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Wilfred Anthony Cooper

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Publications associées (108)

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A 3D MHD equilibrium description of nonlinearly saturated ideal external kink/peeling structures in tokamaks

Wilfred Anthony Cooper, Basil Duval, Olivier Sauter, Trach-Minh Tran, Holger Reimerdes, Laurie Porte, Jonathan Graves

Novel free boundary magnetohydrodynamic equilibrium states with spontaneous three-dimensional (3-D) deformations of the plasmaâ vacuum interface are computed. The structures obtained look like saturated ideal external kink/peeling modes. Large edge pre ...

Cambridge University Press2015

Three-dimensional distortions of the tokamak plasma boundary: boundary displacements in the presence of saturated MHD instabilities

Wilfred Anthony Cooper, Jonathan Graves, Daniele Brunetti

The three-dimensional plasma boundary displacement induced by long-lasting core magnetohydrodynamic (MHD) instabilities has been measured in JET, MAST and NSTX. Only saturated instabilities are considered here since transient rapidly growing modes which de ...

IOP Publishing Ltd2014

Magnetohydrodynamic helical structures in nominally axisymmetric low-shear tokamak plasmas

Wilfred Anthony Cooper, Antoine Pochelon, Olivier Sauter, Holger Reimerdes, Jonathan Graves, Federico David Halpern, Daniele Brunetti

The primary goal of hybrid scenarios in tokamaks is to enable high performance operation with large plasma currents whilst avoiding MHD instabilities. However, if a local minimum in the safety factor is allowed to approach unity, the energy required to ove ...

Iop Publishing Ltd2013

Helical core tokamak MHD equilibrium states

Wilfred Anthony Cooper, Basil Duval, Antoine Pochelon, Olivier Sauter, Holger Reimerdes, Stefano Coda, Jonathan Rossel, Jonathan Graves, Benoît Labit, Mattia Albergante

Bifurcated magnetohydrodynamic tokamak equilibrium states with axisymmetric or helical core structure are computed. When a peaked pressure profile is chosen, the helical core structures appear like the {em snakes} that are observed in the JET tokamak. They ...

Caroline Wilkinson2011

Numerical modelling of electromagnetic turbulent transport of energetic ions in burning plasmas

Wilfred Anthony Cooper, Ambrogio Fasoli, Martin Jucker, Jonathan Graves, Mattia Albergante

We investigate the redistribution of the neutral beam driven current in the presence of small scale turbulence in the ITER steady-state scenario. Gyrokinetic simulations show that anomalous transport of beam ions can be larger than collisional estimates. T ...

Institute of Physics2011

Three-dimensional anisotropic pressure free boundary equilibria

Wilfred Anthony Cooper, Jonathan Graves

Free boundary three-dimensional anisotropic pressure magnetohydrodynamic equilibria with nested magnetic flux surfaces are computed through the minimisation of the plasma energy functional

W={\int}_{V}{d^3}x\left[{B^2}/(2\mu_0)+p_{||}/(\Gamma-1)\right]

. ...

2009

Three-dimensional anisotropic pressure equilibria that model balanced tangential neutral beam injection effects

Wilfred Anthony Cooper

Fixed boundary three-dimensional anisotropic pressure equilibria are computed that are consistent with a family of distribution functions that load particles preferentially towards v parallel to similar or equal to v and model the effects of balanced tange ...

2005

Bifurcated Helical Core Equilibrium States in Tokamaks

Wilfred Anthony Cooper, Basil Duval, Antoine Pochelon, Olivier Sauter, Trach-Minh Tran, Holger Reimerdes, Stefano Coda, Jonathan Graves, Benoît Labit, David Pfefferlé, Federico David Halpern, Daniele Brunetti

Tokamaks with weak to moderate reversed central shear in which the minimum inverse rotational transform (safety factor) qmin is in the neighbourhood of unity can trigger bifurcated magnetohydrodynamic equilibrium states, one of which is similar to a satura ...

IOP Publishing Ltd2013

Extension of operation regimes and investigation of three-dimensional currentless plasmas in the Large Helical Device

Wilfred Anthony Cooper, Terunobu Akiyama

The progress of physical understanding as well as parameter improvement of net-current-free helical plasma is reported for the Large Helical Device since the last Fusion Energy Conference in Daejeon in 2010. The second low-energy neutral beam line was inst ...

IOP Publishing Ltd2013

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

Neoclassical tearing mode seeding by coupling with infernal modes in low-shear tokamaks

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

A numerical and an analytical study of the triggering of resistive MHD modes in tokamak plasmas with low magnetic shear core is presented. Flat q profiles give rise to fast growing pressure driven MHD modes, such as infernal modes. It has been shown that i ...

IOP Publishing Ltd2016

Self-consistent Simulations of ICRH with the Background Equilibrium in Tokamaks and Stellarators

Wilfred Anthony Cooper, Martin Jucker, Jonathan Graves

The SCENIC code package has been developed to integrate self-consistently an anisotropic pressure magnetohydrodynamic equilibrium state with power absorption from Ion Cyclotron Resonance Heating and with a guiding center particle distribution function for ...

American Nuclear Society2014

Overview of the RFX-mod fusion science programme

Wilfred Anthony Cooper, Ambrogio Fasoli, Ivo Furno, Christian Gabriel Theiler, Fabio Avino, Nicola Vianello

This paper reports the highlights of the RFX-mod fusion science programme since the last 2010 IAEA Fusion Energy Conference. The RFX-mod fusion science programme focused on two main goals: exploring the fusion potential of the reversed field pinch (RFP) ma ...

IOP Publishing Ltd2013

Impact of pressure anisotropy on tokamak equilibria and the toroidal magnetic precession

Wilfred Anthony Cooper, Martin Jucker, Jonathan Graves

Using a generalized anisotropic tokamak equilibrium and an exact guiding centre drift formulation, the effect of parallel and perpendicular anisotropy on the toroidal precession drift is investigated. Signiﬁcant differences between parallel and perpendicul ...

2008

A full-wave solver of the Maxwell's equations in 3D cold plasmas

Wilfred Anthony Cooper, Laurent Villard, Pavel Popovitch

A new solver for Maxwell's equations in three-dimensional (3D) plasma configurations is presented. The new code LEMan (Low-frequency ElectroMagnetic wave propagation) determines a global solution of the wave equation in a realistic stellarator geometry at ...

2006

Free boundary equilibrium in 3D tokamaks with toroidal rotation

Wilfred Anthony Cooper, Olivier Sauter, Minh Tâm Tran, Jonathan Graves, David Pfefferlé, Daniele Brunetti, Jonathan Marc Philippe Faustin, Madhusudan Raghunathan

The three-dimensional VMEC equilibrium solver has been adapted to numerically investigate the approximate toroidal rotation model we have derived. We concentrate our applications on the simulation of JET snakes and MAST long-lived modes under free boundary ...

IOP Publishing Ltd2015

Bifurcated Helical Core Equilibrium States in Tokamaks

Wilfred Anthony Cooper, Basil Duval, Antoine Pochelon, Olivier Sauter, Holger Reimerdes, Stefano Coda, Jonathan Rossel, Jonathan Graves, Benoît Labit, David Pfefferlé, Mattia Albergante, Federico David Halpern, Daniele Brunetti

Tokamaks with weak to moderate reversed central shear in which the minimum rotational transform

q_{min}

is in the neighbourhood of unity can trigger bifurcated MagnetoHydrodynamic (MHD) equilibrium states, one of which is similar to a saturated ideal ...

2012

Saturated ideak kink/peeling formations described as three-dimensional magnetohydrodynamic tokamak equilibrium states

Wilfred Anthony Cooper, Basil Duval, Olivier Sauter, Trach-Minh Tran, Holger Reimerdes, Laurie Porte, Jonathan Graves, David Pfefferlé, Daniele Brunetti, Andreas Kleiner, Jonathan Marc Philippe Faustin, Madhusudan Raghunathan, Hamish William Patten

Free boundary magnetohydrodynamic equilibrium states with spontaneous three dimensional deformations of the plasma-vacuum interface are computed for the first time. The structures obtained have the appearance of saturated ideal external kink/peeling modes. ...

American Institute of Physics (AIP)2016

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

Drift stabilization of ballooning modes in an inward-Shifted LHD configuration

Wilfred Anthony Cooper, Jonathan Graves

A drift-magnetohydrodynamic theory is applied to a background anisotropic pressure equilibrium state to generate a drift corrected ballooning mode equation. The ratio of the mode frequency to the hot particle drift frequency constitutes the critical expans ...

Wiley-VCH2010