Inertial Confinement Fusion Research At Imperial College

The paper summarizes experimental and theoretical work relevant to inertial confinement fusion. A quantitative study of laser imprinting and subsequent Rayleigh-Taylor (R-T) growth of directly driven planar, solid, thin foil targets has been carried out. The experimental results are well reproduced by two and three dimensional radiation transport hydrodynamics simulations. The reduction of the hydrodynamic target breakup due to imprinting was investigated for several laser and target conditions on targets which were overcoated with a low density foam jacket facing the incident laser radiation. The shock in the foam produced by laser ablation, and the density and temperature profiles of the shocked material generated in the foam, were measured. The preheating in solid targets caused by the shock and the radiation wave was measured on targets with and without foam overcoats. Measurements were carried out of the R-T instability in planar modulated foil targets driven by soft X ray radiation emitted from a laser heated hohlraum. This allowed the Takabe-Morse rollover due to ablative stabilization to be investigated. Mode coupling was studied by using modulated targets with several short wavelength modes. A new multimode coupling model of the R-T instability was developed. An analytical model was developed which describes the saturation of self generated magnetic fields in laser produced plasmas. Finally, short pulse, high intensity experiments were carried out to study some aspects of the fast ignitor concept. In particular, the propagation of a short laser pulse at relativistic intensities through an underdense plasma was studied.