W. Mostert

Effects of magnetic fields on magnetohydrodynamic cylindrical and spherical Richtmyer-Meshkov instability

The effects of seed magnetic fields on the Richtmyer-Meshkov instability driven by converging cylindrical and spherical implosions in ideal magnetohydrodynamics are investigated. Two different seed field configurations at various strengths are applied over a cylindrical or spherical density interface which has a single-dominant-mode perturbation. The shocks that excite the instability are generated with appropriate Riemann problems in a numerical formulation and the effect of the seed field on the growth rate and symmetry of the perturbations on the density interface is examined. We find reduced perturbation growth for both field configurations and all tested strengths. The extent of growth suppression increases with seed field strength but varies with the angle of the field to interface. The seed field configuration does not significantly affect extent of suppression of the instability, allowing it to be chosen to minimize its effect on implosion distortion. However, stronger seed fields are required in three dimensions to suppress the instability effectively.

Characterisation of the Cylindrical Riemann Problem in Magnetohydrodynamics

In inertial confinement fusion (ICF), high-intensity radiation is distributed over a capsule containing nuclear fuel so that a spherical, converging shock is driven inwards, compressing the fuel to conditions where nuclear fusion can occur [3]. The Richtmyer-Meshkov instability (RMI), which occurs when a density interface is impulsively accelerated, has the potential to disrupt the symmetry of the converging flow, limiting energy production in this process.