The effect of condensates and inner coatings on the performance of vacuum hohlraum targets

Boehly, T. R.; Olson, R. E.; Celliers, P. M.; Munro, D. H.; Seka, W.; Landen, O. L.; Collins, G. W.; Suter, L. J.; Sangster, T. C.; Meyerhofer, D. D.
March 2010
Physics of Plasmas;Mar2010, Vol. 17 Issue 3, p032701
Academic Journal
Experiments on the OMEGA laser system [Boehly et al., Opt. Commun. 133, 495 (1997)] using laser-driven vacuum hohlraum targets show distinct differences between cryogenic (<20 K) and warm targets. The cryogenic targets have 15% lower peak radiation temperatures, and the temporal profile of those temperatures is quite different than in warm targets. The cryogenic targets reflect significantly more (3%–7%) of the laser drive than the warm targets (<1%). The temporal and spectral features of the reflected light from the cryogenic targets show a significantly longer duration and more spectral features than the warm hohlraums. Warm hohlraum targets coated with 2 μm of CH replicate the behavior of cryogenic targets. This indicates that the cryogenic hohlraums are affected by the condensation of background gases on the cold hohlraum surface. The most important effect of low-Z material in the hohlraums is that they significantly reduce the x-ray conversion efficiency, resulting in lower hohlraum radiation temperature. The coatings (both CH and condensates) produce long-scale-length, low-Z plasmas that moderately reduce the absorption of laser light in the hohlraums. This causes higher reflectivity and produces hot electrons that generate hard x rays (hν>20 keV), both of which are detrimental to the performance of hohlraum-driven inertial confinement fusion targets.


Related Articles

  • Cryogenic-target performance and implosion physics studies on OMEGA. Smalyuk, V. A.; Betti, R.; Boehly, T. R.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Glebov, V. Yu.; Goncharov, V. N.; Harding, D. R.; Hu, S. X.; Knauer, J. P.; Marshall, F. J.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Radha, P. B.; Regan, S. P.; Sangster, T. C.; Seka, W.; Short, R. W. // Physics of Plasmas;May2009, Vol. 16 Issue 5, p056301 

    Recent progress in direct-drive cryogenic implosions on the OMEGA Laser Facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] is reviewed. Ignition-relevant areal densities of ∼200 mg/cm2 in cryogenic D2 implosions with peak laser-drive intensities of ∼5×1014 W/cm2 were...

  • High performance silicon hot electron bolometers. Moseley, H.; McCammon, D. // AIP Conference Proceedings;2002, Vol. 605 Issue 1, p103 

    High performance Si bolometers can be made using the electron-phonon conductance in the heavily doped Si to provide thermal isolation from the cryogenic bath. Thermal conductance, response time, noise, and signal frequency resistance are predicted based on laboratory measurements of larger...

  • Characterization of a laser-plasma extreme-ultraviolet source using a rotating cryogenic Xe target. Amano, S.; Masuda, K.; Shimoura, A.; Miyamoto, S.; Mochizuki, T. // Applied Physics B: Lasers & Optics;Oct2010, Vol. 101 Issue 1/2, p213 

    laser-plasma source for extreme-ultraviolet (EUV) light that uses a rotating cryogenic solid-state Xe target has been characterized. We focused on parameters at the wavelength of 13.5 nm with 2% bandwidth required for an EUV lithography source and investigated improvements of the conversion...

  • Radiation symmetry control for inertial confinement fusion capsule implosions in double Z-pinch hohlraums on Z. Vesey, Roger A.; Cuneo, Michael E.; Porter, John L.; Adams, Richard G.; Aragon, Rafael A.; Rambo, Patrick K.; Ruggles, Laurence E.; Simpson, Walter W.; Smith, Ian C.; Bennett, Guy R. // Physics of Plasmas;May2003, Vol. 10 Issue 5, p1854 

    The double Z-pinch hohlraum high-yield concept [Hammer et al., Phys. Plasmas 6, 2129 (1999)] utilizes two 63-MA Z pinches to heat separate primary hohlraums at either end of a secondary hohlraum containing the cryogenic fusion capsule. Recent experiments on the Z accelerator [Spielman et al.,...

  • Direct-drive cryogenic target implosion performance on OMEGA. Sangster, T. C.; Delettrez, J. A.; Epstein, R.; Glebov, V. Yu.; Goncharov, V. N.; Harding, D. R.; Knauer, J. P.; Keck, R. L.; Kilkenny, J. D.; Loucks, S. J.; Lund, L. D.; McCrory, R. L.; McKenty, P. W.; Marshall, F. J.; Meyerhofer, D. D.; Morse, S. F. B.; Regan, S. P.; Radha, P. B.; Roberts, S. // Physics of Plasmas;May2003, Vol. 10 Issue 5, p1937 

    Layered and characterized cryogenic D[SUB2] capsules have been imploded using both low- and high-adiabat (α, the ratio of the electron pressure to the Fermi-degenerate pressure) pulse shapes on the 60-beam OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] at the...

  • First results from cryogenic target implosions on OMEGA. Stoeckl, C.; Chiritescu, C.; Delettrez, J. A.; Epstein, R.; Glebov, V. Yu.; Harding, D. R.; Keck, R. L.; Loucks, S. J.; Lund, L. D.; McCrory, R. L.; McKenty, P. W.; Marshall, F. J.; Meyerhofer, D. D.; Morse, S. F. B.; Regan, S. P.; Radha, P. B.; Roberts, S.; Sangster, T. C.; Seka, W.; Skupsky, S. // Physics of Plasmas;May2002, Vol. 9 Issue 5, p2195 

    Initial results from direct-drive spherical cryogenic target implosions on the 60-beam OMEGA laser system [T. R. Boehly, D. L. Brown, R. S. Craxton et al., Opt. Commun. 133, 495 (1997)] are presented. These experiments are part of the scientific base leading to direct-drive ignition implosions...

  • Ultrahigh-vacuum apparatus for surface spectroscopy and characterization at cryogenic temperatures. Chia, Victor K. F.; Veirs, D. Kirk; Rosenblatt, Gerd M. // Review of Scientific Instruments;Jun89, Vol. 60 Issue 6, p1161 

    An ultrahigh-vacuum apparatus is described that enables the study of molecular adsorbates on well-defined single crystals at controlled temperatures from 14 to 900 K. Sample cooling is achieved with a closed-cycle helium refrigerator coupled to the sample holder via a flexible copper cable. This...

  • Techniques for attainment, control, and calibration of cryogenic temperatures at small single-crystal samples under ultrahigh vacuum. Schlichting, H.; Menzel, D. // Review of Scientific Instruments;Jul1993, Vol. 64 Issue 7, p2013 

    On the basis of detailed considerations of the relevant effects and parameters, we describe techniques which have been developed to accurately set, maintain, and measure the temperature of a small sample (typically a single-crystal disk of about 1 cm in diameter and 1 mm thick) in a strongly...

  • A cryogenic test insert with a high vacuum sample space. Engelhardt, R.; Rando, N.; Peacock, A. // Review of Scientific Instruments;Jan1993, Vol. 64 Issue 1, p197 

    An insert based on a top-loading, fully welded stainless-steel design, with a special steel-copper weld is described. It has been developed explicitly for pumped helium cryostats, down to a temperature of about 1.2 K. The principal characteristics of this insert are a large high vacuum sample...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics