Date Awarded

1991

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Physics

Advisor

Harlan E Schone

Abstract

The discovery of high critical temperature superconductors (HTSC) has raised the temperature at which the greatly reduced surface resistance, characteristic of superconducting materials, may be exploited. For microwave frequencies below 100 GHz, the surface resistance, R{dollar}\sb{lcub}s{rcub}{dollar}, at liquid nitrogen temperatures (77K) of the new HTSC materials is found to be better than copper measured at the same temperature and frequency. Consequently, the miniaturization of passive microwave components will be among the first applications of these new materials. This dissertation details the development, testing and evaluation of a superconducting compact hydrogen maser resonator made from electrophoretic Y{dollar}\sb1Ba\sb2Cu\sb3{dollar}O{dollar}\sb{lcub}7-\delta{rcub}{dollar} (YBCO). Such a resonator could sustain active maser oscillation and would therefore be an excellent compact frequency source. This compact maser could yield significant volume and weight savings for space applications where masers are used as frequency standards. The compact resonator is a loop-gap (split-ring) lumped element resonator similar to that previously suggested for compact maser applications. This resonator is made superconducting using an electrophoretic process developed for the deposition of thick film polycrystalline HTSC on large non-planar metallic substrates. The low R{dollar}\sb{lcub}s{rcub}{dollar} of the YPCO deposited onto the surface of the electrode loading structure, inside of the loop-gap resonator, yields cavity quality factors comparable to those of the much larger TE{dollar}\sb{lcub}011{rcub}{dollar} maser resonator but in a much smaller package. The fields of the loop-gap resonator are uniform in the hydrogen interaction region. However, in the neighborhood of the electrodes, the fields are analogous to the TEM fields associated with stripline geometries. These microwave fields have been investigated by numerical analysis and the dependence of the filling factor, ({dollar}\eta\sp\prime{dollar}) and the cavity quality factor, (Q{dollar}\sb{lcub}c{rcub}{dollar}), as a function of the cavity dimensions is discussed. With this information, the cavity design has been optimized to find the cavity size and shape that will yield the lowest Allan deviation with respect to the random thermal frequency fluctuations.

DOI

https://dx.doi.org/doi:10.21220/s2-7zb1-ge85

Rights

© The Author

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