Verification of Low-n Resistive Tearing Mode Physics in the Electromagnetic X-Point Gyrokinetic Code (XGC)
Thomas Gade Jr, University of Minnesota
Tearing modes in tokamak plasmas are an active area of research, in large part due to their impact on reactor stability. Tearing modes are plasma instabilities occurring as a result of plasma resistivity-induced magnetic reconnection, which can lead to loss of confinement via the rapid transport of particles radially outward towards vessel walls. In the worst cases, disruption occurs, and the whole plasma energy is lost to the material walls within milliseconds, potentially damaging the plasma facing components. Tearing modes in tokamaks have been mainly studied with magnetohydrodynamic (MHD) codes due to the relatively smaller computational cost compared with other methods at the expense of the ability to model small-scale, velocity dependent, collisional particle trajectories that are a source of transport across magnetic flux surfaces.
This work uses the electromagnetic gyrokinetic particle-in-cell code XGC, developed by the Princeton Plasma Physics Laboratory, to model low toroidal periodicity (low "n") tearing mode physics using a recently installed hybrid spectral/finite-element field solver. The previously used field solver in XGC had a tendency to induce numerical instabilities in electromagnetic simulations at low n. The new hybrid solver is expected to correct this numerical instability and allow for the accurate representation of low-n (n ~= 1 … 6) modes. In this poster, verification of the hybrid solver at low n is presented, as well as a verification of the basic physics of resistive tearing modes against prior work.
Abstract Author(s): T. F. Gade, R. Hager