A conceptual design for an LMF accelerator module

The US Department of Energy has initiated a design study of a Laboratory Microfusion Facility (LMF) that will be used to develop high-gain ICF (inertial confinement fusion) targets. A conceptual design for a light ion beam accelerator, has been developed for a multimodule LMF system based on technology demonstrated on Sandia´s Hermes-III accelerator. The LMF accelerator module incorporates 32 linear induction cavities, each operating at 1 MV, to produce an output voltage pulse that ramps from 27 to 32 MV with a peak current of 1.2 MA. The power for the accelerator module is derived from 16 Marx generators that drive 128 4-Ω, 54-ns pulse forming lines (PFLs). Four PFL pulses are combined in each inductive cavity. Nanosecond synchronization of the PFL output pulses is accomplished using KrF-laser-triggered output gas switches and low jitter, self-breakdown water switches. The outputs of the cavities are added in a magnetically insulated transmission line and then delivered to an extraction ion diode. Singly ionized lithium ions are accelerated in the diode. Voltage ramping is used to achieve power compression of the ion beam when ballistically drifted to the ICF target. An equivalent circuit has been developed to model the module from the Marx generator to the ion diode. The timing performance of the gas and water switches has been included in the model to calculate the resulting output waveform and system jitter