Tendency of spherically imploding plasma liners formed by merging plasma jets to evolve toward spherical symmetry

TL;DR

This study uses 3D hydrodynamic simulations to show that plasma liners formed by merging discrete jets tend to become spherical and uniform during implosion, despite initial non-uniformities and instabilities.

Contribution

It demonstrates that plasma liners formed from discrete jets evolve toward spherical symmetry and are robust against Rayleigh-Taylor instability, confirmed by multiple simulation methods.

Findings

Discrete jets lead to nearly uniform plasma liners during implosion.

Liner formation is robust against Rayleigh-Taylor instability.

Mixing rates remain low until after peak compression.

Abstract

Three dimensional hydrodynamic simulations have been performed using smoothed particle hydrodynamics (SPH) in order to study the effects of discrete jets on the processes of plasma liner formation, implosion on vacuum, and expansion. The pressure history of the inner portion of the liner was qualitatively and quantitatively similar from peak compression through the complete stagnation of the liner among simulation results from two one dimensional radiationhydrodynamic codes, 3D SPH with a uniform liner, and 3D SPH with 30 discrete plasma jets. Two dimensional slices of the pressure show that the discrete jet SPH case evolves towards a profile that is almost indistinguishable from the SPH case with a uniform liner, showing that non-uniformities due to discrete jets are smeared out by late stages of the implosion. Liner formation and implosion on vacuum was also shown to be robust to Rayleigh-Taylor instability growth. Interparticle mixing for a liner imploding on vacuum was investigated. The mixing rate was very small until after peak compression for the 30 jet simulation.