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

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.