 2/26 (B)
From: Robert F. Heeter
Date: 23 Nov 1996 06:14:32 GMT
Archive-name: fusion-faq/glossary/b
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 2: Terms beginning with "B"
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
Citations and Acknowledgements appear in Section 11 of the FAQ.
==================================================================
BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
# B: variable used for Magnetic Field
# B: chemical symbol for the element boron; see entry
# Be: chemical symbol for the element beryllium; see entry
@ BCSS: Blanket Comparison and Selection Study (no entry)
@ BHP: Biological Hazard Potential; see entry
@ BPX: Burning Plasma eXperiment; see entry
@ BTU: British Thermal Unit; see entry
@ BWR: Boiling Water Reactor (fission); see entry
* Background Radiation: Level of environmental radation due to
"background" sources. Background sources can be natural, such
as cosmic rays and natural radioactive elements (principally
radon, but including other elements such as isotopes of potassium
(which people get substantial amounts of in foods like bananas)).
They can also be man-made, such as from fossil-fuel combustion,
everyday leakage from nuclear activities, and leftover from
atmospheric nuclear weapons tests. Background radiation is
usually distinguished from acute radiation, such as from medical
x-rays, nuclear accidents, radioisotope therapy, or other short-term
doses. The man-made contribution to background radiation is
quite small compared to the natural contribution; medical uses
dominate human exposure to acute radiation.
& Backscattering: Deflection of incident particle / radiation
through an angle greater than 90 degrees relative to the original
direction of motion/propagation.
* Ballooning Instability: See Ballooning Mode
* Ballooning Mode: A mode which is localized in regions of
unfavorable magnetic field curvature ("bad curvature") and
which becomes unstable when the force due to pressure
gradients (grad p) is greater than the mean magnetic
pressure force (grad B^2)/(8*pi).
* Banana Orbit: The fast spiraling of an charged particle around a
magnetic field line is accompanied by a slow movement ("drift") of
the center of the sprial. Projected onto a poloidal plane, the drift
orbit has the shape of a banana. These orbits are responsible for
neo-classical diffusion (see entry).
$ Barn: Unit of area equal to 1x10^-24 square centimeters
(or 1x10^-28 square meters). Commonly used in describing
cross sections of atomic, nuclear, and particle interactions.
(see cross section).
* Baseball Coils: Used in magnetic-mirror geometries to
produce a minimum-B configuration; so-called because of their
resemblance to the characteristic shape of lacing on a baseball.
* Beam: stream of particles or electromagnetic radiation
travelling in a single direction.
* Beam-Beam Reaction: Fusion reaction which occurs from the
collision of two fast ions originating in injected neutral beams.
* Beam Dump: A mass of shielding material which absorbs
the energy of a beam of particles or electromagnetic radiation.
* Beam-Plasma Reaction: Fusion reaction which occurs from the
collision of a fast beam ion with a thermal plasma ion.
* Beam Splitter: Optical device for dividing a beam of
electromagnetic radiation into two or more separate beams.
* Beam-Wall Reaction: Fusion reaction which occurs from the
collision of a fast beam ion with an ion embedded in or adsorbed
onto the reactor wall.
* Bean-Shaped Plasma: A toroidal plasma indented on the inboard
side (that is, on the side with the "donut hole"); results in
additional stability to ballooning modes (see entry). Moderate
indentation (does, can, may?) provide access to the
second-stability region (high beta). (see relevant entries)
! Becquerel, Antoine-Henri: French scientist and discoverer of
radioactivity; co-winner of Nobel Prize. (See Curie)
$ Becquerel: Unit of radioactivity equal to 1 disintegration per
second. (see Curie)
* Bellows: Flexible mechanical structure with walls like those
of an accordion.
* Bernstein Mode: Type of mode which propagates perpendicular
to the equilibrium magnetic field in a hot plasma. The waves
have their electric field nearly parallel to the wave propagation
vector (nearly longitudinal). The modes propagate in
frequency ranges lying between integer harmonics of the
electron cyclotron frequency. Named after Ira Bernstein.
& Beryllium: (Be) Element with atomic number 4 (four protons).
May be useful in multiplying fusion neutrons to enhance tritium
production in a lithium blanket; rather hazardous to handle.
(See relevant terms mentioned.)
* Beta, or beta-value: Ratio between plasma kinetic pressure and
magnetic-field pressure; proportional to the ratio between plasma
kinetic energy density and magnetic field energy density. Beta
is usually measured relative to the total, local field
(loosely called beta toroidal), but sometimes the plasma pressure
relative to only the poloidal component of the field (beta poloidal)
or relative to some external field (like the maximum field at the
magnetic coils) is more useful. There is also a normalized beta
(beta_N) of interest when discussing the beta limit (see entry).
(lots of help from Art Carlson with the above.)
"Because the cost of a reactor is strongly influenced by the
strength of the magnetic field that must be provided, beta values
are directly related to the economics of fusion power production.
Beta is usually expressed as a percentage, with 5% generally
believed to be the minimum value required for an economical
fusion reactor." - from the PPPL WWW page on PBX-M.
See also: pressure, kinetic pressure, magnetic pressure,
second stability.
* Beta-Normal: Beta-N, the normalized beta, is beta relative to
the beta limit (see below).
* Beta-Poloidal: Beta-P is the same as the ordinary beta, except
only the poloidal field is used in calculating the magnetic field
pressure. Beta-P is > 1 in many modern tokamaks.
* Beta Emission: Form of nuclear decay where a neutron splits
into a proton plus electron plus neutrino set. The proton
stays in the nucleus but the electron ("beta ray") is ejected.
* Beta Limit, also called Troyon Limit: If the plasma pressure in
a tokamak becomes too high, the so-called ballooning modes become
unstable and lead to a loss of confinement (sometimes catastophic,
sometimes not). The exact value at which this occurs depends
strongly on the magnetic field B, the plasma minor radius a, and
the toroidal plasma current I, such that maximum value of the
normalized beta, beta_N=beta*B*a/I, is around 4% (with B in Teslas,
a in meters, and I in Mega-amperes). The exact value depends on
details of the plasma shape, the plasma profiles, and the safety
factor. (Beta entries provided by Art Carlson.)
* Beta Particle / Beta Ray: Original term used for electrons
(and positrons) ejected from decaying nuclei via beta emission.
(Label derives from the old days when we had various kinds of
radiation emission, and they were labeled alpha, beta, and
gamma (the first letters of the Greek Alphabet) because no one
really knew what any of them were.)
* Beta value: See "beta" just above.
* Biasing: [from Art Carlson] The vacuum vessel of a tokamak
(or other device) has a variety of structures--limiters, divertor
plates, the wall itself. These are usually mechanically and
electrically connected, but it is possible to bias (charge) them to
different voltages relative to each other. This allows some control
over the electric fields and currents around the plasma, which can
influence, for example, the thickness of the scrape-off-layer, the
transition between L- and H-mode, and the equilibrium configuration.
Biasing experiments are being done on DIII-D, TEXTOR, and TdeV.
* Binary Collisions: Collisions involving only two particles;
multiparticle collisions (eg, three-body collisions) are usually
neglected/approximated...
* Binding Energy: Energy required to separate two objects;
conversely, energy released when two objects are allow to bind
together. Equivalent to the mass defect (see entry) via E=mc^2.
* Biological Hazard Potential (BHP): Measure of the hazard posed by
a given quantity of radioactive material in which the variation in
biological effects of the various elements are accounted for.
(See also integrated biological hazard potential, IBHP)
& Biot-Savart Law: General formula for determining the magnetic
field due to a steady line (not space) current. Related to Ampere's
Law.
* Blanket: a region surrounding a fusion reactor core within
which the fusion neutrons (if any) are slowed down, heat
is transferred to a primary coolant, and tritium is bred
from lithium (if tritium is used as fuel). In hybrid
applications, fertile materials (U-238 or Th-232) are located
in the blanket for conversion into fissile fuels.
* Bohm diffusion: A rapid loss of plasma across magnetic field
lines caused by microinstabilities. Theory formulated by the
physicist David Bohm. From Chen's book
(see bibliography): "Semiempirical formula for the diffusion
coefficient given by Bohm in 1946 (noted by Bohm, Burhop, and
Massey, who were developing a magnetic arc for use in uranium
isotope separation)." Bohm diffusion was proposed (not derived
from first principles) to scale as 1/B rather than the 1/B^2
scaling predicted by classical diffusion. A 1/B scaling results
from assuming that particles diffuse across field lines at an
optimum rate (effective collision frequency=cyclotron frequency).
The 1/B scaling is observed (approximately) in most reactors.
(Acknowledgements to Philip Snyder) See also: diffusion,
microinstabilities, field lines...
* Boiling Water Reactor (BWR): Class of fission reactor where
water is used as a coolant and allowed to boil into steam.
(I don't remember much more about it - any help out there?)
& Boltzmann constant: k = 1.38 x 10^-16 erg/degree. This
is the ratio of the universal gas constant to Avogadro's number.
It is also used to relate temperatures (Kelvin) to energies (ergs
or Joules) via E = (constant of order unity) * kT.
& Boltzmann Distribution: See Maxwell-Boltzmann distribution;
distribution function.
* Boltzmann Equation: Fundamental equation in kinetic theory
which describes the evolution of the distribution function.
(See also Vlasov equation.)
* Bootstrap Current: Currents driven in toroidal devices by
neo-classical diffusion (see entry). They may amount to a
substantial fraction of the net current in a tokamak reactor,
thus lengthening the pulse time or decreasing the power needed
for current drive.
& Boron: (B) Fifth element (Z=5) in the periodic table; has
5 protons; potential use as an aneutronic fuel. (See FAQ section
1, part on reactions.) Also useful as a neutron-absorber.
* Boronization: Energy confinement in a fusion plasma depends
strongly on the average atomic number (Z) of the elements in the
plasma. Boronization refers to a process whereby boron (atomic
number 5) is injected into a plasma and used to coat the walls
of the reactor; the effect is that impurities from the reactor
walls which enter the fusion plasma are primarily boron (which
has a fairly low Z) rather than the higher-atomic-number metals
typically used in reactor structures. Boronization has been
associated with improved fusion plasma performance. Boronization
is an example of Wall Conditioning. See also Boron, atomic number,
wall conditioning, impurities.
* Bounce Frequency: The average frequency of oscillation of
a particle trapped in a magnetic mirror as it bounces back
and forth between its "turning points" in regions of high
magnetic field. (See also trapped particle, turning points,
banana orbit).
* Boundary Layer: In fluid flow, a narrow region next to a
fixed boundary or surface where the fluid velocity rapidly
changes from zero to some finite value. The term has been
generalized to situations with similar mathematics.
* Branching Ratio: In a fusion reaction involving two nuclei,
there are typically a variety of possible sets of products which
can form. The branching ratio for a particular set of products
is the probability that that set of products will be produced.
* Breakeven: there are several types:
Commercial: When fusion power can be converted into enough
electric power to power the reactor and generate enough
electricity to cover the costs of the plant at economically
competitive rates. (?)
Engineering: When enough energy can be generated from the
fusion power output to supply power for the reactor and
generate a surplus; sort of commercial breakeven without
the economic considerations. (?)
Scientific: When fusion power = input power; Q=1.
(See also Lawson Criterion)
Extrapolated - projected for actual reactor fuel using
an alternative fuel.
Actual - determined using the actual fusion fuel to be
used in the reactor (typically DT).
* Breeder Material: In D-T fusion, refers to lithium or
lithium-containing substances which are placed in the
blanket to convert the fusion neutrons back into tritium,
using nuclear transmutation of lithium isotopes.
* Breeder Reactor: Class of nuclear reactor (could be fission
or fusion) which uses some of the nuclear byproducts (generally
neutrons) to transmute non-fuel materials to new materials which
can be used for fuel in other reactors, in such a way that
the reactor creates more fuel than it consumes (breeding).
Term usually refers to reactors which breed fission fuel.
Use of breeder reactors would greatly extend the fuel supply for
nuclear fission energy, but also creates additional opportunities
for diversion of fissile materials to weapons production and
could exacerbate proliferation of nuclear weapons.
& Bremsstrahlung: (German for "Braking Radiation") Electromagnetic
radiation from a charged particle as it slows down (decelerates),
or as it changes direction due to near collisions with other particles.
Similar to synchrotron radiation (see also). In a plasma
bremsstrahlung occurs when electrons (which are lighter and generally
move faster) collide with ions (which are heavier and generally move
slower); the acceleration/deceleration of the electrons causes them
to radiate bremsstrahlung.
& Brewster's Angle: The angle of incidence at which
electromagnetic waves reflected from a dielectric medium are
completely polarized perpendicular to the plane of incidence;
the component polarized parallel to the plane of incidence is
completely transmitted.
* British Thermal Unit: Unit of energy needed to raise a pound of
water by one degree fahrenheit; equal to 252 calories or 1055 Joules.
(See also calorie, joule). Not part of the metric system.
> Bumpy Torus: I believe this concept tries to combine mirror
concepts with toroidal ones. My understanding is that it is
essentially a series of mirrors stuck end to end and bent into
a ring. - Albert Chou (corrections / enhancements welcome!)
* Bunching: A technique for spatial compression of a pulse
in a beam of charged particles.
* Bundle Divertor: Divertor concept where a toroidal field
coil extracts a "bundle" of toroidal field lines (flux) and
forms a separatrix in the toroidal field. (Hard to do
and tends to mess up axisymmetry of the torus; not used much.)
> Burning Plasma eXperiment (BPX): Proposed U.S. successor to TFTR;
never funded. See also: CIT, TPX.
* Burnout: Rapid reduction in the neutral particle density
in a plasma discharge; occurs when the ionization rate (which
converts neutrals to ions and electrons) exceeds the rate
of recombination (which converts ions to neutrals) and the
rate of influx of neutral particles.
Subject: Conventional Fusion FAQ Glossary Part 3/26 (C)
From: Robert F. Heeter
Date: 23 Nov 1996 06:14:34 GMT
Archive-name: fusion-faq/glossary/c
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 3: Terms beginning with "C"
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).
==================================================================
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
# c: Speed of light; 3.0x10E+8 meters/second or 3.0x10E+10 cm/sec
@ CAMAC: Computer Automated Measurement and Control
@ CANDU: CAnadian Deuterium-Uranium class of fission reactor;
see entry
> CASCADE: See entry (not an acronym as far as I know).
@ CCD: Charge Coupled Device
@ CGS: Centimeters, Grams, Seconds; see CGS Units
@ CGS Units: see entry below; see also CGS above.
@ CFFTP: Canadian Fusion Fuels Technology Project; see entry.
@ CIT: Compact Ignition Tokamak; see entry
@ COE: Cost of Electricity
@ CT: Compact Torus; see entry
@ CTX Facility: Compact Toroid Experimental facility; see entry.
@ cw: Continuous Wave (distinct from pulsed).
@ CY: Calendar Year (as opposed to Fiscal Year, FY)
$ cm: centimeters; unit of distance. See also centi-
* C-Coil: C-shaped magnet coil
* Calorimeter: In conventional fusion research, this name
refers to any device used to measure power or energy in
a laser or particle beam. (e.g., for ICF or neutral beam
heating or a magnetically-confined plasma.)
* Canadian Deuterium-Uranium Fission Reactor: Nuclear fission
reactor type developed in, and prominent in, Canada; characterized
by use of heavy water (deuterium instead of hydrogen, D2O) as
moderator and coolant. Neutrons absorbed by the deuterium create
a source of marketable tritium.
* Canadian Fusion Fuels Technology Project: Fusion power
development project, jointly funded by the National Research
Council of Canada, the Province of Ontario, and Ontario
Hydro (energy company and project manager), to develop
and internationally apply technologies related to management
of fusion fuels. (Any current info, anyone?)
& Carbon: (C) Sixth element (Z=5) in the periodic table; has
6 protons; often described as the basis of life on earth because
of its chemical properties; has potential for use with silicon
as a low-activation structural material for fusion reactors,
in the form silicon carbide. (See relevant parts of FAQ
section 2.) Also useful as a neutron moderator. See also
low-activation materials.
& Carnot Efficiency: maximum possible efficiency for conversion
of thermal energy to useful work (such as electrical energy),
as determined by the laws of thermodynamics. The Carnot efficiency
(eta) for conversion of thermal to electric energy (e.g., the upper
limit on efficiency of a steam turbine) is given by
(eta) = [ (T-hot) - (T-cold) ] / (T-hot). That is, one gets the
efficiency from the values of the input and output temperatures
(measured in Kelvin).
& Capacitor: device used to store electrical energy by accumulating
charges on nearby conductors. Energy may be stored and withdrawn
at varying rates. Used in short-pulse plasma devices where only
a moderate amount of energy is needed.
* Capacity Factor: Index (typically in percent) indicating the
average power supplied by an energy plant, relative to its
maximum rated capacity.
* Capital: Economic term for wealth of a permanent nature, rather
than that which is consumed; includes money and other financial
goods, plant & equipment, etc. (I'm not an economist - anyone
know any better?)
> CASCADE: An inertial-fusion energy conversion concept where
a flowing, replenished layer of ceramic granules (in a rotating
chamber) protects the chamber wall from the fusion environment
while absorbing neutrons, breeding tritium fuel, and serving as
the high-temperature heat exchange fluid.
& Celsius: Temperature scale where zero degrees corresponds to the
freezing point of water (32 Fahrenheit) and 100 degrees corresponds
to the boiling point (212 Fahrenheit). Zero celsius = 273.16 Kelvin.
* Centering Force: Term for the mutual attraction
between the parallel currents in the inboard leg of the toroidal
field coils in a toroidal magnetic fusion system (e.g., a tokamak).
The portion of the coil running "through the doughnut hole" is
attracted towards the center of the hole.
& Centi-: metric prefix indicating 1/100th of a given unit.
e.g., one centimeter is 1/100th of a meter.
& Centigrade: see Celsius
& CGS Units: System of measurement where the fundamental units
are centimeters, grams, and seconds.
& Chain Reaction: (from Herman) A self-sustaining series of
chemical or nuclear reactions in which the products of the
reaction contribute directly to the propagation of the process.
* Channel Transport: In inertial fusion research using light
ion drivers, describes the use of current-carrying plasma
channels (which are magnetically confined to the channel) to
transport electron or ion beams between the ion diode and the
fusion target. This allows the ion source to stand back from
the target.
& Charge Density: See density, and apply to electrical charge.
& Charge, Electrical:
As a noun: A fundamental physical attribute of a
particle, which characterizes the particle's electromagnetic
interaction with other particles and with electric and magnetic
fields. (See also particle, field)
As a verb: Storing energy in a battery or electric capacitor by
running a current through it; opposite of discharge. (It is possible
to charge most capacitors in either direction, but batteries charge
one way, and discharge the other.)
* Charge Exchange: Phenomenon in which an ion colliding with
a molecule (or an atom) neutralizes itself by capturing an electron
from the molecule/atom, and transforming the molecule/atom into a
positive radical/ion.
* Charge Transfer: see charge exchange
* Charged Particle: a particle which carries a positive or
negative electrical charge. In plasma physics, this typically
means an ionized atom or molecule, or an electron.
* China Syndrome: American jargon/slang for a nuclear fission
meltdown accident (see meltdown) in which the molten nuclear core
heats and melts the ground beneath it, thus sinking into the
earth, and heading towards China (which is roughly on the opposite
side of the globe).
* Classical Confinement: Plasma confinement in which energy transfer is
via classical diffusion; best possible case for magnetically
confined plasmas. See entry for classical diffusion below.
* Classical Diffusion: In plasma physics, diffusion due solely
to scattering (collisions) of charged particles (with unlike
charges) via electrical ("Coulomb") interactions. (See also diffusion.)
* Coherent Radiation: Any form of radiation in which the phase
relationship between sections of the wave at different locations is
not random (or incoherent!). Typical example is a laser beam, in
which the phase is more or less uniform across the beam, and changes
along the beam in accordance with the wavelength. Radiation in
which the photons tend to "agree" with one another, rather than
being randomly distributed.
* Cold Plasma Model: Model of a plasma in which the temperature is
neglected with respect to the effects of interest.
* Collision: Refers to the close approach of two or more
particles, photons, atoms, nuclei, etc, during which such quantities
as energy, momentum, and charge may be altered. More-or-less
synonymous with "scattering," except in scattering one generally
thinks of one of the particles as being at rest, and the other
colliding particles "scatter" from their initial direction of
motion due to the collision.
& Collision Cross-Section: Effective surface area of a particle
when it collides with another; describes probability of collisions
between the two particles.
* Collisionless Plasma Model: Model of a plasma in which the density
is so low, or the temperature so high, that close binary (two-body)
collisions have practically no significance (on certain timescales)
because the time scales of interest are smaller than the
collision time. Yields valid physical results for timescales
much shorter than the average collision time in a real plasma.
& Collision Time: Typical time which passes between the time
a particle collides, and when it collides again. Inverse of the
collision frequency; equal to the mean free path divided by the
particle's velocity. The collision time decreases with increasing
density, and increases with increasing temperature.
> Compact Ignition Tokamak (CIT): Proposed U.S. successor to TFTR;
never funded. See also, BPX, TPX.
> Compact Torus: Any of a series of axially symmetric fusion
configurations having closed flux surfaces (like a tokamak, not
like a mirror machine), but having no material objects piercing
the core (as do the toroidal field coils of a tokamak). These
devices have an inherently low aspect ratio, approximately unity.
The most successful variants are the spheromak and the Field
Reversed Configuration. See also: low aspect ratio, spheromak,
field-reversed configuration. (Arthur Carlson,
awc@ipp-garching.mpg.de)
> CTX Facility (Compact Toroid Experimental facility):
Los Alamos facility to investigate plasma physics of compact
toroids. (No longer in operation?)
* Compression Waves: Also known as density waves (I think!);
waves where the quantity which oscillates is the density of the
medium, that is the medium at a given point alternately
compresses and expands. Low-amplitude compression waves in
air or water are commonly known as sound waves; shock waves
are a high-amplitude form. See also waves.
& Conductivity: Degree to which a substance transmits (conducts)
a given physical property, such as heat or electricity.
See electrical conductivity, thermal conductivity.
* Confinement, Classical: See classical confinement.
* Confinement, Electrostatic: See electrostatic confinement.
* Confinement, Inertial: See inertial confinement.
* Confinement, Magnetic: See magnetic confinement.
* Confinement Time: There are several types. The general
definition is that tau = [total]/[loss per unit time];
hence Tau_E = [total energy]/[energy loss per unit time].
Tau_[E, N, ...] is the amount of time the plasma is contained
by magnetic fields before its [energy (E), particles (N or P)]
leak / dissipate away. The different types are, in general,
similar but not equal.
(Note note note: Tau_E is NOT electron confinement time!)
> Constance: Small mirror devices; formerly operated at MIT.
* Containment Vessel: Gas-tight shell or other enclosure
around a fusion (or fission) reactor, to prevent accidental
leakage of radioactive contents.
* Controlled Thermonuclear Fusion: The process in which
light nuclei, heated to a high temperature in a confined
region, undergo fusion reactions under controlled conditions,
with associated release of energy which may be harnessed
for useful purposes.
* Coolant: Substance circulated through a device (including
fusion reactors, fusion reactor magnets, etc.) to remove or
transfer heat. Common types include water, helium, and
liquid-metals such as sodium (Na).
* Cooperative Phenomena: The motion of interacting particles
acting collectively, rather than individually. Includes
plasma oscillations, turbulence, and instabilities. (Plasmas
are distinguished from collections of individual particles
in that they exhibit cooperative phenomena, whereby the plasma
particles "cooperate" with one another. Early fusion researchers
who devised fusion schemes based upon theories where plasmas
acted as merely a collection of individual particles (and
therefore sought to confine only individual particles) often
found themselves frustrated at the ability of plasma
cooperative phenomena (such as MHD instabilities) to thwart
their efforts.
* Core plasma: Hot plasma at the center of a fusion reactor;
distinguished from edge plasma. The core plasma does not
directly feel the effects of the divertor or limiter in the
way the edge plasma does. (More info anyone?)
* Corona: The outermost (?) part of a star's atmosphere;
characterized by high temperatures and low densities; home to
many plasma phenomena.
* Corrosion: Chemical interactions between a fluid, (such
as lithium or water coolant) and the containing material
(such as stainless steel), which results in wall material
dissolving into the fluid, and possibly degradation of
the mechanical properties of the containing structure
$ Coulomb: standard unit of electric charge. A single electron or
proton has a charge of (+/-) 1.6022E-19 coulombs. Hence there are
6.2414E+18 electrons in a coulomb of electrons.
* Coulomb Collision: An interparticle collision where Coulomb's Law
(electrical attraction and repulsion) is the governing force.
(See Coulomb's Law) Coulomb collisions have a number of interesting
properties, but these are better described in textbooks. The
interaction of the charged particles with each other's electric
fields results in deflections of the particles away from their
initial paths.
& Coulomb Force: See Coulomb's Law. Also called
"electrostatic force."
* Coulomb Ionization: Ionization produced by Coulomb forces
between a moving particle ("projectile") and another particle
it interacts/collides with ("target").
& Coulomb's Law: Force law governing the electrical interaction
between charged particles. Force is proportional to (charge of
first particle) * (charge of second particle) / (square of separation
between particles). Constant of proportionality depends on system
of units used. (In SI units, it is 1/(4*pi*epsilon-0), where
epsilon-0 is the permittivity of free space = 8.854 x 10^-12 )
& Cross Section: (usually symbolized with a lower-case Greek sigma)
In physics this usually refers to the (apparent) area presented
by a target particle to an oncoming particle (or electromagnetic
wave). This measures the probability of an interaction occuring.
For typical interactions between ions and electrons, or between
two nuclei, these cross sections are generally measured in barns.
(See relevant entries.)
& Cryogenic: Loosely, "very cold". Used to describe systems which
operate at very low temperatures. Superconducting magnetic field
coils currently need to operate at cryogenic temperatures (e.g.,
liquid helium at 4 Kelvin).
* Curie: Unit of radioactivity roughly equal to the rate of
radioactive decay of a gram of radium; named after Marie
Curie (see below). Corresponds to 3.7 x 10^10
disintegrations/second (37 billion). (See Becquerel)
! Curie: Marie and Pierre; husband-wife pair of French scientists.
Pierre's name is attatched to the "Curie point" in magnetism, which
is not discussed here. He and his wife shared with Antoine-Henri
Becquerel the Nobel Prize for physics in 1903. Marie Curie,
a.k.a. Madame Curie, received the Nobel Prize for chemistry
in 1911, becoming the first person to receive more than
one Nobel Prize. She remains the only person to receive Nobel
Prizes in different fields. (I believe - RFH)
& Current Density: Amount of current flowing through a substance,
per unit area perpendicular to the direction of current flow. (See
also density)
* Current Drive: Any of a variety of techniques used to cause
current flow in a plasma. See inductive current drive, RF current
drive, non-inductive current drive. Usually applied to schemes
used to generate current in tokamaks and other toroidal devices
which require internal plasma currents. See also: bootstrap current.
* Cusped Geometry: I can't figure out how to explain this one in
words; suffice it to say that this is a description of a magnetic
field configuration where the magnetic field lines, rather than
closing in on themselves, tend to squirt out and form cusps at
certain points; I recommend you look this up in a plasma physics
text (e.g., Chen - see bibliography entry) to really understand it.
The magnetic field lines are everywhere convex towards the center.
Such a geometry is interesting because it is theoretically stable
against a variety of MHD instabilities.
> Cyclops: Single-chain, 0.6 terawatt Nd-glass laser system at
Lawrence Livermore National Laboratory that was used for laser
studies and inertial-confinement fusion experiments in 1975-1976.
* Cyclotron: Particle accelerator in which a magnetic field causes
particles to orbit in circles, and an oscillating electric field
accelerates the particles.
* Cyclotron Frequency: Number of times per second that a particle
orbits in a magnetic field. (Often, and incorrectly, called the
Larmor frequency. The cyclotron or gyrofrequency is twice the
Larmor frequency of precession.)
* Cyclotron Radius: Radius of orbit of charged particle about
a magnetic field line. Also called gyroradius, Larmor radius.
* Cyclotron Radiation: See synchrotron radiation
* Cyclotron Resonance: Charged particles in a magnetic field
resonate with (and absorb energy from) an electric field
(perpendicular to the magnetic field) which oscillates at
the particles' cyclotron frequency, or at a harmonic
(multiple) of that frequency.
* Cyclotron Resonance Heating: see Electron Cyclotron Resonance
Heating, Ion Cyclotron Resonance Heating.
Subject: Conventional Fusion FAQ Glossary Part 6/26 (F)
From: Robert F. Heeter
Date: 23 Nov 1996 06:14:43 GMT
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.
Subject: Conventional Fusion FAQ Glossary Part 5/26 (E)
From: Robert F. Heeter
Date: 23 Nov 1996 06:14:39 GMT
Archive-name: fusion-faq/glossary/e
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 5: Terms beginning with "E"
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).
==================================================================
EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
# e: symbol for the electron, for the unit electric
charge (e = 1.6x10^-19 coulombs), and for a Euler's fundamental
mathematical constant e = 2.71828...
# E: Variable typically used for Energy or Electric Field
(usually in vector notation in the latter case; which is meant
is usually clear from context; when both are used in the same place
the energy is usually represented as U instead of E.)
@ EBT: Elmo Bumpy Torus; see entry
@ EC: European Community; see entry
@ ECDC: Electron Cyclotron Discharge Cleaning; see entry
@ ECE: Electron Cyclotron Emission; see entry
@ ECH: Electron Cyclotron Heating; see entry
@ ECRH: Electron Cyclotron Resonance Heating - same as ECH.
@ EF: Equilibrium (vertical) Field Electromagnet Coil; see vertical field
$ ECU: European Currency Unit
@ ELM: Edge-Localized Mode; see entry
@ EM: Electromagnetic
@ EM Wave: Electromagnetic Wave; see entry
@ EPA: Environmental Protection Agency (U.S.); see entry
@ ERDA: Energy Research and Development Agency; see entry
@ ESECOM: Reactor design study done in the mid 1980s to
evaluate the Environmental, Safety, and ECOnoMic potential
of different types of fusion and advanced fission reactors.
@ ESNET: Energy Sciences NETwork; no entry yet
@ ETF: Engineering Test Facility
@ EU: European Union; see entry
@ eV: Electron-volt; see entry
$ Exa: metric prefix for 10^18 or 1,000,000,000,000,000,000
$ Exajoule: unit of energy, 10^18 joules; often used as unit
of measure for world annual energy use. Comparable in size to
a Quad (1 EJ = 0.948 Quads); see entry for Quad.
* E-Coil: The plasma current driving (Ohmic Heating) coil
in a Doublet device (see entry for doublet). Ideally the
E-coil makes no magnetic field in the confinement system. (?)
* E-Layer: Cylinder of relativistic electrons gyrating in
a magnetic field, which produce a self-field strong enough
to dominate the externally applied field and produce a
field-reversal (where the B field changes sign) in the
system. See Field-Reversed Configuration, Field-Reversed Pinch.
* Echoes: Wave packets (pulses) which have been reflected
or otherwise returned to the detector, which are sufficiently
delayed and retain sufficient magnitude so that they are
perceived as a signal distinct from the one transmitted
directly. (In other words, just like sound echoes, only
for analogous phenomena with other waves.)
* Eddy Current: Electric current induced inside a conductor
when the conductor (a) moves through a nonuniform magnetic
field, or (b) experiences a change in the magnetic flux
through its surface.
* Eddy-Current Loss: Energy loss due to eddy currents
circulating in a resistive material.
* Edge Localized Mode: (ELM) Mode found often in H-mode plasmas.
This is a temporary relaxation of the very high edge gradients
found in H-modes. It may be a relaxation back to the L-mode.
(Borrowed from a posting by Paul Stek)
* Edge Plasma: Cooler, less dense plasma away from the center
of a reactor; affected by limiter or divertor, includes
scrape-off layer. Distinguished from core plasma. See entries
for relevant terms used.
* Edge-Localized Mode: (info from Paul Stek) Found often in
H-mode plasmas, this is a temporary relaxation of the very high
edge gradients found in H-modes. It may be a relaxation back
to the L-mode.
* Effective Collision Cross-section: (See collision cross section)
* Effective Collision Radius: Effective size of a particle
equal to the square root of (cross section/pi). Determines the
effective range of interaction of the particle.
* Effective Half-Life: Time required for a radioactive substance
contained in a biological system (such as a person or an animal)
to reduce its radioactivity by half, as a combination result
of radioactive decay and biological elimination from the system.
& Eigenfrequency: One of the characteristic frequencies at
which an oscillatory system can vibrate.
& Eigenfunction: Function describing an eigenstate of a
system.
& Eigenstate: One of the characteristic states of an
oscillatory system, such that the system does not leave the
state unless disturbed. (?)
& Eigenvector: Same thing as an eigenfunction, only from the
perspective that the eigenfunction is a "vector" in an
appropriate mathematical vectorspace.
* Eikonal Equation: An equation for propagation of electromagnetic
or acoustic waves in an inhomogenous medium; valid only when the
scale length for variation in the properties of the medium is
small compared to a wavelength. (Similar in character to WKB?)
& Elastic: Term used to describe a process in which kinetic energy
is conserved; usually refers to (elastic) collisions or (elastic)
scattering.
& Electric Charge: See charge, electrical.
& Electric Field: A property of a patch of space which causes
the acceleration of electric charges located at that patch of
space. The acceleration is given by a = qE/m, where q is the
charge, E the electric field vector, and m the mass of the
particle.
% Electric Power Research Institute: (EPRI) Research organization
funded by the electric power utilities to study, well, electric
power.
* Electric Probe: See Langmuir Probe.
& Electrical Conductivity: Degree to which a substance conducts
electric current. Can be defined by:
(current density) = (conductivity) * (applied electric field)
Electrons and ions both contribute to current in proportion to
their mobility in the system. In a plasma with a magnetic field,
there is no longer a one-to-one correspondence between current
and electric field. Instead, the current in each direction can
be due to combinations of the electric fields in all the other
directions. In this case, the current density and the
electric field are vectors, and the conductivity becomes a
tensor (matrix) which relates them.
* Electromagnetic Coupling: A means of extracting energy from a
magnetically confined plasma, where the plasma expands and pushes
on the confining magnetic field, causing electrical energy to
be generated in the external field-generating circuits.
& Electromagnetic Force:
* Electromagnetic Radiation: Radiation (such as radio waves,
microwaves, infrared, visible light, ultraviolet, x-rays, and
gamma rays) which consists of associated, interacting electric
and magnetic field waves which travel at the speed of light
(because electromagnetic radiation *is* light, except for the
variation in frequencies!). All forms of electromagnetic
radiation can be transmitted through vacuum. Electromagnetic
waves in plasmas are generally more complex in their behavior,
depending on their frequency.
& Electromagnetic Wave: Wave characterized by combined oscillations
of both electric and magnetic fields. The particle equivalent
is the photon. There is a whole spectrum of electromagnetic
waves where the classes are distinguished by energy (or,
equivalently, wavelength or frequency); the spectrum of
electromagnetic waves includes radio waves, microwaves,
infrared light, visible light, ultraviolet light, x-rays, and
gamma rays.
& Electron: Elementary particle with a negative electric
charge. Electrons orbit around the positively charged nucleus
in an atom. The charge on an electron is -1.6x10^-19 coulombs;
the electron has a mass of 9.11 x 10^-31 kg (about 1/1837
times that of a proton.) The configuration of electrons around
an atom determines its chemical properties. The positron
is the antiparticle to the electron, and is identical except
for having a positive charge.
> Electron Beam Fusion Accelerator: See PBFA (Particle Beam
Fusion Accelerator)
* Electron Capture: Nuclear decay process whereby a proton in
the nucleus absorbs an orbiting electron and converts to a
neutron.
* Electron Cyclotron Discharge Cleaning: (ECDC) Using relatively
low power microwaves (at the electron cyclotron frequency) to
create a weakly ionized, essentially unconfined hydrogen plasma
in the vacuum chamber. The ions react with impurities on the
walls of the tokamak and help remove them from the chamber. For
instance, Alcator C-mod typically applies ECDC for a few days
prior to beginning a campaign, and a few hours before each day's run.
* Electron Cyclotron Emission: (ECE) As electrons gyrate around in
a magnetic field (see also larmor radius or cyclotron radius),
they radiate radio-frequency electromagnetic waves. This is
known as electron cyclotron emission, and can be measured to
help diagnose a plasma.
* Electron Cyclotron Heating: (ECH or ECRH) Radiofrequency
(RF) heating scheme that works by injecting electromagnetic (EM)
wave energy at the electron cyclotron gyration frequency.
The electric field of the EM wave at this frequency looks to
a gyrating electron like a static electric field, and it
causes acceleration of the electron. The accelerated
electron gains energy, which is then shared with other particles
through collisions, resulting in heating.
* Electron Cyclotron Wave: Radiofrequency waves at the
electron cyclotron frequency. See also Whistler.
* Electron Density: Number of electrons in a unit volume.
See density for more info.
* Electron Temperature: The temperature corresponding to
the mean kinetic energy of the free electrons in a
plasma.
$ Electron-volt: 1 eV = 1.6 x 10^-12 erg, or 1.6 x 10^-19 Joules.
This is a unit of kinetic energy equal to that of an electron
having a velocity of 5.93 x 10^5 m/sec. This is the energy
an electron (or other particle of charge=1 such as a proton),
gains as it is accelerated through a potential difference
of 1 volt. In plasma physics the eV is used as a unit of
temperature; when the mean particle energy is 1eV, the
temperature of the plasma is roughly 11,700 Kelvin.
* Electrostatic Analyzer: A device which filters an
electrn beam (band-pass), permitting only electrons within
a narrow energy (velocity) range to pass.
> Electrostatic Confinement: An approach to fusion based on
confining charged particles by means of electric fields, rather
than the magnetic fields used in magnetic confinement. See
discussion in Section 4 for more information.
* Electrostatic Waves: Longitudinal oscillations appearing in a
plasma due to a perturbation of electric neutrality. For a cold
unmagnetized plasma, or at large wavelengths, the frequency of
these waves is by definition the plasma frequency.
& Element: One of the fundamental chemical substances which
cannot be divided into simpler substances by chemical means.
Atoms with the same atomic number (# of protons) all belong
to the same element. (e.g., hydrogen, helium, oxygen, lead)
(list and perhaps periodic table in
appendix? isotope table with half-lives and decay modes
might also be useful.)
& Elementary Particles worth knowing about:
(at the nuclear-energy level)
electron & positron - seem to be stable
proton - thought to be stable, life > 10^30 sec
neutron - decays in ?10 min unless it's in a nucleus, which often
extends its life.
other particles important for nuclear energy:
muon, neutrino (m,e,tau),
photon
muonic atoms
pi-meson
antiparticles
this part is new - maybe separate entries with listing
here??
> Elmo Bumpy Torus: Bumpy Torus at ORNL; no longer operating.
See Bumpy Torus, ORNL.
* Elongation: parameter indicating the degree to which the cross
section of a toroidal plasma is non-circular. kappa=b/a, where "b"
and "a" are the vertical and horizontal minor radii. As kappa is
increased, the confinement in relation to the total current improves,
but the plasma also becomes more and more unstable to vertical
displacements. A circular plasma has kappa of 1, a common value for
elongated plasmas is 1.7, and the absolute limit is probably
around 2.
& Energy: Typically defined as "the ability to do work". Power
is the rate at which work is done, or the rate at which energy
is changed. "Work" characterizes the degree to which the properties
of a substance are transformed. Energy exists in many forms,
which can be converted from one to another in various ways.
Examples include: gravitational energy, electrical energy,
magnetic and electric field energy, atomic binding energy (a form
of electrical energy really), nuclear binding energy, chemical
energy (another form of electrical energy), kinetic energy (energy
due to motion), thermal energy ("heat"; a form of kinetic energy
where the motion is due to thermal vibrations/motions), and so on.
* Energy Balance: Comparison of energy put into a plasma with the
energy dissipated by the system; related to energy confinement.
* Energy Confinement Time: See energy loss time.
* Energy Loss Time: Characteristic time in which 1/e (or sometimes
1/2) of a system's energy is lost to its surroundings. In a plasma
device, the energy loss time (or the energy confinement time) is
one of three critical parameters determining whether enough
fusion will occur. (See Lawson criterion)
* Energy Replacement Time: Time required for a plasma to lose
(via radiation or other loss mechanisms) an amount of energy
equal to its average kinetic energy.
% Energy Research and Development Agency (ERDA): US Agency created
by splitting of the AEC into ERDA and NRC in about 1975, charged
with managing US energy R&D; (???). Merged with ??? to become the
Department of Energy in about 1977. (???? correct? help??)
* Entropy Trapping: The process of trapping an ordered beam of
particles in a magnetic field configuration (e.g., cusp geometry)
by randomizing the ordered motion of the particles, with
corresponding increase in the entropy of the system.
% Environmental Protection Agency: Agency within the executive
branch of the U.S. government (under the Department of the Interior?
Independent?) charged with, well, protection of the environment.
Activities include research, regulatory, and cleanup functions.
(Any government people reading this who could help me out?)
* Equations of Motion: Set of equations describing the time
evolution of the variables which describe the state of a
physical system.
* Equilibrium: [ acknowledgements to John Cobb ] An equilibrium is
a state of a system where the critical parameters do not change
significantly, within a given time frame. In the case when this time
frame is infinite, It is called a Thermodynamic equilibrium. There
are many cases where a plasma equilibrium is constant on some fast
time scale, but changes over some slower time scale. For example, an
IDEAL MHD equilibrium is constant over fluid time scales
(microseconds to milliseconds), but it will evolve on the slower
resistive or viscous time scales (milliseconds to seconds). All
terrestial plasmas are NOT in thermodynamic equilibrium, but they may
be constant over very long time periods.
An equilibrium is unstable when a small change in a critical
parameter leads the state of the system to diverge from the
equilibrium. An equilibrium is stable when a small change in a
critical parameter leads to a "restoring force" which tends to
return the system to equilibrium.
* Equilibrium Field: See Vertical Field
$ Erg / ergs: CGS unit for energy. 1E7 ergs = 1 joule.
* Ergodic: A mathematical term meaning "space-filling". If a
magnetic field is ergodic, any field line will eventually pass
arbitrarily close to any point in space. Closely related to
"chaotic".
* Ergodic Regime: In this regime, a given magnetic field
line will cover every single point on a magnetic surface
(see magnetic surface or flux surface) if the rotational
transform (or q) is not rational.
* ESECOM: Reactor design study done in the mid 1980s to
evaluate the Environmental, Safety, and ECOnoMic potential
of different types of fusion and advanced fission reactors.
* Eulerian Coordinates: Coordinates which are fixed in
an inertial reference frame.
% European Community: see European Union
% European Union: (from Herman) Organization of European
countries (formerly European Community, EC, formerly European
Economic Community, EEC) established in 1967 to coordinate policies
on the economy, energy, agriculture, and other matters. The original
member countries were France, Belgium, West Germany, Italy,
Luxembourg, and the Netherlands. Joining later were Denmark,
Ireland, the United Kingdom, Greece, Spain, and Portugal. Other
countries are in the process of joining now.
% Euratom: European Atomic Energy Community. International
organization established in 1958 by members of the European
Economic Community for the purpose of providing joint
funding and management of the scientific research of the
member countries - initially Belgium, France, Italy,
Holland, and West Germany.
* Excitation Radiation: Line radiation (at characteristic
frequencies / wavelengths) as a result of the excitation
of excited states, and the subsequent de-excitation of
these states by radiative transitions.
