Retrapping studies on RITS

Sandia National Laboratories (SNL) is developing intense sources for flash x-ray radiography. In collaboration with Mission Research Corporation, the Atomics Weapons Establishment, and Titan Pulsed Sciences Division, SNL has studied power flow into various electron beam diodes on the radiographic integrated test stand (RITS). Historically, high-impedance accelerators have driven radiographic loads with little excess power flow. However, a number of facilities now under design use lower impedance inductive voltage adder technology to drive these diodes, requiring control of the vacuum electron sheath flow. The diode configuration in this study uses a non-emitting field shaper or "knob" to redirect this excess electron flow away from the diode region. Experiments at SNL have demonstrated retrapping of sheath current along a magnetically insulated transmission line into a blade load. The goals of the experiments presented here were to assess power flow issues and to help benchmark the LSP particle-in-cell code used to design the experiment. Comparisons between LSP simulations and experimental data are presented.