Kinetic Alfven wave dissipation in tokamaks with elliptic magnetic surfaces

The longitudinal permittivity elements of a toroidal plasma with elliptic m agnetic surfaces are evaluated by solving the drift kinetic equation as a b oundary-value problem for waves in the frequency range much more than the d rift frequency. The linearized drift kinetic equation is solved separately for untrapped, and three groups of trapped particles. The quadratic correct ions over the inverse tokamak aspect ratio are taken into account to approx imate the equilibrium magnetic field. Some physical features related to the absorption of monochromatic kinetic Alfven waves in collisionless elongate d tokamaks are analysed for the case when only usual untrapped and trapped particles-electrons can exist in the plasma volume. The radial structure of the imaginary part of the longitudinal permittivity is calculated for a to roidal plasma having the main Joint European Torus (JET) parameters. For si mplicity, the parabolic profiles are considered for plasma density and temp erature. It is shown, that the kinetic Alfven wave dissipation, in cold/war m plasmas, occurs mainly by the effective interaction with untrapped electr ons. There is another situation and other dissipation mechanisms for the sl ow Alfven waves in plasmas with high-temperature electrons, when the bounce resonant interaction between the wave and the trapped electrons becomes su bstantial.