Influences of electron beam properties on spontaneous radiation from an optical klystron

Spectrum of the radiation from an optical klystron is very sensitive to the beam energy spread which is an important factor for the storage ring free electron laser. In order to make use of the spectrum for a measurement of the relative energy spread, we have investigated influences of the transverse beam property on the spectrum using a helical optical klystron on the UVSOR storage ring. From analysis of the experimental results, it has been found that the most important effect comes from inhomogeneous magnetic fields and a horizontal beam size.