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Title: Optimization of laser-driven cylindrical implosions on the OMEGA laser

Abstract

Laser-driven cylindrical implosions were conducted on the OMEGA laser as part of the laser-driven mini-MagLIF (Magnetized Liner Inertial Fusion) Campaign. Gated x-ray images were analyzed to infer shell trajectories and study the energy coupling in these implosions. Two-dimensional and three-dimensional HYDRA simulations were performed and post-processed to produce synthetic x-ray self-emission images for comparison. An analysis technique, which could be applied to both experimental and simulated x-ray images, was developed to characterize the shape and uniformity of the implosion. The analysis leads to a measurement of the average implosion velocity and axial implosion length, which can then be used to optimize the beam pointing and energy balance for future experiments. Discrepancies between simulation results and experiments allude to important physical processes that are not accounted for in the simulations. In 2-D simulations, the laser beam’s azimuthal angle of incidence is not included because the $$\phi$$-direction is not simulated, thus energy absorption is over-predicted. The 3-D simulation results are more consistent with the experiments, but the simulations do not include a calculation of crossbeam energy transfer or non-local thermal transport, which affect the energy coupled to the implosion. Finally, by appropriately adjusting the simulated energy balance and flux limit, the simulations can accurately model the experiments, which have achieved uniform implosions over a 700-μm-long region at velocities of approximately 200 km=s.

Authors:
 [1];  [2]; ORCiD logo [3];  [1]; ORCiD logo [1];  [1];  [1]; ORCiD logo [1];  [1];  [1]
  1. Univ. of Rochester, NY (United States). Lab. for Laser Energetics
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. National Cheng Kung Univ., Tainan City (Taiwan). Inst. of Space and Plasma Sciences
Publication Date:
Research Org.:
Laboratory for Laser Energetics, University of Rochester
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1487200
Grant/Contract Number:  
NA0001944
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 12; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ICF; Soft x-rays; Experiment design; Hydrodynamics; Numerical simulations; Optimization of Laser-driven Cylindrical Implosions on the OMEGA

Citation Formats

Hansen, E. C., Barnak, D. H., Chang, P. -Y., Betti, R., Campbell, E. M., Davies, J. R., Knauer, J. P., Peebles, J. L., Regan, S. P., and Sefkow, A. B. Optimization of laser-driven cylindrical implosions on the OMEGA laser. United States: N. p., 2018. Web. doi:10.1063/1.5055776.
Hansen, E. C., Barnak, D. H., Chang, P. -Y., Betti, R., Campbell, E. M., Davies, J. R., Knauer, J. P., Peebles, J. L., Regan, S. P., & Sefkow, A. B. Optimization of laser-driven cylindrical implosions on the OMEGA laser. United States. doi:10.1063/1.5055776.
Hansen, E. C., Barnak, D. H., Chang, P. -Y., Betti, R., Campbell, E. M., Davies, J. R., Knauer, J. P., Peebles, J. L., Regan, S. P., and Sefkow, A. B. Mon . "Optimization of laser-driven cylindrical implosions on the OMEGA laser". United States. doi:10.1063/1.5055776.
@article{osti_1487200,
title = {Optimization of laser-driven cylindrical implosions on the OMEGA laser},
author = {Hansen, E. C. and Barnak, D. H. and Chang, P. -Y. and Betti, R. and Campbell, E. M. and Davies, J. R. and Knauer, J. P. and Peebles, J. L. and Regan, S. P. and Sefkow, A. B.},
abstractNote = {Laser-driven cylindrical implosions were conducted on the OMEGA laser as part of the laser-driven mini-MagLIF (Magnetized Liner Inertial Fusion) Campaign. Gated x-ray images were analyzed to infer shell trajectories and study the energy coupling in these implosions. Two-dimensional and three-dimensional HYDRA simulations were performed and post-processed to produce synthetic x-ray self-emission images for comparison. An analysis technique, which could be applied to both experimental and simulated x-ray images, was developed to characterize the shape and uniformity of the implosion. The analysis leads to a measurement of the average implosion velocity and axial implosion length, which can then be used to optimize the beam pointing and energy balance for future experiments. Discrepancies between simulation results and experiments allude to important physical processes that are not accounted for in the simulations. In 2-D simulations, the laser beam’s azimuthal angle of incidence is not included because the $\phi$-direction is not simulated, thus energy absorption is over-predicted. The 3-D simulation results are more consistent with the experiments, but the simulations do not include a calculation of crossbeam energy transfer or non-local thermal transport, which affect the energy coupled to the implosion. Finally, by appropriately adjusting the simulated energy balance and flux limit, the simulations can accurately model the experiments, which have achieved uniform implosions over a 700-μm-long region at velocities of approximately 200 km=s.},
doi = {10.1063/1.5055776},
journal = {Physics of Plasmas},
number = 12,
volume = 25,
place = {United States},
year = {Mon Dec 10 00:00:00 EST 2018},
month = {Mon Dec 10 00:00:00 EST 2018}
}

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Works referenced in this record:

Crossed-beam energy transfer in direct-drive implosions
journal, May 2012

  • Igumenshchev, I. V.; Seka, W.; Edgell, D. H.
  • Physics of Plasmas, Vol. 19, Issue 5, Article No. 056314
  • DOI: 10.1063/1.4718594