The Mainz Energy-recovery Superconducting Accelerator is under construction at the Johannes Gutenberg-Universität in Mainz. This recirculating CW-electron-LINAC will operate at average current levels of >1mA, later to be increased to 10mA at 100MeV beam energy.
The extreme beam power of up to 1MW at the target requires beam kinetic energy recuperation (Energy Recovery Linac, - ERL).
This makes realization possible despite strict economic limits and ensures a small ecological footprint. Though the operating principle requires small beam target interaction, innovative experiments in low energy electron scattering are feasible and are also already under construction. Various features and options for the MESA facility will be discussed.