An apparatus, comprising: an output port including two output terminals configured to deliver power to a plasma chamber to ignite a plasma; a DC power supply including two outputs, each output of the DC power supply coupled to a corresponding one of the two output terminals: a shunt switch coupled to the two output terminals in parallel with the DC power supply; and a processor configured to receive an indicator of an arc in the plasma, the processor being configured to close, responsive to the indicator of the arc, the shunt switch for a period of time to couple the two outputs of the DC power supply together to divert current away from the arc and extinguish the arc, the processor being further configured to open the shunt switch after the arc is extinguished to initiate a recovery time period in which a plasma voltage increases to reignite the plasma, characterised by the processor being further configured to close, during the recovery time period while there is no arc in the plasma and the plasma voltage is increasing, the shunt switch for a second period of time to limit the increasing voltage that occurs during the recovery time period to reduce a likelihood of an over-voltage condition. an output port including two output terminals configured to deliver power to a plasma chamber to ignite a plasma; a DC power supply including two outputs, each output of the DC power supply coupled to a corresponding one of the two output terminals: a shunt switch coupled to the two output terminals in parallel with the DC power supply; and a processor configured to receive an indicator of an arc in the plasma, the processor being configured to close, responsive to the indicator of the arc, the shunt switch for a period of time to couple the two outputs of the DC power supply together to divert current away from the arc and extinguish the arc, the processor being further configured to open the shunt switch after the arc is extinguished to initiate a recovery time period in which a plasma voltage increases to reignite the plasma, characterised by the processor being further configured to close, during the recovery time period while there is no arc in the plasma and the plasma voltage is increasing, the shunt switch for a second period of time to limit the increasing voltage that occurs during the recovery time period to reduce a likelihood of an over-voltage condition. a shunt switch coupled to the two output terminals in parallel with the DC power supply; and a processor configured to receive an indicator of an arc in the plasma, the processor being configured to close, responsive to the indicator of the arc, the shunt switch for a period of time to couple the two outputs of the DC power supply together to divert current away from the arc and extinguish the arc, the processor being further configured to open the shunt switch after the arc is extinguished to initiate a recovery time period in which a plasma voltage increases to reignite the plasma, characterised by the processor being further configured to close, during the recovery time period while there is no arc in the plasma and the plasma voltage is increasing, the shunt switch for a second period of time to limit the increasing voltage that occurs during the recovery time period to reduce a likelihood of an over-voltage condition.