전광 효과를 이용한 전자 빔의 다발 길이 측정 실험

Abstract

An electro-optic sampling (EOS) experiment has been carried out at 60MeV electron linac of the Pohang Light Source. Coherent transition radiation (CTR) produced by relativistic electron bunches passed by an optically active ZnTe crystal. The induced birefringence was sampled with ultrashort titanium sapphire (Ti:Sa) laser pulses. The technique of EOS provides the possibility to measure the longitudinal charge distribution with very high resolution, determined by the width of the optical laser pulse. A 150 fs Ti:Sa laser is used to sample the birefringence which is induced in a nonlinear optical crystal by the co-moving electric field of a relativistic electron bunch, or, alternatively by the coherent transition radiation generated by the bunch. The initial linear polarization of the laser pulse is converted into a slightly elliptical polarization which is then converted into an intensity modulation. By shifting the timing of the laser pulse relative to the bunch in sub-picosecond steps, the time profile is obtained by sampling over many bunched.