An electron conductivity model for dense plasmas

Lee, Y. T.; More, R.M.

doi:10.1063/1.864744

Cited by 751 publications

(391 citation statements)

References 17 publications

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“…Finally the LMD model is used [46], [38]. The conductivity for the same parameters as above is found to be  ≈ 52 × 10 3 S/m.…”

Section: Electrical Conductivitymentioning

confidence: 99%

Protection characteristics of a Faraday cage compromised by lightning burnthrough.

Warne¹,

Bystrom²,

Jorgenson³

et al. 2012

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A lightning flash consists of multiple, high-amplitude but short duration return strokes. Between the return strokes is a lower amplitude, continuing current which flows for longer duration. If the walls of a Faraday cage are made of thin enough metal, the continuing current can melt a hole through the metal in a process called burnthrough. A subsequent return stroke can couple energy through this newly-formed hole. This LDRD is a study of the protection provided by a Faraday cage when it has been compromised by burnthrough. We initially repeated some previous experiments and expanded on them in terms of scope and diagnostics to form a knowledge baseline of the coupling phenomena. We then used a combination of experiment, analysis and numerical modeling to study four coupling mechanisms: indirect electric field coupling, indirect magnetic field coupling, conduction through plasma and breakdown through the hole. We discovered voltages higher than those encountered in the previous set of experiments (on the order of several hundreds of volts).3

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“…Finally the LMD model is used [46], [38]. The conductivity for the same parameters as above is found to be  ≈ 52 × 10 3 S/m.…”

Section: Electrical Conductivitymentioning

confidence: 99%

Protection characteristics of a Faraday cage compromised by lightning burnthrough.

Warne¹,

Bystrom²,

Jorgenson³

et al. 2012

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“…1.5 MeV electrons mostly stop in this depth. The time pulse is a 19 ps flattop, and intensity profile I (r) = I 0f exp[−(r/r spot ) 8 ] with r spot = 18 m. Neither of these is optimized for this case, but this r spot gave the smallest E ig f for = 10 • , the PIC-based energy spectrum, and the full Ohm's law [3]. Figure 1 displays the yield vs. fast electron energy E f .…”

Section: Results With a Mono-energetic Sourcementioning

confidence: 99%

“…(1) and the resistive Ohm's law E = J b with scalar (unmagnetized) . is found following Lee and More [8] with Desjarlais' improvements [9], and the charge state from Ref. 9's modified Thomas-Fermi approach.…”

Section: Integrated Pic-hydrodynamic Modelling With Zuma-hydramentioning

confidence: 99%

Cone-guided fast ignition withnoimposed magnetic fields

Strozzi

Tabak

Larson

et al. 2013

EPJ Web of Conferences

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Abstract. Simulations are presented of ignition-scale fast ignition targets with the integrated Zuma-Hydra PIC-hydrodynamic capability. We consider a spherical DT fuel assembly with a carbon cone, and an artificially-collimated fast electron source. We study the role of E and B fields and the fast electron energy spectrum. For mono-energetic 1.5 MeV fast electrons, without E and B fields, ignition can be achieved with fast electron energy E ig f = 30 kJ. This is 3.5× the minimal deposited ignition energy of 8.7 kJ for our fuel density of 450 g/cm 3 . Including E and B fields with the resistive Ohm's law E = J b gives E ig f = 20 kJ, while using the full Ohm's law gives E ig f > 40 kJ. This is due to magnetic self-guiding in the former case, and ∇n × ∇T magnetic fields in the latter. Using a realistic, quasi two-temperature energy spectrum derived from PIC laser-plasma simulations increases E ig f to (102, 81, 162) kJ for (no E/B, E = J b , full Ohm's law). Such electrons are too energetic to stop in the optimal hot spot depth. This paper presents work on ignition-scale transport modelling of fast ignition [1] designs. By "transport" we mean the propagation and deposition of fast electrons, with reasonably self-consistent coupling to the background radiation-hydrodynamics. To achieve this we coupled the hybrid-PIC code Zuma [2,3] to the rad-hydro code Hydra [4]. A detailed publication on this work [3] reports laserplasma PIC modelling that shows a large fast-electron divergence, along with mitigation ideas based on imposed magnetic fields. Here we discuss the fast-electron energy needed for ignition, E ig f , of an artificially-collimated source. Using the resistive Ohm's law E = J b leads to magnetic self-guiding and reduces E ig f compared to runs with no E or B fields. However, using a more complete Ohm's law increases E ig f compared to the no-field case. This ordering applies both for a mono-energetic 1.5 MeV and PIC-based fast electron energy spectrum. The latter gives electrons that are too energetic to stop in the optimal hot spot, and raises E ig f ∼ 3.4× over the 1.5 MeV spectrum.

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“…Foremost, models of the thermal conductivity of a DT plasma at the conditions of the hot spot boundary (∼1 keV and ∼100 g cm −3 ) have never been confirmed against direct experimental data. Furthermore, a comparison of various theoretical models for the conductivity suggest an uncertainty of ∼25% in this regime [41][42][43][44][45][46][47][48][49][50]. The possibility of self-generated magnetic fields in the hot spot has also long been hypothesized to result in a reduced effective hot spot thermal conductivity [51][52][53][54], while simulations have shown that plasma kinetic effects [55,56] can increase the apparent hot spot temperature in a manner similar to inhibited conductivity.…”

Section: Simulationsmentioning

confidence: 99%

Capsule modeling of high foot implosion experiments on the National Ignition Facility

Clark

Kritcher

Milovich

et al. 2017

Plasma Phys. Control. Fusion

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This paper summarizes the results of detailed, capsule-only simulations of a set of high foot implosion experiments conducted on the National Ignition Facility (NIF). These experiments span a range of ablator thicknesses, laser powers, and laser energies, and modeling these experiments as a set is important to assess whether the simulation model can reproduce the trends seen experimentally as the implosion parameters were varied. Two-dimensional (2D) simulations have been run including a number of effects-both nominal and off-nominal-such as hohlraum radiation asymmetries, surface roughness, the capsule support tent, and hot electron pre-heat. Selected three-dimensional simulations have also been run to assess the validity of the 2D axisymmetric approximation. As a composite, these simulations represent the current state of understanding of NIF high foot implosion performance using the best and most detailed computational model available. While the most detailed simulations show approximate agreement with the experimental data, it is evident that the model remains incomplete and further refinements are needed. Nevertheless, avenues for improved performance are clearly indicated.

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An electron conductivity model for dense plasmas

Cited by 751 publications

References 17 publications

Protection characteristics of a Faraday cage compromised by lightning burnthrough.

Protection characteristics of a Faraday cage compromised by lightning burnthrough.

Cone-guided fast ignition withnoimposed magnetic fields

Capsule modeling of high foot implosion experiments on the National Ignition Facility

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