Abstract
When a relativistic electron bunch passes through two different media, transition radiation (TR) is generated from the interface. When the radiation wavelengths are much longer than the bunch length, coherent transition radiation (CTR) will be generated. CTR is high intensity far infrared radiation and terahertz radiation source. It can also be used for short electron bunch length measurements. In this study, the femtosecond electron beam generated by the NSRRC high brightness photoinjector linac system will be used for terahertz CTR experiments. We expect that the resulting CTR frequency will fall in the terahertz band when the electron beam energy is 33.5 MeV, bunch charge is 100 pC, and the beam length is 27 μm (~ 90 femtosecond). In our experiment, the CTR generated from a thin aluminum foil has a pulse energy of 289 nJ. The bunch length measured by the THz interferometer system is 154.94 μm. The radiation spectrum can be obtained from the Fourier transformation of the interferogram and its spectral range falls within 0.1-2 THz.