Two‐Dimensional Simulations of Foil Implosion Experiments on the Los Alamos Pegasus Capacitor Bank

A number of z‐pinch experiments have been conducted at Los Alamos on the Pegasus capacitor bank in which 2‐cm high, 5‐cm radius, thin foil loads were imploded with currents in excess of 3 MA. Two‐dimensional (2‐D) radiation mag‐netohydrodynamic (RMHD) simulations of these implosions have been performed to model the implosion dynamics and subsequent generation of an x‐ray pulse. Comparisons of the simulation instability development with visible light framing camera photographs show good agreement in wavelength and amplitude and illustrate the instability evolution from short to long wavelengths and a final disruption of the imploding plasma shell. The calculations also show good agreement with experimental timing and measured current and voltage waveforms, and also reproduce features characteristic of the x‐ray output. These include a broad pulsewidth, and the presence of multiple peaks and small time scale structures, features which cannot be reproduced by one‐dimensional (1‐D) models. X‐ray spectra obtai...