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Wilfred Anthony Cooper

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Related publications (108)

Page 2 of 6

Anisotropic pressure bi-Maxwellian distribution function model for three-dimensional equilibria

Jonathan Graves, Wilfred Anthony Cooper

A formulation of the anisotropic pressure magnetohydrodynamic equilibrium problem for three-dimensional plasmas with imposed nested magnetic surfaces is developed based on a bi-Maxwellian model of the distribution function for the energetic particle specie ...

IOP Publishing Ltd2006

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

Wilfred Anthony Cooper, David Pfefferlé, Jonathan Graves, 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

Overview of the RFX fusion science program

Wilfred Anthony Cooper, Nicola Vianello

This paper summarizes the main achievements of the RFX fusion science program in the period between the 2008 and 2010 IAEA Fusion Energy Conferences. RFX-mod is the largest reversed field pinch in the world, equipped with a system of 192 coils for active c ...

IOP Publishing Ltd2011

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

Jonathan Graves, Laurent Villard, Wilfred Anthony Cooper, 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

Drift stabilization of ballooning modes in a high-$\langle \beta \rangle$ LHD configuration

Jonathan Graves, Wilfred Anthony Cooper

Ideal MHD yields at best inconclusive predictions about the stability of the LHD heliotron for

\langle \beta \rangle \geq 3\%

. We investigate the impact of the drift stabilization of ballooning modes for the inward shifted LHD configuration (vacuum magne ...

IOP Publishing Ltd2010

Effects of global MHD instability on operational high beta-regime in LHD

Wilfred Anthony Cooper

In the Large Helical Device (LHD), the highest operational averaged beta value has been expanded from 3.2% to 4% in the last 2 years by increasing the heating capability and exploring a new magnetic configuration with a high aspect ratio. Although the magn ...

IOP Publishing Ltd2005

Macroscopic Stability of High Beta MAST plasmas

Jonathan Graves, Wilfred Anthony Cooper

The high-beta capability of the spherical tokamak, coupled with a suite of world-leading diagnostics on MAST, has facilitated significant improvements in the understanding of performance-limiting core instabilities in high performance plasmas. For instance ...

IOP Publishing Ltd2011

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

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

A geometry interface for gyrokinetic microturbulence investigations in toroidal configurations

Wilfred Anthony Cooper

The GENE/GIST code package is developed for the investigation of plasma microturbulence, suitable for both stellarator and tokamak configurations. The geometry module is able to process typical equilibrium files and create the interface for the gyrokinetic ...

American Institute of Physics (AIP)2009

Extended MHD simulations of infernal mode dynamics and coupling to tearing modes

Jonathan Graves, Wilfred Anthony Cooper, Federico David Halpern, Daniele Brunetti

A numerical study of pressure driven magnetohydrodynamic (MHD) instabilities in a low-shear tight aspect ratio configuration is presented. When the magnetic shear is sufficiently small over an extended region in the core, enhanced instability occurs due to ...

Iop Publishing Ltd2015

Three-dimensional distortions of the tokamak plasma boundary: boundary displacements in the presence of resonant magnetic perturbations

Wilfred Anthony Cooper

The three-dimensional plasma boundary displacements induced by applied non-axisymmetric magnetic perturbations have been measured in ASDEX Upgrade, DIII-D, JET, MAST and NSTX. The displacements arising from applied resonant magnetic perturbations (RMPs) ar ...

IOP Publishing Ltd2014

Overview of the RFX-mod fusion science activity

Wilfred Anthony Cooper, Federico Alberto Alfredo Felici, Yi Zhang, Nicola Vianello, Matteo Vallar

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

Ideal MHD spectrum calculations for the ARIES-CS configuration

Wilfred Anthony Cooper

Ideal MHD stability calculations for the ARIES compact stellarator (ARIES-CS) reactor design (Najmabadi et al 2008 Fusion Sci. Technol. 54 655) show a spectrum of instabilities. The ARIES design considered is a three field-period stellarator with engineeri ...

IOP Publishing Ltd2011

Impact of RMP magnetic field simulation models on fast ion losses

Jonathan Graves, Wilfred Anthony Cooper, David Pfefferlé

Two opposing approaches to include resonant magnetic perturbations (RMPs) in fast ion simulations are compared, one where the vacuum field caused by the RMP current coils is added to the axisymmetric MHD equilibrium, the other where the MHD equilibrium inc ...

International Atomic Energy Agency2014

Magnetohydrodynamic properties of nominally axisymmetric systems with 3D helical core

Olivier Sauter, Jonathan Graves, Wilfred Anthony Cooper

Magnetohydrodynamic equilibrium states with a three-dimensional helical core are computed to model the MAST spherical tokamak and the RFX-mod reversed field pinch. The boundary is fixed as axisymmetric. The MAST equilibrium state has the appearance of an i ...

2011

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

Jonathan Graves, Wilfred Anthony Cooper, 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

Overview of the RFX-mod contribution to the international Fusion Science Program

Wilfred Anthony Cooper, Nicola Vianello

The RFX-mod device is operated both as a reversed field pinch (RFP), where advanced regimes featuring helical shape develop, and as a tokamak. Due to its flexibility, RFX-mod is contributing to the solution of key issues in the roadmap to ITER and DEMO, in ...

Iop Publishing Ltd2015

Relativistic Hamiltonian guiding center drift formalism in anisotropic pressure magnetic coordinates

Jonathan Graves, Wilfred Anthony Cooper, Martin Jucker

A Hamiltonian formulation of the relativistic guiding center drifts is extended to anisotropic pressure plasmas. The magnetic coordinates devised by Boozer are adapted to the anisotropic pressure model and retain canonical properties for two-dimensional an ...

2006

JET Snake Magnetohydrodynamic Equilibria

Olivier Sauter, Jonathan Graves, Wilfred Anthony Cooper

Magnetohydrodynamic (MHD) equilibrium states with a three-dimensional helical core that display the characteristics of a saturated ideal internal kink mode are computed to model snake structures that have been observed in the JET tokamak [A.~Weller et al. ...

IOP Publishing Ltd2011

Heavy Impurity Confinement in Hybrid Operation Scenario Plasmas with a Rotating 1/1 Continuous Mode

Jonathan Graves, Wilfred Anthony Cooper, David Pfefferlé, Madhusudan Raghunathan

In future tokamaks like ITER with tungsten walls, it is imperative to control tungsten accumulation in the core of operational plasmas, especially since tungsten accumulation can lead to radiative collapse and disruption. We investigate the behaviour of tu ...

IOP Science2017