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Title: Adiabat-shaping in indirect drive inertial confinement fusion

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.4919694· OSTI ID:1253682

Adiabat-shaping techniques were investigated in this paper in indirect drive inertial confinement fusion experiments on the National Ignition Facility as a means to improve implosion stability, while still maintaining a low adiabat in the fuel. Adiabat-shaping was accomplished in these indirect drive experiments by altering the ratio of the picket and trough energies in the laser pulse shape, thus driving a decaying first shock in the ablator. This decaying first shock is designed to place the ablation front on a high adiabat while keeping the fuel on a low adiabat. These experiments were conducted using the keyhole experimental platform for both three and four shock laser pulses. This platform enabled direct measurement of the shock velocities driven in the glow-discharge polymer capsule and in the liquid deuterium, the surrogate fuel for a DT ignition target. The measured shock velocities and radiation drive histories are compared to previous three and four shock laser pulses. This comparison indicates that in the case of adiabat shaping the ablation front initially drives a high shock velocity, and therefore, a high shock pressure and adiabat. The shock then decays as it travels through the ablator to pressures similar to the original low-adiabat pulses when it reaches the fuel. Finally, this approach takes advantage of initial high ablation velocity, which favors stability, and high-compression, which favors high stagnation pressures.

Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC52-07NA27344
OSTI ID:
1253682
Alternate ID(s):
OSTI ID: 1228616
Report Number(s):
LLNL-JRNL-666536
Journal Information:
Physics of Plasmas, Vol. 22, Issue 5; ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 32 works
Citation information provided by
Web of Science

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Cited By (11)

Inertial-confinement fusion with lasers journal May 2016
Analysis of NIF experiments with the minimal energy implosion model journal August 2015
Stabilization of high-compression, indirect-drive inertial confinement fusion implosions using a 4-shock adiabat-shaped drive journal August 2015
Three-dimensional simulations of low foot and high foot implosion experiments on the National Ignition Facility journal March 2016
Performance of indirectly driven capsule implosions on the National Ignition Facility using adiabat-shaping journal May 2016
Experimental results of radiation-driven, layered deuterium-tritium implosions with adiabat-shaped drives at the National Ignition Facility journal October 2016
Effects of preheat and mix on the fuel adiabat of an imploding capsule journal December 2016
Improving ICF implosion performance with alternative capsule supports journal May 2017
Hydrodynamic instability growth of three-dimensional modulations in radiation-driven implosions with “low-foot” and “high-foot” drives at the National Ignition Facility journal April 2017
Hydro-instability growth of perturbation seeds from alternate capsule-support strategies in indirect-drive implosions on National Ignition Facility journal October 2017
Review of hydro-instability experiments with alternate capsule supports in indirect-drive implosions on the National Ignition Facility journal July 2018