Abstract:
Helmholtz-Zentrum Berlin officially started Jan. 2011 the design and construction of the Berlin Energy Recovery Linac Project BERLinPro. The initial goal of this compact ERL is to develop the ERL accelerator physics and technology required to accelerate a highcurrent low emittance beam. The conversion efficiency of an FEL is about 1% therefore superconducting ERL-based FEL machines look promising. One of the problems of superconducting ERL machines is the Beam Break Up (BBU) instability which limits the current. In this work the threshold current of the BBU instability was calculated for the BERLinPro. The comparison of two 100 MeV linacs based on different type of superconducting cavities is made. Different methods of BBU suppression are investigated (e.g. the influence of solenoid, pseudo-reflector and quadruple triplets in the linac structure on the BBU threshold).