Abstract

Propagation and structure of the pulsed microplasma discharge initiated on the titanium sample surface covered with a thin dielectric film with a thickness of approximately 10 nm was studied experimentally. The discharge duration was 100 μs; the amplitude of the discharge electric current was 200 A. The microplasma discharge was initiated by the plasma flow with wide aperture, a plasma density of 2 × 10¹³ cm^–3 and pulse duration of 25 μs. It was visually found that, on the macroscale, the microplasma discharge glow has a branched structure of the dendrite type, which, on the microscale, it consists of a large number of brightly glowing “point” formations, namely, cathode spots localized on the metal surface. The interaction of microplasma discharge with the titanium sample results in erosion of its surface. In this case, the erosion structure is visually “identical” to the structure of the discharge glow and consists of a large number of individual microcraters with characteristic sizes from 0.3 to 10 microns, localized on the metal surface within an area of ≈1 cm². On the macroscale, the entire set of microcraters forms a branched structure of the dendrite type. It was ascertained that the microplasma discharge propagates over the titanium surface covered with a thin dielectric film at an average velocity of 70 m/s. Moreover, the microplasma discharge propagation has a “jumping” character: the plasma of “immovable” burning cathode spots initiates the excitation of new cathode spots at distances of 3–30 microns from them.

中文翻译：

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微等离子体放电在薄介电膜覆盖的钛表面上的传播

摘要

实验研究了在覆盖有厚度约为 10 nm 的薄介电膜的钛样品表面上引发的脉冲微等离子体放电的传播和结构。放电持续时间为 100 μs；放电电流幅值为200 A。微等离子体放电由大孔径等离子体流引发，等离子体密度为2 × 10 ¹³ cm ^–3和 25 μs 的脉冲持续时间。目视发现，在宏观尺度上，微等离子体放电辉光具有枝晶类型的分支结构，在微观尺度上，它由大量明亮的发光“点”结构组成，即位于阴极上的阴极斑点。金属表面。微等离子体放电与钛样品的相互作用导致其表面被侵蚀。在这种情况下，侵蚀结构在视觉上与放电辉光的结构“相同”，由大量特征尺寸为 0.3 到 10 微米的单个微坑组成，位于金属表面 ≈1 cm ²的区域内. 在宏观尺度上，整个微陨石坑形成了枝晶类型的分支结构。确定微等离子体放电以 70 m/s 的平均速度在覆盖有薄介电膜的钛表面上传播。此外，微等离子体放电传播具有“跳跃”特性：“不可移动”燃烧的阴极点的等离子体在距它们 3-30 微米的距离处启动新阴极点的激发。