Gyro-kinetic Electron and Fully-Kinetic Ion Particle Simulation of Tearing Mode Instability in a Harris Current Sheet

Two-dimensional simulations are carried out using our gyro-kinetic electron and fully-kinetic ion (GeFi, formerly GKe/FKi [1]) particle simulation model to investigate the collisionless tearing mode instability in a Harris current sheet in the presence of a finite guide field, under a realistic ion-to-electron mass ratio m$^{i}$/m$^{e}$. The simulation is performed in the plane that contains the anti-parallel magnetic field B$^{x}$ and the current sheet normal B$^{z}$. First, results based on the linearized delta-f scheme are compared with the eigenfunction and linear growth rate obtained from the drift kinetic eigenmode theory as well as the asymptotic matching results of Drake and Lee [2]. Effect of the electron-to-ion temperature ratio T$^{e}$/T$^{i}$, beta values, and the half-width of the current sheet are investigated. Second, the physics of saturation is studied using the nonlinear simulation scheme. \\[4pt] [1] Lin, Y., X. Y. Wang, Z. Lin, and L. Chen, Plasma Phys. Controlled Fusion, \textbf{47}, 657 ,2005. \\[0pt] [2] Drake, J.F, and Y.C.Lee, Phys.Fluids, \textbf{20}, 1341, 1977