Abstract
One of the main difficulties in the use of secondary-emission multiplier stages in thermionic valves is the instability of the secondary cathode, which is usually characterized by a gradually decreasing secondary-emission ratio during its useful life. In this paper, experiments are described showing that this instability is due to the bombardment of the secondary cathode by the primary electron beam, and it is shown that this bombardment causes disintegration of the surface layer. A new type of secondary cathode, formed from a mixture of magnesium oxide and barium carbonate, has been found to have a stable life of over 1 000 hours, when operating at 400° C and with a primary bombarding current density of 20 mA/cm2. The use of this secondary cathode has made possible the development of a single-stage thermionic electron-multiplier valve, with a mutual conductance of 20 mA/volt.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Proceedings of the IEE - Part III: Radio and Communication Engineering
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
