Fast ignition studies at Sandia National Laboratories

Sandia National Laboratories is developing a combination of experimental and theoretical capabilities useful for the study of fast ignition physics. Pulsed power machines such as the present Z machine have demonstrated the ability to drive inertial fusion implosions. The Z-beamlet laser is currently being used to create multi-kiloelectronvolts photons for backlighting, which can be used to diagnose the compression of deuterium/tritium to high densities. A high-energy petawatt capability is presently being added to the Z-beamlet to extend the backlighting x-ray energy up to 10-50 keV and to enable integrated fast ignition experiments. We are also developing a capability to implode capsules filled with liquid deuterium/tritium, which avoids the stringent temperature control required for beta-layered capsules. In preparation for such experiments, the theory group at Sandia is modelling various aspects of fast ignition physics. Numerical simulations of laser/plasma interaction, electron transport and ion generation are being performed. Simulations of the compression of deuterium/tritium fuel in various geometries are being performed. Analytic and numerical modelling has been performed to determine the conditions required for fast ignition breakeven scaling. These results indicate that breakeven will require about 5% of the laser energy needed for ignition and might be an achievable goal with an upgraded Z-beamlet laser in short pulse mode.