CONTRIBUTION OF TRAPPED AND UNTRAPPED PARTICLES TO THE LONGITUDINAL PERMEABILITY OF A TOROIDAL PLASMA

The contributions of trapped and untrapped particles to the longitudin al permeability of a toroidal plasma are analyzed for radio frequency waves in a wide range of frequencies, mode numbers, and plasma paramet ers. A collisionless plasma model of an axisymmetric tokamak with circ ular magnetic surfaces and large aspect ratio is considered. The analy tical expressions of the longitudinal permeability elements are obtain ed by using the kinetic theory of dielectric tensor components, where the Vlasov equation is solved as a boundary-value problem. The radial structures of the imaginary part of the longitudinal permeability (for both the untrapped and trapped particles) are studied for parabolic p rofiles of plasma density, temperature, and tokamak safety factor. The results of the paper are interesting for the problems of Alfven (and lower-hybrid) resonance heating and current drive by the Cerenkov diss ipation mechanism of the waves in toroidal plasmas. (C) 1997 American Institute of Physics.