Superconducting materials testing with a high-Q copper RF cavity
Superconducting materials testing with a high-Q copper RF cavity
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使用高 Q 铜射频腔进行超导材料测试
DOI：
10.1109/pac.2007.4441253
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
I. Campisi
中科院分区：
文献类型：
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作者：
Sami G. Tantawi;V. Dolgashev;G. Bowden;J. Lewandowski;C. Nantista;A. Canabal;T. Tajima;I. Campisi
超导射频在粒子加速器中具有越来越重要的作用。我们研制了一种用于超导材料测试的高品质因数谐振腔和可互换壁。连接到耦合虹膜上的紧凑型TE01模式发射器选择性地激励方位对称的腔模，该模式允许在可拆卸的壁处有间隙，并且没有可能导致场发射、多电容器和射频击穿的表面电场。腔的形状被定制为将磁场聚焦在测试样品上。我们描述了用这个腔进行的低温实验。以铜为基准的初步实验为我们的仪器提供了基准。然后是用Nb和MgB2进行的测试。除了表征超导开始与温度的关系外，我们的腔体还可以与高功率速调管共振，以确定材料在超导状态下所能承受的表面磁场水平。使用反馈码使低电平射频驱动器跟踪谐振频率。
Superconducting RF is of increasing importance in particle accelerators. We have developed a resonant cavity with high quality factor and an interchangeable wall for testing of superconducting materials. A compact TE01 mode launcher attached to the coupling iris selectively excites the azimuthally symmetric cavity mode, which allows a gap at the detachable wall and is free of surface electric fields that could cause field emission, multipactor, and RF breakdown. The shape of the cavity is tailored to focus magnetic field on the test sample. We describe cryogenic experiments conducted with this cavity. An initial experiment with copper benchmarked our apparatus. This was followed by tests with Nb and MgB2. In addition to characterizing the onset of superconductivity with temperature, our cavity can be resonated with a high power klystron to determine the surface magnetic field level sustainable by the material in the superconducting state. A feedback code is used to make the low level RF drive track the resonant frequency.