Transport efficiency studies for light-ion inertial confinement fusion systems using ballistic transport with solenoidal lens focusing

The proposed Laboratory Microfusion Facility (LMF) will require ⩾10 MJ of 30 MeV lithium ions to be transported and focused onto high-gain, high-yield inertial confinement fusion targets. The light-ion LMF approach uses a multimodular system with individual ion extraction diodes as beam sources. Previous work examined the effect of time-of-flight bunching on energy transport efficiency, η_t, under realistic constraints on diode operation, beam transport, and packing. Target design considerations suggest that the instantaneous power efficiency, Γ_t, be maximized near peak power, Because of time-of-flight bunching, peak power occurs at the end of the power pulse for LMF designs. This work examines the effect of power efficiency tuning on η_t for an LMF design using ballistic transport with solenoidal lens focusing. Results indicate that tuning the power pulse to maximize Γ_t at about three-quarters through the pulse provides high power efficiency at the end of the pulse while still maintaining high η_t. In addition to power efficiency tuning, effects on η_t from variations of the diode impedance model and the diode voltage waveform are also examined