Electron-cyclotron heating of a tokamak reactor with the extraordinary mode

Abstract

Electron-cyclotron resonance absorption for oblique propagation at frequency significantly below the central electron gyrofrequency is considered. It is shown that the extraordinary mode for external launching is suited for additional heating in a tokamak reactor. The properties of wave damping at downshifted frequencies are discussed and are found to differ from those at f ≈ fc. Using the ray-tracing code, the wave damping of the e mode is investigated at high densities for which strong refraction of the wave beam occurs.