The invention provides an arc coating apparatus having a steering magnetic field source comprising steering conductors (62, 64, 66, 68) disposed along the short sides (32c, 32d) of a rectangular target (32) behind the target, and a magnetic focusing system disposed along the long sides (32a, 32b) of the target (32) in front of the target which confines the flow of plasma between magnetic fields generated on opposite long sides (32a, 32b) of the target (32). The plasma focusing system can be used to deflect the plasma flow off of the working axis of the cathode. Each steering conductor (62, 64, 66, 68) can be controlled independently. In a further embodiment, electrically independent steering conductors (62, 64, 66, 68) are disposed along opposite long sides (32a, 32b) of the cathode plate (32), and by selectively varying a current through one conductor, the path of the arc spot shifts to widen the erosion corridor. The invention also provides a plurality of internal anodes, and optionally a surrounding anode for deflecting the plasma flow.