Design of 7.8 MJ 4 GeV Pb++ heavy ion inertial fusion energy driver

A 7.8 MJ 4 GeV Pb⁺⁺ heavy ion (HI) inertial fusion energy (IFE) driver operating at 3.5 Hz has been designed for a prototype 1000 MW thermonuclear power plant planned early in the next century. The HI driver design is based upon a short, ramped gradient (5 MeV) LINAC followed by a longer (~2 km) constant gradient, single beam LINAC operated in a 50 kHz burst mode to generate sequentially eighteen 4 GeV beamlets. A 2-sided irradiation geometry is provided for indirect-drive HI targets. Six beamlets generate the 30 ns precursor HI pulses and are accumulated in 2 superconducting storage rings (SCSRs). Twelve SCSRs accumulate 12 main beamlets with a final buncher generating 8 ns pulses. Ballistic foci of triplet focusing magnets pass through a Pb-vapor neutralization cell onto two Pb stripping jets permit 2-sided, self-pinched propagation through two small openings in the HI TC blanket. HI beam foci ~0.6 cm diameter were estimated, including the effects of beam emittance and residual space charge. Self-pinched HI beam transport in preformed channels greatly simplifies target chamber (TC) shielding and increases blanket coverage