Inexpensive High Quality Electron Sources

70266 The high current densities required for the operation of some vacuum electronic devices used in high energy physics research can be achieved only by operating conventional thermionic cathodes at excessively high temperatures. This shortens the operating life of the cathodes and can result in chemicals from the cathode contaminating the vacuum envelope of the device. This project will develop an alternative to the thermionic cathode that relies on a combination of field emission and secondary emission from thin synthetic diamond films. The approach is based on combining two recently demonstrated phenomena: (1) that very high current densities can be obtained by field emission from diamond films at low current, and (2) that diamond films can act as electron multipliers when they are configured to allow for multiple secondary emission events. The combination will produce a low current, high current density field emission source that will be used to trigger electron amplification through multiple collisions with a secondary electron emitter. The resulting electron source will be a long lived, inexpensive device that will not introduce contaminants into the vacuum envelope. In Phase I, both the diamond film field emission source and a section of the diamond film secondary emission electron amplifier will be built and tested. In addition, computer aided designs of a prototype electron source and compatible electron gun will be conducted. Commercial Applications and Other Benefits as described by the awardee: The electron source developed would be applicable for use with high power klystrons and gyrotrons that have been proposed for use in high resolution radars, linear accelerators, material processing, and the transmutation of atomic waste.