Plasma Physics HEC Consortium

Lead Research Organisation: University of Warwick
Department Name: Physics

Abstract

Plasma physics is the study of the properties of ionised gases. The processes, which need to be investigated, cover kinetic theory of matter far from its equilibrium state, fluid dynamics of magnetised and conductive plasmas and the interaction of these across a huge range of time and length scales, often in complex geometries. Such problems are rarely tractable analytically and thus much of plasma physics relies on High End Computing (HEC) to perform massive simulations.

This HEC Consortium will cover all aspects of computational plasma physics. This includes modelling for magnetic confinement fusion (MCF) devices to optimize reactor performance, simulations to optimize laser-particle accelerator sources, novel approaches to high-intensity laser-plasma experiments and laser-driven fusion. In all these areas HEC resources are needed for simulations which are essential to either guide experiments and research programmes (including providing a reliable predictive capability for the performance of future plasma facilities) or to interpret the complex diagnostic sets from coupled multi-scale, non-linear and often relativistic processes.

To help maintain the UK's leading role in fusion reactor design and basic plasma physics the HEC Consortium requires a block allocation of UK National level computing resource, so called Tier-1 HEC. This will ease the access to such facilities and allow the UK to collectively plan computational programmes, which will require many years to complete, in the certainty that the computing resources will be available. Over the four-year duration of this HEC Consortium computer architectures may change and optimising codes for current and future machines is therefore essential. In addition, new physics packages must be developed and implemented to keep the UK at the cutting edge of this research. The Consortium therefore also requires funding for software development to exploit the computing resources and keep codes world-leading.

Applications of the scientific research enabled by the combination of Tier-1 HEC and software support are diverse. Much of the research of the Consortium will be directed at improving reactor designs for fusion power. This is both MCF and laser fusion energy (IFE). For the former the HEC will concentrate on understanding how energy is transported from the hot plasma core and managing the extreme heat loads incident on surrounding walls. IFE's primary challenge is achieving laser-driven fusion by mitigating non-uniformities in the fuel pellet implosion, understanding the generation of fast-electrons which may prevent fusion and designing novel approached to fusion, e.g. shock or fast ignition schemes. Laser-driven plasma accelerators and radiation sources have many forms, ranging from laser-irradiated solids to compact capillary discharges; with applications including fast-ignition based laser fusion, ion sources for radiotherapy and compact ultrafast x-ray sources for penetrative probing.

Planned Impact

A major driver of the development of laser-driven accelerators is contributing to a reduction in deaths due to cancer through better diagnosis and treatment. Besides offering a reduction in the cost and footprint of particle therapy centres, leading to more widespread availability of particle therapy, a laser-driven approach to particle therapy and radiotherapy offers a number of clinical advantages that will form the basis of new IP emerging from the project. Laser-driven technology can also transform the production of medical radioisotopes impacting on both the production of radiopharmaceuticals for medical imaging and radionuclide therapeutics for cancer treatment. The impact of laser-driven sources will also be realised in a number of additional sectors, including measurement science, laser research, energy, security and space electronics.

In the longer term the HEC project feeds into the international plans to develop fusion energy systems this century. If successful these reactors have the potential to change the world energy market, freeing us from the constraints of fossil fuel supply and directly addressing the problems of electricity supply without carbon dioxide emission. For the UK, this could also guarantee a security of energy supply independent of regions that currently control the fossil fuel market.

Research into basic plasma physics, high-energy density science, radiation-hydrodynamics and optimising codes for HEC systems will be of direct benefit to researchers at AWE. Many members of the laser-plasma community have close links with AWE on research areas of joint interest. This will itself assist AWE in its role in ensuring national nuclear security.

The Consortium will also increase the skill base of UK computational plasma physics. This will be through PhDs and PDRAs who are trained in the use of leading plasma codes and the use of the UK national HPC facility ARCHER. A cohort of new PhD students and PDRAs will be trained through the collaborating Universities in a culture of state-of-the-art software development and HEC. For most major codes this involves expertise in working with a large development team distributed around the world. Many will then choose to take the portable skills acquired from this valuable experience into UK industry, where there is strong demand for individuals with experience in HEC.

Publications

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Description Identified the importance of modelling focused laser speckles over plane waves when evaluating laser-plasma interactions. This has implications for all laser-plasma studies relevant for fusion and defines the way forward for this research.

Simulations of intense laser beams travelling through plasma have shown that two co-propagating short duration pulses, each of a different colour and arranged to produce an intensity pattern shaped like a rotating helical spring, can leave behind a strong magnetic field approaching 100 Tesla. This work is also an example of the new phenomena and possibilities that are actively being opened up in the quest to understand and harness intense twisted light.

Beams of energetic ions are highly effective for oncology as well as being important tools in science and industry. A programme of simulations using the EPOCH code running on the ARCHER high performance computer has resulted in much greater understanding of the fundamental physical mechanisms that give rise to ion acceleration in high intensity laser pulse interactions with ultrathin foils. This new insight into the underlying physics in turn has led to continual improvements in the design and interpretation of experiments, resulting in the recent demonstration of near-100 MeV protons.

We are exploring how electron injection in the laser-plasma wakefield accelerator can be controlled to produce, unprecedented, ultra-short bunches. We have shown that controlling self-injection by modulating the plasma density can result in electron bunches with durations of the order of 100 attoseconds. These unique electron bunches may be useful for ultra-fast imaging, to drive free-electron lasers to produce ultra-short X-ray pulses, or for time-resolved investigations of beam-matter interactions on unprecedented time scales.
Exploitation Route Work on laser-plasma interactions is been taken up at national laboratories and fusion facilities to improve fusion yield. The ion acceleration work is now in collaboration with medical researchers and the use of electron bunches for imaging is being exploited in experiments in collaboration with industry at RAL.
Sectors Education,Energy,Healthcare

 
Title Release of GS2 Code v8.0.1 
Description GS2 is a physics application, developed to study low-frequency turbulence in magnetized plasma. It is typically used to assess the microstability of plasmas produced in the laboratory and to calculate key properties of the turbulence which results from instabilities. It is also used to simulate turbulence in plasmas which occur in nature, such as in astrophysical and magnetospheric systems. 
Type Of Technology Software 
Year Produced 2019 
Open Source License? Yes  
Impact GS2 is one of the pioneering gyrokinetic codes used for the study of plasma turbulence in magnetically confined plasmas, and the code continues to be developed and widely used for state-of-the-art plasma turbulence calculations. GS2 has recently been transferred from svn to git and installed in a new and more functional repository at bitbucket. Adoption of CI improves the software's sustainability, and this first release from the new repository includes a range of bug fixes and other code improvements. 
URL https://zenodo.org/record/2551067