DC non-transferred arc plasma torches
DC non-transferred plasma torches are the more commonly
used plasma-generating devices in materials processing. They produce a high-temperature plasma arc that interacts with a flowing
gas to produce a hot jet into which the material to be processed
can be injected for in-flight melting and vaporisation. A schematic
diagram of a DC non-transferred arc plasma torch is shown in Fig. 2
[13]. Here, an arc is established between an axial, pointed/tip-type
cathode and a toroidal/annular anode. The anode is concentric and
parallel to the jet axis; the gas crosses the boundary layer between
the arc column and the anode inner surface, and is pushed downstream by the pressure of the gas flow.