Factors affecting the exploding characteristics of tungsten wires with negative-polarity current

Abstract

This paper presents the experimental results of electrical explosion of tungsten (W) wires in a vacuum using a negative-polarity current pulse with a magnitude of 1–2 kA. Uniform wire explosions with deposited energy sufficient for full vaporization are achieved for 0.5 cm-long W wires with the help of dielectric coating and soldering. Experimental results show that the dielectric coating can give 2–3 times more energy deposition by delaying the voltage breakdown. In order to improve the electrical contact, the metallic oxide on the surface of the electrodes is removed with sandpaper, and then the W wire is soldered to the electrodes. It is found that the improved electrical contact does not have an obvious influence on increasing the energy deposition. However, from the optical images, it can be seen that the uniformity of the wire explosion is greatly improved, especially for the W wire with 2 μm polyimide coating. Therefore, the dielectric coating and good electrical contact are the two key factors to uniformly transform the W wire into a gaseous state. With this method, the uniform wire explosions for longer tungsten wires (1 and 2 cm) are also realized under the same experimental conditions.