Gyro-Kinetic Particle Simulation of m=1 Internal Kink Mode in the Presence of Density Gradient.

Abstract

Effects of density gradient on the kinetic m=1(m/n=1/1) internal kink mode in a cylindrical tokamak plasma are studied by the gyro-kinetic particle simulations. When the density gradient is not large enough to change the full reconnection process, the phenomena after the full reconnection, such as the secondary reconnection and the evolution of the safety factor profile, are changed considerably due to the self-generated radial electric field, i.e. the m/n=0/0 mode. The radial electric field grows up to the same level as the m/n=1/1 mode, and drives an E×B plasma rotation in the ion diamagnetic direction, which breaks the symmetry of the current reconcentration. The density and current distributions, and therefore minimum safety factor qmin after the full reconnection, are found to be affected by the rotation.