Design descriptions of the Prometheus-L and -H inertial fusion energy drivers

Abstract

Abstract Two innovative drivers have been designed for a prototype 1000 MW thermonuclear power plant planned for operation early in the next century. The Prometheus-L driver is a 4 MJ KrF master oscillator power amplifier laser system designed to operate at a 5.6 Hz repetition rate. Output pulses from the KrF master oscillator are synchronized with the pulsed-power excitation of the KrF power amplifiers and the launching of the inertial fusion energy (IFE) deuterium/tritium targets. The Prometheus-L laser architecture features 960 5 kJ electric discharge KrF power amplifiers pumping 60 crossed stimulated rotational Raman scattering H 2 amplifiers serving as beam accumulators. Pulse compression of the 60 accumulator beams is accomplished in 60 chirped, self-seeded SF 6 stimulated Brillouin scattering pulse compressors. Grazing incidence metal focusing mirrors minimize back-streaming radiation damage from the target chamber. This architecture permits the laser driver to deliver spectrally broad-band, temporally complex optical pulses in 60 beam lines to implode the direct-drive IFE targets within a 5 m radius target chamber. The Prometheus-H driver is a 7.8 MJ 4 GeV Pb ++ heavy ion (HI) inertial fusion energy system designed to operate at a 3.5 He repetition rate. The HI driver design is based on a short, ramped gradient, 5 MeV accelerator, followed by a longer, 2 km constant gradient, single beam linear accelerator operated in a 50 kHz burst mode to generate sequentially 18 4 GeV beamlets. A two-sided irradiation geometry was developed for indirect-drive HI targets. Six beamlets are used for the 45 ns precursor HI pulses stored in two superconducting storage rings, 12 superconducting storage rings accumulate the 12 main beamlets, with a final buncher generating the 8 ns HI pulses which arrive at the target chamber simultaneously. Final focusing is accomplished with large aperture triplet focusing magnets through Pb-vapor neutralization cells to reduce the effect of space charge, ballistically focusing onto two Pb stripping jets to create self-pinched Pb +82 beams which propagate along two preformed channels through two small openings in the HI target chamber blanket.