Patent ID: 7431897

Claim:
Apparatus to replace atmospheric oxygen with an inert gas from at least one laminar air boundary layer of a substrate moving in a direction of advance said apparatus comprising a first chamber, a front mate electrode, a further mate electrode and an inert gas feeding device, wherein the first chamber is open only toward the substrate, and comprises: a front corona electrode to which a high-voltage DC is applied and which is positioned perpendicular to said direction of advance, wherein the front corona electrode is configured as a front side wall of the first chamber and is associated with the front mate electrode situated on the other side of the substrate; a further corona electrode positioned behind the front corona electrode and perpendicular to the direction of advance, wherein the further corona electrode is configured as a rear side wall of the first chamber, is fed with a high DC voltage, and is associated with the further mate electrode situated on the other side of the substrate; a common upper electrode cover covering both the front corona electrode and the further corona electrode, wherein the common upper electrode cover seals the top of the first chamber and isolates the first chamber from an out-side space; and two lateral electrode covers laterally covering said two corona electrodes; wherein the first chamber is positioned adjacent to the laminar air boundary layer of the substrate, such that a partial-vacuum zone is formed between a lower end of the further corona electrode and an adjacent surface of the substrate; and the inert gas feeding device is configured to supply the inert gas into said first chamber at a point downstream of the partial-vacuum zone.