KInetic Effect on Dynamics of Plasma Coherent Structures

Kinetic effects on plasma blob dynamics have been studied by means of a three dimensional electrostatic plasma particle simulation code with particle absorbing boundaries. In the particle simulation, an external magnetic field $B$ is pointing into the $z$ direction (corresponding to the toroidal direction). The strength of magnetic field increases in the positive x direction (corresponding to the counter radial direction), i.e., $\partial B / \partial x > 0$. A coherent structure is initially set as a column along the external magnetic field and propagates in the $-x$ direction. In this study, we have investigated the dependence of blob propagation on the ion-to-electron temperature ratio and the magnetic field strength. When the magnetic field strength is decreased (or the ion-to-electron temperature ratio is increased), we have found that the symmetry breaking in a blob profile occurs. This fact is thought to indicate that the effect of gyro motion of plasma particles induces the symmetry breaking.