Publications by Wilfred Anthony Cooper

Related publications (108)

Full-field drift Hamiltonian particle orbits in 3D geometry

Jonathan Graves, Wilfred Anthony Cooper, Stephan Brunner

A Hamiltonian/Lagrangian theory to describe guiding centre orbit drift motion which is canonical in the Boozer coordinate frame has been extended to include full electromagnetic perturbed fields in anisotropic pressure 3D equilibria with nested magnetic fl ...

IOP2011

Hybrid guiding-centre/full-orbit simulations in non-axisymmetric magnetic geometry exploiting general criterion for guiding-centre accuracy

Jonathan Graves, Wilfred Anthony Cooper, David Pfefferlé

To identify under what conditions guiding-centre or full-orbit tracing should be used, an estimation of the spatial variation of the magnetic field is proposed, not only taking into account gradient and curvature terms but also parallel currents and the lo ...

Iop Publishing Ltd2015

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

Wilfred Anthony Cooper

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

Stability properties of anisotropic pressure stellarator plasmas with fluid and noninteractive energetic particles

Jonathan Graves, Wilfred Anthony Cooper, Trach-Minh Tran

The three-dimensional (3-D) VMEC code has been modified to model an energetic species with a variant of a Bi-Maxwellian distribution function that satisfies the constraint B . del F-h = 0, and the 3-D TERPSICHORE stability code has been extended to investi ...

2006

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

Olivier Sauter, Stefano Coda, Wilfred Anthony Cooper

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

Exploitation of a general-coordinate guiding centre code for the redistribution of fast ions in deformed hybrid tokamak equilibria

Jonathan Graves, Wilfred Anthony Cooper, David Pfefferlé

Self-consistent fast ion distributions are usually obtained using a code that solves the guiding-centre equations, with an appropriate fast ion source (e.g. NBI pinis) and sink (e.g. collision operators). Straight field-line coordinate systems, such as Boo ...

Iop Publishing Ltd2012

ICRH induced particle losses in Wendelstein 7-X

Wilfred Anthony Cooper, David Pfefferlé, Jonathan Graves, Jonathan Marc Philippe Faustin

Fast ions in W7-X will be produced either by neutral beam injection (NBI) or by ion-cyclotron resonant heating (ICRH). The latter presents the advantage of depositing power locally and does not suffer from core accessibility issues (Drevlak et al 2014 Nucl ...

Plasma Physics and Controlled Fusion2016

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

Jonathan Graves, Wilfred Anthony Cooper, 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

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

Jonathan Graves, Wilfred Anthony Cooper, 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

Fast particle loss channels in Wendelstein 7-X

Jonathan Graves, Wilfred Anthony Cooper, David Pfefferlé, Jonathan Marc Philippe Faustin

One of the main goals of Wendelstein 7-X (W7-X) is to demonstrate the fast particle confinement properties of the quasi-isodynamic stellarator concept. Fast particle populations will be produced either by Neutral Beam Injection (NBI) or by minority Ion Cyc ...

Nuclear Fusion2016

Integrated modelling of Ion Cyclotron Resonant Heating in toroidal system

Jonathan Graves, Wilfred Anthony Cooper, Stephan Brunner, Martin Jucker

An integrated model capable of self-consistent Ion Cyclotron Resonant Heating (ICRH) simulations has been developed. This model includes both full shaping and pressure effects, warm contributions to the dielectric tensor, pressure anisotropy and finite orb ...

Elsevier B.V2011

NBI fast ion confinement in the helical core of MAST hybrid-like plasmas

Jonathan Graves, Wilfred Anthony Cooper, David Pfefferlé

Energetic ions are found to be transported strongly from the core of MAST hybrid-like plasmas during long-lived mode (LLM) magnetohydrodynamic activity. The resulting impact on the neutral beam ion deposition and concurrent current drive is modelled usin ...

IOP Publishing Ltd2014

Fluid magnetohydrodynamic stabilit in a heliotron with anisotropic fast particle species

Jonathan Graves, Wilfred Anthony Cooper, Martin Jucker

The local and global fluid magnetohydrodynamic stability properties of anisotropic pressure plasmas are investigated with the Kruskal-Oberman and rigid hot particle Johnson et al energy principles. A Heliotron configuration that models the Large Helical De ...

2007

Effects of magnetic ripple on 3D equilibrium and alpha particle confinement in the European DEMO

Ambrogio Fasoli, Jonathan Graves, Wilfred Anthony Cooper, David Pfefferlé

An assessment of alpha particle confinement is performed in the European DEMO reference design. 3D MHD equilibria with nested flux-surfaces and single magnetic axis are obtained with the VMEC free-boundary code, thereby including the plasma response to the ...

IOP Science2016

MHD equilibrium and stability of tokamaks and RFP systems with 3D helical cores

Olivier Sauter, Jonathan Graves, Wilfred Anthony Cooper

Bifurcated magnetohydrodynamic (MHD) equilibrium states are computed for ITER hybrid scenario and RFX-mod SHAx configurations with very flat or reversed core magnetic shear conditions. In the ITER studies, the minimum inverse rotational transform qmin is n ...

IOP Publishing2011

Stabilization of the vertical instability by non-axisymmetric coils

Wilfred Anthony Cooper

In a published Physical Review Letter (Reiman 2007 Phys. Rev. Lett. 99 135007), it was shown that axisymmetric (or vertical) stability can be improved by placing a set of parallelogram coils above and below the plasma oriented at an angle to the constant t ...

IOP Publishing Ltd2016

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

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

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

Overview of MAST results

Jonathan Graves, Wilfred Anthony Cooper, Mario Ludovico Podesta, Jan Horacek, Ben McMillan, Ricardo Pérez Suárez

The Mega Ampere Spherical Tokamak (MAST) programme is strongly focused on addressing key physics issues in preparation for operation of ITER as well as providing solutions for DEMO design choices. In this regard, MAST has provided key results in understand ...

Iop Publishing Ltd2015

VENUS-LEVIS and its spline-Fourier interpolation of 3D toroidal magnetic field representation for guiding-centre and full-orbit simulations of charged energetic particles

Jonathan Graves, Wilfred Anthony Cooper, David Pfefferlé

Curvilinear guiding-centre drift and full-orbit equations of motion are presented as implemented in the code{VENUS-LEVIS} code. A dedicated interpolation scheme based on Fourier reconstruction in the toroidal and poloidal direction and cubic spline in the ...

Elsevier2014

Three-dimensional equilibria and transport in RFX-mod: A description using stellarator tools

Wilfred Anthony Cooper

RFX-mod self-organized single helical axis (SHAx) states provide a unique opportunity to advance 3D fusion physics and establish a common knowledge basis in a parameter region not covered by stellarators and tokamaks. The VMEC code has been adapted to the ...

American Institute of Physics (AIP)2011