Influence of Au M-band flux asymmetry on implosion symmetry

Abstract

AbstractIn indirect-drive inertial confinement fusion, the radiation symmetry must be controlled for the achievement of hotspot ignition. The radiation symmetry is of great importance. In this paper, we investigate the drive asymmetry of the M-band (2–5 keV) radiation emitted from an Au holhraum wall by using the three-dimensional view-factor code IRAD3D. Analysis of the M-band flux drive at the Shenguang-III laser facility shows that it is asymmetric and that the asymmetry varies with time. For a given cross section over the pole, the initial M-band flux asymmetries are P2 = 11.59, P4 = 1.41, and P6 = −0.64%. When the asymmetries are artificially added to a symmetric radiation drive, the position of the deuterium-tritium (DT) ice/gas interface is asymmetric for a National Ignition Facility capsule in 1D simulation. This means that M-band flux asymmetry can lead to implosion asymmetry even if the total radiation is symmetric. Pure CH and Si-doped CH capsules are considered. The results show that a mid-Z dopant can partly reduce the asymmetry. However, the asymmetry is still very large. Thus, it is necessary to study the M-band flux asymmetry and its influence on the implosion symmetry.