Electron cyclotron radiation, related power loss, and passive current drive in tokamaks: A review

A critical review on emission of weakly damped, high-harmonics electron cyc lotron radiation, the related synchrotron power loss, and passive current d rive in tokamaks with a fish-scale first wall is presented. First, the prop erties of overlapping harmonics are discussed using general analytical form ulas and numerical applications. Next, the radiation power loss and efficie ncy of passive current drive in tokamak reactors are derived for the asymme tric fish-scale first wall. The radiation power loss is determined by the d irection-averaged reflection coefficient sigma (0) and the passive current drive by the differential reflectivity Delta sigma (1-sigma (0)). Finally, the problem of experimental investigations of the high harmonics radiation spectra, of sigma (0) and Delta sigma/(1-sigma (0)) in existing and next-st ep tokamaks, is discussed. Accurate measurements of the radiation spectra a nd the fish-scale reflectivity can be performed at arbitrary electron tempe rature using a partial fish-scale structure located near the tokamak equato rial plane.