Effect of Nonlocal Transport on Heat-Wave Propagation

Gregori, G.; Glenzer, S. H.; Knight, J.; Niemann, C.; Price, D.; Froula, D. H.; Edwards, M. J.; Town, R. P. J.; Brantov, A. V.; Rozmus, W.; Bychenkov, V. Yu.

doi:10.1103/physrevlett.92.205006

Cited by 77 publications

(50 citation statements)

References 28 publications

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“…Recent experiments have shown that f = 0.05 is inappropriate for "open" geometry targets such as gas jets [9] and gas balloons [10]. Nonlocal transport models give good results for these targets.…”

Section: A Electron Thermal Conductionmentioning

confidence: 99%

Role of hydrodynamics simulations in laser-plasma interaction predictive capability

et al. 2007

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Efforts to predict and control laser-plasma interactions (LPI) in ignition hohlraum targets for the National Ignition Facility [G. H. Miller et al., Optical Eng. 43, 2841] are based on plasma conditions provided by radiation hydrodynamic simulations. Recent experiments provide compelling evidence that codes such as hydra [M. M. Marinak et al. , Phys. Plasmas 8, 2275(2001] can accurately predict the plasma conditions in laser heated targets such as gas-filled balloon (gasbag) and hohlraum platforms for studying LPI. Initially puzzling experimental observations are found to be caused by bulk hydrodynamic phenomena. Features in backscatter spectra and transmitted light spectra are reproduced from the simulated plasma conditions. Simulations also agree well with Thomson scattering measurements of the electron temperature. The calculated plasma conditions are used to explore a linear-gain based phenomenological model of backscatter. For long plasmas at ignition-relevant electron temperatures, the measured backscatter increases monotonically with gain and is consistent with linear growth for low reflectivities. These results suggest a role for linear gain postprocessing as a metric for assessing LPI risk.

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Section: A Electron Thermal Conductionmentioning

confidence: 99%

Role of hydrodynamics simulations in laser-plasma interaction predictive capability

et al. 2007

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“…Since λ mfp /L < 100, nonlocality can be expected to be important [15]. The steep temperature gradients caused by intense laser heating in a hohlraum have been shown to result in non-local heat flow [16,17]. Careful consideration of the electron population with 2v th < v < 4v th is required as these carry most of the heat.…”

mentioning

confidence: 99%

Kinetic modeling of Nernst effect in magnetized hohlraums

et al. 2016

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We present nanosecond timescale Vlasov-Fokker-Planck-Maxwell modeling of magnetized plasma transport and dynamics in a hohlraum with an applied external magnetic field, under conditions similar to recent experiments. Self-consistent modeling of the kinetic electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's Law, including Nernst advection of magnetic fields. In addition to showing the prevalence of non-local behavior, we demonstrate that effects such as anomalous heat flow are induced by inverse bremsstrahlung heating. We show magnetic field amplification up to a factor of 3 from Nernst compression into the hohlraum wall. The magnetic field is also expelled towards the hohlraum axis due to Nernst advection faster than frozen-in-flux would suggest. Non-locality contributes to the heat flow towards the hohlraum axis and results in an augmented Nernst advection mechanism that is included self-consistently through kinetic modeling.There has been recent interest in the role of applied magnetic fields in high-energy-density plasmas [1-3] for inertial fusion energy applications [4]. The MagnetoInertial Fusion Electric Discharge System has been developed to provide steady state magnetic fields for long time-scales relative to the experiments. An experiment on the Omega Laser Facility with a 7.5 T external axial magnetic field imposed on an Omega-scale hohlraum measured a rise in observed temperature along the hohlraum axis [5] and modeling showed that external fields can guide hot electrons from laser-plasma interactions [6] through the hohlraum, rather than the capsule [7]. From Ohm's Law, it has been shown that electron heat transport advects such magnetic fields through the Nernst effect [8][9][10][11][12][13][14] in addition to well-known processes like "frozen-in-flow" and resistive diffusion. Dimensionless numbers comparing the ratio of the magnitudes of the Nernst term to the bulk plasma flow term, R N 1 [10], and the Hall term, H N 1 [13], suggest that Nernst convection should be the dominant mechanism for magnetic field transport in a hohlraum. Such a hot and semi-collisional environment is, however, rich in nonequilibrium effects that may complicate the magnetic field dynamics.Laser heating of the plasma results in steep temperature gradients, typically O(3 keV/50 µm). The collisional * archis@ucla.edu † agrt@umich.edu mean-free-path of a 3 keV electron is O(10 µm), depending on the plasma density. Since λ mfp /L < 100, nonlocality can be expected to be important [15]. The steep temperature gradients caused by intense laser heating in a hohlraum have been shown to result in non-local heat flow [16,17]. Careful consideration of the electron population with 2v th < v < 4v th is required as these carry most of the heat. Additionally, inverse-bremsstrahlung heating of a plasma [18,19] not only leads to deviations from Braginskii transport [20], but also new transport terms [21,22]. Both non-locality and laser heating result in modifications to the distribution function an...

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“…This is often done to treat nonlocal transport in plasmas with low collisionality, in which particle and energy fluxes at a given location are affected by conditions in distant regions of the plasma, which represents an important and complex problem. Often, ad hoc schemes are used in which the flux is simply limited to a fraction of its free-streaming value [1,8,13,[52][53][54]. Data such as presented here can provide a measurement of fluxes and thermodynamic gradients with high temporal and spatial resolution.…”

Section: Discussionmentioning

confidence: 99%

“…Because of the increasing mean free path with particle kinetic energy, the situation can already change for mean free path on the order of or longer than 1% of the length scale of plasma gradients [1]. This gives rise to kinetic effects such as streaming plasmas and non-local transport, which are intensely studied because of their importance in many plasma environments, such as high-density laser-produced plasmas [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and astrophysical plasmas like the solar wind [19], solar atmosphere [20,21], solar flares [22], and supernovae [23].…”

Section: Introductionmentioning

confidence: 99%

Emergence of kinetic behavior in streaming ultracold neutral plasmas

et al. 2015

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We create streaming ultracold neutral plasmas by tailoring the photoionizing laser beam that creates the plasma. By varying the electron temperature, we control the relative velocity of the streaming populations, and, in conjunction with variation of the plasma density, this controls the ion collisionality of the colliding streams. Laser-induced fluorescence is used to map the spatially resolved density and velocity distribution function for the ions. We identify the lack of local thermal equilibrium and distinct populations of interpenetrating, counter-streaming ions as signatures of kinetic behavior. Experimental data is compared with results from a one-dimensional, two-fluid numerical simulation.

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Effect of Nonlocal Transport on Heat-Wave Propagation

Cited by 77 publications

References 28 publications

Role of hydrodynamics simulations in laser-plasma interaction predictive capability

Role of hydrodynamics simulations in laser-plasma interaction predictive capability

Kinetic modeling of Nernst effect in magnetized hohlraums

Emergence of kinetic behavior in streaming ultracold neutral plasmas

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