Observation of Rayleigh-Taylor-Instability Evolution in a Plasma with Magnetic and Viscous Effects

TL;DR

This study observes the evolution of Rayleigh-Taylor instability in a plasma, highlighting the roles of magnetic and viscous effects in its growth and stabilization, supported by experimental data and simulations.

Contribution

First time time-resolved observations of RTI evolution in a plasma with magnetic and viscous effects, supported by theoretical estimates and simulations.

Findings

RTI growth time around 10 microseconds

Mode wavelength nearly doubles within linear growth time

Magnetic and viscous effects influence RTI evolution

Abstract

We present time-resolved observations of Rayleigh--Taylor-instability (RTI) evolution at the interface between an unmagnetized plasma jet colliding with a stagnated, magnetized plasma. The observed instability growth time ($\sim 10$~$\mu$s) is consistent with the estimated linear RTI growth rate calculated using experimentally inferred values of density ($\sim 10^{14}$~cm$^{-3}$) and deceleration ($\sim 10^9$~m/s$^2$). The observed mode wavelength ($\gtrsim 1$~cm) nearly doubles within a linear growth time. Theoretical estimates of magnetic and viscous stabilization and idealized magnetohydrodynamic simulations including a physical viscosity model both suggest that the observed instability evolution is subject to magnetic and/or viscous effects.