An investigation of shock formation versus shock mitigation of colliding plasma jets

TL;DR

This study uses a kinetic model to analyze when colliding plasma jets form shocks versus when they interpenetrate without shock, aiding fusion research and astrophysical understanding.

Contribution

Introduces a continuum-kinetic Vlasov-Maxwell-Dougherty model with a novel coupling for efficient simulation of plasma jet interactions.

Findings

Simulation results agree with Plasma Liner Experiment outcomes.

Model captures shock heating accurately in plasma jet collisions.

Parameter scans predict shock formation versus mitigation regimes.

Abstract

This work studies the interaction between colliding plasma jets to understand regimes in which jet merging results in shock formation versus regimes in which the shock formation is mitigated due to the collisionless interpenetration of the jets. A kinetic model is required for this study because fluid models will always produce a shock upon the collision of plasma jets. The continuum-kinetic, Vlasov-Maxwell-Dougherty model with one velocity dimension is used to accurately capture shock heating, along with a novel coupling with a moment equation to evolve perpendicular temperature for computational efficiency. As a result, this relatively inexpensive simulation can be used for detailed scans of the parameter space towards predictions of shocked versus shock-mitigated regimes, which is of interest for several fusion concepts such as plasma-jet-driven magneto-inertial fusion (PJMIF), high-energy-density plasmas, astrophysical phenomena, and other laboratory plasmas. The initial results obtained using this approach are in agreement with the preliminary outcomes of the Plasma Liner Experiment (PLX).