Superconducting high-Q radio-frequency circuit using niobium stannide above 4.2°K

Measurements of the circuit Q of a self-resonant coil of niobium stannide, a Type II superconductor, have been made at radio frequencies (26.8 MHz). Unloaded Q´s of 3.7 million at 4.2°K, and near 450 000 up to 16.2°K, were obtained. The above values of Q were limited by dielectric and radiation loss, rather than by the superconductor.