Shunting arc generation by co-axial electrode configuration

Shunting arc is a plasma formed around a heated rod. This article describes the generation and arc characteristics of a pulsed carbon-shunting arc, where a co-axial electrode system is employed. This includes eight carbon rods 2 mm in diameter and 40 mm in length for connecting the anode and cathode. It is found that the current through the rod before arcing uniformly flows through each rod. The arc is initiated at 2–3 μs after the release of energy stored in a 20-μF capacitor bank. The shunting arc current is transient and shows a damping oscillation due to the circuit parameters. The peak current is approximately 4 kA at 15 μs for a charging voltage of 2.0 kV. A pulse voltage of −5 kV is applied to the target in order to extract an ion beam from the shunting arc. The ion current changes by the time that the pulse voltage is applied to the target, because the shunting arc discharge is pulsed and expands at approximately 20 km/s.