Abstract: A plasma arc torch is disclosed which has an elongated electrode with an open front and a nozzle with a plasma discharge opening that is coaxial with the electrode. A mounting arrangement includes a ceramic ring that engages the front end of the electrode and a gas ring which concentrically surrounds the ceramic ring. A forward portion of the gas ring, the forward end of the electrode, and the nozzle define a swirl chamber of the torch, and opposing, spaced-apart concentric cylindrical surfaces of the ceramic ring and the gas ring, respectively, form an annulus which extends rearwardly from the swirl chamber. The ceramic ring closes the aft end of the annulus, and the gas ring houses a plurality of plasma gas injection ports which are located immediately forward of the aft end of the annulus.

Abstract: A plasma arc torch that is capable of operating in a non-transferred arc mode and a transferred arc mode, and that is intended for use for use with a plasma arc treatment system. The plasma arc torch includes an electrode, a plasma gas ring and a nozzle. At least one power supply within the plasma arc treatment system is connected to the electrode, the nozzle and a workpiece. While the torch operates in a non-transferred arc mode, the non-transferred arc heats gas supplied by the plasma gas ring to create plasma gas that heats the workpiece to raise its conductivity. Once the workpiece is at an appropriately conductive level, the arc is automatically transferred since the ground point can now be found.