Date of Award

Spring 1-1-2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

First Advisor

Scott E. Parker

Second Advisor

Dmitri A. Uzdensky

Third Advisor

Yang Chen

Fourth Advisor

Tobin Munsat

Fifth Advisor

Xiao-Chuan Cai

Abstract

This thesis presents a second-order accurate, semi-implicit $delta!f$ hybrid simulation with Lorentz force ions and fluid electrons. This model includes full ion kinetic effects and is suitable for studying magnetohydrodynamics (MHD) scale physics. We report the first particle-in-cell simulation of nonlinear ion Landau damping of ion acoustic waves, and the results agree with theory. The numerical damping associated with the implicit time advance is also analyzed. We have investigated the full evolution of resistive tearing mode. The linear growth rate is in reasonable agreement with resistive MHD theory. The nonlinear growth and saturation stage has been observed and compared quantitatively with the resistive MHD theory. The simulation shows that current sheets of large aspect ratio tend to develop multiple islands and eventually coalesce to a single elongated island. During this process, significant ion heating inside the island was observed. The simulation shows that over 50% of the dissipated magnetic energy is converted into the kinetic energy of ions for a current sheet with sufficiently large aspect ratios, which is comparable with previous experimental measurements. We also compared the simulation to the extended-MHD NIMROD code for the ion-temperature-gradient-driven instability. The hybrid kinetic and fluid calculations agree well near the marginal stability point, but disagree as kperp ρi or ρi/LTi increases where the kinetic effects become important. Good agreement between the models for the shape of the unstable global eigenfunction is reported. The results help quantify how far fluid calculations can be extended accurately into the kinetic regime.

Share

COinS