It has been shown that the source of current and erosion plasma in a unipolar arc is explosive electron emission, which occurs as ejection of individual portions of electrons named ectons. This phenomenon is responsible for the numerous microcraters left by unipolar arcs on metal surfaces. An arc of this type is self-sustained due to the interaction of the erosion plasma with the electrode surface. The duration of an arc is determined by the conditions of its initiation: the higher the arc current, and hence, the number of cells in the spot formed on arc initiation, the longer the arc operation.
Arc tracks in the T-10 tokamak