Taylor State Merging Studies: Simulation

We present the results of a resistive Magnetohydrodynamic (MHD) simulation of the evolution and merging of two Taylor state plasmas. We write our simulation program in the Dedalus framework, a module that solves differential equations with spectral methods (http://dedalus-project.org/). The computation is performed with the Pittsburgh Supercomputer Center. The simulation models merging experiments at the Swarthmore Spheromak Experiment (SSX), where we have characterized the magnetic structure, velocity (40 km/s), density (0.5x10¹⁶cm^-3), proton temperature(20 eV), and magnetic field (0.4 T) of relaxed helical Taylor states. We compare data generated through the simulation and the experimental data collected at SSX using 16 Langmuir probes (see K. Butterfield et al. this session). Quantities of interest are the line averaged plasma density, vector B-field, and plasma temperature.

We simulated the merging of both co- and counter-helicity Talyor states. Simulations are run on a rectangular grid ((N_x,N_y,N_z) = (72,72,540)). We initialize our configuration with a 2 x 2 x 10 rectangular box using two spheromaks with perturbation and dense plasma regions at each end and low-density regions in the middle. We impose free slip and perfectly conducting boundary conditions.