F. J. Casson
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View article: Validation and predictions of reduced models for stochastic electron transport in MAST and MAST-U
Validation and predictions of reduced models for stochastic electron transport in MAST and MAST-U Open
Magnetic stochastic perturbations can strongly influence cross-field transport in high β tokamak plasmas. The impact of stochastic magnetic fields on electron heat transport in MAST/MAST-U is studied over a range in collisionality. The phy…
View article: WEST L-mode record long pulses guided by predictions using Integrated Modeling
WEST L-mode record long pulses guided by predictions using Integrated Modeling Open
A new record was set on the WEST Tokamak, designed to operate long duration plasmas in a tungsten (W) environment, with an injected energy of and a plasma duration . Scenario development was supported by integrated modeling using…
View article: Transport and confinement physics: Chapter 2 of the special issue: on the path to tokamak burning plasma operation
Transport and confinement physics: Chapter 2 of the special issue: on the path to tokamak burning plasma operation Open
Progress in physics understanding and theoretical model development of plasma transport and confinement (TC) in the ITPA TC Topical Group since the publication of the ITER Physics Basis (IPB) document (Doyle et al 2007 Nucl. Fusion 47 S18)…
View article: Full radius integrated modelling of ohmic ramp-up at TCV including self consistent density prediction
Full radius integrated modelling of ohmic ramp-up at TCV including self consistent density prediction Open
The ramp-up is a critical phase in the operations of a Tokamak, during which engineering and physics aspects must be taken into account to ensure stability, minimize flux consumption and avoid disruptions. Predicting ramp-up phases faces c…
View article: A quasi-linear model of electromagnetic turbulent transport and its application to flux-driven transport predictions for STEP
A quasi-linear model of electromagnetic turbulent transport and its application to flux-driven transport predictions for STEP Open
A quasi-linear reduced transport model is developed from a database of high- $\beta$ electromagnetic nonlinear gyrokinetic simulations performed with spherical tokamak for energy production (STEP) relevant parameters. The quasi-linear mode…
View article: Duqtools: Dynamic uncertainty quantification for Tokamak reactor simulations modelling
Duqtools: Dynamic uncertainty quantification for Tokamak reactor simulations modelling Open
Large scale validation and uncertainty quantification are essential in the experimental design, control, and operations of fusion reactors. Reduced models and increasing computational power means that it is possible to run many simulations…
View article: Validation of prediction capability of operating space for plasma initiation in MAST-U
Validation of prediction capability of operating space for plasma initiation in MAST-U Open
DYON is a plasma initiation modelling code that solves the differential equation system of the full circuit equations (plasma current, active coil currents and eddy currents in full passive structures) and 0D global energy and particle bal…
View article: Controlling a new plasma regime
Controlling a new plasma regime Open
Success of the UK’s Spherical Tokamak for Energy Production (STEP) programme requires a robust plasma control system. This system has to guide the plasma from initiation to the burning phase, maintain it there, produce the desired fusion p…
View article: Flat-top plasma operational space of the STEP power plant
Flat-top plasma operational space of the STEP power plant Open
STEP is a spherical tokamak prototype power plant that is being designed to demonstrate net electric power. The design phase involves the exploitation of plasma models to optimise fusion performance subject to satisfying various physics an…
View article: Plasma control for the step prototype power plant
Plasma control for the step prototype power plant Open
In 2019 the UK launched the Spherical Tokamak for Energy Production (STEP) programme to design and build a prototype electricity producing nuclear fusion power plant, aiming to start operation around 2040. The plant should lay the foundati…
View article: A quasi-linear model of electromagnetic turbulent transport and its application to flux-driven transport predictions for STEP
A quasi-linear model of electromagnetic turbulent transport and its application to flux-driven transport predictions for STEP Open
A quasi-linear reduced transport model is developed from a database of high-$β$ electromagnetic nonlinear gyrokinetic simulations performed with Spherical Tokamak for Energy Production (STEP) relevant parameters. The quasi-linear model is …
View article: Multi-Objective Bayesian Optimization for Design of Pareto-Optimal Current Drive Profiles in STEP
Multi-Objective Bayesian Optimization for Design of Pareto-Optimal Current Drive Profiles in STEP Open
The safety factor profile is a key property in determining the stability of tokamak plasmas. To design the safety factor profile in the United Kingdom's proposed Spherical Tokamak for Energy Production (STEP), we apply multi-objective Baye…
View article: On electromagnetic turbulence and transport in STEP
On electromagnetic turbulence and transport in STEP Open
In this work, we present first-of-their-kind nonlinear local gyrokinetic (GK) simulations of electromagnetic turbulence at mid-radius in the burning plasma phase of the conceptual high- β , reactor-scale, tight-aspect-ratio tokamak Spheric…
View article: Gaussian process surrogate models for the properties of micro-tearing modes in spherical tokamaks
Gaussian process surrogate models for the properties of micro-tearing modes in spherical tokamaks Open
Spherical tokamaks (STs) have many desirable features that make them a suitable choice for fusion power plants. To understand their confinement properties, accurate calculation of turbulent micro-instabilities is necessary for tokamak desi…
View article: Validated edge and core predictions of tungsten erosion and transport in JET ELMy H-mode plasmas
Validated edge and core predictions of tungsten erosion and transport in JET ELMy H-mode plasmas Open
Predictive edge and core simulations of tungsten (W) erosion and transport in JET ITER-like wall plasmas are shown to be consistent with the experimentally inferred W density in the main plasma, within the uncertainty inherited from the me…
View article: Conceptual design workflow for the STEP Prototype Powerplant
Conceptual design workflow for the STEP Prototype Powerplant Open
The STEP (Spherical Tokamak for Energy Production) Programme aims to deliver a UK prototype fusion energy plant, targeting 2040, and a path to commercial viability of fusion. To deliver on this aim, we have performed initial scoping to ide…
View article: Efficient training sets for surrogate models of tokamak turbulence with Active Deep Ensembles
Efficient training sets for surrogate models of tokamak turbulence with Active Deep Ensembles Open
Model-based plasma scenario development lies at the heart of the design and operation of future fusion powerplants. Including turbulent transport in integrated models is essential for delivering a successful roadmap towards operation of IT…
View article: Gaussian process regression models for the properties of micro-tearing modes in spherical tokamaks
Gaussian process regression models for the properties of micro-tearing modes in spherical tokamaks Open
Spherical tokamaks have many desirable features that make them an attractive choice for a future fusion power plant. Power-plant viability is intrinsically related to plasma heat and particle confinement, and this is often determined by th…
View article: Overview of interpretive modelling of fusion performance in JET DTE2 discharges with TRANSP
Overview of interpretive modelling of fusion performance in JET DTE2 discharges with TRANSP Open
In the paper we present an overview of interpretive modelling of a database of JET-ILW 2021 D-T discharges using the TRANSP code. The main aim is to assess our capability of computationally reproducing the fusion performance of various D-T…
View article: Tungsten accumulation during ion cyclotron resonance heating operation on WEST
Tungsten accumulation during ion cyclotron resonance heating operation on WEST Open
The observation of radiative collapses during ion cyclotron resonance heating (ICRH) operation on the full tungsten WEST tokamak constitutes a unique opportunity to get a quantitative balance of the sources and sinks in the core region of …
View article: Electromagnetic gyrokinetic instabilities in STEP
Electromagnetic gyrokinetic instabilities in STEP Open
We present herein the results of a linear gyrokinetic analysis of electromagnetic microinstabilites in the conceptual high reactor-scale, tight-aspect-ratio tokamak Spherical Tokamak for Energy Production, https://step.ukaea.uk . We exami…
View article: Efficient training sets for surrogate models of tokamak turbulence with Active Deep Ensembles
Efficient training sets for surrogate models of tokamak turbulence with Active Deep Ensembles Open
Model-based plasma scenario development lies at the heart of the design and operation of future fusion powerplants. Including turbulent transport in integrated models is essential for delivering a successful roadmap towards operation of IT…
View article: The JET hybrid scenario in Deuterium, Tritium and Deuterium-Tritium
The JET hybrid scenario in Deuterium, Tritium and Deuterium-Tritium Open
The JET hybrid scenario has been developed from low plasma current carbon wall discharges to the record-breaking Deuterium-Tritium plasmas obtained in 2021 with the ITER-like Be/W wall. The development started in pure Deuterium with refine…
View article: Modelling performed for predictions of fusion power in JET DTE2: overview and lessons learnt
Modelling performed for predictions of fusion power in JET DTE2: overview and lessons learnt Open
For more than a decade, an unprecedented predict-first activity has been carried in order to predict the fusion power and provide guidance to the second Deuterium–Tritium (D–T) campaign performed at JET in 2021 (DTE2). Such an activity has…
View article: Validation of D–T fusion power prediction capability against 2021 JET D–T experiments
Validation of D–T fusion power prediction capability against 2021 JET D–T experiments Open
JET experiments using the fuel mixture envisaged for fusion power plants, deuterium and tritium (D–T), provide a unique opportunity to validate existing D–T fusion power prediction capabilities in support of future device design and operat…
View article: Multi-objective Bayesian optimization for design of Pareto-optimal current drive profiles in STEP
Multi-objective Bayesian optimization for design of Pareto-optimal current drive profiles in STEP Open
The safety factor profile is a key property in determining the stability of tokamak plasmas. To design the safety factor profile in the United Kingdom's proposed Spherical Tokamak for Energy Production (STEP), we apply multi-objective Baye…
View article: Gaussian Process Regression models for the properties of micro-tearing modes in spherical tokamak
Gaussian Process Regression models for the properties of micro-tearing modes in spherical tokamak Open
Spherical tokamaks (STs) have many desirable features that make them an attractive choice for a future fusion power plant. Power plant viability is intrinsically related to plasma heat and particle confinement and this is often determined …
View article: On electromagnetic turbulence and transport in STEP
On electromagnetic turbulence and transport in STEP Open
In this work, we present first-of-their-kind nonlinear local gyrokinetic simulations of electromagnetic turbulence at mid-radius in the burning plasma phase of the conceptual high-$β$, reactor-scale, tight-aspect-ratio tokamak STEP (Spheri…
View article: Electromagnetic gyrokinetic instabilities in STEP
Electromagnetic gyrokinetic instabilities in STEP Open
We present herein the results of a linear gyrokinetic analysis of electromagnetic microinstabilites in the conceptual high-$β$, reactor-scale, tight-aspect-ratio tokamak STEP (Spherical Tokamak for Energy Production, https://step.ukaea.uk)…
View article: Neon seeding effects on two high-performance baseline plasmas on the Joint European Torus
Neon seeding effects on two high-performance baseline plasmas on the Joint European Torus Open
We present the JETTO-QuaLiKiz-SANCO fully predictive modelling of two JET-ILW high-performance baseline plasmas, a Ne seeded shot and an equivalent unseeded one. The motivation of the work lies in the experimental observation of a slightly…