Patent ID: 7880403

Claim:
A method of detecting arc discharge in a glow-discharge apparatus that has a high-frequency power source, comprising: determining a load to the glow-discharge apparatus to undergo impedance matching, when Vr/Vf is at a third level or a lower level, where Vf and Vr are a traveling-wave voltage and a reflected-wave voltage applied to the glow-discharge apparatus, respectively; determining the arc discharge to have developed in the glow-discharge apparatus, when Vr/Vf thereafter increases to a second level or a higher level; stopping the supply of power to the glow-discharge apparatus for a time T 1 ; re-starting the supply of power after the supply of power to the glow-discharge apparatus is stopped during the time T 1 ; and determining the arc discharge to have developed again in the glow-discharge apparatus, when Vr/Vf thereafter increases to a second level or a higher level within a preset time To after the supply of power is re-started again.