Chinese Acad Sci, Inst High Energy Phys, Beijing 100080, Peoples R China
Measurement of electron bunch length through its generated CTR is a new frequency domain technique developed in the accelerator and FEL fields recently. In this paper we analyze theoretically and calculate numerically CTR produced by a train of RF-linac electron bunches of a few picoseconds at BFEL. For the CTR emitted at wavelengths longer than the bunch length (lambdagreater than or equal to root2pisigma(2)) the intensity is enhanced by a factor of 10(8) which is the number of electrons in the bunch; CTR energy is mainly concentrated near the beam axis and can be up to several millijoules for Gaussian and rectangular bunches. A polarized-type Michelson interferometer was designed to measure autocorrelation interferograph of CTR, from which one can diagnose longitudinal length of this bunches and derive its electron density distribution.