Conventional Fusion FAQ Glossary Part 17/26 (Q)

From: Robert F. Heeter <rfheeter@princeton.edu>
Newsgroups: sci.physics.fusion
Subject: Conventional Fusion FAQ Glossary Part 17/26 (Q)
Date: 11 Nov 1999 12:26:07 GMT
Message-ID: <fusion-faq/glossary/q_942323057@rtfm.mit.edu>
Reply-To: rfheeter@pppl.gov
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: 1995/02/22

Archive-name: fusion-faq/glossary/q
Last-modified: 21-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 17:  Terms beginning with "Q"

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).
==================================================================

QQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQQ

# q - Variable used to indicate electric charge; also used for
the "safety factor" (see charge, safety factor).  Usually clear
from context which is meant.

# Q: See Q-factor

* Q-enhancement:  Refers to methods for improving the power
balance in mirror-based magnetic confinement fusion reactors.

* Q-factor:  Ratio of power produced by fusion to power
put into the reactor to heat the plasma and drive the
magnetic fields.  Q = 1 is the definition of scientific
breakeven, where power out = power in.  Economical fusion
will require Q significantly greater than 1.  Fortunately
Q increases dramatically as the plasma parameters 
approach the Lawson criterion for ignition.  Power to drive
the magnetic fields is frequently ignored in discussions of
Q, with the justification that a steady-state, continuous-output
fusion reactor will have superconducting magnet coils.

* Q-machine:  Plasma device studied in the 1960s; noted for
its natural quiescence, which made it attractive for plasma
wave phyics experimentation.

* Q-switch:  Optical switch used to rapidly change the Q of
an optical resonator (see entry for oscillator); utilized
in the optical resonator of a laser to prevent lasing action
until a high level of gain and energy storage are achieved
in the laser medium.  When the switch is triggered and
rapidly increases the Q of the cavity, a stronger laser 
pulse is generated.

$ Quad:  Unit of energy equal to a Quadrillion BTUs (10^15)
or roughly one exajoule (see entry for joule, exajoule, BTU).

* Quasi-linear Theory:  A weakly nonlinear theory of plasma
oscillations which uses perturbation theory and the random
phase approximation to find the time-evolution of the 
plasma state.

* Quasi-neutral plasma: an ionized gas in which positive 
and negative charges are present in approximately 
equal numbers.