Völker, J.; Frahm, A.; Jankowiak, A.; Keckert, S.; Knobloch, J.; Kourkafas, G.; Kugeler, O.; Neumann, A.; Plötz, H.: A Superconducting Magnetic Shield for the Photoelectron Injector of BERLinPro. In: Peter Michel ... [Ed.] : SRF2019, Proceedings of the 19th International Conference on RF Superconductivity, Dresden, Germany. Geneve: JACoW, 2019. - ISBN 978-3-95450-211-0, p. MOP105/335-339
http://accelconf.web.cern.ch/AccelConf/srf2019/papers/mop105.pdf
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Abstract:
Magnetic fields are a big issue for SRF cavities, especially in areas with strong electromagnets or ferromagnetic materials. Magnetic shieldings consisting of metal alloys with high magnetic permeability are often used to reroute the external magnetic flux from the cavity region. Those Mu metal shields are typically designed for weak magnetic fields like Earth’s magnetic field. Next to strong magnetic field sources like superconducting (SC) solenoids, those shields can be easily saturated, resulting in a degradation of the shielding efficiency and a permanent magnetization. For the photoinjector of bERLinPro a new SC solenoid will be installed inside the cryomodule next to the SRF gun cavity. Calculations show that the fringe fields of the solenoid during operation can saturate the cavity Mu-metal shields. Therefore we designed an SC magnetic shield placed between the solenoid and the cavity shield to protect the latter during magnet operation. In this paper we will present the design and first testings of this SC magnetic shield.