Numerical Simulation of Trapped-Electron Instabilities in Toroidal Geometry

Dissipative trapped-particle instabilities are studied by means of three-dimensional particle simulations in toroidal geometry. In the linear stage, growth rates of the unstable modes and the radial and poloidal ballooning mode structures observed in the simulation agree reasonably well with linear theory. In the nonlinear stage, the ballooning effect diminishes because of the generation of strong plasma turbulence resulting in the broad frequency spectrum and convective cells consistent with experimental observations.