Lawrence Berkeley National Laboratory

In free-electron laser (FEL) oscillators, as in self-amplified spontaneous emission (SASE) FELs, the buildup of cavity power starts from shot noise resulting from the discreteness of electronic charge. It is important to do the start-up analysis for the build-up of cavity power in order to fix the macropulse width from the electron accelerator such that the system reaches saturation. In this paper, we use the time-dependent simulation code GINGER [1] to performthis analysis. We present results of this analysis for the parameters of the Compact Ultrafast TErahertz FEL (CUTE-FEL) [2] being built at RRCAT.