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

高能密度物理（HEDP）中的激光等离子体实验和核聚变研究引发了动力学尺度不稳定性，其影响必须包括在大规模流体模拟中。动力学模型和流体模型在时间和空间尺度上的差异，以及动力学模型的成本，阻碍了在激光驱动聚变模拟中充分包含重要的动力学过程。解决这个问题对于实验的设计和解释是至关重要的。本项目旨在开发一种适合于流体尺度模拟的动力学过程替代模型。高能密度物理（HEDP）中的激光等离子体实验和核聚变研究引发了动力学尺度不稳定性，其影响必须包括在大规模流体模拟中。动力学不稳定性是三波参数耦合，产生显著的非热电子居群。这些所谓的热电子可以比驱动激光更深入地传播到目标中，并改变流体动力压缩。这可能会阻碍HEDP实验的解释，并可能阻止成功的激光聚变实验所需的压缩水平。三波激光等离子体相互作用（LPI）已经研究了50多年，但直到最近才有可能实现与观测相匹配的真实模拟。Warwick是EPOCH代码的主要开发者，该代码目前被用于执行（世界领先的）LPI模拟，但它只能在皮秒时间尺度上运行，并且需要大量的国家高性能计算资源。流体时间尺度以纳秒为单位，因此这些过程的耦合需要为LPI推导一个合适的替代模型，该模型适用于可包括在辐射流体动力学模拟中的特定实验配置。Warwick也是英国Odin代码的开发者，这是一个用于HEDP和聚变的任意拉格朗日-欧拉辐射流体动力学代码。该项目将开发耦合EPOCH-Odin模拟所需的多尺度模型，能够解释由双等离子体衰变和受激拉曼散射lpi主导的实验。

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.