Field-dependent surface resistance for superconducting niobium accelerating cavities
Superconducting cavities made from niobium allow accelerating gradients of about 50 MV/m close to the theoretical limit. Quite often, however, the rf losses increase with the gradient faster than quadratic. This observation is equivalent with a decrease of the quality factor Q with the gradient, ca...
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| Format: | Article |
| Language: | English |
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American Physical Society
2011-10-01
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| Series: | Physical Review Special Topics. Accelerators and Beams |
| Online Access: | http://doi.org/10.1103/PhysRevSTAB.14.101002 |
| Summary: | Superconducting cavities made from niobium allow accelerating gradients of about 50 MV/m close to the theoretical limit. Quite often, however, the rf losses increase with the gradient faster than quadratic. This observation is equivalent with a decrease of the quality factor Q with the gradient, called “Q slope” for intermediate gradients, and “Q drop” for larger ones. The paper provides an explanation by an elementary model based on the two-fluid theory of rf superconductivity and applies it to experimental data for a large variety of cavity tests. |
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| ISSN: | 1098-4402 |