Method and apparatus for ion modification of the inner surface of tubes

Abstract

A method and apparatus for modifying the inner surface of a tube by ion surface modification techniques, such as ion implantation, ion mixing and ion beam assisted coating. The apparatus includes a plasma source, preferably a vacuum arc, a first magnet for guiding the plasma into a drift tube. A second magnet is spaced from the first magnet and has a current running opposite to the first magnet. A radial extractor surrounds the area between the magnets, which form a cusp therebetween. The plasma follows the field lines, exiting the drift tube to the extractor, where the ions are removed and accelerated outwardly in a radial direction. With the entire apparatus placed in a tube, the ions will impact the inner wall of the tube. The resulting ion implantation advantageously modifies the surface, typically increasing wear and erosion resistance, improving corrosion resistance, increasing fatigue life, etc. The apparatus may be used to coat the tube interior with the cathode material by operating the extractor at a lower voltage or omitting the extractor. The apparatus may be inserted in tubes and moved along the tube to treat the walls of very long tubes.

Dependencies are inferred from the claim text.