Simulating a pulsed power-driven plasma with ideal MHD

TL;DR

This paper introduces a computationally efficient ideal MHD method for simulating pulsed power-driven plasma in vacuum chambers, enabling detailed 3D analysis of plasma phenomena and instabilities.

Contribution

The authors propose a novel coupling technique that models vacuum as a perfectly conducting fluid, simplifying simulations and making them more accessible for complex plasma phenomena.

Findings

Verified the method with exact solutions showing convergence

Demonstrated simulation of complex 3D pulsed power devices

Released code for public use

Abstract

We describe a simple practical numerical method for simulating plasma driven within a vacuum chamber by a pulsed power generator. Typically, in this type of simulation, the vacuum region adjacent to the plasma is approximated as a highly resistive, light fluid; this involves computationally expensive solvers describing the diffusion of the magnetic field through this fluid. Instead, we provide a recipe for coupling pulsed power generators to the MHD domain by approximating the perfectly insulating vacuum as a light, perfectly conducting, inviscid MHD fluid and discuss the applicability of this counter-intuitive technique. This, much more affordable ideal MHD representation, is particularly useful in situations where a plasma exhibits interesting three-dimensional phenomena, either due to the design of the experiment or due to developing instabilities. We verified that this coupling recipe works by modeling an exactly solvable flux compression generator as well as a self-similar Noh-like solution and demonstrated convergence to the theoretical solution. We also showed examples of simulating complex three-dimensional pulsed power devices with this technique. We release our code implementation to the public.