the program objectives are focused on increasing the voltage applied across an electron beam diode. two objectives were pursued during the program. the first was to increase the total voltage applied to an electron gun anode--cathode (a-k) structure by suppressing electron emission from regions other than the electron source. the second objective was to prevent surface flashover from the cathode surface due to fiber contamination from the carbon felt used to enhance electron emission from the source. the primary approach consisted of using a dielectric coating (or a surface treatment), to suppress undesired electron emission from non-emission areas of the cathode in addition to the dielectric coating, the electrode surfaces were profiled to eliminate field enhancements in the transition areas. the program objectives were met by demonstrating 300 kv/cm fields across the gap during current conduction with no breakdown or surface flashover. this field value was obtained with electrodes coated with a dielectric polymer on the surfaces around the electron source (carbon felt) and with electrodes without the coating. total pulse width duration was 300 nsec for electrodes with no emitter (carbon felt) and 100 nsec for electrodes with the emitter