Strong Meissner screening change in superconducting radio frequency cavities due to mild baking
Strong Meissner screening change in superconducting radio frequency cavities due to mild baking
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DOI：
10.1063/1.4866013
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发表时间：
2014-02-17
影响因子：
4
通讯作者：
Prokscha, T.
中科院分区：
文献类型：
--
作者：
Romanenko, A.;Grassellino, A.;Prokscha, T.
本文利用低能量μ子自旋（LE-mu SR）对粒子加速器体铌超导射频腔中的高场耗散“热”区进行了研究。我们证明了铌在伦敦穿透深度λ (L) = 23 +/- 62 nm的清洁极限下，热区的超导特性可以用非局域pipppard /BCS模型很好地描述。相比之下，从120摄氏度烘烤腔中取出的样品显示出更大的λ > 100 nm和深度相关的平均自由程，可能是由于空位浓度的梯度。我们认为这些空位可以有效地捕获氢，从而防止在热区形成导致rf损失的氢化物。(C) 2014作者。除另有说明外，所有文章内容均采用知识共享署名3.0未移植许可协议。
We investigate "hot" regions with anomalous high field dissipation in bulk niobium superconducting radio frequency cavities for particle accelerators by using low energy muon spin rotation (LE-mu SR) on corresponding cavity cutouts. We demonstrate that superconducting properties at the hot region are well described by the non-local Pippard/BCS model for niobium in the clean limit with a London penetration depth lambda(L) = 23 +/- 62 nm. In contrast, a cutout sample from the 120 degrees C baked cavity shows a much larger lambda > 100 nm and a depth dependent mean free path, likely due to gradient in vacancy concentration. We suggest that these vacancies can efficiently trap hydrogen and hence prevent the formation of hydrides responsible for rf losses in hot regions. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.