Slow Wave Excitation in the ICRF and HHFW Regimes

Abstract

Theoretical considerations and high spatial resolution numerical simulations of radio frequency (rf) wave heating in tokamaks and in spherical toruses (ST) indicate that fast waves launched into tokamaks in the ion cyclotron range of frequencies (ICRF) or into spherical toruses in the high harmonic fast wave (HHFW) regime may excite a short wavelength slow mode inside of the plasma discharge due to the presence of hot electrons that satisfy the condition ω<k∥vte, where ω is the launched wave frequency, k∥ is the local parallel component of the wave vector, and vte is the local electron thermal speed. This excited slow wave may be related to the electrostatic ion cyclotron wave that propagates for frequencies above the fundamental ion cyclotron frequency [1] in warm plasmas or to a high frequency version of a kinetic Alfvén wave [2]. This slow wave, if physically real, would provide another path for rf power absorption in tokamaks and ST devices.