Direct measurements of DT fuel preheat from hot electrons in direct-drive inertial confinement fusionONLINE ONLY

In laser driven inertial confinement fusion, a spherical shell of a low-Z ablator (CH, HDC, Be or others) layered with cryogenic deuterium and tritium (DT) ice is accelerated inward at a high velocity to achieve high fusion yields and areal densities with minimal driver energy.  Hot electrons generated from laser plasma instabilities can degrade the performance of direct drive implosions by preheating the DT fuel which can cause early decompression and lower areal densities at stagnation. The hot-electron energy deposition in the DT fuel has been directly measured for the first time by comparing the hard x-ray signals between DT-layered and mass-equivalent ablator-only implosions. The electron energy deposition profile within the fuel is then inferred through dedicated experiments using Cu-doped payloads of varying thickness.  The measured preheat energy accurately explains the areal-density degradation observed in many OMEGA implosions.  A similar experimental campaign on the National Ignition Facility using Ge-doped shells has led to the inference of the spatial distribution of preheat energy and provided critical information on the scaling of hot electron preheat at megajoule driver energies.

Zoom-Meeting
https://gsi-fair.zoom.us/j/96629963798

Meeting-ID: 966 2996 3798
Kenncode: 130302