Improving the hot-spot pressure and demonstrating ignition hydrodynamic equivalence in cryogenic deuterium tritium implosions on OMEGA

Journal Article · Thu May 01 00:00:00 EDT 2014 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4876618· OSTI ID:1172492

Goncharov, V. N. ^[1]; Sangster, T. C. ^[1]; Betti, R. ^[1]; Boehly, T. R. ^[1]; Bonino, M. J. ^[1]; Collins, T. J. ^[1]; Craxton, R. S. ^[1]; Delettrez, J. A. ^[1]; Edgell, D. H. ^[1]; Epstein, R. ^[1]; Follett, R. K. ^[1]; Forrest, C. J. ^[1]; Froula, D. H. ^[1]; Yu. Glebov, V. ^[1]; Harding, D. R. ^[1]; Henchen, R. J. ^[1]; Hu, S. X. ^[1]; Igumenshchev, I. V. ^[1]; Janezic, R. ^[1]; Kelly, J. H. ^[1] ; Kessler, T. J. ^[1]; Kosc, T. Z. ^[1]; Loucks, S. J. ^[1]; Marozas, J. A. ^[1]; Marshall, F. J. ^[1]; Maximov, A. V. ^[1]; McCrory, R. L. ^[1]; McKenty, P. W. ^[1]; Meyerhofer, D. D. ^[1]; Michel, D. T. ^[1]; Myatt, J. F. ^[1]; Nora, R. ^[1]; Radha, P. B. ^[1]; Regan, S. P. ^[1]; Seka, W. ^[1]; Shmayda, W. T. ^[1]; Short, R.W. ^[1]; Shvydky, A. ^[1]; Skupsky, S. ^[1]; Stoeckl, C. ^[1]; Yaakobi, B. ^[1]; Frenje, J. A. ^[2]; Gatu-Johnson, M. ^[2]; Petrasso, R. D. ^[2]; Casey, D. T. ^[3]

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1. Univ. of Rochester, NY (United States). Lab. for Laser Energetics
2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Reaching ignition in direct-drive (DD) inertial confinement fusion implosions requires achieving central pressures in excess of 100 Gbar. The OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] is used to study the physics of implosions that are hydrodynamically equivalent to the ignition designs on the National Ignition Facility (NIF) [J. A. Paisner et al., Laser Focus World 30, 75 (1994)]. It is shown that the highest hot-spot pressures (up to 40 Gbar) are achieved in target designs with a fuel adiabat of α ≅ 4, an implosion velocity of 3.8 × 10⁷ cm/s, and a laser intensity of ~10¹⁵ W/cm². These moderate-adiabat implosions are well understood using two-dimensional hydrocode simulations. The performance of lower-adiabat implosions is significantly degraded relative to code predictions, a common feature between DD implosions on OMEGA and indirect-drive cryogenic implosions on the NIF. Simplified theoretical models are developed to gain physical understanding of the implosion dynamics that dictate the target performance. These models indicate that degradations in the shell density and integrity (caused by hydrodynamic instabilities during the target acceleration) coupled with hydrodynamics at stagnation are the main failure mechanisms in low-adiabat designs. To demonstrate ignition hydrodynamic equivalence in cryogenic implosions on OMEGA, the target-design robustness to hydrodynamic instability growth must be improved by reducing laser-coupling losses caused by cross beam energy transfer.

• Research Organization: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: NA0002035
• OSTI ID: 1172492
• Journal Information: Physics of Plasmas, Vol. 21, Issue 5; ISSN 1070-664X
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY