Wire position system to consistently measure and record the location change of girders following ground changes

8th International Particle Accelerator Conference

Choi, H.J.^1 ; Lee, S.B.^1 ; Lee, H.G.^1 ; Back, S.Y.^1 ; Kim, S.H.^1 ; Kang, H.S.^1

Pohang Accelerator Laboratory, Pohang, Gyeongbuk

37673, Korea, Republic of^1

关键词: Accelerator tube;    Building floors;    Current situation;    Electron-beam parameters;    Operating principles;    Position systems;    Three dimensional locations;    X-ray free electron lasers;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/874/1/012088/pdf
DOI  :  10.1088/1742-6596/874/1/012088

来源: IOP

【 摘 要 】

Several parts that comprise the large scientific device should be installed and operated at the accurate three-dimensional location coordinates (X, Y, and Z) where they should be subjected to survey and alignment. The location of the aligned parts should not be changed in order to ensure that the electron beam parameters (Energy 10 GeV, Charge 200 pC, and Bunch Length 60 fs, Emittance X/Y 0.481 μm/0.256 μm) of PAL-XFEL (X-ray Free Electron Laser of the Pohang Accelerator Laboratory) remain stable and can be operated without any problems. As time goes by, however, the ground goes through uplift and subsidence, which consequently deforms building floors. The deformation of the ground and buildings changes the location of several devices including magnets and RF accelerator tubes, which eventually leads to alignment errors (X, Y, and Z). Once alignment errors occur with regard to these parts, the electron beam deviates from its course and beam parameters change accordingly. PAL-XFEL has installed the Hydrostatic Leveling System (HLS) to measure and record the vertical change of buildings and ground consistently and systematically and the Wire Position System (WPS) to measure the two dimensional changes of girders. This paper is designed to introduce the operating principle and design concept of WPS and discuss the current situation regarding installation and operation.