Impact of the gas choice and the geometry on the breakdown limits in Micromegas detectors

In this study we investigate the stability limits of Micromegas detectors upon irradiationwith alpha particles. The results are obtained with meshes with different optical transparency andgeometry of wires. The measurements are performed in Ar- and Ne- based mixtures with differentCO$_{2}$ content. We observe that the breakdown limit strongly depends on the gas and that a higheramount of quencher in the mixture does not necessarily correlate with higher stability. Inaddition, we observe discharge probability scaling with the wire pitch. This suggests that aMicromegas mesh cell can be treated as an independent amplification unit, similar to a hole in aGEM foil. The outcome of these studies provides valuable input for further optimization of MPGDdetectors, multi-layer stacks in particular.