Present status of the Israeli FEL: Increasing FEL power by electron beam energy boosting

The status of a R&D work aimed on increasing the FEL power by boosting the electron beam energy after the radiation build-up is reported. A fine control of the electron beam energy during the radiation pulse is designed to compensate the small energy degradation during the pulse. Also, a controlled ramp (up or down) in the electron energy during the pulse will be applicable. Theoretical estimations of the output power in the presence of an electron energy change during the pulse are presented. Two models, showing agreement between them are compared: Analytical model based on the pendulum equation, and, Rigorous 3D FEL interaction model solved numerically. Another expected result of the design is to further extend the pulse duration with stable conditions and to obtain improved coherency. The electrical and mechanical lay-outs of the highvoltage boosting (leading to electron beam energy boosting) are also presented.