Abstract: The apparatus comprises a consumable cathode (1) having a working end face (3), a solenoid (4) coaxially disposed relative to the consumable cathode (1) and having a tubular anode (5) received therein, an igniting electrode (6). Solenoid (4) encircles the tubular anode (5) and the consumable cathode (1), the number of turns per unit length of the solenoid (4) around the consumable cathode (1) being greater than the number of turns per unit length in the remaining portion of the solenoid (4).Moreover, the solenoid (4) extends beyond the igniting electrode (6) at the side opposite to the working end face (3) by a length exceeding half the length of the portion of the solenoid (4) disposed around the consumable cathode (1).

Abstract: An arc plasma generator comprises a consumable cathode, a cylindrical anode, and a focusing solenoid arranged coaxially with the consumable cathode. A power unit for maintaining the arc is electrically connected to the consumable cathode and the anode. In accordance with the invention the arc plasma generator further comprises a tubular plasma guide connected to an end face of the anode and an electromagnet. The electromagnet is arranged in the tubular plasma guide on the axis thereof and is enclosed in a housing made of a nonmagnetic material and having a cross-sectional area sufficient to conceal the cathode from the viewer's sight, looking in the direction of the cathode through the plasma guide. Also, the focusing solenoid is arranged on the tubular plasma guide and is connected in opposition with the coil of the electromagnet. A plasma arc apparatus for treating the surfaces of work-pieces comprises an arc plasma generator of the invention and an assembly for holding the work-piece to be treated.