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Title: The relationship between gas fill density and hohlraum drive performance at the National Ignition Facility

Abstract

Indirect drive inertial confinement fusion experiments were conducted at the National Ignition Facility to investigate the performance of the hohlraum drive as a function of hohlraum gas fill density by imploding high-density-carbon capsules using a 2-shock laser pulse. Our ,easurements characterize the backscatter behavior, the production of hot electrons, the motion and brightness of the laser spots on the hohlraum wall, and the efficiency of the hohlraum x-ray drive as a function of gas fill density ρ gf between 0.03 mg/cc (“near vacuum”) and 1.6 mg/cc. For hohlraums with ρ gf up to 0.85 mg/cc, very little stimulated Raman backscatter (SRS) was observed. Furthermore, for higher ρ gf, significant SRS was produced and was observed to occur during the rise to peak laser power and throughout the main pulse. The efficiency with which laser energy absorbed by the hohlraum is converted into drive energy was measured to be the same for ρ gf ≥ 0.6 mg/cc once the laser reached peak power. But, for the near vacuum case, the absorbed energy was converted to drive energy more efficiently throughout the pulse and maintained an efficiency ~10% higher than the gas filled hohlraums throughout the main pulse.

Authors:
ORCiD logo [1];  [1]; ORCiD logo [1];  [1];  [1];  [1];  [1]; ORCiD logo [1];  [1]; ORCiD logo [1];  [1];  [1];  [1];  [1];  [1];  [1]; ORCiD logo [1];  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1361586
Alternate Identifier(s):
OSTI ID: 1361880
Report Number(s):
LLNL-JRNL-716217
Journal ID: ISSN 1070-664X; PHPAEN
Grant/Contract Number:  
AC52-07NA27344; NA0001808
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 5; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION

Citation Formats

Hall, G. N., Jones, O. S., Strozzi, D. J., Moody, J. D., Turnbull, D., Ralph, J., Michel, P. A., Hohenberger, M., Moore, A. S., Landen, O. L., Divol, L., Bradley, D. K., Hinkel, D. E., Mackinnon, A. J., Town, R. P. J., Meezan, N. B., Berzak Hopkins, L., and Izumi, N. The relationship between gas fill density and hohlraum drive performance at the National Ignition Facility. United States: N. p., 2017. Web. doi:10.1063/1.4983142.
Hall, G. N., Jones, O. S., Strozzi, D. J., Moody, J. D., Turnbull, D., Ralph, J., Michel, P. A., Hohenberger, M., Moore, A. S., Landen, O. L., Divol, L., Bradley, D. K., Hinkel, D. E., Mackinnon, A. J., Town, R. P. J., Meezan, N. B., Berzak Hopkins, L., & Izumi, N. The relationship between gas fill density and hohlraum drive performance at the National Ignition Facility. United States. doi:10.1063/1.4983142.
Hall, G. N., Jones, O. S., Strozzi, D. J., Moody, J. D., Turnbull, D., Ralph, J., Michel, P. A., Hohenberger, M., Moore, A. S., Landen, O. L., Divol, L., Bradley, D. K., Hinkel, D. E., Mackinnon, A. J., Town, R. P. J., Meezan, N. B., Berzak Hopkins, L., and Izumi, N. Thu . "The relationship between gas fill density and hohlraum drive performance at the National Ignition Facility". United States. doi:10.1063/1.4983142. https://www.osti.gov/servlets/purl/1361586.
@article{osti_1361586,
title = {The relationship between gas fill density and hohlraum drive performance at the National Ignition Facility},
author = {Hall, G. N. and Jones, O. S. and Strozzi, D. J. and Moody, J. D. and Turnbull, D. and Ralph, J. and Michel, P. A. and Hohenberger, M. and Moore, A. S. and Landen, O. L. and Divol, L. and Bradley, D. K. and Hinkel, D. E. and Mackinnon, A. J. and Town, R. P. J. and Meezan, N. B. and Berzak Hopkins, L. and Izumi, N.},
abstractNote = {Indirect drive inertial confinement fusion experiments were conducted at the National Ignition Facility to investigate the performance of the hohlraum drive as a function of hohlraum gas fill density by imploding high-density-carbon capsules using a 2-shock laser pulse. Our ,easurements characterize the backscatter behavior, the production of hot electrons, the motion and brightness of the laser spots on the hohlraum wall, and the efficiency of the hohlraum x-ray drive as a function of gas fill density ρgf between 0.03 mg/cc (“near vacuum”) and 1.6 mg/cc. For hohlraums with ρgf up to 0.85 mg/cc, very little stimulated Raman backscatter (SRS) was observed. Furthermore, for higher ρgf, significant SRS was produced and was observed to occur during the rise to peak laser power and throughout the main pulse. The efficiency with which laser energy absorbed by the hohlraum is converted into drive energy was measured to be the same for ρgf ≥ 0.6 mg/cc once the laser reached peak power. But, for the near vacuum case, the absorbed energy was converted to drive energy more efficiently throughout the pulse and maintained an efficiency ~10% higher than the gas filled hohlraums throughout the main pulse.},
doi = {10.1063/1.4983142},
journal = {Physics of Plasmas},
number = 5,
volume = 24,
place = {United States},
year = {Thu May 11 00:00:00 EDT 2017},
month = {Thu May 11 00:00:00 EDT 2017}
}

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