Direct-drive, cryogenic target implosions on OMEGA
- Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States)
Direct-drive spherical implosions of cryogenic, D{sub 2}-filled capsules are performed on the 60-beam OMEGA laser system [T. R. Boehly, D. L. Brown, R. S. Craxton, R. L. Keck, J. P. Knauer, J. H. Kelly, T. J. Kessler, S. A. Kumpan, S. J. Loucks, S. A. Letzring, F. J. Marshall, R. L. McCrory, S. F. B. Morse, W. Seka, J. M. Soures, and C. P. Verdon, Opt. Commun. 133, 495 (1997)]. The targets are energy scaled from the base line ignition design developed for the National Ignition Facility [W. J. Hogan et al., Nucl. Fusion 41, 567 (2001)]. Thin-walled ({approx}4 {mu}m), {approx}860 {mu}m diam deuterated polymer shells are permeation filled with D{sub 2} gas and cooled to the triple point ({approx}18.7 K). Cryogenic ice layers with a uniformity of {approx}2 {mu}m rms are formed and maintained. The targets are imploded with high-contrast pulse shapes with full single-beam smoothing (1 THz bandwidth, two-dimensional smoothing by spectral dispersion with polarization smoothing) to study the effects of the acceleration- and deceleration-phase Rayleigh-Taylor growth on target performance. Two-dimensional hydrocode simulations show good agreement with the experimental observations. Scattered-light and neutron-burn-history measurements are consistent with predicted absorption and hydrodynamic coupling calculations. Time-resolved and static x-ray images show the progress of the imploding shell, the shape, and temperature of the stagnating core. Particle-based instruments measure the fusion yield and rate, the ion temperature in the core, and the fuel areal density at the time of neutron production. These experiments have produced fuel areal densities of up to {approx}100 mg/cm{sup 2}, primary neutron yields of {approx}4x10{sup 10}, and secondary neutron yields of 1% to 2% of the primary yield. These results validate the hydrocode predictions for the direct-drive ignition-point design, giving increasing confidence in the direct-drive approach to inertial confinement fusion ignition.
- OSTI ID:
- 20736594
- Journal Information:
- Physics of Plasmas, Vol. 12, Issue 5; Other Information: DOI: 10.1063/1.1873832; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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