The FI-HEDP group conducts research in the basic science of fast ignition and short-pulse high-intensity laser-plasma interaction physics. Fast ignition is an alternate approach to achieving thermonuclear fusion to that being taken by the National Ignition Facility. The NIF achieves ignition densities and temperatures through the simultaneous compression and heating of a spherical fuel capsule in an implosion. In the fast ignition approach these phases are separated—compression of the fuel is achieved through an implosion, but the heating of a hot spot to ignition temperatures of 5-10 keV is accomplished through a separate high-intensity ultrashort-pulse laser. The fast ignition approach holds the promise of reduced laser driver energy and increased fusion energy gains, exceeding gains of 100, and thus offers a potentially attractive pathway toward an eventual inertial fusion energy plant.
In the electron cone-guided fast ignition scheme a high-energy relativistic intensity laser pulse generates an intense fast electron beam close to the centre of an imploding fuel capsule. The fast electrons heat a small region of the compressed core to achieve ignition and propagating burn. The FI-HEDP group is developing state-of-the-art simulation tools to study the complex physics underpinning the fast ignition process.
The 192-beam National Ignition Facility will enable the first experiments to study fast ignition using the full-scale hydrodynamic fuel assembly required for ignition. One quad of NIF beams is undergoing conversion to high-intensity picosecond-duration pulses to provide an Advanced Radiographic Capability (ARC). These beams will also provide up to 10 kJ in a 5 ps pulse that can be used as a sub-scale ignitor pulse to study fast electron core heating in integrated fast ignition experiments.
Fast Ignition at Titan
Interior view of TITAN target chamber. The TITAN laser, part of the Jupiter Laser Facility at LLNL, combines a 200J, 500fs short-pulse beam with a 1kJ, 3ns long-pulse beam.