Emission characteristics of several field emission cathode materials

The comparative studies by using a tri-cathode accelerator are presented on the cathode emission capability, relative emission delay and emission-time jitter of several common cathode materials, that is, stainless-steel, brass, aluminum, velvet and graphite. The stainless-steel has better quality than other metal cathode materials. At 300~450 kV diode voltage and 30 mm anode-cathode gap, the stainless-steel cathode emission current density is 0.78 ~1.50 kA/cm2 accordingly. With a constant diode voltage, the emission-time jitter of the stainless-steel is less than 8 ns, and both the velvet and graphite emission-time jitters are less than 4 ns. The cathode emission starting time of all those materials shortens when cathodes work shot by shot frequently.