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@inproceedings{enomoto:ipac2021-wepab144, author = {Y. Enomoto and K. Abe and N. Okada and T. Takatomi}, title = {{A New Flux Concentrator Made of Cu Alloy for the SuperKEKB Positron Source}}, booktitle = {Proc. IPAC'21}, pages = {2954--2956}, eid = {WEPAB144}, language = {english}, keywords = {positron, operation, vacuum, target, GUI}, venue = {Campinas, SP, Brazil}, series = {International Particle Accelerator Conference}, number = {12}, publisher = {JACoW Publishing, Geneva, Switzerland}, month = {08}, year = {2021}, issn = {2673-5490}, isbn = {978-3-95450-214-1}, doi = {10.18429/JACoW-IPAC2021-WEPAB144}, url = {https://jacow.org/ipac2021/papers/wepab144.pdf}, note = {https://doi.org/10.18429/JACoW-IPAC2021-WEPAB144}, abstract = {{Flux concentrator (FC) is one of important device for positron source which translates position and momentum spread of the particles adiabatically to match them to the acceptance of the following section. To realize higher positron yield, higher magnetic field is desired. However, higher field by higher current generate stronger force on the coil. Since the gap between each turn of the coil is as narrow as 0.2 mm and the voltage across them is about as high as 1 kV at the design current, slight deformation of the coil cause discharge between the gap. To avoid such problem, a new FC made of Cu alloy which has 40 times higher yield strength than that of pure Cu was designed and tested. Finally, during summer shutdown in 2020, the old FC made of pure Cu was replaced by the new one made of Cu alloy in the KEK electron positron injector linac. The new one has been working stably at the design current, 12 kA, since Oct. 2020, and positron yield of 0.5 was realized. There were no discharge and other trouble till now.}}, }