Electron outcoupling scheme for the Novosibirsk FEL

One of the main problems of contemporary high power FELs is the mirror heating. One of the possible solutions of this problem is the use of electron outcoupling [N.G. Gavrilov, et al., Nucl. Instr. and Meth. A 304 (1991) 63; G.N. Kulipanov, A.S. Sokolov, N.A. Vinokurov, Nucl. Instr. and Meth. A 375 (1996) 576]. In this case the mirrors of optical resonator are not transparent and the coherent radiation from an additional undulator in the FEL magnetic system is used. To provide the output of this radiation the electron beam in the auxiliary undulator is deflected from the optical resonator axis. To save bunching it is preferable to use the achromatic deflecting bend. The project of electron outcoupling for the Novosibirsk FEL is described. Simulation results are presented.