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 cyclotron radiation, the related synchrotron power loss, and passive current drive in tokamaks with a fish-scale first wall is presented. First, the properties of overlapping harmonics are discussed using general analytical formulas and numerical applications. Next, the radiation power loss and efficiency of passive current drive in tokamak reactors are derived for the asymmetric fish-scale first wall. The radiation power loss is determined by the direction-averaged reflection coefficient ₀ and the passive current drive by the differential reflectivity /(1 - ₀). Finally, the problem of experimental investigations of the high harmonics radiation spectra, of ₀ and /(1 - ₀) in existing and next-step tokamaks, is discussed. Accurate measurements of the radiation spectra and the fish-scale reflectivity can be performed at arbitrary electron temperature using a partial fish-scale structure located near the tokamak equatorial plane.