Method and device of arc detection in a plasma process

The method involves determining a point of time, at which an output signal acts as an evaluating signal or a signal that is correlated with an output signal exceeding reference values (R1-R4) during a positive half-cycle of the evaluating signal or lying below the reference values during a negative half cycle of the evaluating signal. A sequence of time point is determined, and time intervals are determined under application of the time point and are compared. An arc recognizing signal is generated, when the corresponding time intervals deviate more than an allowable tolerance. An independent claim is also included for an arc recognizing device for recognizing an arc in a plasma process.