Combined thermionic and photoelectric emission from dispenser cathodes

Photoelectric emission from dispenser cathodes has been studied earlier. Photoelectric emission in conjunction with themionic emission can provide a convenient and flexible means of modulating emission from thermionic cathodes with programmable formats and high bandwidth. This may be useful for experimental studies the beam dynamics of space charge dominated beams, such as in the University of Maryland electron ring (UMER). We have studied combined photoelectric and thermionic emission from a dispenser cathode using a nitrogen laser operating at 337 nm. Results will be presented for the effect on emission of laser intensity, cathode temperature, and accelerating voltage.