Fast Ignition Studies at Sandia National Laboratories

This talk will describe ongoing and planned fast ignition theoretical and experimental work using the Z-machine in concert with the upgraded Z-Beamlet/PW laser system. Z can produce x-ray powers of 100-250TW, x-ray energies 1-1.8MJ, and > 200eV radiation temperatures and thus represents an interesting platform for compressing large quantities of matter for use as fast ignition targets. Soon Z will undergo refurbishment, and the resulting parameters for Z-R are even more interesting. The Z-Beamlet system is currently undergoing short pulse conversion with the plan that Z-Beamlet/PW will deliver 0.5-2 kJ in 0.5-10 psec in FY07 when Z-R will be available. Numerical simulations of laser/plasma interaction, electron transport, and ion generation at relevant densities are being performed using LSP, a 3D implicit hybrid PIC code. LASNEX simulations of the compression of deuterium/tritium fuel in various reentrant cone geometries are being performed. Analytic and numerical modeling has been performed to determine the conditions required for fast ignition breakeven scaling. These theoretical results indicate that to achieve fusion output equal to the energy deposited by fast particles will require about 5% of the laser energy needed for ignition and might be an achievable goal (within a factor of 2) with Z-Beamlet/PW.