Experimental and theoretical investigation of local synergy between ion Bernstein and lower hybrid waves in the Princeton Beta Experiment{emdash}Modified
- Columbia University, Department of Applied Physics and Applied Mathematics, 500 West 120th Street, New York, New York 10027 (United States)
- Associazione Euratom-ENEA sulla Fusione, Centro Ricerche Energia Frascati, C.P. 65, 00044 Frascati, Rome (Italy)
- Princeton University, Plasma Physics Laboratory, Forrestal Campus, P.O. Box 451, Princeton, New Jersey 08543 (United States)
The local synergistic behavior of lower hybrid and ion Bernstein waves on the Princeton Beta Experiment-Modified tokamak [Phys. Fluids B {bold 2}, 1271 (1990)] is experimentally studied using a two-dimensional hard x-ray camera. The hard x-ray bremsstrahlung emission from suprathermal electrons, generated with lower hybrid current drive, is enhanced during ion Bernstein wave power injection. This enhancement is observed in limited regions of space, suggesting the formation of localized current channels. The effects on plasma electrons during combined application of these two types of waves are theoretically investigated using a quasilinear model. The numerical code simultaneously solves the three-dimensional (R,Z,{Phi}) torbidal wave equation for the electric field, in the Wentzel{endash}Kramers{endash}Brillouin{endash}Jeffrey approximation, and the Fokker{endash}Planck equation for the distribution function in two dimensions (v{sub {parallel}},v{sub {perpendicular}}) with an added quasilinear diffusion coefficient. The radial profile of the noninductively generated current density, the transmitted power traces, and the total power damping curve are calculated. The beneficial effects of a combined utilization of ion Bernstein and lower hybrid waves on the current drive are emphasized. The numerical results are compared with the experimental observations. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 321496
- Journal Information:
- Physics of Plasmas, Vol. 6, Issue 3; Other Information: PBD: Mar 1999
- Country of Publication:
- United States
- Language:
- English
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