Lawrence Livermore National Laboratory



Drew Higginson

Overview

We successfully demonstrated the feasibility and utility of modeling the effects of kinetic physics in gas-filled hohlraums using high-fidelity simulation tools. We found that hybrid particle-in-cell simulations utilizing quasi-neutral, fluid electrons and kinetic ions are powerful tools to understand the kinetic physics of interpenetration and mix relevant to low-gas-fill (near-vacuum) hohlraums. We have benchmarked the code, Chicago, against OMEGA laser experiments designed to mimic conditions found in hohlraums. The code was able to reproduce data from x-ray imaging and Thomson spectra resolved over both time and space. The experiments highlighted kinetic-ion effects, such as increased penetration depth, that could only be resolved with a kinetic model. Using Chicago, we have run preliminary simulations of full-scale hohlraum experiments that include laser raytracing, equation-of-state and ionization, radiation transport, and accurate experimental geometries. Continuation of this work will support predictive hohlraum models at low-gas-fill and identify the better regimes of hohlraum design with the potential for improved coupling and capsule symmetry.

Impact on Mission

The development of predictive hohlraum capability is of fundamental interest for achieving ignition on the National Ignition Facility (NIF) and for design of other high-energy-density experiments. This project supports Lawrence Livermore National Laboratory's mission focus area of inertial fusion science and technology and the DOE mission in science and energy as part of the strategic objective to support an environmentally responsible, secure, and resilient U.S. energy infrastructure. Our research has proven the ability of hybrid kinetic-ion simulations to model large-scale NIF-relevant experiments. This simulation technique has the potential to improve the physics basis for predictive hohlraum models and identify better regimes of hohlraum design with the potential for improved coupling and capsule symmetry.

Publications, Presentations, Etc.

Higginson, D., et al. 2017. "Diagnosing Collisionless Phenomena via Neutron Self-Emission on the National Ignition Facility." Conference on Laser Energy Science: Laser and Accelerator Neutron Sources and Applications, Yokohama, Japan, April 2017. LLNL-PRES-729345.

Higginson, D., et al. 2018. "Quasi-Neutral Particle-in-Cell Simulations for Inertial Confinement Fusion Experiments." Second Workshop on Kinetic Physics in Inertial Confinement Fusion. LLNL-ABS-748786.

——— . 2018. "Application of Kinetic-Ion MHD Particle-in-Cell Modeling to Laboratory Plasmas." 60th Annual Meeting of the American Physical Society Division of Plasma Physics, Portland, OR, November 2018. LLNL-PRES-760448.

——— . 2019. "Kinetic-Ion Quasineutral Hybrid Particle-in-Cell Modeling of Interpenetrating Flows Relevant to ICF." 11th International Conference on Inertial Fusion Sciences and Applications, Osaka, Japan, September 2019. LLNL-PRES-790165.

——— . 2019. "Kinetic Effects on Neutron Generation in Moderately Collisional Interpenetrating Plasma Flows." Physics of Plasmas 26 (1): 012113. LLNL-JRNL-752479.

Rinderknecht, H., et al. 2017. "The Kinetic Physics in ICF Workshop: Findings and Paths Forward." 47th Annual Anomalous Absorption Conference, Berkeley, CA, June 2017. LLNL-ABS-730754.

——— . 2018. "Highly Resolved Measurements of a Developing Strong Collisional Plasma Shock." Physical Review Letters 120: 095001. doi: 10.1103/PhysRevLett.120.095001. LLNL-JRNL-755398.

——— . 2018. "Kinetic Physics in ICF: Present Understanding and Future Directions." Plasma Physics and Controlled Fusion 60: 064001. LLNL-JRNL-755501.

——— . 2018. "Progress Toward Fully-Formed Collisionless Astrophysically Relevant Shock Experiments on OMEGA and the National Ignition Facility." 12th International Conference on High Energy Density Laboratory Astrophysics (HEDLA), Kurashiki, Okayama, Japan, June 2018. LLNL-ABS-748079.

Wilks, S., et al. 2018. "Proton Deflectometry as a Tool for Diagnosing Kinetic Effects in ICF." Second Workshop on Kinetic Physics in Inertial Confinement Fusion. LLNL-ABS-748679.