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=============================================================== Glossary Part 17: Terms beginning with "Q" FREQUENTLY USED TERMS IN CONVENTIONAL FUSION RESEARCH AND PLASMA PHYSICS Edited by Robert F. Heeter, firstname.lastname@example.org 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.