Events in Physics
Duncan Barlow (University of Bordeaux): Optimization of Polar Direct Drive Illumination for Mega-Joule Laser Facilities
Abstract: I will present the use of Bayesian optimisation, gradient descent and genetic algorithms to produce improved laser parameters for polar direct drive. Laser inertial confinement fusion (ICF) now enters the regime of ignition, the next step is higher energy yield which requires coupling more energy to the target. Laser direct drive achieves improved coupling as there is no hohlraum acting as an intermediary. However, the mega-joule laser facilities (National Ignition Facility and Laser Mega-Joule) are configured with beams entering at the poles for indirect drive, and so require beam re-pointing to recover a direct-drive compatible illumination. A polar direct drive scheme has already been tested on the NIF, however the irradiation configuration may not be optimal. The National Ignition Facility features: 8 cones of quads with independent wavelength tuning; 48 quads entering from different ports with independent pointing, power balance and defocusing; and the quads may be split to 192 beams with individual pointing offsets. There is a large parameter space which likely features different optimal setups for solid target illumination, conventional hotpot ignition, and shock ignition.