|WED02||Absorbed Radiation Doses on the European XFEL Undulator Systems During Early User Experiments||569|
The EuXFEL is a FEL user facility based on a superconducting accelerator with high duty cycle. Three gap movable SASE Undulator Systems using hybrid NdFeB permanent magnet segments are operated. Radiation damage on undulators can impact the quality of the SASE process and ultimately threaten user operation. We observed  in the commissioning phase doses up to 4 kGy and 3% demagnetization effect in a diagnostic undulator. Currently all SASE systems are used for user photon delivery and in this work we present characteristics of the absorbed radiation doses on undulators under stable conditions. Doses on the upstream segments are found to be originated in the event of occasional high energy electron losses. In contrast, towards the downstream end of a SASE system, individual segments show persistent absorbed doses which are proportional to the transmitted charge and are dominated by low energy radiation. This energy-dependence depiction shall result in distinct radiation damage thresholds for individual segments. Portable magnetic flux measurement systems allow in-situ tunnel assessment of undulator properties in order to estimate radiation dose limits for future user operation.
 F. Wolff-Fabris et al., J. of Phys. - Conf. Series 1067, 032025 (2018)
|Slides WED02 [7.344 MB]|
|DOI •||reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WED02|
|About •||paper received ※ 19 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019|
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