# US 2014/0197726 A1 · Method for improving the wettability of a rotating electrode in a gas discharge lamp > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197726 A1 - Document ID: US20140197726A1 - Status: Published application - Kind: A1 - Application number: 14/150,995 - Filed: 2014-01-09 - Published: 2014-07-17 - Earliest claimed: 2013-01-11 - Assignees: Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V.; Ushio Denki Kabushiki Kaisha - Applicants: Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. - Inventors: KLAUS BERGMANN; RALF PRUEMMER - Web page: https://patentgrep.com/patent/US20140197726A1 ## CPC - H01J 61/06: Main electrodes - H05G 2/002: {Supply of the plasma generating material} - H05G 2/0035: {the material containing metals as principal radiation-generating components} - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - H05G: X-RAY TECHNIQUE (investigating or analysing materials by the use of X-rays G01N23/00; apparatus for X-ray photography G03B42/02; X-ray tubes H01J35/00; TV systems having X-ray input H04N5/321) ## Abstract The present invention relates to a method for improving the wettability of a rotating electrode with a liquid medium in a discharge lamp, in particular for the production of EUV radiation or soft X-rays, and a correspondingly designed gas discharge lamp. In the method, the edge surface of the rotating electrode to which the liquid medium is applied is microstructured by means of external processing. This microstructure significantly improves the wettability of the edge surface for the liquid medium. Furthermore, the distribution of the liquid medium over the edge surface can be controlled selectively by suitable choice of the microstructure. ## Claims ### Claim 1 Method for improving the wettability of a rotating electrode with a liquid medium in a gas discharge lamp, in particular for generating EUV radiation or soft X-rays, in which the liquid medium is applied to an edge surface of the rotating electrode, characterized in that the edge surface of the electrode is microstructured by means of external processing. ### Claim 2 (depends on 1) Method according to claim 1, characterized in that side faces of the electrode that are adjacent to the edge surface are also microstructured in at least one area adjacent to the edge surface. ### Claim 3 (depends on 1) Method according to claim 1, characterized in that by means of the external processing, a microstructure with a periodic geometric pattern is generated in the edge surface or in the edge surface and in side faces of the electrode. ### Claim 4 (depends on 1) Method according to claim 1, characterized in that by means of the external processing, a microstructure with cruciform, honeycombed, trapezoidal, pyramid-shaped, circular, annular, strip-like and/or linear elevations and/or indentations is generated in the edge surface or in the edge surface and in side faces of the electrode. ### Claim 5 (depends on 1) Method according to claim 1, characterized in that by means of the external processing a microstructure with structural dimensions is generated in the edge surface or in the edge surface and in side faces of the electrode, at least one of said dimensions being a width, a length or a depth less than 300 μm. ### Claim 6 (depends on 1) Method according to claim 1, characterized in that the edge surface or the edge surface and side faces of the electrode are microstructured by processing with energetic radiation, in particular with laser radiation. ### Claim 7 Apparatus for generating radiation by an electrically operated discharge, in particular for generating EUV radiation or soft X-rays, having two electrodes separated by a small distance to form a discharge path, and at least one electrode of which is mounted such that it can be rotated about an axis, and having a device for applying a liquid medium to an edge surface of the at least one electrode characterized in that the edge surface has a microstructure produced by external processing. ### Claim 8 (depends on 7) Apparatus according to claim 7, characterized in that the device for applying a liquid medium comprises a container for holding the liquid medium, into which the at least one electrode is immersed during the rotation. ### Claim 9 (depends on 7) Apparatus according to claim 7 characterized in that both electrodes are each mounted such that they can rotate about an axis, respectively, and have the microstructure in their edge surface. ### Claim 10 (depends on 7) Apparatus according to claim 7, characterized in that electrodes are formed in the shape of circular discs. ### Claim 11 (depends on 7) Apparatus according to claim 7, characterized in that side faces of the electrode or electrodes that are adjacent to the edge surface are also microstructured in at least one area adjacent to the edge surface. ### Claim 12 (depends on 7) Apparatus according to claim 7, characterized in that the microstructure has a periodic geometric pattern. ### Claim 13 (depends on 7) Apparatus according to claim 7, characterized in that the microstructure is formed by cross-shaped, honeycombed, trapezoidal, pyramid-shaped, circular, annular, lamellar and/or linear increases and/or indentations. ### Claim 14 (depends on 7) Apparatus according to claim 7, characterized in that the microstructure has structure dimensions, of which at least one width, length or depth is less than 300 μm. ### Claim 15 (depends on 7) Electrode wheel, which in one edge surface has a microstructure produced by external processing and is designed as an electrode for an apparatus according to claim 7.