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

Lead Research Organisation: University of Warwick
Department Name: Physics


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.

Planned Impact

Impact on Students. The primary impact will be on the 50+ PhD students trained by the Centre. They will be high-quality computational scientists who can develop and implement new methods for modelling complex systems in collaboration with scientists and end-users, who are comfortable working in interdisciplinary environments, have excellent communication skills and be well prepared for a wide range of future careers. The students will tackle and disseminate results from exciting PhD projects with strong potential for direct impact. Exemplar research themes we have identified together with our industrial and international partners: (i) design of electronic devices, (ii) catalysis across scales, (iii) high-performance alloys, (iv) direct drive laser fusion, (v) future medicine exploration, (vi) smart nanofluidic interfaces, (vii) composite materials with enhanced functionality, (viii) heterogeneity of underground systems.

Impact on Industry. Students trained by HetSys will make a significant impact on UK industry as they will be ideally prepared for R&D careers to help to address the skills shortage in science and engineering. They will be in high demand for their ability to (i) work across disciplines, (ii) perform calculations that come along with error estimates, and (iii) develop well-designed software that other researchers can readily use and modify which implements novel solutions to scientific problems. More generally, incorporating error bars into models to take account of incomplete data and insufficient models could lead to significantly enhanced adoption of materials modelling in industry, reducing trial and error, and costly/time-consuming R&D procedures. The global market for simulation software is expected to more than double from now to 2022 indicating a very strong absorptive capacity for graduates. Moreover, a recent European Materials Modelling Consortium report identified a typical eight-fold return on investment for materials modelling research, leading to cost savings of 12M Euros per industrial project.

Impact on Society. Scarcity of resources and high energy requirements of traditional materials processing techniques raise ever-increasing sustainability concerns. Limitations on jet engine fuel efficiency and the difficulties of designing materials for fusion power stations reflect the social and economic cost of our incomplete knowledge of how complex heterogeneous systems behave. High costs of laboratory investigations mean that theory must aid experiment to produce new knowledge and guidance. By training students who can develop the new methodology needed to model such issues, HetSys will support society's long term need for improved materials and processes.

There will also be a direct impact locally and regionally through engagement by HetSys in outreach projects. For example we will encourage CDT students to be involved with annual 'Inspire' residential courses at Warwick for Year 11 girls, which will show what STEM subjects are like at degree level. CDT students will present highlights from projects to secondary-school pupils during these courses and also visit local schools, particularly in areas currently under-represented in the student body, in coordination with relevant professional bodies.

Impact on collaboration. Our international partners have identified the same urgent challenges for computational modelling. We will build flourishing links with research institutes abroad with long term benefit on UK research via our links to computational science networks. Shared research projects will strengthen links between academic staff and industry R&D personnel and across disciplines. The work will also lead to accessible, robust and reusable software. The Centre will achieve cross-disciplinary academic impact on the physical and materials sciences, engineering, manufacturing and mathematics communities at Warwick and beyond, and on the generation of new ideas, insights and techniques.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/S022848/1 01/04/2019 30/09/2027
2588325 Studentship EP/S022848/1 04/10/2021 30/09/2025 Benjamin Gosling