The plasma arc
generators can be divided into (i) non-transferred
are plasma torch (Fig. 1a), (ii) transferred arc
plasma torch (Fig. 1b). In the non-transferred arc
torch the two electrodes do not participate in the
process and have the sole function of plasma
generation. The couple of electrodes could have
different geometry; a cylindrical bar (cathode) and
a hollow cylinder (anode) or two coaxial cylinders
that could operate with opposite polarities. Nontransferred ac arc torches employ cylindrical
electrodes because of easiest inversion of polarity
in this configuration.