The coherent radiation spectrum extends into the far-infrared/THz region when the electron bunch is shorter than 1 ps (0.3 mm). Such ultra-short electron bunches can be produced using a variety of bunching schemes in electron accelerators. We have designed a photocathode RF electron gun, named ECC RF gun, specifically for ultra-short bunch generation. ECC stands for energy chirping cell. This paper describes the brief principle of the ECC RF gun, CTR (coherent transition radiation) observation using Schottky barrier diodes (SBD) and spectrum measurement using interferometry with SBDs. We have successfully confirmed the generation of 0.05–0.3 THz high peak power pulsed CTR.
