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Wilfred Anthony Cooper

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Publications associées (108)

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Venus plus delta f: A bootstrap current calculation module for 3-D configurations

Wilfred Anthony Cooper, Stephan Brunner, Trach-Minh Tran

A new three-dimensional code, VENUS+delta f, for neoclassical transport calculations in nonaxisymmetric toroidal systems is presented. Numerical drift orbits from the original VENUS code and the delta f method developed for tokamak transport calculations a ...

2006

Three-dimensional magnetohydrodynamic equilibrium of quiescent H-modes in tokamak systems

Olivier Sauter, Basil Duval, Jonathan Graves, Wilfred Anthony Cooper, Trach-Minh Tran, Jonathan Marc Philippe Faustin, Hamish William Patten, Samuel Lanthaler, Madhusudan Raghunathan, Andreas Kleiner

Three dimensional free boundary magnetohydrodynamic equilibria that recover saturated ideal kink/peeling structures are obtained numerically. Simulations that model the JET tokamak at fixed = 1.7% with a large edge bootstrap current that flattens t ...

IOP Publishing2016

Simulation of bootstrap current in 2D and 3D ideal magnetic fields in tokamaks

Olivier Sauter, Wilfred Anthony Cooper, Jonathan Graves, Madhusudan Raghunathan

We aim to simulate the bootstrap current for a MAST-like spherical tokamak using two approaches for magnetic equilibria including externally caused 3D effects such as resonant magnetic perturbations (RMPs), the effect of toroidal ripple, and intrinsic 3D e ...

Iop Publishing Ltd2016

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

Jonathan Graves, Wilfred Anthony Cooper, 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

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

Jonathan Graves, Wilfred Anthony Cooper, 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

Ion cyclotron resonance heating with consistent finite orbit widths and anisotropic equilibria

Jonathan Graves, Wilfred Anthony Cooper, Martin Jucker

Minority ion cyclotron resonance heating is studied using the self-consistent numerical model SCENIC. This model includes 3D geometries with full shaping and anisotropic pressure effects, warm contributions to the dielectric tensor and full orbit effects. ...

Institute of Physics2011

Ideal saturated MHD helical structures in axisymmetric hybrid plasmas

Wilfred Anthony Cooper, Jonathan Graves, Daniele Brunetti

Kinked saturated m = 1 helical structures are frequently observed in tokamak hybrid plasmas and in reversed field pinches (RFP). These modes occur when an extremum in the safety factor is close to, but necessarily resonant with, a low order rational (typic ...

International Atomic Energy Agency2014

MHD Stability Analysis of IDB Plasma in LHD

Wilfred Anthony Cooper

The characteristics of magnetohydrodynamics (MHD) stability of plasmas with the internal diffusion barrier (IDB) are intensively studied in the Large Helical Device (LHD) experiment. These plasma are produced by the rapid fueling into the core region with ...

The Japan Society of Plasma Science and Nuclear Fusion Research2009

Diamagnetic drift stabilized ballooning modes in a 3D heliotron

Wilfred Anthony Cooper, Ben McMillan

An analysis of kinetic ballooning modes is presented, ray trajectories for the inward shifted Large Helical Device configuration at modest $$ and with an anisotropic pressure profile due to the hot particles are evaluated and an estimate of the margi ...

IOP Publishing2012

Convolution and iterative methods applied to low frequency waves in 3D configurations

Laurent Villard, Wilfred Anthony Cooper, Stephan Brunner

Kinetic effects have been implemented in the three-dimensional full-wave code LEMan. These allow modeling Landau damping as well as the Kinetic Alfvén Wave (KAW). Special attention has been taken on the exact computation of the parallel wave vector as it c ...

Elsevier2011

Ideal magnetohydrodynamic stability of the NCSX

Wilfred Anthony Cooper

The ideal magnetohydrodynamic (MHD) stability of the National Compact Stellarator Experiment (NCSX) is extensively analyzed using the most advanced three-dimensional MHD codes. It is shown that the NCSX is stable to finite-n MHD modes, including the vertic ...

2007

Helical ITER hybrid scenario equilibria

Olivier Sauter, Jonathan Graves, Wilfred Anthony Cooper

Numerical computations of ITER equilibria in the hybrid scenario using a three-dimensional (3D) magnetohydrodynamic equilibrium code with nested magnetic flux surfaces demonstrate the formation of internal 3D helical cores similar to saturated ideal intern ...

IOP2011

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

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

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

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

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

BECOOL: Ballooning eigensolver with COOL finite elements

Jonathan Graves, Wilfred Anthony Cooper

An incompressible variational ideal ballooning mode equation is discretized with the COOL finite element discretization scheme using basis functions composed of variable order Legendre polynomials. This reduces the second order ordinary differential equati ...

2009

3-D ideal MHD stability of super dense core plasma in LHD

Wilfred Anthony Cooper

2007

Tokamak Magnetohydrodynamic Equilibrium States with Axisymmetric Boundary and a 3D Helical Core

Olivier Sauter, Jonathan Graves, Laurent Villard, Antoine Pochelon, Wilfred Anthony Cooper

Magnetohydrodynamic (MHD) equilibrium states with imposed axisymmetric boundary are computed in which a spontaneous bifurcation develops to produce an internal three-dimensional (3D) configuration with a helical structure in addition to the standard axisym ...

American Physical Society2010

3D warm effects for low-frequency wave propagation in magnetically confined plasmas

Laurent Villard, Wilfred Anthony Cooper, Stephan Brunner, Trach-Minh Tran

2007

Bootstrap current calculations with the SPBSC and the VENUS delta f codes for the Large Helical Device

Olivier Sauter, Wilfred Anthony Cooper, Trach-Minh Tran

Total bootstrap current calculations with the updated VENUS+δf code that incorporates energy convolution and the momentum correction technique have been performed for the reference tokamak JT-60U cases and for the experimental Large Helical Device (LH ...

IOP Publishing Ltd2009

Single particle orbits in anisotropic fully shaped plasmas

Jonathan Graves, Wilfred Anthony Cooper, Martin Jucker

2007