Colliding of two high Mach-number quantum degenerate plasma jets

TL;DR

This study investigates the collision dynamics of high Mach-number quantum degenerate plasma jets using first-principle kinetic simulations, revealing an optimal velocity for maximum density compression relevant to fusion and astrophysics.

Contribution

It provides the first detailed kinetic analysis of high Mach-number quantum plasma jet collisions, highlighting the non-monotonic relationship between Mach number and density compression.

Findings

Density compression decreases at very high Mach numbers due to kinetic effects.

An optimal Mach number exists for maximum plasma compression.

Results inform the design of inertial confinement fusion experiments and astrophysical models.

Abstract

Colliding of two high Mach-number quantum degenerate plasmas is one of the most essential components in the double-cone ignition (DCI) inertial confinement fusion scheme, in which two highly compressed plasma jets from the cone-tips collide along with rapid conversion from the colliding kinetic energies to the internal energy of a stagnated isochoric plasma. Due to the effects of high densities and high Mach-numbers of the colliding plasma jets, quantum degeneracy and kinetic physics might play important roles and challenge the predictions of traditional hydrodynamic models. In this work, the colliding process of two high Mach number quantum degenerate Deuterium-plasma jets with sizable scale ($\sim 1000\ \si{\mu m}$, $\sim 300\ \si{ps}$, $\sim 100\ \si{g/cc}$, $\sim 300\ \si{km/s}$) were investigated with first-principle kinetic simulations and theoretical analyses. In order to achieve high-density compression, the colliding kinetic pressure should be significantly higher than the pressure raised by the quantum degeneracy. This means high colliding Mach numbers are required. However, when the Mach number is further increased, we surprisingly found a decreasing trend of density compression, due to kinetic effects. It is therefore suggested that there is theoretically optimal colliding velocity to achieve the highest density compression. Our results would provide valuable suggestions for the base-line design of the DCI experiments and also might be of relevance in some violent astrophysical processes, such as the merger of two white dwarfs.