Experimental Demonstration of the Stabilizing Effect of Dielectric Coatings on Magnetically Accelerated Imploding Metallic Liners

Abstract

Enhanced implosion stability has been experimentally demonstrated for magnetically accelerated liners that are coated with $70\mu \mathrm{m}$ of dielectric. The dielectric tamps liner-mass redistribution from electrothermal instabilities and also buffers coupling of the drive magnetic field to the magneto-Rayleigh-Taylor instability. A dielectric-coated and axially premagnetized beryllium liner was radiographed at a convergence ratio [$\mathrm{CR}=R_{\text{in},0}/R_{\text{in}}(z,t)$] of 20, which is the highest CR ever directly observed for a strengthless magnetically driven liner. The inner-wall radius $R_{\text{in}}(z,t)$ displayed unprecedented uniformity, varying from 95 to $130\mu \mathrm{m}$ over the 4.0 mm axial height captured by the radiograph.