Comparison studies of electrical explosion of bare and coated wires in water

Summary form only given. Thin metal wire with insulation coating has distinctive behaviors comparing to bare wire's behaviors in vacuum, according to previous research. The insulation layer might be a key role impeding the formation of corona around the core, thus increasing the energy deposition of the wire. However, in terms of water media, it is widely accepted that there is no plasma shell or the effect of corona layer is limited. Therefore, the energy deposition is extraordinarily high in this media. Nevertheless, it may not indicate coating is meaningless in underwater electrical wire explosion. Since the depiction of boundary layer between discharge channel and water is quite obscure, an extra thin layer formed by insulation coating or other material could influence the explosion process of the wire in water. In this study, Al and Cu wires with polyester coating layer and gold layer were studied and compared with bare wires in several aspects, including light emission, energy deposition, and shock wave. A 6 μF pulse capacitor with different initial voltages and a three-electrode switch were utilized to generate different microsecond timescale pulsed currents. A Φ1200 mm stainless steel chamber was adopted to provide water environment. Besides, light emission was recorded by a spectroscope and photomultipliers. Current and Voltage were measured by Pearson Coil (Model 101) and voltage divider respectively. Shock wave waveforms were recorded by PCB 138A piezoelectric probes and PVDF probes. The results revealed that the insulation layer could postpone the burst time to some extent. In contrast, the light emission patterns are obviously different of the bare wires and coated wires.