Beam stabilization at the ELBE electron accelerator and the FELBE infrared user facility

Abstract

The high current SRF electron accelerator facility ELBE started user operation at the Bremsstrahlung facility in 2003, followed straight-line by channeling X-rays production and the infrared FEL beam. For a large number of experiments carried out, automated beam stabilization in terms of energy, intensity and also trajectory has become a clear necessity since then. This contribution depicts the instabilities of the electron beam and the infrared beam we observe and alludes to the sources we found and expect. For slow (mHz) beam energy drift compensation, a dispersion based feedback loop was implemented, using strip line beam position monitors and the accelerating RF gradient. Further, the IR beam intensity is measured by a newly developed scatter wire detector system and stabilized via the electron beam current up to the 50 Hz range. The implementation of both systems into the existing control landscape of ELBE is shown, as well as performance characteristics and improvement of the beam quality.