Towards a more universal understanding of radiation drive in gas-filled hohlraums

9th International Conference on Inertial Fusion Sciences and Applications

Jones, O.S.^1 ; Thomas, C.A.^1 ; Amendt, P.A.^1 ; Hall, G.N.^1 ; Izumi, N.^1 ; Barrios Garcia, M.A.^1 ; Berzak Hopkins, L.F.^1 ; Chen, H.^1 ; Dewald, E.L.^1 ; Hinkel, D.E.^1 ; Kritcher, A.L.^1 ; Marinak, M.M.^1 ; Meezan, N.B.^1 ; Milovich, J.L.^1 ; Moody, J.D.^1 ; Moore, A.S.^1 ; Patel, M.V.^1 ; Ralph, J.E.^1 ; Regan, S.P.^2 ; Rosen, M.D.^1 ; Schneider, M.B.^1 ; Sepke, S.M.^1 ; Strozzi, Dj^1 ; Turnbull, D.P.^1

Lawrence Livermore National Laboratory, Livermore

CA, United States^1

Laboratory for Laser Energetics, Rochester

NY, United States^2

关键词: Ablators;    Gas density;    Gas-filled capsules;    High flux;    Hohlraums;    Pulse energies;    Radiation drive symmetry;    Radiation hydrodynamics;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/717/1/012026/pdf
DOI  :  10.1088/1742-6596/717/1/012026

来源: IOP

【 摘 要 】

We have found that radiation-hydrodynamic calculations that use the high flux model assumptions [1] can accurately predict the radiation drive produced by a laser-heated hohlraum under certain conditions, but can not predict drive over a broad range of parameters (pulse energy, hohlraum gas fill density, hohlraum case-to-capsule ratio). In particular, the model is accurate for ∼7 ns long laser pulses used to implode capsules with high density carbon (HDC) ablators in hohlraums with helium fill gas densities of 0-0.6 mg/cc. By systematically varying the gas fill density from 0 to 1.6 mg/cc we found that the agreement with drive begins to diverge for fills > 0.85 mg/cc. This divergence from the model coincides with the onset of measureable SRS backscatter. In this same set of experiments the radiation drive symmetry inferred from the imploded shape of a gas-filled capsule is not predicted with this model. Finally, several possible fixes to the model to reduce the observed discrepancies are considered.