Magnetic-field generation and its effect on ablative Rayleigh–Taylor instability in diffusive ablation fronts
Magnetic-field generation and its effect on ablative Rayleigh–Taylor instability in diffusive ablation fronts
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磁场的产生及其对扩散烧蚀前沿烧蚀瑞利-泰勒不稳定性的影响
DOI：
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
H. Aluie
中科院分区：
文献类型：
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作者：
F. García;R. Betti;J. Sanz;H. Aluie
在线性状态下研究了自生磁场对烧蚀瑞利-泰勒 (RT) 不稳定性的影响。主要控制参数是弗劳德数（Fr），它代表烧蚀对流与目标加速度之间的比率，以及烧蚀前沿的马赫数（Ma），假设很小（等压性）。在 RT 不稳定性的发展过程中，由于压力和密度梯度之间的错位（比尔曼电池效应）而产生磁场。它们聚集在烧蚀前沿的能斯特速度和等离子体速度相互抵消的部分。磁场通过里吉-勒杜克项修改不稳定性的动力学，该项充当能量方程中的热源。研究发现，B 场会影响短波长的扰动，直至光谱中最不稳定的波。 B 场对于中等弗劳德数起不稳定作用，而对于大弗劳德数则变得稳定。对于塑料烧蚀器，Fr 阈值被发现为 Fr = 5。
The effects of self-generated magnetic fields on the ablative Rayleigh–Taylor (RT) instability are investigated in the linear regime. The main governing parameters are the Froude number (Fr), which stands for the ratio between ablative convection and acceleration of the target, and the Mach number at the ablation front (Ma), assumed to be small (isobaricity). During the development of the RT instability, magnetic fields are generated due to misalignment between pressure and density gradients (Biermann-battery effect). They accumulate at the section of the ablation front where the Nernst and the plasma velocities cancel each other. The magnetic field modifies the dynamics of the instability through the Righi–Leduc term, which acts as a heat source in the energy equation. It is found that the B fields affect perturbations with short wavelengths up to the most unstable wave in the spectrum. The B field plays a destabilizing role for moderate Froude numbers and becomes stabilizing for large Froude numbers. For plastic ablators, the Fr threshold is found to be Fr = 5.