Efficient expulsion of magnetic flux in superconducting radiofrequency cavities for high Q0 applications
| Autor: | S. Posen, M. Checchin, A. C. Crawford, A. Grassellino, M. Martinello, O. S. Melnychuk, A. Romanenko, D. A. Sergatskov, Y. Trenikhina |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Superconductivity
Materials science Condensed matter physics Transition temperature Niobium General Physics and Astronomy chemistry.chemical_element Flux 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Magnetic flux Magnetic field Temperature gradient Quality (physics) chemistry 0103 physical sciences 010306 general physics 0210 nano-technology |
| Zdroj: | Journal of Applied Physics. 119:213903 |
| ISSN: | 1089-7550 0021-8979 |
| DOI: | 10.1063/1.4953087 |
| Popis: | Even when cooled through its transition temperature in the presence of an external magnetic field, a superconductor can expel nearly all external magnetic flux. This Letter presents an experimental study to identify the parameters that most strongly influence flux trapping in high purity niobium during cooldown. This is critical to the operation of superconducting radiofrequency cavities, in which trapped flux degrades the quality factor and therefore cryogenic efficiency. Flux expulsion was measured on a large survey of 1.3 GHz cavities prepared in various ways. It is shown that both spatial thermal gradient and high temperature treatment are critical to expelling external magnetic fields, while surface treatment has minimal effect. For the first time, it is shown that a cavity can be converted from poor expulsion behavior to strong expulsion behavior after furnace treatment, resulting in a substantial improvement in quality factor. Future plans are described to build on this result in order to optimize treatment for future cavities. |
| Databáze: | OpenAIRE |
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