Theory of high-power cyclotron-resonance heating in an inhomogeneous magnetic field

Abstract

Wave-energy absorption of a plasma due to cyclotron harmonic resonance is evaluated analytically and by a simulation. The static magnetic field is characterized with B VB =0, and a longitudinal wave is supposed to propagate across the magnetic field. In the calculation an orbit modification of the cyclotron motion of particles is taken into account. It is found that the absorption for the fundamental harmonic resonance (m =1) is depressed from that of the conventional linear theory while the absorptions for m~2 are enhanced, where m is the harmonic number. The enhancement is significant when kp, &(1 (k the perpendicular wave number and p, the gyroradius of the thermal particle) and when the interaction time between the plasma particles and the wave exceeds a critical value that is obtainable analytically. For all m and kp" there appear peaks or saturations in the time evolution of the absorbed energy.PACS number(s): 52.50. Gj, 52.65.+z, 52.35.Fp, 52.35.Nx