Pumping light source for laser-active media

Abstract

In order to improve a pumping light source for laser-active media comprising an outer member enclosing a gas discharge medium, a first electrode acting as a cathode and having a first electrode end located within the outer member, a second electrode acting as an anode and having a second electrode end located within the outer member and a gas discharge chamber located within the outer member between the electrode ends facing one another, in such a manner that the service life thereof is longer it is suggested that the first electrode end be essentially cooled by radiation and that a predominantly diffuse gas discharge be formed proceeding from an areally extended surface area located at the first electrode end.

1 . Pumping light source for laser-active media comprising 
 an outer member ( 36 ) enclosing a gas discharge medium, a first electrode ( 44 ) acting as a cathode and having a first electrode end ( 54 ) located within the outer member ( 36 ), a second electrode ( 64 ) acting as an anode and having a second electrode end ( 74 ) located within the outer member ( 36 ) and a gas discharge chamber located within the outer member ( 36 ) between the electrode ends ( 54 ,  74 ) facing one another,    characterized in that the first electrode end ( 54 ) is essentially cooled by radiation and that a predominantly diffuse gas discharge ( 80 ) is formed proceeding from an areally extended surface area ( 84 ) located at the first electrode end ( 54 ).    
     
     
         2 . Pumping light source as defined in  claim 1 , characterized in that the surface area ( 84 ) has essentially a uniformly high temperature.  
     
     
         3 . Pumping light source as defined in  claim 1  or  2 , characterized in that the surface area overlaps a volume area ( 82 ) at the first electrode end ( 54 ), said volume area having essentially a uniformly high temperature.  
     
     
         4 . Pumping light source as defined in any one of the preceding claims, characterized in that the surface area ( 84 ) is essentially free from steps.  
     
     
         5 . Pumping light source as defined in  claim 4 , characterized in that the surface area ( 84 ) is defined by a section from a mathematical surface area extending in a continuous manner.  
     
     
         6 . Pumping light source as defined in any one of the preceding claims, characterized in that the surface area ( 84 ) has an extension greater than two thirds of an average cross-sectional surface area of the volume area ( 82 ) at the first electrode end ( 54 ).  
     
     
         7 . Pumping light source as defined in any one of the preceding claims, characterized in that the first electrode end ( 54 ) is coupled to the outer member ( 36 ) by way of heat conduction only via the electrode extending to an electrode opening ( 42 ) in the outer member ( 36 ).  
     
     
         8 . Pumping light source as defined in any one of the preceding claims, characterized in that the extension of the first electrode ( 44 ) between an electrode opening ( 42 ) of the outer member ( 36 ) and the first electrode end ( 54 ) relative to the average cross section of the first electrode ( 44 ) is such that the extension is greater than ten times the average cross section of the first electrode ( 44 ).  
     
     
         9 . Pumping light source as defined in  claim 8 , characterized in that in the first electrode ( 44 ) the heat resistance between the first electrode end ( 54 ) and the electrode opening ( 42 ) is at the most 10° C./W.  
     
     
         10 . Pumping light source as defined in any one of the preceding claims, characterized in that the first electrode end ( 54 ) consists of a high melting metal.  
     
     
         11 . Pumping light source as defined in any one of the preceding claims, characterized in that material forming the first electrode end ( 54 ) is provided with a dope additive leading during operation to a lower electrode operating temperature than in the case of the undoped material.  
     
     
         12 . Pumping light source as defined in any one of the preceding claims, characterized in that the electrode operating temperature of the electrode end is lower than the melting temperature of the material of the electrode end.  
     
     
         13 . Pumping light source as defined in any one of the preceding claims, characterized in that the first electrode end ( 54 ) consists of tungsten doped with a material with a work function for electrons smaller than that of pure tungsten.  
     
     
         14 . Pumping light source as defined in  claim 13 , characterized in that the first electrode end ( 54 ) consists of tungsten doped with at least 0.1% by weight of lanthanum.  
     
     
         15 . Pumping light source as defined in  claim 14 , characterized in that the first electrode end ( 54 ) consists of tungsten doped at the most with 5% by weight of lanthanum.  
     
     
         16 . Pumping light source as defined in any one of the preceding claims, characterized in that the first electrode ( 44 ) has a holding section ( 48 ) passing through the electrode opening ( 42 ), said holding section consisting of a material wettable by the material of the outer member ( 36 ), and that an end section ( 52 ) supporting the first electrode end ( 54 ) adjoins this holding section ( 48 ).  
     
     
         17 . Pumping light source as defined in  claim 16 , characterized in that the holding section ( 48 ) passing through the electrode opening ( 42 ) and the end section ( 52 ) are connected in a form-locking manner.  
     
     
         18 . Pumping light source as defined in  claim 17 , characterized in that the connection of the holding section ( 48 ) and the end section ( 52 ) is brought about via a sleeve-like form-locking member ( 90 ).  
     
     
         19 . Pumping light source as defined in any one of  claims 16  to  18 , characterized in that the holding section ( 48 ) of the first electrode ( 44 ) passing through the electrode opening ( 42 ) and the end section ( 52 ) are connected to one another by way of joining.  
     
     
         20 . Pumping light source as defined in any one of the preceding claims, characterized in that the first electrode ( 44 ) extends essentially as a pin-like member between the electrode opening ( 42 ) and the first electrode end ( 52 ).  
     
     
         21 . Pumping light source as defined in any one of the preceding claims, characterized in that the end section ( 52 ) of the first electrode ( 44 ) is designed as a pin-like member.  
     
     
         22 . Pumping light source as defined in  claim 20  or  21 , characterized in that the first electrode end ( 54 ) has approximately the same cross section as the pin-like member.  
     
     
         23 . Pumping light source as defined in  claim 21  or  22 , characterized in that the first electrode end ( 54 ) has a cross section increased in size in comparison with the pin-like member.  
     
     
         24 . Pumping light source as defined in  claim 23 , characterized in that the end section ( 52 ) is thickened to form the first electrode end ( 54 ).  
     
     
         25 . Pumping light source as defined in any one of the preceding claims, characterized in that a surface discontinuity ( 106 ) is provided at the first electrode end ( 54 ) for forming a gas discharge starting in a punctiform manner at this discontinuity.  
     
     
         26 . Pumping light source as defined in  claim 25 , characterized in that the surface discontinuity ( 106 ) is located outside the surface area ( 84 ).  
     
     
         27 . Pumping light source as defined in any one of the preceding claims, characterized in that this operates in the electric power range of approximately 0.1 kW to approximately 10 kW.  
     
     
         28 . Process for the operation of a pumping light source as defined in any one of the preceding claims, characterized in that the gas discharge is started as an essentially punctiform gas discharge and subsequently transfers into a predominantly diffuse gas discharge.