The DC abnormal-glow discharges with magnetic field assistance near the cathode targets are particularly useful in magnetron sputtering and are extensively used in industrial plasma processing applications [Thornton JA. J Vacuum Sci Technol 1978; 15(2): 171-177]. In this work, an experimental study of the magnetic field influence on planar magnetron abnormal-glow discharges of argon on copper targets is presented. A confinement power parameter CB is proposed and takes into account the useful volume and the average parallel component of the magnetic induction in that volume. The I-V characteristics at constant pressure and at several confinement power values are discussed in the scope of the Thornton empirical law, I = kV(n). The evolution of n and log(k), is neither monotonic with pressure, nor with confinement power. A linear relation between n and log(k) was found and allows to present an empirical expression I = a(bV)(n) for the I-V characteristics with two constants a and b and only n as free parameter. (C) 2007 Elsevier Ltd. All rights reserved.