Experimental Investigation of Sheared Flow Stabilization of Z-pinches

Abstract

The wire array z-pinch is an efficient x-ray source [1] which has been proposed for use in indirect drive inertial confinement fusion schemes [2]. The z-pinch can become a more efficient x-ray source if its stability is improved. Cylindrical wire array z-pinch experiments where the Rayleigh-Taylor instability was suppressed showed increased x-ray yield and power [1]; however the pressure driven MHD instabilities (sausage and kink instabilities) were still present and possibly limited the x-ray production of the pinch. Linear MHD calculations of z-pinch stability with an axial velocity shear predict that a supersonic axial flow with a radial gradient is capable of stabilizing the MHD instabilities [3][4][5]. A sheared flow can be introduced to a pinch by using a conical wire array with a fine metallic wire on axis [6]. The wire on axis will carry a fraction of the total current during the implosion which will cause the center wire to create a conducting plasma column while a flow passes over it. This presentation will compare the experimental results of a z-pinch with and without a sheared flow. From this comparison it will be shown that the sheared flow in these experiments has a stabilizing effect on the MHD instabilities present in the z-pinch plasma column.