High-current electron emission of thin diamond films deposited on molybdenum cathodes

•High-current molybdenum cathode with diamond coating was investigated.•The emission properties strongly depend on CH4 and N2 concentration in gas mixture.•The homogeneous emission with current density of 220 A/cm2 was obtained.•The prepared cathodes were successfully tested in high-power rf pulse compressor.

The results of investigation of emission characteristics of cold cathodes employing diamond and related films are presented. The films were deposited in a new millimeter wave plasma-assisted CVD reactor using Ar–H2–CH4 and Ar–H2–CH4–N2 gas mixtures. To study the emission properties of the high-current cathodes they were subjected to ~ 50 ns high-voltage pulses with amplitudes up to 100 kV. Experiments show that the emission properties strongly depend on methane and nitrogen concentration in gas mixture. The homogeneous emission with current density of 220 A/cm2 has been obtained. The prepared cathodes were successfully tested in high-power rf pulse compressor employing electron beam triggering.