Uncertainty quantification for Tokamak experimental analysis and reactor design

Calleja, Dominic
(2021) Uncertainty quantification for Tokamak experimental analysis and reactor design. PhD thesis, University of Liverpool.

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Society faces major challenges to ensuring the future sustainability of energy generation in the presence of climate change. The world is facing the need for a rapid decarbonisation of energy generation technologies. Current alternatives to satisfy the worlds growing energy demand, particularly wind and solar energy, suffer from low energy density generation. That is, the present options require large areas of land and consistent environmental conditions to reliably generate energy. Thermonuclear fusion promises an alternative solution that is both carbon neutral and offer high density generation with no dependence on the external environment. To realise this opportunity there are several technical challenges that must first be overcome. This is the enduring focus of nuclear fusion research. One of the main outstanding challenges to the realisation of thermonuclear fusion for energy generation is related to the power handling capacity of plasma facing components in fusion reactors. This challenge has two main components. The first is finding materials that can withstand the conditions inside fusion reactors. The second is to better understand those conditions to enhance the predictive capability of models that can be used to design future plasma facing components. The work of this thesis fits within that second class. Simplified edge physics models can be used to predict the power deposition of plasma facing components. These models are, however, generally deterministic. Yet the power deposition experienced by plasma facing components experiences significant stochastic variability. There is also a great deal of uncertainty in the characterisation of those plasma facing components power deposition characteristics. Several approaches to deal with uncertainties and to characterise the stochastic variability relating to the characterisation of power deposition in plasma facing components have been explored. This includes a full Bayesian analysis of uncertain parameters in deterministic simplified edge physics models. A novel approach is proposed to disentangle the effect of short duration transient edge localised modes and the steady state escape of power into the edge layer. This approach, as will be explored within the thesis, can be used to enhance understanding of experimental data and to predict power deposition on plasma facing components in future fusion devices. Finally a full stochastic model for the prediction of power deposition in the Joint European Torus is explored. This model includes the effect of the steady state escape of energised particles into the edge of the fusion plasma, the effect of transient events, the stochastic properties of each of these phenomena, and a model for the temporal dependence of these phenomena during a discharge.

Item Type: Thesis (PhD)
Divisions: Faculty of Science and Engineering > School of Engineering
Depositing User: Symplectic Admin
Date Deposited: 02 Sep 2022 10:25
Last Modified: 18 Jan 2023 20:46
DOI: 10.17638/03162873
  • Patelli, Edoardo
  • Arter, Wayne
URI: https://livrepository.liverpool.ac.uk/id/eprint/3162873