Publications de Wilfred Anthony Cooper

Understanding JET-C quiescent phases with edge harmonic magnetohydrodynamic activity and comparison with behaviour under ITER-like wall conditioning

Wilfred Anthony Cooper, Jonathan Graves, Daniele Brunetti, Andreas Kleiner, Alberto Mariani, Guillermo Bustos Ramirez

An analysis of edge localised mode-free (quiescent) H-mode discharges exhibiting edge harmonic magnetoydrodynamic activity in the JET-carbon wall machine is presented. It is observed that the otherwise quiescent pulses with multiple-n harmonic oscillations ...

IOP Publishing Ltd2022

DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy

Wilfred Anthony Cooper, Olivier Sauter, Stefano Coda

DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with funda ...

IOP Publishing Ltd2022

ICRF modelling in 2D and 3D magnetic configurations using a hot plasma model

Wilfred Anthony Cooper, Jonathan Graves, Mike Machielsen

The generation of energetic trapped ions is important for experiments investigating their confinement in 3D magnetic fields, for plasma heating, for studies into unwanted drive of instabilities, and improved transport regimes. An effective way to generate ...

2021

Effect of the tangential NBI current drive on the stability of pressure and energetic particle driven MHD modes in LHD plasma

Wilfred Anthony Cooper, Joao Varela

The aim of the present study is to analyze the stability of the pressure gradient driven modes (PM) and Alfven eigenmodes (AE) in the large helical device (LHD) plasma if the rotational transform profile is modified by the current drive of the tangential n ...

IOP Publishing Ltd2020

Identification of an Optimized Heating and Fast Ion Generation Scheme for the Wendelstein 7-X Stellarator

Wilfred Anthony Cooper, Jonathan Graves, David Pfefferlé, Hamish William Patten

A Doppler shifted resonance minority species ion cyclotron range of frequency (ICRF) scheme for heating neutral beam ions has been identified and optimized for theWendelstein 7-X stellarator. Compared with more conventional methods, the synergetic scheme i ...

2020

Anisotropy and shaping effects on the stability boundaries of infernal ideal MHD modes in tokamak hybrid plasmas

Wilfred Anthony Cooper, Jonathan Graves, Daniele Brunetti

Anisotropy and some limiting toroidal flow effects on the stability of nearly resonant ideal magnetohydrodynamic modes in hybrid shaped tokamak plasmas are investigated within the ideal MHD infernal mode framework. Such effects are found to alter the plasm ...

2020

DIII-D research towards establishing the scientific basis for future fusion reactors

Wilfred Anthony Cooper, Richard Pitts, Olivier Sauter, Stefan Müller, Mario Ludovico Podesta, Francesca Maria Poli, Dongbin Zhao, Gang Yu, Huan Du, Alessandro Bortolon, Alessandro Marinoni, Jeffrey Huang, Sun Hee Kim, Jérôme Guterl, Zhixian Yan, Fang Liu, Terunobu Akiyama, Xin Yang, Wei Wu, Lorenzo Anton-Louis Talà, Federico David Halpern, Gabriele Merlo, Yu Fu, Shouguo Wang, Sung Chul Park, Xi Chen, Tzu-Hsien Shen, Bingying Zhao, Kyungjin Kim, Ji Hyun Kim, Yi Wang, Hui Wang, Zheng Wang

DIII-D research is addressing critical challenges in preparation for ITER and the next generation of fusion devices through focusing on plasma physics fundamentals that underpin key fusion goals, understanding the interaction of disparate core and boundary ...

IOP Publishing Ltd2019

Helical equilibrium magnetohydrodynamic flow effects on the stability properties of low-n ideal external-infernal modes in weak shear tokamak configurations

Wilfred Anthony Cooper, Jonathan Graves, Patrycja Nowak-Sliwinska, Daniele Brunetti, Alberto Mariani

The impact of equilibrium helical flows on the stability properties of low shear tokamak plasmas is assessed. The corrections due to such helical flow to the equilibrium profiles (mass density, pressure, Shafranov shift, magnetic fluxes) are computed by mi ...

IOP PUBLISHING LTD2019

Guiding-centre theory for kinetic-magnetohydrodynamic modes in strongly flowing plasmas

Wilfred Anthony Cooper, Jonathan Graves, David Pfefferlé, Samuel Lanthaler

A kinetic-magnetohydrodynamic model with kinetic pressure closure is derived from a consistent guiding-centre framework. Higher-order (gyroviscous) corrections to the pressure tensor are derived in complex geometry from a reduced kinetic equation. The prop ...

IOP PUBLISHING LTD2019

Excitation Mechanism of Low-n Edge Harmonic Oscillations in Edge Localized Mode-Free, High Performance, Tokamak Plasmas

Wilfred Anthony Cooper, Jonathan Graves, Daniele Brunetti, Alberto Mariani

2019

Current and pressure gradient triggering and nonlinear saturation of low-n edge harmonic oscillations in tokamaks

Wilfred Anthony Cooper, Jonathan Graves, Daniele Brunetti, Andreas Kleiner, Antoine Pierre Emmanuel Alexis Merle

Non-axisymmetric free-boundary equilibrium computations are shown to represent nonlinearly saturated external kink modes and external kink-like sidebands coupled to pressure-driven infernal modes. In this study of edge harmonic oscillations associated with ...

IOP PUBLISHING LTD2019

Analytic stability criteria for edge MHD oscillations in high performance ELM free tokamak regimes

Wilfred Anthony Cooper, Jonathan Graves, Daniele Brunetti, Alberto Mariani

A new dispersion relation, and associated stability criteria, is derived for low-n external kink and infernal modes, and is applied to modelling the stability properties of quiescent H-mode like regimes. The analysis, performed in toroidal geometry with la ...

IAEA2018

Free boundary 3D ideal MHD equilibrium calculations for non-linearly saturated current driven external kink modes in tokamaks

Wilfred Anthony Cooper, Jonathan Graves, Andreas Kleiner

IOP Publishing Ltd2018

The effect of magnetic equilibrium on auxiliary heating schemes and fast particle confinement in Wendelstein 7-X

Wilfred Anthony Cooper, Jonathan Graves, David Pfefferlé, Jonathan Marc Philippe Faustin, Hamish William Patten

2018

Benchmark of gyrokinetic, kinetic MHD and gyrofluid codes for the linear calculation of fast particle driven TAE dynamics

Wilfred Anthony Cooper, Alberto Bottino

Fast particles in fusion plasmas may drive Alfven modes unstable leading to fluctuations of the internal electromagnetic fields and potential loss of particles. Such instabilities can have an impact on the performance and the wall-load of machines with bur ...

IOP Publishing Ltd2018

Stellarator nonlinearly saturated periodicity-breaking ideal magnetohydrodynamic equilibrium states

Wilfred Anthony Cooper, Jonathan Graves, Andreas Kleiner, Jonathan Marc Philippe Faustin, Madhusudan Raghunathan, Hamish William Patten, Samuel Lanthaler

The relaxation of the constraint of periodicity imposed by the external confining magnetic field coils in a nominally 4-field period Helias Advanced Stellarator configuration produces weak periodicity-breaking deformations of the plasma. The corrugations a ...

IOP Publishing Ltd2018

Analytic study on low-n external ideal infernal modes in tokamaks with large edge pressure gradients

Wilfred Anthony Cooper, Jonathan Graves, Daniele Brunetti, Alberto Mariani

The problem of pressure driven infernal type perturbations near the plasma edge is addressed analytically for a circular limited tokamak configuration which presents an edge flattened safety factor. The plasma is separated from a metallic wall, either idea ...

Cambridge University Press2018

Modelling of advanced three-ion ICRF heating and fast ion generation scheme for tokamaks and stellarators

Wilfred Anthony Cooper, Laurent Villard, Jonathan Graves, David Pfefferlé, Jonathan Marc Philippe Faustin, Samuel Lanthaler

Absorption of ion-cyclotron range of frequencies waves at the fundamental resonance is an efficient source of plasma heating and fast ion generation in tokamaks and stellarators. This heating method is planned to be exploited as a fast ion source in the We ...

2017

Overview of the RFX-mod fusion science activity

Wilfred Anthony Cooper, Federico Alberto Alfredo Felici, Elena Gaio, Leonardo Pigatto, Nicola Vianello, Yi Zhang, Matteo Vallar, Alberto Ferro

This paper reports the main recent results of the RFX-mod fusion science activity. The RFX-mod device is characterized by a unique flexibility in terms of accessible magnetic configurations. Axisymmetric and helically shaped reversed-field pinch equilibria ...

IOP Publishing Ltd2017

Higher order Larmor radius corrections to guiding-centre equations and application to fast ion equilibrium distributions

Wilfred Anthony Cooper, Jonathan Graves, David Pfefferlé, Samuel Lanthaler

An improved set of guiding-centre equations, expanded to one order higher in Larmor radius than usually written for guiding-centre codes, are derived for curvilinear flux coordinates and implemented into the orbit following code VENUS-LEVIS. Aside from gre ...

Iop Publishing Ltd2017