pulse should be longer than 300 u03bcs if the duration of the pulse should be longer than about 300 u03bcs the risk to come into an arc discharge rises arc discharges should be avoided because they lead to target and substrate damages arc discharges can be detected by a huge current rise or a huge current rise velocity this can be monitored with the current sensor 66 and when an arc discharge is detected the switch 64 may be opened immediately by pulse control 65 the arc then quenches in about 100 u03bcs only the remaining energy in the power lines and matching circuit is delivered to the plasma which is often too much to avoid even the delivery of this energy a further arc diverter is necessary which will be explained later on to avoid the arcing it is advantageous to control or to limit the current after a time of about 1 u03bcs to 200 u03bcs this can also be done with the current sensor 66 and with the pulse control 65 if the current rises over a given threshold which may be variable the switch 64 is turned off as can be seen from fig9 the current does not break down immediately but falls with an e.