Air breakdown plasma induced by a strong electromagnetic (EM) wave field with a millimeter wavelength has a self-formed filamentary structure. The scale of the breakdown plasma is much larger than the wavelength scale, and the power density is lower than the self-ignition threshold of atmospheric breakdown. We observed the breakdown plasma that consisted of small plasma spots, and their trajectory was identical to that of the filamentary structure observed in a macroscopic view. The numerical analysis showed that the interaction of the ionization front, EM field, and neutral-gas heating determines the self-organized structure of branching plasma. The plasma trajectory identified in the analysis was identical to that of the experimental results. This novel physical process was totally different from the discrete filament formation observed in breakdown plasma formed under a focused beam, and the physical process of the breakdown strongly depended on the scale and power density.

中文翻译：

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大功率毫米波击穿等离子体宏观自组织结构研究

由具有毫米波长的强电磁 (EM) 波场引起的空气击穿等离子体具有自形成的丝状结构。击穿等离子体的尺度远大于波长尺度，功率密度低于大气击穿的自燃阈值。我们观察到由小等离子体点组成的击穿等离子体，它们的轨迹与宏观观察到的丝状结构的轨迹相同。数值分析表明，电离前沿、电磁场和中性气体加热的相互作用决定了分支等离子体的自组织结构。分析中确定的等离子体轨迹与实验结果相同。