Numerical calculation on coherent synchrotron radiation intensity due to inter-bunch interference in the bunch train

A novel model for the inter-bunch interference in a bunch train is presente d where a train of electron bunches passing through a bending or undulator magnetic field is considered as a moving multi-slit diffraction array from which multi beams of coherent radiation emitted with definite phase differe nce. Based on this model,interference among multi-beams of coherent synchro tron radiation emitted from consecutive bunches accelerated by a 30 MeV RF- Linac at BFEL is analyzed and numerically calculated. From the discussions it is shown that: 1. Rapidly oscillating radiation enhancement due to inter -bunch interference is overlapped on the single bunch power spectrum; 2. Su ch radiation enhancement consists of series of spectrum lines corresponding to harmonics of the fundamental of RF-Linac; 3. Main maximum positions are determined by the "diffraction condition"; 4. Intensity enhancement is abo ut as high as the number of bunches in a macropulse; 5. The axially measure d radiation frequency is lower than the off axis one. Experimental design t o measure interference from separate bunches at the BFEL Linac with the dev eloped mm-wave Michelson interferometer is presented.