| Title |
Cryogenic RF Characterization of Superconducting Materials at SLAC With Hemispherical Cavities |
| Authors |
- P.B. Welander, M.A. Franzi, S.G. Tantawi
SLAC, Menlo Park, California, USA
|
| Abstract |
For the characterization of SRF materials, we have commissioned a second-generation, X-band cavity cryostat that can rapidly analyze thin-film coatings or bulk samples. The system operates at 11.4 GHz, at temperatures down to 4 K, and utilizes two interchangeable hemispherical cavities (one Cu, one Nb) that can accommodate 51 mm-diameter samples on the flat side. The cavities are designed to operate with a TE032-like mode where the magnetic field is strongest on the sample surface. As a result, the sample accounts for 33% of the overall cavity loss, despite comprising less than 8% of the total surface area. For low-power testing we utilize a programmable network analyzer, while for high-power testing we connect the cavity to a 50 MW XL-4 klystron. With the Nb cavity we can measure surface resistances down to 0.7 microhm, while with the Cu cavity we can measure quenching fields up to 360 mT. X-band operation permits a compact cavity and cryostat design with a reasonable sample size, while the closed-cycle pulse-tube cryorefrigerator allows for rapid sample cycling. We will discuss cryostat design, cavity modeling, measurement limits, and recent sample testing results.
|
| Paper |
download TUPB065.PDF [0.856 MB / 4 pages] |
| Conference |
SRF2015, Whistler, BC, Canada |
| Series |
International Conference on RF Superconductivity (17th) |
| Proceedings |
Link to full SRF2015 Proccedings |
| Session |
Poster Session |
| Date |
15-Sep-15 14:30–17:40 |
| Main Classification |
Fundamentals SRF R&D - Other Materials |
| Keywords |
cavity, niobium, SRF, factory, cryogenics |
| Publisher |
JACoW, Geneva, Switzerland |
| Editors |
Robert E. Laxdal (TRIUMF, Vancouver, BC, Canada); Jana Thomson (TRIUMF, Vancouver, BC, Canada); Volker RW Schaa (GSI, Darmstadt, Germany) |
| ISBN |
978-3-95450-178-6 |
| Published |
December 2015 |
| Copyright |
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