Wilfred Anthony Cooper

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A simple configuration that consists of a set of toroidal, helical and vertical field coils is used to calculate free boundary equilibria with non-zero plasma current and approximately helically symmetric plasma boundary shape. The amount of helical boundary deformation is controlled by the ratio of the current in the helical field coils to the current in the toroidal field coils. When this ratio is increased, the (m, n) = (2, 1) external kink is stabilized at beta similar or equal to 1% for inverse rotatio

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 ...

The impact of the bootstrap current (BC) has become an important issue in the modeling of quasi-symmetric stellarator devices. Magnetohydrodynamic equilibria have been calculated with self-consistent BC in the collisionless l/nu regime for characteristic quasi-symmetric configurations: a three-period quasi-axisymmetric and a four-period quasi-helically symmetric stellarator. The relationship between magnetic geometry and BC is shown along with its effect on the equilibrium when beta is increased. The releva

Stability results for high-n ideal local pressure-driven instabilities (ballooning and interchange: modes) are calculated from the COBRA and TERPSICHORE codes and compared for several low aspect ratio stellarators. Such a comparison is important because of the predominant roles that these codes are playing in the design of compact stellarators at several laboratories around the world. The code development required to reach the levels of convergence and accuracy needed for reliable operation at low aspect ra

Development and results of the MHD description of stellarators over the past half-decade are reviewed. Major events were the acceleration of convergence of those equilibrium codes which assume nested surfaces, the advent of equilibrium codes which do not a priori assume nested surfaces, and the advent of stability codes for nonlocal modes. Major results having these developments as prerequisites were that stellarators can definitely be optimized, can have nicely nested surfaces at finite beta at least in a

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 ...

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 ...

A quasi-isodynamic stellarator with poloidally closed contours of the magnetic field strength B (Mikhailov 2002 Nucl. Fusion 42 L23) has been obtained by an integrated physics optimization comprising MHD and neoclassical theory. For a configuration with si ...

An analytic derivation of the dispersion relation for resistive instabilities in a low-shear tokamak configuration is presented. The resistive infernal mode model (Charlton et al 1989 Phys. Fluids B 1 798) is generalized to include plasma diamagnetism, sub ...

To evaluate the bootstrap current in nonaxisymmetric toroidal plasmas quantitatively, a deltaf Monte Carlo method is incorporated into the moment approach. From the drift-kinetic equation with the pitch-angle scattering collision operator, the bootstrap cu ...

Thomson scattering measurements with subcentimeter spatial resolution have been made during a sawtooth crash in a Mega Ampere Spherical Tokamak fusion plasma. The unparalleled resolution of the temperature profile has shed new light on the mechanisms that ...

It is shown that the coexistence of toroidally nonlocalized ideal-hydromagnetic ballooning instabilities, with a quasidiscrete spectrum, and toroidally localized ballooning instabilities with a broad continuous spectrum, as predicted by Dewar and Glasser [Phys. Fluids 26, 3038 (1983)] can be realized in a Mercier-unstable equilibrium case modeling the Large Helical Device (LHD) [A. Iiyoshi et al., Fusion Technol. 17, 148 (1990)] with a broad pressure profile. The quasidiscrete, interchange branch correspond

A Hamiltonian/Lagrangian theory to describe guiding center orbit drift motion that is canonical in Boozer magnetic coordinates is developed to include full electrostatic and electromagnetic perturbed fields in axisymmetric tokamak geometry. Furthermore, th ...

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 ...

A survey of the magnetohydrodynamic (MHD) properties of the quasi-axisymmetric configuration MHH2 has been performed using a suite of MHD codes: the PIES code at Princeton for studying loss of equilibrium flux surfaces; three-dimensional Mercier and ballooning codes at Lausanne; and the global ideal MHD stability code CAS3D as well as Mercier and ballooning codes at IPP, Greifswald.

Wilfred Anthony Cooper

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Global ideal MHD stability of plasmas with toroidal, helical and vertical field coils

BECOOL: Ballooning eigensolver with COOL finite elements

Bootstrap current and quasi-symmetry in reactor-size stellarators

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

Ideal MHD stability calculations for compact stellarators

MHD-Theoretical Aspects of Stellarators

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

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

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

Single particle orbits in anisotropic fully shaped plasmas

Integrated physics optimization of a quasi-isodynamic stellarator with poloidally closed contours of the magnetic field strength

Single particle orbits in anisotropic fully shaped plasmas

Fast growing resistive two fluid instabilities in hybrid-like tokamak configuration

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

Moment approach to the bootstrap current in nonaxisymmetric toroidal plasmas using deltaf Monte Carlo methods

Magnetic Reconnection Triggering Magnetohydrodynamic Instabilities during a Sawtooth Crash in a Tokamak Plasma

Toroidally localized and nonlocalized ballooning instabilities in a stellarator

Full-field drift Hamiltonian particle orbits in axisymmetric tokamak geometry

Magentohydrodynamic Properties of Nominally Axisymmetric Systems with 3D Helical Core

MHD calculations for MHH2