Ryoji Nagai

The TM010 microwave cavity made of YBa2Cu3O7−d

The cavity made of bulk YBa2Cu3O7-d was resonant at 7 GHz in the TM010 mode without any dielectric interior. At 25 K the quality factor was measured to be just around 105 (the maximum of 2×105 by reducing microwave power) which represents an improvement by a factor of several hundreds from the normal state at 100 K.

Fabrication and RF properties of the microwave cavity made of YBaCuO and BiPbSrCaCuO superconductors

After the discovery of new metal oxide superconductors with higher transition temperatures raised the possibility of a new class of superconducting microwave devices operating at temperatures well above liquid He, a feasibility study of the superconductor devices at r.f., microwave, and millimeter-wave frequencies, i.e., cavity resonator, transmission lines, waveguide, mirror, and antenna, was started at JAERI (Japan Atomic Energy Research Institute), Tokai in April 1987. In order to examine the feasibility of such devices and to investigate the nature of the superconductivity in these new superconductors, we have studied the microwave response of the oxide superconductors. In addition, we have also studied the fabrication and microwave properties of these devices using the new superconductors. We report here the status of the feasibility study, especially about the BSCCO and YBCO superconductor cavities, and the r.f. characterization apparatus using several cavity resonators. The cavities have potential applications for particle accelerators, resonant filters, ultrastable clocks, and so on.