Towards a more universal understanding of radiation drive in gas-filled hohlraums. (May 2016)

• Record Type: Journal Article
• Authors: Jones, O S; Thomas, C A; Amendt, P A; Hall, G N; Izumi, N; Barrios Garcia, M A; Berzak Hopkins, L F; Chen, H; Dewald, E L; Hinkel, D E; Kritcher, A L; Marinak, M M; Meezan, N B; Milovich, J L; Moody, J D; Moore, A S; Patel, M V; Ralph, J E; Regan, S P; Rosen, M D; Schneider, M B; Sepke, S M; Strozzi, DJ; Turnbull, D P
• Is Part Of: Journal of physics. Volume 717(2016)
• Publication Date: 2016-05
• Subjects: Physics -- Congresses; 530.5
• DOI: 10.1088/1742-6596/717/1/012026
• Languages: English
• ISSNs: 1742-6588

Abstract

Abstract: 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.