Microwave Breakdown in RF Devices Containing Sharp Corners

The present work reports on an analytical, numerical, and experimental analysis of the importance of electric field singularities around sharp corners for the determination of the breakdown strength of microwave RF devices. It is shown that only under certain physical circumstances, does the singularity and the concomitant strongly enhanced microwave field determine the breakdown strength. In particular, in situations where diffusion is the dominating loss mechanism for the electron density, it is shown that breakdown is a volumetric process and that the field singularity does not determine the breakdown threshold. Conditions for volumetric and localized breakdown respectively are established analytically and the validity is demonstrated by numerical simulations. Finally an experimental investigation is made which confirms the predicted behavior and demonstrates the accuracy which is possible to obtain for the determination of the breakdown threshold