High speed plasma species interpenetration and implications in hohlraums*

The effect of high speed interpenetrating plasma species on the transport and collisionality in Inertial Confinement Fusion (ICF) hohlraum physics is examined. The AMR multi-species radiation hydrodynamic code, xRage, includes low speed fluid models for plasma transport including species mass diffusion, viscous effects in momentum and species thermal equilibration. Corrections for high speed plasma species flows are recently added to the code, based on work by Burgers (1969), Schunk (1977) and in a recent review (Hunana, Gomez, Tenerani,,et.al. (2022). The high speed species flows reduce the collisionality and species coupling thus increasing species interpenetration (runaway effect) and reducing species thermal equilibration rates. The high speed correction increases with the ratio of the species drift speeds relative to thermal speed and for a ratio of order unity, this reduces momentum coupling by about 40% and thermal coupling by about 60%. The change in collisionality is examined in test problems including studies in ICF indirect-drive hohlraum physics where interpenetrating plasma moves inward from the hohlraum inner surface and outward from the capsule surface during laser irradiation.