Surface resistance measurement of Pd coating films using cavity resonator method

Recently, it was found that Pd coating films exhibited ultra-low photon-stimulated desorption and low resistivity values. These advantages suggest that Pd coatings could be applied to small aperture tubes, including undulator vacuum tubes, which have a significant effect on resistive wall impedance. In previous studies, the DC electrical resistivity of Pd films was measured using the four-probe technique. The surface resistance under high-frequency conditions relevant to accelerators remained insufficiently explored. This study aims to address this gap by employing the “cavity resonator method” to measure the surface resistance of this film under high-frequency electromagnetic fields. By depositing Pd films onto the inner surface of a copper alloy resonator, the quality factor (Q-factor) was measured and compared to that of the uncoated copper alloy, allowing for the calculation of the practical surface resistance. These results could provide a basis for evaluating the heat generation and cooling requirements of this film in accelerator applications.