To Study the RF Properties of Superconducting A15 Compounds.
Abstract
The purpose of the work was to study the low rf-field loss of A15 superconducting compounds. This type of superconducting material has potential for application to the construction of microwave energy storage cavities whose energy can be dumped in a very short time so as to produce a very large microwave power pulse. An apparatus, using a calorimetric technique, was developed to measure the surface resistance of small-area superconducting samples deposited on sapphire substrates. Both a Nb and a Nb3Sn sample (the latter in the A15 structure) were prepared, characterized and measured. These initial measurements revealed additional losses that are most likely due to the region near the superconductor-sapphire interface. Measurements of the superconducting transition temperature were made as a function of film thickness to study the effect of the interface. The interface losses can be avoided in practice, and in our measurements they can be circumvented by employing a circularly cylindrical geometry which shields the interface region from the rf fields. In the course of developing the surface resistance apparatus, dielectric loss measurements were made on pure sapphire samples.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1981
- Accession Number
- ADA103723
Entities
People
- H. A. Schwettman
- Malcolm Beasley
- Theodore H. Geballe
Organizations
- Stanford University