The Role of Fast-Electron Preheating in Low-Adiabat Cryogenic Implosions on OMEGA

Journal Article · Fri Jul 18 04:00:00 EDT 2008 · Journal of Physics, Conference Series

DOI:https://doi.org/10.1088/1742-6596/112/2/022005· OSTI ID:934912

Shvarts, D ^[1]; Smalyuk, V A; Betti, R; Delettrez, J A; Edgell, D H; Glebov, V Yu; Goncharov, V N; McCrory, R L; McKenty, P W; Meyerhofer, D D; Marshall, F J; Radha, P B; Regan, S P; Sangster, T C; Seka, W; Skupsky, S; Stoeckl, C; Yaakobi, B; Frenje, J A; Li, C K ; Petrasso, R D; Seguin, F H

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1. Laboratory for Laser Energetics, University of Rochester, Rochester, NY

The compression in direct-drive, low-adiabat spherical implosions was studied using cryogenic D2 targets on the 60-beam, 351-nm OMEGA laser in the range of laser intensities from ~3 x 10^14 to ~1.5 x 10^15 W/cm^2. The neutron-burn–averaged areal densities decreased as the laser intensity increased. This decrease in areal density is highly correlated with the increased hard-x-ray signals, caused by hot electrons generated by the two-plasmon-decay instability. The areal-density reduction up to ~2, observed in the experiments, requires a preheat energy of ~60 J (~0.3% of total laser energy), which is consistent with the estimated preheat levels inferred from the hard-x-ray signal levels. Mitigating the generation of fast-electrons results in high areal densities which are close to the 1D predictions.

• Research Organization: Laboratory for Laser Energetics, University of Rochester
• Sponsoring Organization: USDOE
• DOE Contract Number: FC52-08NA28302
• OSTI ID: 934912
• Report Number(s): DOE/NA/28302-836; 2007-47; 1808
• Journal Information: Journal of Physics, Conference Series, Journal Name: Journal of Physics, Conference Series Journal Issue: 2 Vol. 112; ISSN 1742-6588; ISSN 1742-6596
• Country of Publication: United States
• Language: English