Plasma jet torch having converging anode and gas vortex in its nozzle for arc constriction

A plasma jet torch comprising a first nozzle-type anode having an entrance end and an exit end and an axial bore which converges uniformly from said entrance end to said exit end, a second nozzle-type anode positioned collinearly to the first anode at said exit end thereof, said second anode having a bore which is appreciably larger in diameter than said first anode bore at said exit end so that there is a sharp knife-edge transition between the two bores, said anode bores forming an arc passageway having a longitudinal axis, a cathode mounted on said axis and having a portion extending adjacent to said first anode entrance end, means for introducing a strong swirl of working gas into said arc passageway at a location therein adjacent to said first anode entrance end, the general plane of which swirl is perpendicular to said axis and means for applying a direct current voltage between said cathode and said second anode so that said torch can operate in a nontransferred arc mode.