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Cold Cathode for Ultraviolet Lamp

IP.com Disclosure Number: IPCOM000039946D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

McCorkle, RA: AUTHOR [+2]

Abstract

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.

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Cold Cathode for Ultraviolet Lamp

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. An example is the POCO graphite, produced by Union Oil Company. This cathode will provide electrons that bombard a gas to produce an ionized plasma.

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