Instabilities in cylindrical plasma liners imploded by high magnetic fields

It has been predicted theoretically and demonstrated experimentally that the hydromagnetic Rayleigh-Taylor instability is present in some devices in which plasma cylinders are imploded by high current. It has also been observed that this instability is less damaging for implosions of cylindrical gas puffs than for implosions of cylindrical foils. In this presentation we show that this instability is different for foils, which correspond to thin shells of high aspect ratio, than it is for gas puffs, which have a very low aspect ratio. We, furthermore, relate this to recent work in which the effects of the Rayleigh-Taylor instability in thin foils are related to load design parameters. We find that the improved stability of gas puffs allow larger radius implosions with higher implosion velocities. Finally, we show that a hybrid system with a uniform density gas inside a cylindrical foil offers much of the stability of gas puffs together with the uniformity and low inductance of a foil system