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- 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 9/26 (I)
- Supersedes: <fusion-faq/glossary/i_934543711@rtfm.mit.edu>
- Followup-To: sci.physics.fusion
- Date: 11 Nov 1999 12:25:31 GMT
- Organization: Princeton University
- Lines: 318
- Approved: news-answers-request@MIT.EDU
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- Expires: 23 Feb 2000 12:24:17 GMT
- Message-ID: <fusion-faq/glossary/i_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 Glossary 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 Glossary does NOT
- discuss unconventional forms of fusion (like Cold Fusion).
- X-Last-Updated: 1995/02/07
- Originator: faqserv@penguin-lust.MIT.EDU
- Xref: senator-bedfellow.mit.edu sci.physics.fusion:44257 sci.answers:10854 news.answers:170840
-
- Archive-name: fusion-faq/glossary/i
- Last-modified: 4-Feb-1995
- Posting-frequency: More-or-less-quarterly
- Disclaimer: While this section is still evolving, it should
- be useful to many people, and I encourage you to distribute
- it to anyone who might be interested (and willing to help!!!).
-
- ===============================================================
- Glossary Part 9: Terms beginning with "I"
-
- FREQUENTLY USED TERMS IN CONVENTIONAL FUSION RESEARCH
- AND PLASMA PHYSICS
-
- Edited by Robert F. Heeter, rfheeter@pppl.gov
-
- Guide to Categories:
-
- * = plasma/fusion/energy vocabulary
- & = basic physics vocabulary
- > = device type or machine name
- # = name of a constant or variable
- ! = scientists
- @ = acronym
- % = labs & political organizations
- $ = unit of measurement
-
- The list of Acknowledgements is in Part 0 (intro).
- ==================================================================
-
- IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
-
- # I: variable used to indicate total current through a conductor.
-
- @ IAEA: International Atomic Energy Agency; see entry
-
- @ IBHP: Integrated Biological Hazard Potential; see entry
-
- @ ICE: Ion Cyclotron Emission; see entry
-
- @ ICF: Inertial Confinement Fusion; see entry
-
- @ ICH: Ion Cyclotron Heating - see ICRH
-
- @ ICRF: Ion Cyclotron Range of Frequencies
-
- @ ICRH: Ion Cyclotron Resonance Heating; see entry
-
- @ IEEE: Institute of Electrical and Electronic Engineers; see entry
-
- @ INEL: Idaho National Engineering Laboratory; see entry
-
- @ IPP: Max Planck Institute for Plasma Physics; see entry
-
- @ IR: Infrared (region of the electromagnetic spectrum)
-
- @ ITER: International Thermonuclear Experimental Reactor; see entry
-
- % Idaho National Engineering Laboratory: U.S. Department of energy
- laboratory involved in engineering studies for fusion and fission
- reactors, among other things. Not surprisingly, located in Idaho.
-
- * Ignition: In fusion, as in an ordinary (chemical) fire,
- ignition is the point where the temperature and confinement
- of heat in the fuel (plasma in the case of fusion) are
- such that energy released from ongoing reactions is sufficient
- to maintain the temperature of the system, and no external
- heating is needed. An ignited fusion plasma produces so
- much energy from fusion reactions that the plasma is fully
- heated by fusion reaction products (alpha particles in the
- case of D-T fusion), and the plasma no longer needs any
- external source of power to maintain its temperature.
- (The plasma may, however, still need something to maintain
- its confinement; this gives us control over the fusion
- reaction and helps prevent fusion reactors from having
- "meltdown" problems like fission reactors.)
-
- * Ignition Temperature: For given values of density and
- energy confinement, the temperature at which ignition occurs.
- (see ignition above)
-
- > Impact Fusion: Fusion approach where a "fuel" projectile
- is acclerated and impacted into either a stationary target or
- another projectile. (Valuable for scientific purposes but
- not a candidate for a fusion energy source because the
- likelihood of fusion occurring in a single collision is
- too low. Multiple accelerated pellets colliding with spherical
- symmetry might be a viable inertial confinement approach, though.)
-
- * Impact fusion drivers: macroparticle/projectile accelerator
- which could be used in inertial confinement fusion.
-
- * Impurities: atoms of unwanted elements in the plasma,
- which tend to degrade plasma performance, and in the case of
- fusion plasmas tends to inhibit fusion ("poisoning the reactor").
- See also poisoning.
-
- * Impurity Control: Processes which reduce or control the level
- of impurities in a plasma, and thereby improve its quality;
- see also wall conditioning.
-
- * Inboard side: portion of a tokamak (or other toroidal device)
- closest to the central axis. (As distinguished from "outboard side.")
-
- * Incoherent scattering: Type of scattering in which the scattering
- elements act independently, so that no definite phase relationships
- exist among the different parts of the scattered
- beam (particles or photons).
-
- & Index of Refraction: For a given wavelength, this is the ratio
- of the velocity of light in vacuum (c) to the velocity of light
- in a refractive material (e.g., glass, plasma, etc.).
-
- & Inductance: Characteristic relating the magnetic flux generated
- through a loop of wires to the current in the wires; Phi=LI.
-
- & Induction: A changing magnetic flux through a current loop will
- induce an electric field which will drive a current through the loop.
- This is the principle behind an AC transformer, where an oscillating
- electric voltage in one loop of the transformer creates a current
- which generates an oscillating magnetic field, which then induces
- a different voltage and current in a second loop.
-
- * Inductive Current Drive: Method to drive current in a toroidal
- plasma by using the torus of conducting plasma as the second coil
- in a transformer. The primary coil usually runs down the center
- of the torus; changes in the current driven through the primary
- coil create changing magnetic fields which drive current in
- the plasma. The current thus driven can be used to heat the plasma
- as well (see also ohmic heating; induction).
-
- * Inertial Confinement Fusion: Approach to fusion where the plasma
- is imploded so quickly that the inertia of the converging particles
- is so high that many fuse before they disperse. This is the method
- used in a hydrogen bomb; ICF schemes for power production usually
- use small pellets of fuel in an attempt to make "miniature"
- h-bomb type explosions. Methods for imploding the pellet include
- bombardment from all sides with high-powered laser and particle
- beams, and of course implosion in a fission bomb. Parts of ICF
- fusion research remain classified due to their military
- implications and applications, though much ICF research was recently
- declassified.
-
- * Instability: A state of a plasma (or any other physical system)
- in which a small perturbation amplifies itself to a considerable
- alteration of the state of the system. In plasmas instabilities
- sometimes leads to disruptions (see entry). Most instabilities are
- associated with waves and other natural modes of oscillation in the plasma,
- which can sometimes grow. There are (unfortunately!)
- many kinds. See also: Flute instability, MHD instability,
- Interchange instability, microinstability, kink instability,
- resistive instability, trapped particle instability,
- two-stream instability, universal instability, and
- velocity-space instability.
-
- % Institute of Electrical and Electronic Engineers: Professional
- society for this branch of engineering.
-
- * Integrated Biological Hazard Potential (IBHP): Total
- biological hazard potential of a collection of radioactive
- materials summed over their decay lifetimes. See also BHP.
- One measure of the IBHP is the amount of water one would need
- to use to dilute the materials to the point where the water
- would be safe to drink.
-
- * Integrated neutron flux: Sum (integral) of the neutron
- flux (neutrons per unit time per unit area, see flux)
- over all time; total number of neutrons which passed through
- a unit area. Important figure-of-merit in testing effects of
- neutron radiation on materials, and in assessing how long
- such materials can survive exposure to neutron sources
- (such as fission reactor cores and D-T fusion plasmas).
-
- * Intensity: This term has different meanings in different
- contexts. Can refer to the amount of power (energy per unit
- time) incident on a unit surface area, or flowing through a
- unit volume. Can refer to the number of particles or photons
- incident, per unit time, on a unit area, or flowing through
- a unit volume. Also, for an amount of a radioactive material,
- intensity can refer to the number of radioactive disintegrations
- per unit time.
-
- * Interchange Instability: In the simplest form, if you
- place a high-density fluid on top of a low density fluid,
- gravity will pull the high density fluid downwards so that
- the low-density fluid ends up on top. The two fluids
- therefore interchange places. More generally, an interchange
- instability occurs when two types of fluid are situated with
- an external force such that the potential energy is not
- a minimum; the two fluids will then interchange locations to
- bring the potential energy to a minimum. In plasmas with
- magnetic fields, the plasma may interchange position with
- the magnetic field. A prime example is the flute instability
- in mirror machines. (See MHD, instability, flute, mirror.)
-
- * Interference: When two waves propagate through the same
- region of space, they interfere with each other. Neither
- wave is altered, but the amplitudes of the waves add (or
- cancel, if they're of opposite sign) to give the total
- effect to the medium at that point.
-
- * Interferometer: Device which measures changes in a medium
- by looking at effects on the interference of two waves which
- are passed through that medium. See interferometry,
- laser interferometer, optical inteferometer, Fabry-Perot
- interferometer, microwave interferometer.
-
- * Interferometry: Method of gathering information about a
- medium by using an interferometer or similar technique.
- Optical - Uses light as the wave to be interfered.
- Microwave - Uses microwaves instead. Microwave interferometry
- is especially useful in plasma physics for measuring plasma
- densities.
-
- > Internal ring devices: Toroidal configurations in which
- current-carrying rings are suspended (either mechanically
- or magnetically) inside the plasma chamber.
-
- % International Atomic Energy Agency: (from Herman) An
- autonomous intergovernmental organization established in 1956
- with the purpose of advancing peaceful uses of atomic energy,
- with headquarters in Vienna.
-
- > International Thermonuclear Experimental Reactor (ITER):
- Huge fusion reactor being planned by the EC, US, Japan,
- and Russia (former USSR?). Should generate far more
- energy than it consumes. Research goals include engineering
- studies of reactor materials, component designs for steady-state
- devices, and testing/proving commercial feasibility. Discussed
- in sections 5 and 9.
-
- * Ioffe Bars: Special configuration of conductors which, when
- added to a conventional magnetic mirror, generate a "magnetic
- well" which stabilizes the mirror against MHD instabilities.
-
- & Ion: An atom (or molecule) which has become charged as a
- result of gaining or losing one or more orbiting electrons.
- A completely ionized atom is one stripped of all its electrons.
-
- * Ion acoustic wave: a longitudinal compression wave in the
- ion density of a plasma, which can occur at high electron
- temperatures and low frequencies, caused by a
-
- * Ion Cyclotron Emission (ICE): As ions gyrate around in a magnetic
- field (see also larmor radius or cyclotron radius), they radiate
- radio-frequency electromagnetic waves. This is known as ion
- cyclotron emission, and can be measured to help diagnose a plasma.
-
- * Ion Cyclotron Resonance Heating: Like Electron Cyclotron
- Heating, but heats ions using waves near the ion cyclotron
- frequency. See Electron Cyclotron Heating.
-
- * Ion diode: Device for producing and accelerating ion beams
- for light ion drivers for inertial confinement fusion. Ions
- are produced in an anode plasma, extracted as space-charge-limited
- ion flow, and accelerated to the cathode, composed of a confined
- electron swarm, by an applied electric field. Millions of
- amperes of current at millions of volts have been produced this way.
-
- * Ion Temperature: the temperature corresponding to the
- mean kinetic energy of the ions in a plasma.
-
- & Ionization: Process by which a neutral atom is converted to an ion
- (or one ion is converted to another of a different type), by
- removal or addition of electrons.
-
- & Ionization Energy: Generally refers to the amount of energy
- required to strip a particular electron from an atom. The
- first-ionization-energy is a commonly used quantity in many fields
- of physics and chemistry. Typically measured in electron-volts.
- Equivalent to the atomic binding energy of the electron.
-
- & Ionization Potential: See ionization energy.
-
- * Ionizing radiation: Any high-energy radiation which can
- displace electrons from atoms or molecules, thereby producing ions.
- Examples: alpha-particle radiation; beta radiation; x-rays,
- gamma, and hard ultraviolet light; and accelerated ions.
- Ionizing radiation in large quantities may cause severe skin
- and tissue damage and adverse effects. (On the other hand,
- but not to belittle the hazards of radiation, we are
- continuously exposed to a "natural background" of ionizing
- radiation too.)
-
- * Ionosphere: Ionized region of the upper earth atmosphere, which
- behaves like a plasma, including reflection of AM radio waves and
- generation of auroral glows.
-
- * Irradiation: Process of exposure to radiation.
-
- * Isomer, Nuclear: two nuclei with the same nuclear mass (total
- number of protons and neutrons) but different nuclear compostions.
- (e.g.: T & 3He are isomers: T has 1p, 2n; 3He has 2p, 1n)
-
- & Isotope: One of several species of the same element,
- possessing different numbers of neutrons but the same number
- of protons in their nuclei. Most elements have several
- stable isotopes, and also several possible unstable and
- semi-stable isotopes. The chemical and physical properties
- of the different isotopes are generally the same (except for the
- slight mass difference and the possibility of radioactivity).
- Examples include the hydrogen isotopes protium (ordinary
- hydrogen), deuterium, and tritium (two neutrons, one proton);
- also uranium 238, 233, and 235. The chemistry of an element
- depends only on the number of protons (nuclear charge) and
- is therefore the same for all isotopes of an element, but
- the nuclear properties of different isotopes will be
- different. There are roughly 300 known stable isotopes,
- and over 1000 unstable ones.
-
- & Isotropic: adjective which describes a medium whose
- physical properties are independent of the direction in
- which they are measured.
-
-
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