Cold Cathode for Ultraviolet Lamp
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Helium lamps are used for ultraviolet photo-electron spectroscopy and for other purposes. These lamps provide ultraviolet radiation and utilize a cold cathode discharge at approximately TORR. pressures. The cold cathode faces into a water-cooled quartz capillary and into an ultra-high vacuum chamber through a series of subsequent capillaries which allow differential pumping in order to be vacuum compatible and to maintain optically suitable paths for radiation transport from the source to the target. These cathodes undergo degradation caused by the plasma, and as the cathode is sputtered, the material deposits on all surfaces, causing electrical instability and failure in the discharge region. In order to solve this problem, a high density carbon cathode is used.