The Evolving Structure of Plasma Formed From the Surface of Aluminum Rods Driven to Megaampere Current

Plasma formation from thick Al rods ohmically heated during the diffusion of pulsed multimegagauss magnetic field is examined experimentally. Rods in the Z-pinch configuration are driven to 1.0-MA peak current. The evolution of the resultant surface plasma is complex yet highly reproducible. Surface plasmas first form at discrete hot spots. As the pulsed current grows, plasma filaments form, first along the current, and then transverse to it. As the plasma temperature rises, emissions become increasingly uniform until instabilities grow and modulate the surface.