Abstract

A model of resonance absorption of laser radiation in a plasma involving the deformation of the density profile by the ponderomotive force has been proposed. A mechanism of the linear transformation of laser radiation into plasma waves at resonance absorption has been discussed. The quasilinear diffusion equation for the electron distribution function in the plasma field has been used to describe the generation of fast electrons by plasma waves. Formulas have been obtained to estimate the energy fraction absorbed through the resonance mechanism and the energy of fast electrons. These formulas have been used in the two-dimensional hydrodynamic code ATLANT-HE. The hydrodynamics of the plasma and the absorption of laser radiation have been calculated for conditions of the NIF facility experiment at a radiation power of 30 ТW and a base pulse duration of 7.5 ns. The plasma has the spatial dimensions appearing upon the irradiation of a spherical target for the initiation of the fusion reaction. The calculations have shown that the resonance absorption mechanism leads to the generation of fast electrons with an energy of about 40–80 keV. Fast electrons carry an energy of about 1–1.5% of the laser energy. These results are close to the experimental data.

中文翻译：

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等离子体中激光辐射吸收的数值模拟，包括核聚变靶点点火条件下的共振机理和快速电子的产生

摘要

已经提出了一种等离子体中激光辐射的共振吸收模型，该模型涉及由重磁动力引起的密度分布的变形。讨论了在共振吸收下激光辐射线性转化为等离子体波的机理。用于等离子体场中电子分布函数的准线性扩散方程已用于描述等离子体波产生快速电子的过程。已获得公式来估计通过共振机制吸收的能量分数和快速电子的能量。这些公式已在二维流体动力代码ATLANT-HE中使用。对于NIF设施实验条件，在30ТW的辐射功率和7.5 ns的基本脉冲持续时间下，已计算出等离子体的流体动力学和激光辐射的吸收。等离子体具有在球形靶材的辐照下出现的空间尺寸，以引发聚变反应。计算表明，共振吸收机制导致能量约为40-80 keV的快速电子的产生。快电子的能量约为激光能量的1–1.5％。这些结果接近实验数据。计算表明，共振吸收机制导致能量约为40-80 keV的快速电子的产生。快电子的能量约为激光能量的1–1.5％。这些结果接近实验数据。计算表明，共振吸收机制导致能量约为40-80 keV的快速电子的产生。快电子的能量约为激光能量的1–1.5％。这些结果接近实验数据。