Abstract: The invention relates to an apparatus for the plasma treatment of substrates in a plasma discharge excited by radiofrequency between two electrodes 3, 8, supplied by a radiofrequency source, of which the first is configured as a hollow electrode 3 and the second an electrode 8 bearing a substrate 7 is placed in front of the cavity (10) of the first electrode and can be moved past the latter, the hollow electrode being surrounded by a dark-space shielding (14) and has a margin 9 pointing toward the second electrode 8 and projections 12 lying between the margins at the same potential as the first electrode 3. Between the projections 12 permanent magnets 34 are provided by which the substrate bias (self-bias) is adjustable independently of the discharge geometry, the discharge pressure and the radiofrequency power.