Kramer F, Keckert S, Kugeler O, Knobloch J
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
Universität Siegen, Department Physik, Walter-Flex-Str. 3, 57068 Siegen, Germany.
Rev Sci Instrum. 2024 Sep 1;95(9). doi: 10.1063/5.0202546.
Many modern accelerators rely on superconducting radio-frequency (SRF) cavities to accelerate particles. When these cavities are cooled to the superconducting state, a fraction of the ambient magnetic field (e.g., Earth's magnetic field) may be trapped in the superconductor. This trapped flux can significantly increase the power dissipation of the SRF cavities. It is, therefore, crucial to understand the underlying mechanism of how magnetic flux is trapped and what treatments and operating conditions can reduce the flux-trapping efficiency. A new experiment was designed that enables a systemic investigation of flux trapping. It allows for independent control of cooldown conditions, which might have an influence on flux trapping: temperature gradient across the superconductor during cooldown, cooldown rate, and ambient magnetic field. For exhaustive studies, the setup was designed for quick thermal cycling, permitting up to 300 superconducting transitions in one day. In this paper, the setup and operation is described in detail and an estimation of the measurement errors is given. Exemplary data are presented to illustrate the efficacy of the system.
许多现代加速器依靠超导射频（SRF）腔来加速粒子。当这些腔被冷却到超导状态时，一部分环境磁场（例如地球磁场）可能会被困在超导体中。这种俘获磁通会显著增加SRF腔的功率损耗。因此，了解磁通俘获的潜在机制以及哪些处理方法和运行条件可以降低磁通俘获效率至关重要。设计了一个新实验，能够对磁通俘获进行系统研究。它允许独立控制可能影响磁通俘获的冷却条件：冷却过程中超导体上的温度梯度、冷却速率和环境磁场。为了进行详尽的研究，该装置设计用于快速热循环，一天内可实现多达300次超导转变。本文详细描述了该装置和操作，并给出了测量误差的估计。还给出了示例数据来说明该系统的有效性。
