Measurement of Microwave Parameters of a Superconducting Niobium Cavity

This paper describes a method for direct measurement of the amplitude–frequency characteristics and the Q factor of empty superconducting niobium radio frequency Tesla-type cavities. An automated measuring complex that permits recording the superconductivity effect and measuring high Q values has been developed. Measurements have been made of the Q factors of the investigated objects (the first domestic 1.3-GHz niobium cavities) at a level no lower than 0.1·10 9 (with a maximum value of ~1.2·10 10 ) and a level of relative losses lower than ~130 dB (with a minimum factor of ~139.7 dB) at liquid nitrogen temperature.