Microwave response of a cylindrical cavity made of bulk MgB2 superconductor

TL;DR

This study investigates the microwave properties of a bulk MgB2 superconducting cylindrical cavity, highlighting its high quality factor and temperature-dependent surface resistance, relevant for superconducting microwave applications.

Contribution

First detailed measurement of microwave response of a bulk MgB2 cavity, demonstrating high quality factors and consistency with small sample measurements.

Findings

Quality factor of 10^5 at 4.2-30K

Resonance mode TE011 at 9.79GHz

Surface resistance matches small sample data

Abstract

We report on the microwave properties of a resonant cylindrical cavity made of bulk MgB2 superconductor, produced by the reactive liquid Mg infiltration process. The frequency response of the cavity has been measured in the range 5-13GHz. Among the various modes, the TE011, resonating at 9.79GHz, exhibits the highest quality factor. For this mode, we have determined the temperature dependence of the quality factor, obtaining values of the order of 10^5 in the temperature range 4.2-30K. The values of the surface resistance deduced from the measurements of the quality factor agree quite well with those independently measured in a small sample of MgB2 extracted from the same specimen from which the cavity has been obtained.