Stabilized Z-pinch loads with tailored density profiles

Abstract

We discuss the design of structured Z-pinch loads capable of mitigating the detrimental effect of Rayleigh-Taylor (RT) instability on the performance of fast Z-pinch devices used as plasma radiation sources. The stabilizing effects of density tailoring in both the radial and the axial directions are considered. Our 2-D numerical simulations demonstrate that using a structured gaseous load with a radial density profile specifically tailored for a given current wave form, it is possible to delay the onset of the RT instability development while a shock wave propagates through the load. Once the acceleration of the magnetic field/plasma interface is inverted, perturbations are shown to oscillate rather than to grow exponentially. Our simulation results indicate the possibility of high-quality implosions producing significant Ar K-shell yield from initial radii in the range between 4 and 8 cm, with current pulse duration of 250 ns and longer. Axial density tailoring can actually mitigate the RT instability, or even suppress it completely, at the expense of decreased hydrodynamic efficiency of acceleration. Seeking the best trade-off between stability and performance, it would be natural to combine the two approaches.