Abstract: In an ion etching method for reducing a substrate thickness, an electric arc is generated in a vacuum chamber such that the electric arc is locally separated from the substrate and circulates about the substrate. A plasma of a supplied etching gas is produced by the electric arc, and the ions of the etching gas are accelerated onto the substrate by an electric potential. The employed device has a vacuum chamber, an etching gas supply, and first and second electrodes supplied with direct or alternating voltage for generating the electric arc that produces the plasma of the etching gas. The first electrode is ring-shaped and the second electrode is arranged centrally to the ring of the first electrode. A magnetic coil creates a migrating magnetic field such that the electric arc is locally separated from the substrate and circulates about the substrate in a carousel fashion.