Neutral beam driven impurity flow reversal in tokamaks
A theory for the effect of neutral beam injection on the transport of impurity ions in a tokamak plasma was extended to include the effect of temperature gradients. A theory for the effect of neutral beam momentum input on the radial heat conduction was also developed. Injection of neutral beam momentum in the direction of the toroidal magnetic field, called co-injection, was found to reverse the normally inward flow of impurities. The theory was found to provide a reasonable basis for interpretation of impurity flow reversal experiments performed in the Princeton Large Torus (PLT), when a multiplicative factor of two was applied to the predicted impurity fluxes. The model that was adjusted to fit the experimental results in PLT was then applied to the Tokamak Fusion Test Reactor (TFTR) and to models based on designs of future tokamaks. Using the maximum available co-injected beam power (16 MW) in TFTR is predicted to lead to a substantial reduction (relative to balanced momentum injection) in the penetration of impurites to the center of the discharge and to substantially increase the impurity radiation from the plasma edge. This would possibly lead to a cold, radiating edge which would reduce sputtering erosion of the limiter.
- Research Organization:
- Georgia Inst. of Tech., Atlanta (USA)
- OSTI ID:
- 5868331
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
BEAM INJECTION
CLOSED PLASMA DEVICES
IMPURITIES
NEUTRAL ATOM BEAM INJECTION
PLT DEVICES
TFTR REACTORS
THERMONUCLEAR DEVICES
THERMONUCLEAR REACTORS
TOKAMAK DEVICES
TOKAMAK TYPE REACTORS