Long risetime pulsed power as a driver for magnetized experiments in high energy density physics

Experiments investigating basic plasma physics, inertial fusion and laboratory astrophysics in the high energy density regime detailed design and analysis. Recent work on the COBRA generator (1MA, 100ns) and the Bertha generator (1.1μs, 200kA) indicate that plasma acceleration in pulsed power experiments depends on the drive parameters, and so it becomes feasible to field experimental studies with specific requirements on the correct generator when options are available. Since the system evolution depends on the energy delivery timescale, long drive time (~1ms) experiments can be an advantage. ‘Steady-state’ conditions can be generated for magnetized flow and shock systems, and compression and implosion loads can take advantage of an energy-rich driver.

We present short circuit and initial plasma loads on a new 750 kA generator at UC San Diego. Rama is designed to have a risetime of ~1.2μs at peak current, but each of the 6 switches are triggered independently using a new spiral generator unit developed at Imperial College London. This provides significant pulse shaping abilities, and allows a arrange of loads including wires and liner loads to be driven. Gated XUV self-emission and interferometry data will be presented along with Thomson scattering, and these will be compared to 3D simulation work.