Counterstreaming-ion tokamak fusion reactors
Tokamak plasmas fueled and heated by energetic neutral-atom beams are characterized by total ion pressure greatly exceeding the electron pressure. For smaller devices with relatively low injection energy, the largest fusion reactivity of energetic-ion plasmas is obtained when oppositely injected D/sup 0/ and T/sup 0/ beams sustain large densities of counterstreaming deuterons and tritons (CIT mode). In this study steady-state ion velocity distributions for the CIT are calculated with a multi-species Fokker-Planck code, and are found to have sufficient thermal spread so that all infinite-medium velocity-space modes are stable. Quasi-stationary operation seems physically realizable, because the injected beams provide all fueling, and the counterstreaming ions can be made to carry the bulk of the plasma current required for equilibrium; a satisfactory magnetic flux-surface configuration is revealed by a particle simulation code. Steady-state radial profiles of plasma parameters are determined with a coupled Fokker-Planck/radial transport code that includes charge-exchange effects and particle and heat diffusion of ''warm'' ions and electrons. With inclusion of realistic charge-exchange loss and a significant warm-ion population, the ideal CIT Q-values are found to be reduced by 60 to 70 percent for a given (n/sub e/tau/sub Ee/). For example, Q = 1.0 for W/sub inj/ = 80 keV (D/sup 0/) and 120 keV (T/sup 0/), when (n/sub e/tau/sub Ee/) = 8 x 10/sup 12/ cm/sup -3/s and (n/sub hot//n/sub e/) approximately equal to 0.7. Generally, the total ion pressure is 3 to 5 times the electron pressure, and the warm-ion temperature approximately 2T/sub e/.
- Research Organization:
- Princeton Univ., N.J. (USA). Plasma Physics Lab.
- OSTI ID:
- 7140892
- Report Number(s):
- PPPL-1278; CONF-761012-22
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
BEAM INJECTION
DIFFERENTIAL EQUATIONS
EQUATIONS
FOKKER-PLANCK EQUATION
NEUTRAL ATOM BEAM INJECTION
PLASMA PRESSURE
PLASMA SIMULATION
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
TRANSPORT THEORY