home *** CD-ROM | disk | FTP | other *** search
- Path: senator-bedfellow.mit.edu!faqserv
- From: Robert F. Heeter <rfheeter@princeton.edu>
- Newsgroups: sci.physics.fusion,sci.answers,news.answers
- Subject: Conventional Fusion FAQ Glossary Part 6/26 (F)
- Supersedes: <fusion-faq/glossary/f_934543711@rtfm.mit.edu>
- Followup-To: sci.physics.fusion
- Date: 11 Nov 1999 12:25:16 GMT
- Organization: Princeton University
- Lines: 245
- Approved: news-answers-request@MIT.EDU
- Distribution: world
- Expires: 23 Feb 2000 12:24:17 GMT
- Message-ID: <fusion-faq/glossary/f_942323057@rtfm.mit.edu>
- References: <fusion-faq/glossary/intro_942323057@rtfm.mit.edu>
- Reply-To: rfheeter@pppl.gov
- NNTP-Posting-Host: penguin-lust.mit.edu
- Summary: Fusion energy represents a promising alternative to
- fossil fuels and nuclear fission for world energy
- production. This FUT is a compendium of Frequently Used
- Terms in plasma physics and fusion energy research. Refer
- to the FAQ on Conventional Fusion for more detailed info
- about topics in fusion research. This FUT does NOT
- discuss unconventional forms of fusion (like Cold Fusion).
- X-Last-Updated: 1995/02/05
- Originator: faqserv@penguin-lust.MIT.EDU
- Xref: senator-bedfellow.mit.edu sci.physics.fusion:44254 sci.answers:10851 news.answers:170837
-
- 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.
-
-
-
-
-
-
-
-