Beam breakup in a solid-state powered linear induction accelerator

Abstract

Scorpius is a new multi-pulse linear induction accelerator (LIA) for flash radiography of large-scale, explosivelydriven hydrodynamic experiments. It has been proposed to use solid-state pulsed-power modules to provide the accelerating voltages for Scorpius. It is expected that this approach can provide four programmable 50-kV accelerating pulses to a single gap. Cascading these to form an LIA to accelerate four injected 2-kA, 2-MeV electron-beam pulses to 20-MeV is proposed. Since this highcurrent accelerator will have more than five times the number of cells as present radiography LIAs, it is natural to be concerned about the beam-breakup (BBU) instability. This concern is addressed using one of our beam dynamics codes. The results of these early simulations are presented here. They indicate that BBU can be suppressed to the same level as in designs powered by conventional pulsed power, if the calculated cell impedance can be achieved in practice. The magnetic focusing field required for this is of the same order as the field required for a conventionally powered LIA if the transverse impedance can indeed be constrained to the values obtained in simulations of the cell.