Tubular photocell with secondary emission from internal surface

Claim 1

A photocell comprising: a hollow, evacuated generally tubular dielectric body having a partially conductive internal surface adapted to support secondary emission; first means for enclosing a first end of said body, said first means including a copper layer fixed around said first end of said body, said layer extending over a portion of the exterior surface of said body and to a predetermined distance within, and in electrical contact with, said internal surface; window means including a substantially translucent circular disc having an integral, substantially concentric, solid, cylindrical projection from one face thereof, said window means also having a copper layer substantially covering the cylindrical periphery of said projection and the portion of said disc radially outward from said projection; a photocathode affixed to the free end of said projection; means comprising an indium seal holding said window in place with said photocathode projecting within said first end of said body, said indium providing a vacuum seal between said first means and said window means copper layer; third means at the second end of said body, said third means including a cylindrical layer of copper sealed within a portion of said second end and in electrical contact with said internal surface, an electrode inserted substantially coaxially within said cylindrical layer into said second end of said body, and dielectric sealing means holding and vacuum sealing said electrode in place; first potential means operative between the copper layer of said first means and said cylindrical copper layer of said third means for energizing said internal surface, said third means connection being the more positive in polarity; and second potential means for energizing said electrode of said third means at a more positive potential than the maximum positive potential of said internal surface.