Research Institution

Florida International University

Miami, FL  

Cathodes have a dominant influence on the quality of the electron beams produced from laser photo-cathodes in radio frequency (rf) guns used as injectors in many electron accelerators.  Similar limitations are also suffered by thermionic cathodes in diode guns used in high-power rf amplifiers for accelerator applications.  These limitations could be surmounted by a field-emission cold cathode capable of high current density.  This project will combine the high-current-density field emission from an array of carbon nanotubes with secondary electron channel multiplication in a ceramic facing structure, to produce a cold cathode of exceptional promise for rf guns and diode guns.  The cathode will be installed and tested in an existing S-band 2-1/2 cell rf gun.  With emission control and modulation, and with current density in the range of 1 kA/cm², this cathode could provide performance and long-life not enjoyed by other currently-available cathodes.  In Phase I, electrodynamic and space-charge flow simulations will be conducted to specify the cathode configuration as well as the range of emission current density from the field-emission cold cathode.  Design and preliminary tests will be conducted prior to the fabrication of the gun during Phase II.  

Commercial Applications and Other Benefits as described by the awardee:  Replacing thermionic cathodes and laser photocathodes in rf guns and diode guns by a cold cathode with high-current-density and long lifetime could improve device performance and lower costs.  Applications in a range of commercial and military vacuum electronics devices could be anticipated.