Modeling Plasma Physics in the Z-Pinch Fusion Concept

A computational modeling program is under way at Zap Energy to explore the plasma physics of sheared-flow-stabilized Z-pinch fusion reactor technology. The WARPXM high-order discontinuous Galerkin modeling framework developed at U. Washington is the primary computational tool. Using a two-fluid model, linear and nonlinear stages of m=0 and m=1 Z-pinch instabilities are simulated in a short axial segment of the Z-pinch plasma, beginning from Bennett equilibrium profiles. Results suggest that although linear stability may not be easily achieved, a system that begins with sufficient equilibrium sheared flow undergoes nonlinear relaxation, leading to a quasi-equilibrium state that may approximate experimental reality. In addition to two-fluid modeling focused on local plasma stability, an MHD-based multi-fluid model is under development for simulating an entire Z-pinch discharge, including gas injection, breakdown, pinch formation, and sustainment via deflagration and entrainment of residual gas in the coaxial acceleration region. The high-order approach employed in WARPXM is arithmetically intensive and suitable to GPU acceleration, and plans in that direction will be discussed. GPU-accelerated continuum kinetic modeling is of particular interest, and may be applied in a whole-device-modeling framework in regions where plasma distributions are non-Maxwellian.