An alternating magnetic field is applied to a transferred arc to create a plasma arc for heating a large metal surface. The arc root oscillates on the metal surface at the frequency of alternating electromagnetic force (I x B force). The magnitude of the applied magnetic field controls the amplitude of the oscillatory motion. By changing the waveform of the applied field, the distribution of the heat flux density is adjustable. An overly strong magnetic field renders the oscillatory are motion unstable. Experimental observations reveal that the heat flux is affected considerably by the neutral gas flow surrounding the arc. (c) 2006 Elsevier B.V. All rights reserved.