Particle simulation method for the electron temperature gradient instability in toroidal plasmas

The gyrokinetic equations for the electrostatic electron-temperature gradient modes in toroidal plasmas are solved with particle simulation method. An axisymmetric geometry with circular flux surfaces is employed. The full kinetics, including finite Larmor radius effects, transit k(//) v(//), and toroidal (curvature and magnetic gradient) drift motion, is retained. The basic method of the particle simulation is described briefly. The fourth-order adaptive stepsize scheme is adopted, that saves computer time and is simple. The basic characteristics of the modes are discussed. The scaling of the critical gradient with respect to toroidicity and to the ratio of electron temperature over ion temperature is given. Comparison with experiments are made and the theoretical results are close to the experimental observations.