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| WED01 |
Commissioning of the Delta Polarizing Undulator at LCLS |
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- H.-D. Nuhn, S.D. Anderson, R.N. Coffee, Y. Ding, Z. Huang, M. Ilchen, Yu.I. Levashov, A.A. Lutman, J.P. MacArthur, A. Marinelli, S.P. Moeller, F. Peters, Z.R. Wolf
SLAC, Menlo Park, California, USA
- J. Buck
XFEL. EU, Hamburg, Germany
- G. Hartmann, J. Viefhaus
DESY, Hamburg, Germany
- A.O. Lindahl
University of Gothenburg, Gothenburg, Sweden
- A.B. Temnykh
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
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Funding: Work was supported by U.S. DOE, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515. A.B. Temnykh is supported U.S. National Science Foundation awards DMR-0807731 and DMR-DMR-0936384.
The LCLS generates linearly polarized, intense, high brightness x-ray pulses from planar fixed-gap undulators, which provides only limited taper capability and lacks polarization control. The latter is of great importance for soft x-ray experiments. A new 3.2-m-long compact undulator (based on the Cornell University fixed-gap Delta design) has been developed and installed as the last LCLS undulator segment (U33) in October 2014. The Delta undulator provides full control of the polarization degree and K parameter through array position adjustments. Used on its own, it produces fully polarized spontaneous radiation in the selected state (linear, circular or elliptical). To increase the output power by orders of magnitude, the electron beam is micro-bunched by several (5-15) upstream LCLS undulator segments operated in the linear FEL regime. This micro-bunching process produces horizontally linear polarized (background) radiation. This unwanted radiation component has been greatly reduced by a reversed taper configuration, as suggested by Schneidmiller. Full elimination of the linear polarized component was achieved through spatial separation combined with transverse collimation. The paper will describe the methods tested during commissioning and will also present results of polarization measurements showing high degrees of circular polarization in the soft x-ray wavelength range.
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Slides WED01 [10.165 MB]
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WED02 |
An Online Diagnostic Unit for FEL Photon Parameter Determination and Optimization |
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- J. Viefhaus
DESY, Hamburg, Germany
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Originally developed for the Variable Polarization XUV Beamline P04 at PETRA III, an online diagnostic unit for beamline quality control was successfully applied to FEL radiation as well. The relevant photon properties include relative photon flux, photon energy and bandpass, beam position and especially the degree of linear polarization of the photon beam. The device consist of sixteen individual electron time-of-flight electron spectrometers which are oriented in a plane perpendicular to the incoming radiation. A gas-phase target (usually rare gases at pressures of about 10-08 to 10-06 hPa) with very low absorption allows to put the device in front of the user experiment for online diagnostics of the x-ray beam. The efficient time-of-flight method with flight times in the order of tens of ns together with a fast multi-channel digitizer system and multi-threaded data evaluation algorithms allows true online shot-by-shot visualization at high repetition rates with minimal delay. Results from different FEL sources showing the flexibility as well as the real-time capabilities of the system will be presented. This work was only made possible by fruitful collaborations and extensive support from the facilities PETRA III and FLASH (DESY, Hamburg), European XFEL (Hamburg), FERMI (Elettra, Sincrotrone Trieste) and LCLS (SLAC, Menlo Park).
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Slides WED02 [180.803 MB]
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| WED03 |
Photon Diagnostics and Photon Beamlines Installations at the European XFEL |
764 |
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- J. Grünert, B. Baranasic, J. Buck, F. Dietrich, M. Dommach, W. Freund, A. Koch, N.G. Kujala, J. Liu, S. Molodtsov, M. Planas, H. Sinn
XFEL. EU, Hamburg, Germany
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The European X-ray Free-Electron-Laser (XFEL. EU) is a new a 4th generation light facility which will deliver radiation with femtosecond and sub-Ångström resolution at MHz repetition rates, and is currently under construction in the Hamburg metropolitan area in Germany. Special diagnostics [1,2] for spontaneous radiation analysis is required to tune towards the lasing condition. Once lasing is achieved, diagnostic imagers [3], online monitors [4], and the photon beam transport system [5] need to cope with extreme radiation intensities. In 2015 the installation of machine equipment in the photon area of the facility is in full swing. This contribution presents the progress on final assemblies of photon diagnostics, the installation status of these devices as well as of the beam transport system, and recent design developments for diagnostic spectrometers and temporal diagnostics.
[1] J. Grünert, XFEL. EU TR-2012-003(2012)
[2] W. Freund, XFEL. EU TN-2014-001-01(2014)
[3] A. Koch, Proc. SPIE 95121R(2015)
[4] J. Buck et al., Proc. SPIE 85040U(2012)
[5] H. Sinn et al., XFEL. EU TR-2012-006(2012)
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Slides WED03 [14.557 MB]
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| WED04 |
Status Report of PAL-XFEL Undulator Program |
769 |
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- D.E. Kim, M.-H. Cho, Y.-G. Jung, H.-S. Kang, I.S. Ko, H.-G. Lee, S.B. Lee, W.W. Lee, B.G. Oh, K.-H. Park, H.S. Suh
PAL, Pohang, Kyungbuk, Republic of Korea
- S. Karabekyan, J. Pflüger
XFEL. EU, Hamburg, Germany
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PAL-XFEL is a SASE based FEL using S-band linear accelerator, photo cathode RF Gun, and hybrid undulator system for final lazing. The undulator system is based on EU-XFEL undulator design with necessary modifications. The changes include new magnetic geometry reflecting changed magnetic requirements, and EPICs based control system. The undulator system is in measurement and tuning stage targeting to finish installation within 2015. In this report, the development, tuning, measurement efforts for PAL-XFEL undulator system will be reported.
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Slides WED04 [3.317 MB]
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