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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 16/26 (P)
- Supersedes: <fusion-faq/glossary/p_934543711@rtfm.mit.edu>
- Followup-To: sci.physics.fusion
- Date: 11 Nov 1999 12:26:02 GMT
- Organization: Princeton University
- Lines: 392
- Approved: news-answers-request@MIT.EDU
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- Expires: 23 Feb 2000 12:24:17 GMT
- Message-ID: <fusion-faq/glossary/p_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: 1995/02/26
- Originator: faqserv@penguin-lust.MIT.EDU
- Xref: senator-bedfellow.mit.edu sci.physics.fusion:44264 sci.answers:10861 news.answers:170847
-
- Archive-name: fusion-faq/glossary/p
- Last-modified: 25-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 16: Terms beginning with "P"
-
- 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).
- ==================================================================
-
- PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP
-
- # p, P: Variables used for plasma (kinetic) pressure.
- # p: also used as symbol for the proton
- $ p: also the metric prefix for pico (10^-12 * base unit)
-
- @ PBFA-II: Particle Beam Fusion Accelerator-II; see entry
-
- @ PBX-M: Princeton Beta eXperiment-Modified; see entry
-
- @ PCS: Plasma Control System (Alcator C-Mod)
-
- @ PCX: Neutral Particle Analyzer
-
- @ PDX: Poloidal Divertor eXperiment; see entry
-
- @ PEOS: Plasma Erosion Opening Switch; see entry for
- Plasma Opening Switch (POS)
-
- @ PEP: Pellet Enhanced Performance; see entry on pellet injection
-
- @ PEST: Plasma Equilibrium and STability code; see entry
-
- @ PF: Poloidal Field; Poloidal Field Magnet Coil
-
- @ PLT: Princeton Large Torus; see entry
-
- @ PNL: Pacific National (Northwest?) Laboratory; no entry yet.
-
- @ POS: Plasma Opening Switch; see entry
-
- @ PPPL: Princeton Plasma Physics Lab; see entry
-
- @ PV: Photo-Voltaic; see entry
-
- @ PWR: Pressurized Water Reactor (fission); see entry
-
- * Parametric Instability: Instability which occurs in a
- system whose equilibrium is weakly modulated in time or
- space. The modulation produces a coupling of the linear
- eigenmodes of the system and can lead to destabilization.
-
- & Particle:
-
- > Particle Beam Fusion Accelerator II: Light ion accelerator
- inertial confinement fusion research system at Sandia National
- Laboratories.
-
- & Particle Density: number of particles present per unit volume
- (typically a cubic centimeter). See also density; typically
- represented by the variable "n".
-
- * Pellet Injection / Pellet Injector: This is a device
- which accelerates (shoots) small (less than 4 mm diameter)
- frozen pellets of hydrogen (or other) isotopes; these are then
- launched at high speed (ca. 1000 m/sec) into the inner
- regions of hot plasmas. Use of lithium and boron pellets
- allows coating of the vacuum vessel walls, and is useful for
- impurity control. Pellet injection can also be used to fuel
- the plasma, and the light emitted by the pellet's ablation
- cloud is useful for diagnostic purposes.
-
- * Pfirsch-Schluter Regime, P-S Transport: One of the
- neoclassical transport parameter regimes in a tokamak plasma;
- characterized by the collisional mean free path being shorter
- than the connection length. (This is the high-collisionality
- end of the spectrum; plateau transport is in the middle, and
- the banana regime is on the low-collisionality end.)
- In this regime the diffusion coefficient is q^2 times greater
- than the classical value (q being the safety factor, q > 1).
- See also classical transport, neoclassical transport,
- plateau transport, banana transport, safety factor.
-
- & Phase Velocity: Defined as w/k, this describes the rate
- of propagation of a wave through space.
-
- & Photoionization: The ionization of an atom or molecule
- by the collision of a high-energy photon (i.e., electromagnetic
- radiation) with the particle.
-
- & Photo-voltaic: Adjective used to describe devices which
- convert light, particularly solar energy, into electricity.
-
- $ pico-: Metric prefix indicating 10^-12 times the base unit.
-
- * Pinch effect: General term for a class of phenomena
- whereby the plasma is compressed or restricted ("pinched").
- There are a variety of types of pinches. The Z-pinch
- is a constriction of a plasma carrying a large current,
- caused by the interaction of that current with its own
- encircling magnetic field. The Theta pinch is a constriction
- of a plasma by an increase in the axial magnetic field
- generated by an external solenoidal current. The Ware pinch
- arises in tokamaks due to neoclassical effects. And there
- are others.
-
- > Pinch Device or Pinch Machine: Device which confines
- plasma using a pinch effect. (Typically the Z or Theta pinch.)
-
- * Pinch Reflex Diode: A self-insulated ion diode in which
- the magnetic field from the ion and electron flow alone
- provide electron control, and the ion source is an anode
- plasma formed by relexing the electrons through a thin
- plastic foil.
-
- * Pitch Angle: For a charged particle moving in a magnetic field,
- this is the angle arctan (v-perp/v-parallel), where v-parallel
- is the component of the particle's velocity parallel to the
- magnetic field, and v-perp is the perpendicular component.
- The pitch angle is zero when the particle moves purely parallel
- to the field, and 90-degrees when the particle has no parallel
- velocity at all.
-
- * Pitch Angle Scattering: Scattering (collisional, or due
- to wave-particle effects) of particles in velocity space,
- in which the pitch angle (see entry above) is changed.
-
- * Plant Factor: Another term for Capacity Factor; see entry.
-
- * Plasma: A "Fourth State of Matter" in which many of the
- atoms or molecules are ionized. Plasmas have unique physics
- compared to solids, liquids, and gases. (Most plasmas can be
- thought of at first as extremely hot gases, but their properties
- are generally quite different.) Some (but not all!) Examples:
- the sun, fluorescent light bulbs and other gas-discharge tubes,
- very hot flames, much of interplanetary, interstellar, and
- intergalactice space, the earth's ionosphere, parts of the
- atmosphere around lightning discharges, and of course fusion plasmas.
-
- * Plasma Beta: see Beta
-
- * Plasma, Cold: See Cold Plasma Model
-
- * Plasma Containment: (quoting from the PPPL Glossary of Fusion
- Terms) "In plasma physics experiments or nuclear fusion experiments,
- operation is intended to prevent, in an effective and sufficiently
- prolonged manner, the particles of a plasma from striking the walls
- of the container in which this plasma is produced. Plasma
- confinement is a fundamental requirement for obtaining net energy
- from a fusion plasma. The reason is that scattering (hence
- diffusion) is at least an order of magnitude more probable than
- fusion reactions. Hence, without confinement, the plasma fuel would
- disperse before enough fusion reactions could take place."
-
- * Plasma Equilibrium and STability Code: (PEST) This is a
- widely-used, well-developed computer simulation ("code") used
- to calculate MHD equilibrium and stability in various fusion
- devices.
-
- > Plasma Focus: The Plasma Focus is another device which depends
- on the pinch effect. Possible applications include both fusion
- and plasma propulsion, as well as other plasma research. In essence
- the plasma focus is generated by discharge of a current across
- the ends of two coaxial insulated conducting pipes.
- The Plasma Focus caused a huge stir when they generated copious
- neutrons, until it was discovered that the source of the neutrons
- was knockoffs from deuterium due to pinch accelerated electrons or
- ions. Plasma focus is sort of a point version of the "Z"pinch.
- For more information on the plasma focus, see the entry in the
- section on confinement approaches (4B).
-
- * Plasma Frequency: The natural collective oscillation frequency
- of a charge species (electrons, ions, etc.) in a plasma, in the
- absence of (or at least parallel to) a magnetic field. Also
- known as Langmuir or Langmuir-Tonks frequency; see also
- electrostatic waves, plasma oscillations.
-
- * Plasma Oscillations: Class of electrostatic oscillations
- which occur at/near the plasma frequency (see entry) and involve
- oscillations in the plasma charge density. Also known as
- Langmuir Oscillations; In Stix's _Waves in Plasmas_ these
- are called Langmuir-Tonks Plasma Oscillations.
-
- * Plasma-Plasma Reaction: Fusion reaction which occurs from the
- collision of two thermal plasma ions. (See also beam-wall,
- beam-beam, and beam-plasma reaction entries.)
-
- * Plasma Wave: A disturbance of a plasma away from equilibrium,
- involving oscillations of the plasma's constituent particles
- and of an electromagnetic field. Plasma waves can propagate
- from one point in the plasma to another without net motion
- of the plasma.
-
- > Plasmak: Controversial advanced spheromak-type concept using
- a fluid rather than solid conducting shell and a plasma with purely
- internal magnetic fields, whose pressure is supported by a
- surrounding gas; for more information see entry in section 4.
-
- * Plasmoid: An isolated plasma which holds together for a
- duration much longer than the collison times for the consituent
- particles.
-
- * Plateau Region, Plateau Transport: The collision frequency
- (and transport) regime characterized by an effective coulomb
- scattering rate equal to or greater than the poloidal transit
- ("bounce") frequency, but where collisional mean free path
- is less than the connection length (2qR*PI). In this regime,
- the transport coefficients are independent of the collision
- frequency. (Thus a plot of transport coefficients vs.
- frequency becomes horizontal line in this regime, forming
- a "plateau" in the graph; hence the name.)
-
- & Plutonium: Radioactive metallic element (Pu). The primary
- isotope, plutonium-239, is a product of neutron absorption
- by U-238, esp. in fission reactors. Pu is used in nuclear
- weapons and as a fission reactor fuel.
-
- * Poisoning: Buildup of ash and impurities in a fusion plasma
- tends to reduce the quality of the plasma and reduce the fusion
- output; this sort of process is sometimes called "poisioning"
- the reactor or the plasma. See also ash, impurities.
-
- & Polarization:
-
- * Polarization of Reacting Particles: See Spin-Polarized Fusion.
-
- * Poloidal: In toroidal geometries, the direction along the
- circumference of a slice through one side of the torus.
- "The short way around a torus".
- - Albert Chou, albert@seas.ucla.edu
-
- * Poloidal Divertor: A divertor (see entry) which takes a
- bundle of poloidal field lines, forming a separatrix in the
- poloidal magnetic field which creates separate plasma regions
- (which can then have different physical parameters, since
- transport is reduced across the separatrix where q => infinity).
-
- > Poloidal Divertor Experiment: (PDX) A medium-size, high-current
- divertor tokamak which was operated at Princeton, whose primary
- research objective was to determine the effectiveness of
- poloidal magnetic divertors in controlling impurities in reactorlike
- fusion plasmas. PDX was modified and became PBX, which was
- modified again and is now PBX-M (see entry for Princeton Beta
- Experiment).
-
- * Poloidal Field: In toroidal devices, the magnetic field that
- encircles the plasma axis. (i.e., loops around the torus
- "the short way".)
-
- * Poloidal Field Coils: In toroidal devices (eg, tokamaks), the
- sets of windings which are (typically) aligned along the plasma
- axis and produce poloidal fields. These include ohmic heating,
- shaping, vertical, equilibrium, and divertor windings.
-
- * Poloidal Field Windings: See Poloidal Field Coils above.
-
- * Positive Column: The luminous glow, often striated, which
- occurs between the Faraday dark space and the anode in a
- glow discharge plasma tube.
-
- & Positron: Antiparticle to the electron; this particle has the
- mass of the electron but the opposite charge.
-
- * Positron Emission: Form of nuclear decay where a proton
- disintegrates into a neutron, positron, and some sort of
- neutrino. (?)
-
- & Power: Defined as amount of work per unit time, or change in
- energy per unit time.
-
- * Power Density: In fusion, the rate at which energy is
- generated per unit volume in the reactor core. (See also entries
- for power, density.)
-
- & Pressure: Defined as force per unit area.
-
- * Pressure Tensor: A generalized pressure (can be anisotropic)
- which plays a role in MHD (see entry) analogous to that of
- pressure in ordinary fluid mechanics.
-
- > Pressurized-Water Reactor (fission): Type of nuclear reactor
- where the coolant is water kept under pressure to prevent it
- from turning to steam inside the plant. (I think!)
-
- * Price-Anderson Act: U.S. Federal law passed in the 1950s (?)
- which limits utility liability for nuclear fission plant
- accident damages. U.S. Government effectively insures the
- utilities against external costs associated with nuclear
- accidents.
-
- * Primary Energy: Energy before conversion. For instance,
- the United States uses about 30,000 megajoules of electricity
- per capita per year, but electricity is generally obtained
- by converting other forms of energy (primarily chemical/heat)
- at an efficiency of around 30%, so the U.S. consumes 90,000
- megajoules of primary energy per capita for electrical use.
- (Total U.S. primary energy consumption is 300,000 megajoules
- per capita.)
-
- % Princeton - See Princeton University and/or Princeton Plasma
- Physics Lab
-
- > Princeton Beta Experiment-Modified (PBX-M): mid-sized tokamak
- research device at Princeton, which evolved from the Poloidal
- Divertor Experiment (PDX) machine. Research on PBX is aimed
- at investigating advanced tokamak regimes, such as indented
- plasmas (kidney-bean cross sections) with high-beta, providing
- access to the second-stability regirme.
-
- > Princeton Large Torus (PLT): Large tokamak formerly operated
- at the Princeton Plasma Physics Laboratory (PPPL). Was operated
- in the 1970s and 80s and studied RF heating and current drive,
- as well as neutral beam injection heating and other aspects of
- tokamak physics. Roughly a predecessor to TFTR.
-
- % Princeton Plasma Physics Lab (PPPL): Located in Princeton,
- New Jersey. Single largest fusion research facility in the
- United States; sole U.S. single-purpose plasma physics
- laboratory; operated by Princeton University for the Department
- of Energy. Site of PLT, PBX-M, TFTR, several other past and
- present experiments, and future site of TPX.
- (Refer to entries for relevant machines, both here and in FAQ.)
-
- % Princeton University: Among other research activities, the
- University operates the Princeton Plasma Physics Laboratory for the
- Department of Energy (see above entry for PPPL).
-
- * Process Heat: Heat produced by a powerplant (could be a
- nuclear reactor, or a fusion reactor someday) and used directly
- for industrial processes, such as metals manufacturing or
- chemical production.
-
- * Project Matterhorn: Code name of the United States' first
- secret controlled fusion project, started by Lyman Spitzer
- at Princeton University in 1951. Became a subprogram within
- Project Sherwood (see entry below.)
-
- * Project Sherwood: Name often used to describe the U.S. controlled
- fusion program in the 1950s and '60s.
-
- * Proliferation (nuclear): Proliferation generally describes
- the way something spreads (rapidly) from one area to another;
- in the case of nuclear weapons, nuclear proliferation refers
- to the spread of nuclear bomb-building technology from one
- state to another.
-
- > Proto II: A high-power (10 TW) pulsed (24 ns) electron
- accelerator which was (is?) used for inertial-confinement
- research.
-
- & Proton: (from Herman) An elementary particle found in the
- nucleus of all atoms. It carries a single positive electrical
- charge.
-
- & Pulse Height Analyzer: Instrument which records and stores
- pulses and indicates ("Analyzes") the number of pulse occurrences
- falling within each of a set of amplitude ("height") ranges.
-
- * Pulsed Power: The technology of using electrical energy
- stores for producing multi-terawatt (10^12 Watts or higher)
- pulses of electrical power for inertial confinement fusion,
- nuclear weapon effects simulation, and directed energy weapons.
- High efficiency and cost effectiveness make it desirable
- technology for large energy experiments.
-
- * Pumpout: Name given to the anomalously high loss of particles
- to the walls in (some) stellarator discharges; the loss rate
- when pumpout occurs is substantially greater than that expected
- from normal classical diffusion processes.
-
-
-
-
-