A generating electric arc is disclosed herein, which thermally and mechanically acts on a material in such a manner that the electrical arc is shaped and guided by the action of a magnetic field and hydro-mechanical forces on the electrical arc. Generally, a substantial part of the electric arc acts directly and areally on a conductive and/or non-conductive material to be disrupted, a substantial part of the electric arc's heat flow is directed into the material to be disrupted, both electric arc roots move on the electrodes of a generator, and the electric arc has preferably a shape of a spiral.A device is also provided herein for generating an electric arc with thermal and mechanic action on a material containing axially symmetrical electrodes, i.e. an anode (4) and a cathode (6), a spark gap (7), nozzles (5) for the working medium flow, cooling media inlet and outlet (12), electric power supply (14), and ring-shaped magnets (9) whose section has the shape of a triangle. Typically, the anode (4) has the shape of the diffuser with an angular span from 5° to 130°.