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 C B 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.