Photographic, magnetic, and interferometric measurements of current sheet canting in a pulsed electromagnetic accelerator

The propagation speed and canting angle of current sheets in a pulsed electromagnetic accelerator were measured using three different techniques: high-speed photography, magnetic field probes, and laser interferometry. Current sheet canting may have ad-verse effects on accelerator performance. The goal of the present work is to provide a database of cant-ing angles under a variety of experimental condi-tions. Eight different propellants (hydrogen, deu-terium, helium, neon, argon, krypton, xenon, and methane) were tested in a rectangular-geometry ac-celerator, at pressures ranging from 50-400 mTorr. The photographic, magnetic, and interferometric di-agnostics were used to infer the spatial configura-tion of the current sheet by measuring the its opti-cal emission, current density, and electron density, respectively. The three techniques gave qualitative agreement; the magnetic and interferometric mea-surements gave general quantitative agreement as well. The canting angle was found to depend o