Two-dimensional modeling of magnetically driven Rayleigh–Taylor instabilities in cylindrical Z pinches

Abstract

A two-dimensional computational methodology has been developed that uses a phenomenological representation of initial perturbations to model the evolution of magnetically driven Rayleigh–Taylor instabilities in a hollow Z pinch. The perturbed drive current waveform and x-ray output obtained from the two-dimensional models differ qualitatively from the results of unperturbed (one-dimensional) models. Furthermore, the perturbed results reproduce the principle features measured in a series of capacitor bank-driven pulsed power experiments. In this paper we discuss the computational approach and the computational sensitivity to initial conditions (including the initial perturbations). Representative examples are also presented of instability evolution during implosions, and the results are compared with experimentally measured current waveforms and visible framing camera images of perturbed implosions. Standard magnetohydrodynamic modeling, which includes instability growth in two dimensions, is found to reproduce the features seen in experiments.