Systematically characterising the exotic material properties of weakly collisional plasmas

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£5,088,870

Sept. 25, 2022

Sept. 25, 2026

Many of the most challenging conundrums currently being addressed by frontier scientific research in astrophysics involve interactions between exotic objects of colossal sizes and/or energies, typically resulting in instances of extraordinary energy release:
- the electromagnetic fireworks accompanying black-hole mergers, which are now observable with the advent of gravitational- wave and multi-messenger astronomy;
- galaxy formation in clusters;
- accretion discs and jets, which are now serially observable by the Event Horizon radio-telescope network;
- gamma-ray and fast radio bursts; ultra-high-energy cosmic rays; and many other occurrences.
To model these phenomena, a key challenge is to have a detailed understanding of the dilute hot gas (known as `plasma') making up the astrophysical environments where these events occur.

Unsurprisingly, this plasma is believed to behave very differently to the gases we all encounter in everyday life, on account of being millions of degrees hotter, and one sextillionth the density! While this state of matter has been studied by physicists for nearly a century - most famously, in the contexts of stars and nuclear fusion energy research - there remain a number of surprisingly fundamental uncertainties about its properties: for example, how do plasmas conduct heat, and what is their viscosity? However, recent technological advances in both our computing capabilities and high-energy laser facilities mean that we can now investigate the behaviour of plasmas as never before in the laboratory and on supercomputers.

In this research project, I will be undertaking a systematic programme that will significantly advance our understanding of the fundamental properties of the type of plasma typically encountered in astrophysical environments (whose thermal energy exceeds their magnetic energy). More specifically, I will run numerical simulations with state-of-the-art codes to investigate several different characteristics: viscosity, thermal and electrical conductivity, and the spontaneous generation of charged particles with anomalously high energies. I am particularly interested in behaviours which depart markedly from conventional gases. I will then test theoretical frameworks developed in "laboratory astrophysics" experiments, which use lasers to realise extreme conditions on Earth with many similarities to relevant astrophysical environments.

In addition to the astrophysical observations, I am also interested in leveraging anomalous properties of magnetised plasmas to aid inertial confinement fusion (ICF) efforts. In ICF schemes, a small capsule of deuterium-tritium fuel is ignited using laser beams; if the scheme is successful, the resulting nuclear fusion reactions produce much more energy than initially applied with the lasers. At present, successful ICF schemes have not yet been achieved; however, I believe that significant improvements to current attempts could be attained by considered use of applied magnetic fields.