Method for improving the wettability of a rotating electrode in a gas discharge lamp

Patent metadata

Field	Value
Publication number	US-9589783-B2
Application number	US-201414150995-A
Country	US
Kind code	B2
Filing date	Jan 9, 2014
Priority date	Jan 11, 2013
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

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.

First claim

The invention claimed is:

1. Method for forming a rotating electrode used with a liquid medium in a gas discharge lamp that generates EUV radiation or soft X-rays, in which the liquid medium is applied to an edge surface of the rotating electrode, comprising:
pre-processing an edge surface of the electrode to form external microstructures on said edge surface, wherein pre-processing said external microstructure has structural dimensions 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, said microstructures improving a wettability of the edge surface for the liquid medium.

2. Method according to claim 1 , further comprising:
pre-processing side faces of the electrode that are adjacent to the edge surface to form microstructures in at least one area adjacent to the edge surface.

3. Method according to claim 1 , further comprising:
pre-processing said external microstructure with a periodic geometric pattern in the edge surface or in the edge surface and in side faces of the electrode.

4. Method according to claim 1 , further comprising:
pre-processing said external microstructure with cruciform, honeycombed, trapezoidal, pyramid-shaped, circular, annular, strip-like and/or linear elevations and/or indentations in the edge surface or in the edge surface and in side faces of the electrode.

5. Method according to claim 1 , further comprising:
pre-processing the edge surface or the edge surface and side faces of the electrode that are microstructured with energetic radiation.

6. Apparatus for generating radiation by an electrically operated discharge 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 pre-processing, wherein the microstructure has structure dimensions, of which at least one width, length or depth is less than 300 μm, said microstructure improving a wettability of the edge surface for the liquid medium.

7. Apparatus according to claim 6 , 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.

8. Apparatus according to claim 6 , 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.

9. Apparatus according to claim 6 , characterized in that electrodes are formed in the shape of circular discs.

10. Apparatus according to claim 6 , 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.

11. Apparatus according to claim 6 , characterized in that the microstructure has a periodic geometric pattern.

12. Apparatus according to claim 6 , characterized in that the microstructure is formed by cross-shaped, honeycombed, trapezoidal, pyramid-shaped, circular, annular, lamellar and/or linear increases and/or indentations.

13. Electrode wheel, which in one edge surface has a microstructure produced by external pre-processing, said microstructure improving a wettability of the edge surface for a liquid medium, and is designed as an electrode for an apparatus according to claim 6 .

14. An apparatus for generating radiation by an electrically operated discharge device, the apparatus comprising:
a container for holding a liquid medium; and
two electrodes separated by a small distance to form a discharge path, wherein at least one of the electrodes is rotatably mounted about an axis and has an edge surface that contacts the liquid medium, and wherein said edge surface has pre-processed external microstructures improving a wettability of the edge surface for the liquid medium, wherein the microstructures have structure dimensions, of which at least one width, length or depth is less than 300 μm.

15. The apparatus according to claim 14 , wherein both said electrodes are rotatably mounted about their respective axes, and each said edge surface has external microstructures.

16. The apparatus according to claim 14 , wherein each said electrode has opposed side faces connected to said edge surface, and wherein said side faces are also microstructured in at least one area adjacent to said edge surface.

Assignees

• Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E V
• Ushio Electric Inc

Inventors

• Bergmann Klaus
• Pruemmer Ralf

Classifications

• H01J61/06 Primary

  Main electrodes · CPC title

• H05G2/0035

  the material containing metals as principal radiation-generating components · CPC title

• H05G2/002 Primary

  Supply of the plasma generating material · CPC title

• H05G2/005

  Electricity · mapped topic