Johannes Gutenberg University Mainz is currently constructing a new electron accelerator that employs an energy recovery scheme. The Mainz Energy Recovery Superconducting Accelerator (MESA) will provide two modes of operation: the Energy Recovery (ER) mode, which will supply an internal gas target experiment, and the Extraction Beam (EB) mode, primarily used in the P2 experiment where MESA's spin-polarized electrons will be directed towards a target. As an Energy Recovery Linac (ERL), MESA shows potential as an accelerator for an Inverse Compton Scattering (ICS)-based gamma source. To anticipate the impact of the scattering on electron beam parameters, significant for energy recovery, a novel quasi-analytical simulation code, "COMPARSE", has been developed and used for the feasibility studies. The investigations examine various applications of ICS sources at MESA. This paper gives an overview of the results as well as the limitations and possibilities of the underlying mathematical approach.

We discuss the design and properties of a proposed planar cryogenic permanent magnet undulator with 20 mm period length called CPMU-20. The undulator is set to use (Pr,Nd)2Fe14B as permanent magnet material and Permendur poles and is set to be part of the planned SoTeXS beamline at the BESSY-II upgrade which will offer a unique working environment for research into energy-materials – especially energy-storage materials. The CPMU-20 is designed to produce high photon fluxes in the energy range of 0.5 to 5 keV with a maximum K-value of 2.2 which permits research into a wide range of materials used in state of the art batteries. The optimization process that led to the specific device properties like the period length, the width of the poles and the end-magnet configuration – which ensures an aligned electron beam through the device for the whole gap-range from 6 to 22 mm - will be presented in detail. This includes a discussion of the usage of the UNDUMAG and WAVE software written by Michael Scheer for the optimization and simulations.