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Center for Nonlinear Studies |
The performance of magnetic fusion devices depends sensitively on the current and rotation profiles of the plasma. As a result, a substantial amount of effort has been placed on identifying intrinsic mechanisms of current and rotation generation as well as external means through which profiles may be modified. With regard to the plasma's current profile, present day fusion devices rely heavily on inductive current drive. While this current drive mechanism is appropriate for the relatively short discharges studied in current fusion devices, it will be of limited utility for steady state fusion discharges due to its fundamentally transient nature. Within this presentation, means through which waves may drive plasma current and hence provide a mechanism for non-inductive current drive will be described. In particular, a moment approach to the calculation of the plasma current is exploited in order to identify the relevant wave stresses, as well as the relevant symmetries in the wave spectrum which must be removed in order to drive plasma current. In addition, mean field theory is utilized in order to identify means through which waves may drive mean flows in strongly magnetized plasmas. A non-acceleration" theorem for small amplitude waves is derived and analyzed. Particular emphasis is placed on utilizing this theorem to describe the spatial organization of turbulent stresses in the presence of a background of drift wave microturbulence.
Host: Humberto C Godinez Vazquez, Mathematical Modeling and Analysis Theoretical Division, 5-9188