PASSIVE CYCLOTRON CURRENT GENERATION WITH FISH-SCALE STRUCTURES

The paper presents a theoretical and a numerical treatment of the prob lem of passive current drive in a fusion plasma. In such a scenario th e current is driven by the self-generated cyclotron radiation. The nec essary asymmetry is introduced with the help of fish-scale structures on the reflecting wall which surrounds the plasma. The problem of the photon equilibrium in a bounded system is the subject of the first par t of this paper. The general case of a plasma surrounded by a reflecti ng wall is presented in the form of a Fredholm integral equation of th e second kind. This integral equation is then simplified for small fis h-scale-like structures on the first wall with the help of a probabili stic approach. A self-consistent solution for the radiation intensity distribution is obtained numerically for a cylindrical plasma model un der such boundary conditions. Based on this and on local current drive efficiencies derived in a companion paper [S. V. Kasilov and W. Kernb ichler, Phys. Plasmas, 3, 4115 (1996)], the radial profile of a steady toroidal current as well as overall efficiencies are computed. (C) 19 96 American Institute of Physics.