Generally when phase electrode closes to neutral as second electrode with different potential, we will face to arc discharges probability. If the current in the gap is increased to about 1 A or more, the voltage across the gap suddenly reduces to a few volts (20-50 V). The discharge becomes very luminous and noisy. This phase is called the arc discharge and the current density over the cathode region increases to very high values of 103
Arcing is associated with high temperatures, ranging from 1000°C to several thousand degrees Celsius. The discharge will contain a very high density of electrons and positive ions, called the arc plasma.