Materials research related to W-band cavity construction

Low power RF measurements, S11, of electro-discharge machined (EDM) diffusion bonded mm-wave traveling wave RF cavities were not in satisfactory agreement with electromagnetic simulations. During subsequent mechanical inspection, the cell-to-cell iris were found to be distorted. This led to a series of systematic experiments to study the mechanical properties of oxygen free high conductivity copper and Glidcop AL-15. Results of these studies which include cell-to-cell iris distortion, EDM machining accuracies, surface quality, and the results of different bonding techniques are presented. The results of our mechanical studies are used to develop a set of mechanical design constraints for a second series of constant impedance W-band structures that also used wire EDM and high temperature bonding for their manufacture