arXiv subjects

John Hedditch

Publications and source records attributed to John Hedditch.

3 recordsLinked to original sources

arXiv2019

A different approach to the MHD equilibrium

Equations describing plasma equilibria are derived from the total energy of the system. The MHD equilibrium is shown to hold even for systems where the magnetic field may locally vanish. Through conservation of helicity, confinement is shown to be intimately related to electromagnetic tension. For an axisymmetric device, the presence of a magnetic field or current circling the axis is shown to be destabilising. This provides a simple explanation for the poor performance of some devices for which MHD predicts stability.

physics.plasm-ph↗

arXiv2015

Fusion in a magnetically-shielded-grid inertial electrostatic confinement device

Theory for a gridded inertial electrostatic confinement (IEC) fusion system is presented that shows a net energy gain is possible if the grid is magnetically shielded from ion impact. A simplified grid geometry is studied, consisting of two negatively-biased coaxial current-carrying rings, oriented such that their opposing magnetic fields produce a spindle cusp. Our analysis indicates that better than break-even performance is possible even in a deuterium-deuterium system at bench-top scales. The proposed device has the unusual property that it can avoid both the cusp losses of traditional magnetic fusion systems and the grid losses of traditional IEC configurations.

physics.plasm-ph↗

arXiv2003

Low-lying eigenmodes of the Wilson-Dirac operator and correlations with topological objects

The probability density of low-lying eigenvectors of the hermitian Wilson-Dirac operator is examined. Comparisons in position and size between eigenvectors, topological charge and action density are made. We do this for standard Monte-Carlo generated SU(3) background fields and for single instanton background fields. Both hot and cooled SU(3) background fields are considered. An instanton model is fitted to eigenmodes and topological charge density and the sizes and positions of these are compared.

hep-lat↗