Micro-discharge devices and applications

Abstract

A high pressure gas discharge device and methods of using the device as a UV gas discharge light source are disclosed. The device has a cathode covered partially with a dielectric layer which separates the cathode from an anode. A discharge device utilizes one or more microhollows in the uncovered part of the cathode. Methods of utilizing the discharge devise as a gas discharge light source for producing ultapure water.

1 . A gas discharge light source comprising:
 a cathode having a portion of its surface covered with a dielectric wherein said dielectric has an opening that forms at least one uncovered surface region of said cathode, wherein at least a longest dimension of said surface region is substantially greater than the dielectric thickness;   an anode spaced from said cathode by at least the dielectric thickness, wherein an edge of said anode is positioned at or near an edge of said opening; and   a gas discharge medium in contact with the anode and the cathode.   
     
     
         2 . The gas discharge light source of  claim 1 , wherein a ratio of said longest dimension to the dielectric thickness is at least 10 to 1. 
     
     
         3 . The gas discharge light source of  claim 1 , wherein the uncovered surface region of the cathode comprises a slit. 
     
     
         4 . The gas discharge light source of  claim 3 , wherein the anode extends along one side of the slit. 
     
     
         5 . The gas discharge light source of  claim 3 , wherein a first portion of the anode extends from one end of the slit and a second portion of the anode extends from the opposite end of the slit. 
     
     
         6 . The gas discharge light source of  claim 1 , wherein the uncovered surface region of the cathode is substantially circular. 
     
     
         7 . The gas discharge light source of  claim 1 , wherein the gas discharge medium is at pressure in the range from 10 Torr to 1500 Torr. 
     
     
         8 . The gas discharge light source of  claim 1  wherein the dielectric has a thickness of 10 micrometers to 200 micrometers. 
     
     
         9 . The gas discharge light source of  claim 1  wherein the dielectric comprises at least one material selected from the group consisting of alumina and zirconia. 
     
     
         10 . The gas discharge light source of  claim 1 , further comprising:
 a housing enclosing the anode and the cathode; and   a window covering a portion of the housing.   
     
     
         11 . The gas discharge light source of  claim 1 , further comprising
 gas-tight passages transverse to the anode and the cathode;   a gas input port coupled to each passage; and   a gas exhaust port coupled to each passage.   
     
     
         12 . The gas discharge light source of  claim 1 , wherein the gas discharge medium comprises a noble gas. 
     
     
         13 . The gas discharge light source of  claim 1 , wherein the gas discharge medium is selected from a group consisting of helium, neon, argon, krypton, xenon, and mixtures thereof. 
     
     
         14 . The gas discharge light source of  claim 1 , wherein the gas discharge medium is a mixture comprising noble gases and electronegative gases. 
     
     
         15 . The gas discharge light source of  claim 1 , wherein at least one of the cathode and the anode is positioned to radiate light through a light-transmitting window. 
     
     
         16 . The gas discharge light source of  claim 1 , wherein the transmitted light has a predominant wavelength in the range of about 150-400 nm. 
     
     
         17 . The gas discharge light source of  claim 1 , wherein the anode comprises at least one material selected from the group consisting of molybdenum, titanium and tungsten. 
     
     
         18 . The gas discharge light source of  claim 1 , further comprising, one or more microhollows penetrating into the uncovered region of the cathode, wherein said microhollows are positioned within said region and have a longest dimension less than the longest dimension of said uncovered region. 
     
     
         19 . The gas discharge light source of  claim 1 , wherein the cathode comprises a refractory metal. 
     
     
         20 . The gas discharge light source of  claim 1 , wherein the cathode comprises at least one material selected from the group consisting of molybdenum, titanium and tungsten.