Electrical and sputtering characteristics of a 10-cm-diam inverted magnetron configuration have been investigated in the transition region from positive to negative space-charge modes. Radial voltage and ion energy distributions were obtained for both modes. The positive space-charge mode resulted in the most efficient transport of sputtered material from cathode to anode. Dependence of space-charge sign reversal on apparatus dimensions and magnetic field strength are discussed showing that operation in the 10 -5 Torr range can be expected for a 40-cm-diam configuration. The deposition profile at the anode was in good agreement with the calculated profile showing that ion current and hence sputtering is uniform over the effective cathode area. © 1965 The American Institute of Physics.