论文标题
通过原位等离子体加工在LCLS-II腔中进行现场排放缓解研究
Field emission mitigation studies in LCLS-II cavities via in situ plasma processing
论文作者
论文摘要
现场发射是可以限制超导射频腔的性能的因素之一。为了减少LCLS-II（Linac Cooherent Light Source II）的可能场排放，我们正在开发1.3 GHz 9细胞腔的等离子体加工。可以在冷冻模块中原位应用血浆处理，以减轻与腔表面存在的碳氢化合物污染相关的场发射。在本文中，将血浆清洁应用于单细胞和9细胞腔，无论是干净和污染的。为了比较其性能，在血浆加工之前和之后对腔进行了冷测试。事实证明，血浆清洁不会对氮掺杂表面处理产生负面影响。相反，它保留了高质量因素和淬火场。等离子体加工也应用于具有自然田间发射或人为污染的空腔。已经发现，该技术成功地消除了从腔虹膜中的基于碳的污染，并且能够在自然发射腔中去除现场发射。在四个空腔上模拟了真空失败实验，在某些情况下，等离子体处理能够提高性能。
Field emission is one of the factors that can limit the performance of superconducting radio frequency cavities. In order to reduce possible field emission in LCLS-II (Linac Coherent Light Source II), we are developing plasma processing for 1.3 GHz 9-cell cavities. Plasma processing can be applied in situ in the cryomodule to mitigate field emission related to hydrocarbon contamination present on the cavity surface. In this paper, plasma cleaning was applied to single cell and 9-cell cavities, both clean and contaminated; the cavities were cold tested before and after plasma processing in order to compare their performance. It was proved that plasma cleaning does not negatively affect the nitrogen doping surface treatment; on the contrary, it preserves the high quality factor and quench field. Plasma processing was also applied to cavities with natural field emission or artificially contaminated. It was found that this technique successfully removes carbon-based contamination from the cavity iris and that it is able to remove field emission in a naturally field emitting cavity. Vacuum failure experiments were simulated on four cavities, and in some cases plasma processing was able to achieve an increase in performance.
