Space charge and microbunching studies for the injection arc of MESA

For intense electron bunches traversing through bends, as for example the recirculation arcs of an energy recovery linac (ERL), space charge (SC) may result in beam phase-space degradation. SC modifies the electron transverse dynamics in dispersive regions along the beam line and causes emittance growth for mismatched beams or for specific phase advances. On the other hand, longitudinal space charge together with dispersion can lead to the microbunching instability (MBI). The present study focuses on the 180° low energy (5 MeV) injection arc lattice for the multi-turn Mainz Energy-recovering Superconducting Accelerator (MESA), which should deliver a CW beam at 105 MeV for physics experiments with an internal target. We will discuss matching conditions with space charge together with the estimated microbunching gain for the arc. The implication for the ERL operation is outlined, using 3D envelope and tracking simulations.