Girder deformation related phase errors on the undulators for the European X-Ray Free Electron Laser

Li, Yuhui; Ketenoglu, Bora; Pflueger, J.

doi:10.1103/physrevstab.18.060704

Cited by 11 publications

(14 citation statements)

References 9 publications

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“…The explanation is that on all European XFEL undulators small parabolic girder deformations have been observed, which result from changing magnetic forces, which are well within the specifications. Therefore different extensions of the bulk field lead to different phase matching requirements [10]. Since the curve in Fig.…”

Section: Phase Matching Using the Optical Phasementioning

confidence: 99%

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Phase matching strategy for the undulator system in the European X-ray Free Electron Laser

Pflueger

2017

Phys. Rev. Accel. Beams

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The undulator system in the European X-ray Free Electron Laser is mainly comprised of 5-m long undulator segments and 1.1 m long intersections in between. The longitudinal component of the electrons' velocity is reduced when traveling inside an undulator due to the wiggle motion. Therefore the optical phase is detuned. The detune effect is also from the undulator fringe field where electron longitudinal speed also deviates from the oscillation condition. The total detune effect is compensated by a magnetic device called phase shifter, which is correspondingly set for a specific undulator gap. In this paper we investigate the homogeneity of the fringe field from different undulators. Different phase matching criteria are studied. The field fitting technique for the phase matching in high accuracy is demonstrated in detail. The impact by air coil is also studied. Eventually the matching test by spontaneous radiation simulation is made. A test method for high sensitivity to matching error is proposed.

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Section: Phase Matching Using the Optical Phasementioning

confidence: 99%

“…optical phase errors, trajectory wander, etc. All phase shifters were well tuned and characterized as well [10][11][12][13]. Field integral errors were corrected below XFEL tolerance levels for all gaps [12].…”

Section: Introductionmentioning

confidence: 99%

Phase matching strategy for the undulator system in the European X-ray Free Electron Laser

Pflueger

2017

Phys. Rev. Accel. Beams

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“…One of the most important requirements for an undulator is that of low phase errors [18], and phase errors strongly depend on the gap profile shape [19]. Therefore, strongback distortions, such as "bowing," should be kept to an acceptable level.…”

Section: Strongback Deformationsmentioning

confidence: 99%

Vertically polarizing undulator with dynamic compensation of magnetic forces

Strelnikov

Vasserman

et al. 2017

Phys. Rev. Accel. Beams

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As part of the R&D program of the LCLS-II project, a novel 3.4-meter-long undulator prototype with horizontal magnetic field and dynamic force compensation has recently been developed at the Advanced Photon Source (APS). Previous steps in this development were the shorter 0.8-meter-long and 2.8-meterlong prototypes. Extensive mechanical and magnetic testing were carried out for each prototype, and each prototype was magnetically tuned using magnetic shims. The resulting performance of the 3.4-meter-long undulator prototype meets all requirements for the LCLS-II insertion device, including limits on the field integrals, phase errors, higher-order magnetic moments, and electron-beam trajectory for all operational gaps, as well as the reproducibility and accuracy of the gap settings.

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“…For deeper analysis, field measurements need to be analyzed. First, for each pole a local is defined for each pole using the following definition [11, 12] : This is a half-period field integral around the th pole of the field profile. Fluctuations of local from the average describe the error.…”

Section: Undulatormentioning

confidence: 99%

“…For deeper analysis, field measurements need to be analyzed. First, for each pole a local K is defined for each pole using the following definition [11,12] :…”

Section: Undulatormentioning

confidence: 99%

A study on low emittance injector and undulator for PAL-XFEL

Hong

Han

Park

et al. 2015

High Pow Laser Sci Eng

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For the success of PAL-XFEL, two critical systems, namely a low emittance injector and a variable gap out-vacuum undulator, are under development. In order to realize the target emittance of the PAL-XFEL injector we carried out an optimization study of various parameters, such as the laser beam transverse profile, the laser pulse length, the laser phase, and the gun energy. The transverse emittance measured at the Injector Test Facility (ITF) is ε x = 0.48 ± 0.01 mm mrad. An undulator prototype based on the EU-XFEL design and modified for PAL-XFEL was built and tested. A local-K pole tuning procedure was developed and tested. A significant reduction (90%) of the local-K fluctuation was observed. The requirement of undulator field reproducibility better than 2 × 10 −4 and the undulator gap setting accuracy below 1 µm were achieved for the prototype. The optical phase jitter after the pole height tuning at the tuning gap was calculated to be 2.6 • rms, which satisfies the requirement of 5.0 • .

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Girder deformation related phase errors on the undulators for the European X-Ray Free Electron Laser

Cited by 11 publications

References 9 publications

Phase matching strategy for the undulator system in the European X-ray Free Electron Laser

Phase matching strategy for the undulator system in the European X-ray Free Electron Laser

Vertically polarizing undulator with dynamic compensation of magnetic forces

A study on low emittance injector and undulator for PAL-XFEL

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