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 /spl ges/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, /spl eta//sub t/, under realistic constraints on diode operation, beam transport, and packing. Target design considerations suggest that the instantaneous power efficiency, /spl Gamma//sub 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 /spl eta//sub t/ for an LMF design using ballistic transport with solenoidal lens focusing. Results indicate that tuning the power pulse to maximize /spl Gamma//sub t/ at about three-quarters through the pulse provides high power efficiency at the end of the pulse while still maintaining high /spl eta//sub t/. In addition to power efficiency tuning, effects on /spl eta//sub t/ from variations of the diode impedance model and the diode voltage waveform are also examined.<
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