Investigation of radiation flux in certain band via the preheat of aluminum sample

Zhang, Chen; Wang, Zhebin; Zhao, Baozhen; Hu, Guang-yue; Wang, Rui; Peng, Xiaoshi; Jiang, Shaoen; Ding, Yongkun; Zheng, Jian

doi:10.1063/1.4844015

Cited by 8 publications

(3 citation statements)

References 47 publications

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“…By dividing the incident radiation source into a low frequency Planckian and a high frequency Gaussian distribution, the shock velocities can be obtained through radiation hydrodynamic simulations and the M-band fraction can be obtained along with the radiation temperature. Analyzing the motion of a sample due to preheat has also been used to provide information on the fraction of soft and hard x-rays in the source [10]. To determine the rear surface spectral temperature, the spectral intensity averaged over a 200 ps window at the time of shock breakout was compared to a Planck form.…”

Section: Introductionmentioning

confidence: 99%

“…Preheating ahead of the shock front also causes significant shock propagation variation in the capsule thereby reducing the final yield [14]. As the rear surface of the foil expands due to preheating, large uncertainties in EOS diagnostics creep in [10]. Preheating also makes it difficult to maintain a low adiabat in ICF capsules thereby requiring much higher implosion kinetic energy [15].…”

Section: Introductionmentioning

confidence: 99%

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Effect of soft and hard x-rays on shock propagation, preheating and ablation characteristics in pure and doped Be ablators

Ghosh,

Mishra

2021

Preprint

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In this paper, we analyze the performance of pure and doped Be ablators used for Inertial Confinement Fusion (ICF) pellets in terms of shock velocity, shock breakout temperature, preheat temperature and mass ablation rate through radiation hydrodynamic (RHD) simulations. For this study, we apply a constant radiation profile (drive temperatures varying from 120 -200 eV) consisting of a low frequency Planck spectrum (soft x-rays) and a high frequency Gaussian spectrum (hard x-rays, commonly termed as "M-band") on a planar foil of the ablator. The fraction of energy density in the hard x-ray spectrum (α) has been varied from 0 to 0.25. In pure Be, at lower drive temperatures, the shock velocities are found to rise slowly with α. Beyond 170 eV, the shock velocities do not change with α. The predominant effect of hard x-rays is to preheat the ablator ahead of the shock front. Steady rise in preheat temperature and shock breakout temperature is observed on increasing the fraction of hard x-rays. Also, mass ablation rates in Be are found to be unaffected by hard x-rays. Preheating can be mitigated by doping Be with a mid-Z element Cu as its opacity is much higher in the high frequency region. On doping Be with 1% Cu, the shock velocities decrease slightly compared to pure Be. However, higher shock velocities are observed on increasing the fraction of M-band. Similar to pure Be, preheat and shock breakout temperatures have a strong dependence on α. We observe significant decrease in shock breakout and maximum preheat temperature in doped Be foil. Steady rise in these temperatures is observed on increasing α. Unlike pure Be, the mass ablation rate is found to increase slowly with M-band fraction in Cu doped Be. We have proposed new scaling relations for shock velocity, shock breakout temperature, maximum preheat temperature and mass

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of soft and hard x-rays on shock propagation, preheating and ablation characteristics in pure and doped Be ablators

Ghosh,

Mishra

2021

Preprint

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“…The front surface of target is covered by 300 nm thick Al foil to prevent direct laser penetration. While half of the rear surface is coated with 3 µm of Al as a preheat tracer [33][34][35]. This tracer could avoid preheat induced blinding inside GDP and give a reliable shock breakout time.…”

mentioning

confidence: 99%

Investigation of preheat induced degradation on material compression for double shock drive under different picket power

Zhang¹,

Yang²,

Duan³

et al. 2020

Plasma Phys. Control. Fusion

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Material compressibility and entropy is of great significance for inertial confinement fusion research. Preheat induced degradation on material compression under double shock compression is studied on ShenGuang series laser facility. The deviations on rear surface expansion and multiple shock timing are contrasted under different picket power. The measured preheat besides shocks could provide more physical boundaries and benchmarks from experiment. 1% silicon dopants is mandatory to keep ablator/fuel interface stable with P picket = 9.60 TW and T r = 146 eV in a double-shock compression. While pure GDP ablator is applicable to P picket = 3.36 TW. This study demonstrates a new testbed to provide in-situ preheat evaluation for implosion experiment. It aims to validate the preheat level and effects on material compression for a double shock, low convergence ratio design. It could also provide valuable information for target dopant design and upcoming shock tuning process.

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A method for evaluating the mean preheat temperature in X-ray driven ablation

Jiang

et al. 2015

Physics of Plasmas

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A novel method is proposed for evaluating the mean preheat temperature in X-ray driven ablation, based on the equation of state (EOS) of the ablator and the radiation hydrodynamic simulation. The equation of state of plastic (CH) has been discussed in detail. There are two types of planar CH in simulations, with the thick target being 10 μm thicker than the thin target. The difference between the transmission fluxes of the two types of targets can represent the energy absorbed by the last 10 μm of the thick target (or the preheated layer). This energy approximates the internal energy of the preheated layer. The mean preheat temperature of the preheated layer has also been obtained from simulations. The simulation results show that the relationship between the absorbed energy and the mean preheat temperature is similar to the EOS of CH for different conditions (e.g., different values of M-band fraction and radiation temperature) and can be written as ε=2.530×1011T¯1.444 when the mean preheat temperature is below 12 eV. For these cases, the relationship between the surface preheat temperature TS and the mean preheat temperature T¯ was TS=0.63T¯. This relation provides the means for demonstrating the proposed method, because the transmission fluxes and the surface preheat temperature TS can be measured experimentally.

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Investigation of radiation flux in certain band via the preheat of aluminum sample

Cited by 8 publications

References 47 publications

Effect of soft and hard x-rays on shock propagation, preheating and ablation characteristics in pure and doped Be ablators

Effect of soft and hard x-rays on shock propagation, preheating and ablation characteristics in pure and doped Be ablators

Investigation of preheat induced degradation on material compression for double shock drive under different picket power

A method for evaluating the mean preheat temperature in X-ray driven ablation

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