Collisional Effects on Nonlinear Saturation and Evolution of Mirror Instability

Mirror instability is a low-frequency compressible electromagnetic mode driven by the pressure anisotropy, and this can only occur in the high-beta plasmas. It has been widely studied due to its possible connection to the understanding of low-frequency compressible magnetic turbulence in magnetized plasma. A gyrokinetic particle simulation was formulated to study this instability, and it shows that at a relatively weak drive, phase-space trapping of the particles plays a dominant role in the evolution of the instability's nonlinear saturation [Nonlinear Saturation of Mirror Instability, H. Qu, Z. Lin, and L. Chen, Geophy. Res. Lett. 35, L10108 (2008)]. Here, we extend this gyrokinetic particle simulation model of the mirror mode to include the Coulomb collisional effects by implementing the Lorentz pitch-angle scattering operator. We will study the role of the collision in the nonlinear saturation and evolution of the mirror instability.