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@inproceedings{sajaev:ipac2021-thpab065,
author = {V. Sajaev and J.C. Dooling and K.C. Harkay},
title = {{Experimental Verification of the Source of Excessive Helical SCU Heat Load at APS}},
booktitle = {Proc. IPAC'21},
pages = {3904--3906},
eid = {THPAB065},
language = {english},
keywords = {vacuum, radiation, photon, synchrotron-radiation, synchrotron},
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-THPAB065},
url = {https://jacow.org/ipac2021/papers/thpab065.pdf},
note = {https://doi.org/10.18429/JACoW-IPAC2021-THPAB065},
abstract = {{Immediately after the installation of the Helical superconducting undulator (HSCU) in the APS storage ring, higher than expected heating was observed in the cryogenic cooling system. Steering the electron beam orbit in the upstream dipole reduced the amount of synchrotron radiation reaching into the HSCU and allowed the device to properly cool and operate. The simplest explanation of the excessive heat load was higher than expected heat transfer from the vacuum chamber to the magnet coils. However, modeling of the synchrotron radiation interaction with the HSCU vacuum chamber showed that Compton scattering could also result in synchrotron radiation penetrating the vacuum chamber and depositing energy directly into the HSCU coils**. In this paper, we present experimental evidence that the excessive heat load of the HSCU coils is not caused by the heat transfer from the vacuum chamber but resulted from the synchrotron radiation penetrating the vacuum chamber.}},
}