A plasma arc torch system comprising: a plasma arc torch (402, 502) including: an electrode; a nozzle spaced from the electrode to define a plasma chamber therebetween, the nozzle comprising a nozzle exit orifice at the distal end thereof, a nozzle body, a liner disposed within the nozzle body and having a liner exit orifice between a distal end face of the electrode and the nozzle exit orifice, wherein the plasma chamber is configured to receive a plasma gas; a vent passage formed in the nozzle body and having an inlet and an outlet both positioned upstream from the nozzle exit orifice, the vent passage being adjacent and in fluid communication with a venting channel configured to direct a portion of the plasma gas exiting the plasma chamber from between the liner exit orifice and the nozzle exit orifice to the vent passage, the vent passage being configured to divert said portion of the plasma gas to the outlet of the vent passage, wherein, in operation, venting by the venting channel and the vent passage upstream of the nozzle exit orifice between the liner and the nozzle body constricts a plasma arc; and a shield spaced from the nozzle to define a liquid passageway and a flow region therebetween, the shield comprising a shield exit orifice in fluid communication with the nozzle exit orifice, wherein the liquid passageway is configured to receive a liquid and introduce the liquid to the flow region, the flow region being configured to expel the liquid out of the torch via the shield exit orifice, such that, in operation, the liquid substantially surrounds the plasma arc and also constricts the plasma arc as the liquid and the arc pass through the shield exit orifice. a plasma arc torch (402, 502) including: an electrode; a nozzle spaced from the electrode to define a plasma chamber therebetween, the nozzle comprising a nozzle exit orifice at the distal end thereof, a nozzle body, a liner disposed within the nozzle body and having a liner exit orifice between a distal end face of the electrode and the nozzle exit orifice, wherein the plasma chamber is configured to receive a plasma gas; a vent passage formed in the nozzle body and having an inlet and an outlet both positioned upstream from the nozzle exit orifice, the vent passage being adjacent and in fluid communication with a venting channel configured to direct a portion of the plasma gas exiting the plasma chamber from between the liner exit orifice and the nozzle exit orifice to the vent passage, the vent passage being configured to divert said portion of the plasma gas to the outlet of the vent passage, wherein, in operation, venting by the venting channel and the vent passage upstream of the nozzle exit orifice between the liner and the nozzle body constricts a plasma arc; and a shield spaced from the nozzle to define a liquid passageway and a flow region therebetween, the shield comprising a shield exit orifice in fluid communication with the nozzle exit orifice, wherein the liquid passageway is configured to receive a liquid and introduce the liquid to the flow region, the flow region being configured to expel the liquid out of the torch via the shield exit orifice, such that, in operation, the liquid substantially surrounds the plasma arc and also constricts the plasma arc as the liquid and the arc pass through the shield exit orifice. an electrode; a nozzle spaced from the electrode to define a plasma chamber therebetween, the nozzle comprising a nozzle exit orifice at the distal end thereof, a nozzle body, a liner disposed within the nozzle body and having a liner exit orifice between a distal end face of the electrode and the nozzle exit orifice, wherein the plasma chamber is configured to receive a plasma gas; a vent passage formed in the nozzle body and having an inlet and an outlet both positioned upstream from the nozzle exit orifice, the vent passage being adjacent and in fluid communication with a venting channel configured to direct a portion of the plasma gas exiting the plasma chamber from between the liner exit orifice and the nozzle exit orifice to the vent passage, the vent passage being configured to divert said portion of the plasma gas to the outlet of the vent passage, wherein, in operation, venting by the venting channel and the vent passage upstream of the nozzle exit orifice between the liner and the nozzle body constricts a plasma arc; and a shield spaced from the nozzle to define a liquid passageway and a flow region therebetween, the shield comprising a shield exit orifice in fluid communication with the nozzle exit orifice, wherein the liquid passageway is configured to receive a liquid and introduce the liquid to the flow region, the flow region being configured to expel the liquid out of the torch via the shield exit orifice, such that, in operation, the liquid substantially surrounds the plasma arc and also constricts the plasma arc as the liquid and the arc pass through the shield exit orifice.