Discharge channel development of microsecond tungsten wire explosion in air

The discharge channel development of microsecond electrical exploding tungsten in air was investigated. A microsecond pulsed current source was used to trigger the electrical explosion of tungsten wires with a length of 40 cm and a diameter of 0.3 mm. Charged with a 26 kV voltage, a 6 μF capacitor possessed a stored energy of 2028 J, which was not enough to vaporize the tungsten wire. We proposed two parameters, the total cross-sectional area and the granular border area, to quantitatively describe the discharge channel development. We also adopted an image processing method to study the entire discharge channel development throughout the wire explosion. Evident results suggested that the trend of the electrical explosion was layer by layer from the surface to the core, and the outward expanding speed of the channel was gradually decreasing. The results also demonstrated clear distinction between the discharge channel developments at upper and lower electrodes. During the electrical explosion, the granular border area increased in an approximate exponential way, while the total cross-sectional area increased linearly until 1.43 ms and then decreased, which was caused by hollow regions formed in the discharge channel.