107-A load-current B-dot monitor: Simulations, design, and performance

Abstract

A B-dot monitor that measures the current 6cm from the axis of dynamic loads fielded on 107-A multiterawatt pulsed-power accelerators has been developed. The monitor improves upon the multimegampere load-current gauge described in Phys. Rev. ST Accel. Beams 11, 100401 (2008)PRABFM1098-440210.1103/ PhysRevSTAB.11.100401. The design of the improved monitor was developed using three-dimensional particle-in-cell simulations that model vacuum electron flow in the transmission line near the monitor. The simulations include important geometric features of the B-dot probe and model the deposition of electron energy within the probe. The simulations show that the improved design reduces by as much as a factor of 5 the electron energy deposition to the interior of the monitor. Data taken on accelerator shots demonstrate that the improved monitor works as well as the original monitor on shots with low-impedance loads, and delivers superior performance on higher-impedance-load shots. © 2010 The American Physical Society.