Simulation and assessment of ion kinetic effects in a direct-drive capsule implosion experiment

Lê, A.; Kwan, Thomas J. T.; Schmitt, Mark J.; Herrmann, H. W.; Batha, S. H.

doi:10.1063/1.4965913

Cited by 28 publications

(12 citation statements)

References 34 publications

(32 reference statements)

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“…(5. 19) In the frame of reference of the moving wall, an elastic scatter will reflect the particle's parallel (to wall normal vector) velocity component,…”

Section: Elastic Moving Wall and Symmetry Boundary Conditionsmentioning

confidence: 99%

“…Contrary to the rad-hydro predictions, however, the National Ignition Facility (NIF) has not achieved ignition of ICF targets to date. Various authors have proposed the importance of kinetic effects [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26] and their potential role in altering the rad-hydro predictions. Some of these effects include, but are not limited to: 1) plasma ion stratification due to differential motion of multiple ions; 2) long-mean-free path modification to transport physics (e.g., heat flux and viscosity); and 3) laser-plasma interactions.…”

Section: Introductionmentioning

confidence: 99%

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An Eulerian Vlasov-Fokker-Planck Algorithm for Spherical Implosion Simulations of Inertial Confinement Fusion Capsules

Taitano,

Keenan,

Chacon

et al. 2020

Preprint

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We present a numerical algorithm that enables a phase-space adaptive Eulerian Vlasov-Fokker-Planck (VFP) simulation of an inertial confinement fusion (ICF) capsule implosion. The approach relies on extending a recent mass, momentum, and energy conserving phase-space moving-mesh adaptivity strategy to spherical geometry. In configuration space, we employ a mesh motion partial differential equation (MMPDE) strategy while, in velocity space, the mesh is expanded/contracted and shifted with the plasma's evolving temperature and drift velocity. The mesh motion is dealt with by transforming the underlying VFP equations into a computational (logical) coordinate, with the resulting inertial terms carefully discretized to ensure conservation. To deal with the spatial and temporally varying dynamics in a spherically imploding system, we have developed a novel nonlinear stabilization strategy for MMPDE in the configuration space. The strategy relies on a nonlinear optimization procedure that optimizes between mesh quality and the volumetric rate change of the mesh to ensure both accuracy and stability of the solution. Implosions of ICF capsules are driven by several boundary conditions: 1) an elastic moving wall boundary; 2) a time-dependent Maxwellian Dirichlet boundary; and 3) a pressure-driven Lagrangian boundary. Of these, the pressure-driven Lagrangian boundary driver is new to our knowledge. The implementation of our strategy is verified through a set of test problems, including the Guderley and Van-Dyke implosion problems -the first-ever reported using a Vlasov-Fokker-Planck model.

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“…(5. 19) In the frame of reference of the moving wall, an elastic scatter will reflect the particle's parallel (to wall normal vector) velocity component,…”

Section: Elastic Moving Wall and Symmetry Boundary Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Eulerian Vlasov-Fokker-Planck Algorithm for Spherical Implosion Simulations of Inertial Confinement Fusion Capsules

Taitano,

Keenan,

Chacon

et al. 2020

Preprint

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show abstract

“…Shocks, especially at high Mach numbers, can experience non-equilibrium behavior such as deviations from MB velocity distributions and temperature anisotropies [44][45][46][47]. One example are two-component velocity distributions found in kinetic ICF implosion simulations that are caused by energetic run-away ions and the mixture of matter upstream and downstream of the shock [48][49][50]. Another example are rarefied hypersonic flows that are prone to anisotropies in T (or P ) components longitudinal and transverse to the direction of shock propagation.…”

Section: Mean-free-path and Non-equilibrium Studymentioning

confidence: 99%

Two-dimensional implosion simulations with a kinetic particle code

2017

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We perform two-dimensional (2D) implosion simulations using a Monte Carlo kinetic particle code. The application of a kinetic transport code is motivated, in part, by the occurrence of nonequilibrium effects in inertial confinement fusion (ICF) capsule implosions, which cannot be fully captured by hydrodynamic simulations. Kinetic methods, on the other hand, are able to describe both, continuum and rarefied flows. We perform simple 2D disk implosion simulations using one particle species and compare the results to simulations with the hydrodynamics code RAGE. The impact of the particle mean-free-path on the implosion is also explored. In a second study, we focus on the formation of fluid instabilities from induced perturbations. We find good agreement with hydrodynamic studies regarding the location of the shock and the implosion dynamics. Differences are found in the evolution of fluid instabilities, originating from the higher resolution of RAGE and statistical noise in the kinetic studies.

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“…Multi-ion and kinetic physics can lead to measurable changes in implosion performance such as yield degradation, 5 anomalous yield scaling, 6,7 ion thermal decoupling, 8 and ion species separation. 9,10 These multi-ion/kinetic effects related to the ion mean free path, 11 ion mass, 12 and ion charge 13 have been modeled using reduced ion-kinetic models, 14 particle-in-cell (PIC) simulations, [15][16][17] and kinetic-ion simulations. [18][19][20][21][22] This work follows the experiments described by Sio et al, 10 and greatly expands on this previous work through the inclusion of (1) two new experiments on DD and D 3 He reaction histories, (2) one new experiment on DD, DT, and D 3 He reaction histories, and (3) kineticion FPION simulations in the interpretation of the data.…”

Section: Introductionmentioning

confidence: 99%

Probing ion species separation and ion thermal decoupling in shock-driven implosions using multiple nuclear reaction histories

et al. 2019

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Simultaneously measured DD, DT, and D 3 He reaction histories are used to probe the impacts of multi-ion physics during the shock phase of inertial confinement fusion implosions. In these relatively hydrodynamiclike (burn-averaged Knudsen number hN K i $0.3) shock-driven implosions, average-ion hydrodynamic DUED simulations are able to reasonably match burnwidths, nuclear yields, and ion temperatures. However, kineticion FPION simulations are able to better simulate the timing differences and time-resolved reaction rate ratios between DD, DT, and D 3 He reactions. FPION simulations suggest that the D 3 He/DT reaction rate ratio is most directly impacted by ion species separation between the 3 He and T ions, whereas the D 3 He/DD reaction rate ratio is affected by both ion species separation and ion temperature decoupling effects.

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Simulation and assessment of ion kinetic effects in a direct-drive capsule implosion experiment

Cited by 28 publications

References 34 publications

An Eulerian Vlasov-Fokker-Planck Algorithm for Spherical Implosion Simulations of Inertial Confinement Fusion Capsules

An Eulerian Vlasov-Fokker-Planck Algorithm for Spherical Implosion Simulations of Inertial Confinement Fusion Capsules

Two-dimensional implosion simulations with a kinetic particle code

Probing ion species separation and ion thermal decoupling in shock-driven implosions using multiple nuclear reaction histories

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