Opacity of germanium and silicon in ICF plasmas

Benredjem, D.; Mondet, Guillaume; Calisti, A.; Gilleron, F.; Pain, Jean‐Christophe

doi:10.1117/12.2008508

Cited by 4 publications

(1 citation statement)

References 9 publications

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“…Calculating opacity is very important in understanding many high-energy processes. This is particularly evident in inertial confinement fusion (ICF) schemes, where germanium is one of the elements used as a dopant in the ablator of the ignition target and is extensively studied by Benredjem et al (2013) and Lee et al (2020). In astrophysics, germanium is rarely found in high concentrations.…”

Section: Introductionmentioning

confidence: 99%

Electron-Impact Excitation of Ge iii and Photoionisation of Ge ii

Dunleavy

Ballance

Ramsbottom

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Energy levels, Einstein A-values and oscillator strengths are calculated for doubly-ionised germanium (Ge iii). We have undertaken a study of the electron-impact excitation of Ge iii and have also completed a study of the photoionisation of Ge ii. Ge iii target structures were generated using the relativistic GRASP0 package. Several scattering models were investigated to assess the uncertainty quantification of our results. Initially, the lowest lying 64 jj fine-structure levels were included in the close-coupling expansion resulting from 14 non-relativistic configurations. A second larger model was subsequently generated using the GASP package and incorporated the lowest 589 jj fine-structure levels from 17 non-relativistic configurations. Both the DARC and Breit-Pauli parallel suite of R-matrix collision codes were utilised in the scattering calculations to generate the collision strengths for incident electron-energies between 0 and 5 Rydbergs and subsequently the Maxwellian averaged effective collision strengths for temperatures in the range 1000 to 200000 Kelvin. The photoionisation calculations comprised of two studies, a DARC and a Breit-Pauli calculation incorporating the 250 lowest lying levels. Photoionisation cross sections for Ge ii are presented in the range 0-5 Ryds. Due to the lack of data available in the literature, the present radiative data and electron-impact/photoionisation cross sections are compared between the models presented in this paper. To assess their significance for astrophysics, the data are incorporated into the stellar atmosphere package sterne. Test models for the heavy-metal subdwarf LSIV−14○116 are not affected by the new data, but models for cooler stars may be sensitive to them.

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Section: Introductionmentioning

confidence: 99%

Electron-Impact Excitation of Ge iii and Photoionisation of Ge ii

Dunleavy

Ballance

Ramsbottom

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The M-band transmission flux of the plastic foil with a coated layer of silicon or germanium

Zhang

Jiang

et al. 2014

Applied Physics Letters

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Silicon (Si) and Germanium (Ge) can be used as the dopant in the ablator material for the purpose of reducing preheating in indirect-drive inertial confinement fusion. Their performances in reducing preheating are quite different. A method to evaluate the difference of these two kinds of dopants has been presented in this letter. In the Shenguang-II high power laser facility, the M-band (1.6–4.4 keV) transmission flux of Si-coated plastic (CH) and Ge-coated plastic (CH) has been measured by using the M-band x-ray diode. In the experiment, we find that the Si-coated CH can absorb more M-band x-rays and thus reduce the preheating of the fuel in our experiment condition. By using the radiation hydrodynamic code MULTI-1D, we got the simulation result which was well suited for the experiment. The comparison of their opacities (Te = 60–100 eV and ρ = 0.1–0.5 g/cm3) also shows that the opacity of Si is higher than that of Ge almost in the whole range of 1.6–4.4 keV.

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The importance of the transmission flux in evaluating the preheat effect in x-ray driven ablation

Jiang

Zhang

et al. 2015

Physics of Plasmas

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In x-ray driven ablation, the preheat effect is caused by the high energy x-rays that pass through the ablator. Thus, the transmission flux can be used to characterize preheat effect in a certain degree. With the radiation temperature being 200 eV, the transmission flux and preheat temperature of pure polymer (CH) have been studied by using the one-dimensional multi-group radiation hydrodynamic code MULTI-1D. By studying the spectrum of the transmitted x-rays, it is found that the energy of the transmitted x-rays is in the range of 2–5 keV for pure CH ablator. This is of importance for selecting a dopant for CH ablator. We also calculated both the preheat temperature of CH near the surface of thick target (47.66 μm) and the transmission flux of a thinner target (38.66 μm). It is found that the more transmission flux leads to the higher preheat temperature. Preheat effect of graded Si-doped CH targets with different doped concentrations has also been studied. The results are consistent with this phenomenon. By analyzing the relationship between the transmission flux and the preheat temperature, we have presented a novel method to evaluate preheat effect in x-ray driven ablation.

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Opacity of germanium and silicon in ICF plasmas

Cited by 4 publications

References 9 publications

Electron-Impact Excitation of Ge iii and Photoionisation of Ge ii

Electron-Impact Excitation of Ge iii and Photoionisation of Ge ii

The M-band transmission flux of the plastic foil with a coated layer of silicon or germanium

The importance of the transmission flux in evaluating the preheat effect in x-ray driven ablation

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