Asymmetric radiative equilibria in tokamak edge and the detached plasma transition

Abstract

The nonlinear saturated state of the radiative thermal-condensation instability responsible for the phenomenon of multifaceted asymmetric radiation observed in tokamak edge plasmas has been investigated. The essential problem to study two-dimensional thermal equilibria where perpendicular and parallel heat conduction balances the radiated power and heat flux to the limiter. In certain reasonable limits, the nonlinear Poisson's equation can be solved exactly to display many features of the observed detached plasma transition. Numerical results taking realistic temperature dependences for thermal-conductivity coefficients and a common coronal radiation model are also presented.