An order of magnitude difference was observed in the energy deposition during a microsecond explosion of thin nickel wires in a vacuum, depending on the design of the wire-holding electrodes. In one case, cylindrical polished stainless steel (ss) electrodes with a rounded edge have a small axial hole of 0.3 mm to hold a thin wire. In the second case, these were the same polished electrodes without an axial hole, and the wire was attached to the side of the electrode with a kapton tape. For the electrodes with an axial hole, a voltage breakdown appears when the wire reaches a low temperature of ∼570 K due to the generation of the parasitic plasma discharges from the wire-holder contact. In a long timescale of ∼30 μs, wire resistive heating was interrupted by plasma generations 6 times up to the moment of melting. For the same electrodes without holes, the wire reaches a temperature of ∼1870 K during an ∼2 μs single-stage heating, and the shunting plasma was generated due to the evaporation of impurities from the hot metal surface and avalanche ionization by thermo-emitted electrons from the hot metal surface. We observe similar effects for Cu, Ti, and Pt wires. This effect is important for slow microsecond exploding wires in a vacuum and negligible for fast nanosecond explosions.

中文翻译：

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电极对金属细线真空微秒爆炸的影响

在真空中细镍线微秒爆炸期间，观察到能量沉积存在数量级差异，这取决于线固定电极的设计。在一种情况下，圆形边缘的圆柱形抛光不锈钢 (ss) 电极有一个 0.3 毫米的小轴向孔来固定细线。在第二种情况下，这些是相同的抛光电极，没有轴向孔，电线用聚酰亚胺胶带连接到电极的侧面。对于带有轴向孔的电极，当导线达到~570 K 的低温时，由于导线架接触处产生的寄生等离子体放电，会出现电压击穿。在~30 μs 的长时间尺度内，直到熔化的那一刻，线电阻加热被等离子体产生中断了 6 次。对于相同的无孔电极，在约 2 μs 的单级加热过程中，金属丝达到约 1870 K 的温度，由于热金属表面的杂质蒸发和热发射的雪崩电离而产生分流等离子体。来自热金属表面的电子。我们观察到 Cu、Ti 和 Pt 线的类似效果。这种效应对于真空中的慢微秒爆炸线很重要，而对于快速纳秒爆炸则可以忽略不计。