The first measurements of soft x-ray flux from ignition scale Hohlraums at the National Ignition Facility using DANTE (invited)

Journal Article · Fri Oct 15 00:00:00 EDT 2010 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3491032· OSTI ID:22055874

Kline, J L ^[1]; Widmann, K; Warrick, A; Thomas, C A; Suter, L J; Landen, O; Callahan, D; Azevedo, S; Liebman, J; Glenzer, S H; Conder, A; Dixit, S N; Dewald, E L; Kamperschroer, J; Atherton, L J; Beeler, R Jr; Berzins, L; Celeste, J; Haynam, C; Hsing, W ^[2] ; others, and

---

1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

The first 96 and 192 beam vacuum Hohlraum target experiments have been fielded at the National Ignition Facility demonstrating radiation temperatures up to 340 eV and fluxes of 20 TW/sr as viewed by DANTE representing an {approx}20 times flux increase over NOVA/Omega scale Hohlraums. The vacuum Hohlraums were irradiated with 2 ns square laser pulses with energies between 150 and 635 kJ. They produced nearly Planckian spectra with about 30{+-}10% more flux than predicted by the preshot radiation hydrodynamic simulations. To validate these results, careful verification of all component calibrations, cable deconvolution, and software analysis routines has been conducted. In addition, a half Hohlraum experiment was conducted using a single 2 ns long axial quad with an irradiance of {approx}2x10{sup 15} W/cm{sup 2} for comparison with NIF Early Light experiments completed in 2004. We have also completed a conversion efficiency test using a 128-beam nearly uniformly illuminated gold sphere with intensities kept low (at 1x10{sup 14} W/cm{sup 2} over 5 ns) to avoid sensitivity to modeling uncertainties for nonlocal heat conduction and nonlinear absorption mechanisms, to compare with similar intensity, 3 ns OMEGA sphere results. The 2004 and 2009 NIF half-Hohlraums agreed to 10% in flux, but more importantly, the 2006 OMEGA Au Sphere, the 2009 NIF Au sphere, and the calculated Au conversion efficiency agree to {+-}5% in flux, which is estimated to be the absolute calibration accuracy of the DANTEs. Hence we conclude that the 30{+-}10% higher than expected radiation fluxes from the 96 and 192 beam vacuum Hohlraums are attributable to differences in physics of the larger Hohlraums.

• OSTI ID: 22055874
• Journal Information: Review of Scientific Instruments, Vol. 81, Issue 10; Other Information: (c) 2010 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ACCURACY
CALIBRATION
COMPARATIVE EVALUATIONS
COMPUTER CODES
DANTE TOKAMAK
EFFICIENCY
EV RANGE 100-1000
GOLD
LASER CAVITIES
LASER TARGETS
LASER-RADIATION HEATING
NONLINEAR PROBLEMS
PLASMA
RADIANT FLUX DENSITY
SENSITIVITY
SOFT X RADIATION
SPECTRA
SPHERES
THERMAL CONDUCTION
THERMONUCLEAR IGNITION
US NATIONAL IGNITION FACILITY