The probe diagnostics of free-burning arc in the atmosphere

A procedure of ac probe measurements is suggested for spatially unstable and unsteady-state atmospheric-pressure plasma. The procedure is evaluation tested by way of measuring the distribution of concentrations of charged particles in the interelectrode space of extended arc with graphite electrodes, which burns in free atmosphere of air. This arc is distinguished by an atypical geometry of the discharge channel, significant instability of its position in space, and appreciable current and voltage fluctuations.