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Title: Systematic Fuel Cavity Asymmetries in Directly Driven Inertial Confinement Fusion Implosions

Abstract

Here, we present narrow-band self-emission x-ray images from a titanium tracer layer placed at the fuel-shell interface in 60-laser-beam implosion experiments at the OMEGA facility. The images are acquired during deceleration with inferred convergences of ~9-14. Novel here is that a systematically observed asymmetry of the emission is linked, using full sphere 3D implosion modeling, to performance-limiting low mode asymmetry of the drive.

Authors:
 [1]; ORCiD logo [1];  [1];  [2];  [3];  [4]; ORCiD logo [1];  [3];  [4]; ORCiD logo [1];  [5];  [4];  [4]; ORCiD logo [1];  [3];  [4];  [4];  [4]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Univ. of Rochester, NY (United States). Lab. for Laser Energetics
  5. Univ. of Nevada, Reno, NV (United States). Dept. of Physics
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1369182
Alternate Identifier(s):
OSTI ID: 1349399
Report Number(s):
LA-UR-16-24296
Journal ID: ISSN 0031-9007; TRN: US1702755
Grant/Contract Number:
AC52-06NA25396; NA0001944
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 118; Journal Issue: 13; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; hydrodynamic instability; inertial confinement fusion; symmetry; direct-drive; ignition

Citation Formats

Shah, Rahul C., Haines, Brian Michael, Wysocki, Frederick Joseph, Benage, J. F., Fooks, J., Glebov, V., Hakel, Peter, Hoppe, M., Igumenshchev, I. V., Kagan, Grigory, Mancini, R. C., Marshall, F. J., Michel, D. T., Murphy, Thomas Joseph, Schoff, M. E., Stoeckl, C., Yaakobi, B., and Silverstein, K. Systematic Fuel Cavity Asymmetries in Directly Driven Inertial Confinement Fusion Implosions. United States: N. p., 2017. Web. doi:10.1103/PhysRevLett.118.135001.
Shah, Rahul C., Haines, Brian Michael, Wysocki, Frederick Joseph, Benage, J. F., Fooks, J., Glebov, V., Hakel, Peter, Hoppe, M., Igumenshchev, I. V., Kagan, Grigory, Mancini, R. C., Marshall, F. J., Michel, D. T., Murphy, Thomas Joseph, Schoff, M. E., Stoeckl, C., Yaakobi, B., & Silverstein, K. Systematic Fuel Cavity Asymmetries in Directly Driven Inertial Confinement Fusion Implosions. United States. doi:10.1103/PhysRevLett.118.135001.
Shah, Rahul C., Haines, Brian Michael, Wysocki, Frederick Joseph, Benage, J. F., Fooks, J., Glebov, V., Hakel, Peter, Hoppe, M., Igumenshchev, I. V., Kagan, Grigory, Mancini, R. C., Marshall, F. J., Michel, D. T., Murphy, Thomas Joseph, Schoff, M. E., Stoeckl, C., Yaakobi, B., and Silverstein, K. Thu . "Systematic Fuel Cavity Asymmetries in Directly Driven Inertial Confinement Fusion Implosions". United States. doi:10.1103/PhysRevLett.118.135001. https://www.osti.gov/servlets/purl/1369182.
@article{osti_1369182,
title = {Systematic Fuel Cavity Asymmetries in Directly Driven Inertial Confinement Fusion Implosions},
author = {Shah, Rahul C. and Haines, Brian Michael and Wysocki, Frederick Joseph and Benage, J. F. and Fooks, J. and Glebov, V. and Hakel, Peter and Hoppe, M. and Igumenshchev, I. V. and Kagan, Grigory and Mancini, R. C. and Marshall, F. J. and Michel, D. T. and Murphy, Thomas Joseph and Schoff, M. E. and Stoeckl, C. and Yaakobi, B. and Silverstein, K.},
abstractNote = {Here, we present narrow-band self-emission x-ray images from a titanium tracer layer placed at the fuel-shell interface in 60-laser-beam implosion experiments at the OMEGA facility. The images are acquired during deceleration with inferred convergences of ~9-14. Novel here is that a systematically observed asymmetry of the emission is linked, using full sphere 3D implosion modeling, to performance-limiting low mode asymmetry of the drive.},
doi = {10.1103/PhysRevLett.118.135001},
journal = {Physical Review Letters},
number = 13,
volume = 118,
place = {United States},
year = {Thu Mar 30 00:00:00 EDT 2017},
month = {Thu Mar 30 00:00:00 EDT 2017}
}

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  • Anomalous thermonuclear yield degradation (i.e., that not describable by single-fluid radiation hydrodynamics) in Inertial Confinement Fusion (ICF) implosions is ubiquitously observed in both Omega and National Ignition experiments. Multiple experimental and theoretical studies have been carried out to investigate the origin of such a degradation. Relative concentration changes of fuel-ion species, as well as kinetically enhanced viscous heating, have been among possible explanations proposed for certain classes of ICF experiments. In this study, we investigate the role of such kinetic plasma effects in detail. To this end, we use the iFP code to perform multi-species ion Vlasov-Fokker-Planck simulations of ICFmore » capsule implosions with the fuel comprising various hydrodynamically equivalent mixtures of deuterium (D) and helium-3 (3He), as in the original. We employ the same computational setup as in O. Larroche, which was the first to simulate the experiments kinetically. However, unlike the Larroche study, and in partial agreement with experimental data, we find a systematic yield degradation in multi-species simulations versus averaged-ion simulations when the D-fuel fraction is decreased. This yield degradation originates in the fuel-ion species stratification induced by plasma shocks, which imprints the imploding system and results in the relocation of the D ions from the core of the capsule to its periphery, thereby reducing the yield relative to a non-separable averaged-ion case. By comparing yields from the averaged-ion kinetic simulations and from the hydrodynamic scaling, we also observe yield variations associated with ion kinetic effects other than fuel-ion stratification, such as ion viscous heating, which is typically neglected in hydrodynamic implosions' simulations. Since our kinetic simulations are driven by hydrodynamic boundary conditions at the fuel-ablator interface, they cannot capture the effects of ion viscosity on the capsule compression, or effects associated with the interface, which are expected to be important. As a result, studies of such effects are left for future work.« less
  • Directly driven implosions on the Omega laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] have measured the presence of atomic mix using D+T neutron yield rates from plastic capsules with and without deuterated layers, and a nearly pure tritium fuel containing 0.7% deuterium. In 15, 19, and 24 {mu}m thick plastic shells, D+T neutron yields increased by factors of 86, 112, and 24 when the 1.2 {mu}m thick inner layer was deuterated. Based on adjusting a fully atomic mix modvfel to fit yield degradation in the un-deuterated capsule and applying it to the capsule with the deuteratedmore » layer, atomic mixing accounts for 40-75% of the yield degradation due to mix. For the first time, the time dependence of mixed mass was measured by the ratio of the yield rates from both types of capsules. As expected, the amount of mix grows throughout the D+T burn.« less
  • We investigate yield degradation due to applied low mode P2 and P4 asymmetries in layered inertial confinement fusion implosions. This study has been performed with a large database of >600 2D simulations. We show that low mode radiation induced drive asymmetries can result in significant deviation between the core hot spot shape and the fuel ρR shape at peak compression. In addition, we show that significant residual kinetic energy at peak compression can be induced by these low mode asymmetries. We have developed a metric, which is a function of the hot spot shape, fuel ρR shape, and residual kineticmore » energy at peak compression, that is well correlated to yield degradation due to low mode shape perturbations. It is shown that the ρR shape and residual kinetic energy cannot, in general, be recovered by inducing counter asymmetries to make the hot core emission symmetric. In addition, we show that the yield degradation due to low mode asymmetries is well correlated to measurements of time dependent shape throughout the entire implosion, including early time shock symmetry and inflight fuel symmetry.« less