TRIM Simulation of Plasma Merging and Magnetic Reconnection on the Swarthmore Spheromak Experiment

Research Objectives

Simulate plasma formation, merging, and magnetic reconnection using the adaptive magnetohydrodynamic (MHD) code called TRIM (developed by D. Schnack) in order to directly compare with experimental results from the Swarthmore Spheromak Experiment (SSX).

Computational Approach

The TRIM code solves the two-dimensional MHD equations on an adaptive triangular mesh. When gradients in field quantities exceed a threshold, a triangular grid element is subdivided for higher resolution. The simulations took about 100 hours on the NERSC C90.

Accomplishments

Preliminary results demonstrate that TRIM can adequately simulate formation and merging of SSX spheromak plasmas. More quantitative comparison needs to be done, but the time scales and spatial structures appear to closely match what we measure experimentally.

In the future, we hope to use the TRIM results with a particle code to see if plasma merging and reconnection is a plausible mechanism for particle acceleration.

Significance

High-energy particles are a common product of turbulent magnetofluids (fusion plasmas, solar flares, astrophysical plasmas). Magnetic reconnection could be the engine that drives particle acceleration, and could be the source of the hot solar corona and energetic cosmic rays.

Publications

M. R. Brown, "Experimental studies of magnetic reconnection," Bulletin of the American Physical Society 42 (1998).