Diamond cold cathodes for electron guns

Cold cathodes based on single sharp silicon tip with diamond coating were tested for electron gun application. Emission stability, reproducibility of current-voltage characteristics as well as emission divergence were studied. No hysteresis or shift of the emission characteristics at long-time repeated measurements have been found. Low-frequency current fluctuations were less than 10%. The life test of a cathode have been performed during 120 hours. The current decrease was within 10% of the initial value at the end of the test. The angular divergence of the emission was within 3/sup 0/.