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Using surrogate models to optimise designs for laser-driven fusion power production

tony2
Supervisors: Tony Arber, Tom Goffrey, Keith Bennett

THIS PROJECT IS NOW FILLED

Laser-plasma experiments in high-energy density physics (HEDP) and fusion research trigger kinetic scale instabilities whose effects must be included in large-scale fluid simulations. The difference in time and spatial scales between the kinetic and fluid models, along with the cost of the kinetic modelling, have hindered the full inclusion of important kinetic processes in laser-driven fusion simulations. It is critical for the design and interpretation of experiments that this is solved. This project aims to develop a surrogate model for the kinetic processes suitable for including in fluid scale simulations.

Laser-plasma experiments in high-energy density physics (HEDP) and fusion research trigger kinetic scale instabilities whose effects must be included in large-scale fluid simulations. The kinetic instabilities are three-wave parametric couplings which generate significant non-thermal electron populations. These so called hot-electrons can propagate deeper into the target than the driving laser and alter the hydrodynamic compression. This can hinder the interpretation of HEDP experiments and possibly prevent the level of compression required for a successful laser-fusion experiment. Three-wave laser-plasma interactions (LPI) have been studied for over 50 years but only recently have realistic simulations been possible which match observations.

Warwick is the lead developer of the EPOCH code which is currently being used to perform (world leading) LPI simulations but this can only be run for pico-second time-scales and requires large National HPC resources. The fluid time-scale is on nano-seconds and thus a coupling of these processes requires deriving a suitable surrogate model for the LPI appropriate for specific experimental configurations which can be included in radiation hydrodynamics simulations. Warwick is also the developer of the UK Odin code which is an arbitrary Lagrangian-Eulerian radiation hydrodynamics code for HEDP and fusion. This project will develop the multi-scale modelling required for coupled EPOCH-Odin simulations able to interpret experiments which are dominated by two-plasmon decay and stimulated Raman scattering LPIs.

Detailed wave-particle coupling analysis from the EPOCH code required to interpret fusion relevant laser-plasma interactions.
From Seaton & Arber, Physics of Plasmas, 082704 (2020).