Electron cyclotron absorption and emission: ‘‘Vexatae Questiones’’

Abstract

The salinet features of the theory of electron cyclotron absorption and emission for the parameter range for which the radiation spectrum has a line structure are touched upon and contrasted with erroneous results of a recent paper by Arunasalam [Phys. Fluids B 4, 1643 (1992)]. In particular, i) the crucial role of the thermal effects on the mode polarization, which in turn affects the absorption profile around the fundamental frequency, is emphasized, showing that using a ‘‘Trubnikov O‐mode factor’’ as advocated by Arunasalam is not correct; ii) the profile of the absorption around the fundamental frequency results to be single‐humped in all cases, in contrast to Arunasalam’s assertion that the absorption profile of the first harmonic O‐mode is double‐humped; iii) an expression for the local radiation temperature for a bi‐Maxwellian electron distribution obtained by Arunasalam and upon which the analysis of the emission spectra of supershot plasmas in TFTR has been based [G. Taylor et al., Proceedings of...