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arXiv 1603.03327physics.plasm-ph
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密度调制引起的绝对laser等离子体不稳定性:模拟和理论

Density modulation-induced absolute laser-plasma-instabilities: simulations and theory

J. Li, R. Yan, C. Ren

摘要:

流体模拟表明,当正弦密度调制叠加在线性密度分布上时,对流不稳定性可以变得绝对不稳定。这种转换可以发生在现实的直接驱动惯性约束聚变条件下的两个等离子体衰变和受激拉曼散射不稳定性,并且可以影响热电子产生和激光能量沉积。三波模型的分析表明,足够大的变化的密度梯度的线性密度分布可以把对流不稳定性变成绝对的。给出了梯度变化阈值的解析表达式,它只依赖于对流增益。

英文摘要:

Fluid simulations show that when a sinusoidal density modulation is superimposed on a linear density profile, convective instabilities can become absolutely unstable. This conversion can occur for two-plasmon-decay and stimulated Raman Scattering instabilities under realistic direct-drive inertial confinement fusion conditions and can affect hot electron generation and laser energy deposition. Analysis of the three-wave model shows that a sufficiently large change of the density gradient in a linear density profile can turn convective instabilities into absolute ones. An analytical expression is given for the threshold of the gradient change, which depends on the convective gain only.

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