铜镍合金丝电爆炸放电特性与时空演化行为

Discharge characteristics and spatial-temporal evolution of Cu-Ni alloy wire explosion

脉冲电流驱动金属丝电爆炸可产生具有较高能量密度的等离子体,并伴随脉冲电磁辐射、强冲击波等效应,广泛应用于Z箍缩、电热化学武器、油气助采等领域;与纯金属相比,合金具备电阻率高、成分可调、相变复杂等特点,在电爆炸效应参数的调控方面具有很大潜力。开展了大气空气介质中铜、镍、铜镍(康铜)丝在微秒时间尺度电脉冲作用下电爆炸实验研究,通过放电参数与自辐射图像诊断,获取电爆炸过程放电参数与时空演变的特性规律,得到脉冲电流作用下合金电爆炸在相变与等离子体方面的特征。实验发现,在电爆炸早期,铜镍合金的高电阻率能够提高能量沉积效率:铜52%、镍74%、铜镍合金78%;而相爆开始后,合金丝负载则更接近纯镍丝负载性能。等离子体通道早期膨胀速率在5 mm/μs量级,随后迅速衰减;合金丝等离子体膨胀时间更久,击穿后平均电阻率上升缓慢,且等离子体辐射与金属爆炸产物在空间尺度上存在关联性。特别地,铜镍合金气溶胶分层同时具有横向和纵向特征(特征尺度10^(−1) mm),但整体较铜气溶胶更为均匀。

Electrical explosion of wires(EEW) driven by pulse current can produce plasmas with high energy density, and is accompanied by electromagnetic pulses, strong shock waves, etc., therefore it is widely adopted in Zpinch, electrothermal chemical weapons, oil and gas exploitation and other fields. Compared to pure metal, alloy has characteristics of the high resistivity, adjustable composition, and complex phase transitions. It has great potential in regulating parameters of EEW. This paper presents an experimental study on exploding Cu, Ni, and Cu-Ni alloy(constantan) wires in atmospheric air under a microsecond time-scale pulsed current. Through the diagnoses of electrical parameters and self-emission images, the discharge characteristics and spatial-temporal evolution of explosion products were obtained. Features of the alloy wire explosion in phase transition and plasma were acquired as well. Experiments revealed that in the early stage of EEW, the high resistivity of the alloy could improve the energy deposition efficiency, namely 52% for Cu, 74% for Ni, and 78% for Cu-Ni, while after the explosion, performance of the alloy wire was closer to that of the Ni wire. The initial expansion rate of the plasma channel reached 5 mm/μs level but then decayed. The expansion process of alloy wire endured longer, and the average resistivity went up slowly after the breakdown. Also, a correlation was found between plasma radiation and metal aerosol in spatial scale.Especially, the alloy aerosol has crossed striation features(10^(-1) mm), but it is more uniform than Cu aerosol generally.