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| WEOAA03 | Experimental Study on Optical Vortex from a Helical Undulator at UVSOR-III | 2036 |
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A relativistic electron in helical undulator emits an optical vortex which carries orbital angular momentum. Sasaki and McNulty predicted theoretically that higher harmonics of helical undulator is optical vortex* and the experimental verification was made at BESSY** and UVSOR-III***. Further, we have made a systematic study to characterize the optical vortex from a helical undulator at UVSOR-III. Synchrotron radiation in UV region from an optical klystron undulator system consisting of two APPLE-II helical undulators and a buncher was used for the experiment. Patterns resulting from inferences between two undulator radiation carrying different angular momentums were clearly observed. To investigate the optical properties of the radiation, diffraction experiments were carried out. Specific diffraction patterns due to the phase singularity in the radiation center were clearly observed. The experimental results are compared with simulation.
* S. Sasaki, I. McNulty, Phys. Rev. Lett. 100, 124801 (2008) ** J. Bahrdt et al., Phys. Rev. Lett. 111, 034801 (2013) *** e.g. S. Sasaki et al., presented in SRI2015 (2015) |
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Slides WEOAA03 [11.023 MB] | |
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| THPMB050 | The Commmissioning of Phase-I Insertion Devices in TPS | 3360 |
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| The Taiwan Photon Source (TPS) is a low-emittance 3-GeV light source at Natioal Synchrotron Radiation Research Center, next to the Taiwan Light source (1.5 GeV). On March 26, 2015, the TPS storage ring with two 5-cell PETRA cavities has successfully operated in 100 mA in top-up mode without the installation of insertion devices (IDs). To reach the design goal of 500 mA, the machine was shut down for 5 months to replace PETRA cavitites with superconducting RF (SRF) cavities and to install 10 IDs: 7 in-vacuum undulators (IU) and 3 elliptically polarized undulators (EPU). The commissioning of TPS storage ring with SRF cavities and IDs began in Sep. 2015. In this paper, we present our results and proceedures of ID commissioning. | ||
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| THPOW036 | Evaluation of Immutability against Radiation-induced Demagnetization for a Hybrid Wiggler with NdFeB Magnets at the Canadian Light Source | 4022 |
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| The BioXAS beamline at Canadian Light Source installed a hybrid wiggler in 2013. Quantitative studies building on the experience of other facilities suggest the wiggler's NdFeB magnets are at risk of demagnetization due to radiation induced by the synchrotron's 2.9 GeV electrons. We use a phenomenological model to convert simulated peak demagnetizing fields into a radiation dose corresponding to a chosen %-demagnetization, and compare against an estimated dose per year due to injected beam. We find that injecting with the wiggler closed will cause 1% demagnetization in sections of its magnet blocks within 2 years of operation, assuming a worst case scenario. The wiggler has thus far been forced open for injections, but this will cease to be an option when CLS moves to top-up operation. In a related test, qualitative measurements of radiation during injections with the wiggler closed were taken by covering its magnets in Polaroid film. We find that radiation drops significantly when the injection efficiency is well-tuned. Our results suggest the wiggler will not receive damaging levels of radiation at closed gap so long as the injection system remains optimized. | ||
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| THPOW037 | Simulated and Measured Magnetic Performance of a Double APPLE-II Undulator at the Canadian Light Source | 4025 |
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| Assembly and shimming are underway for a double APPLE-II type elliptically polarized undulator (i.e. two magnet arrays installed side by side on a single support structure) at the Canadian Light Source. The device is planned to be installed in spring 2017. Extensive preparation was done prior to device assembly, particularly in development of a simulated annealing algorithm for magnet virtual shimming, as well as assembly procedures that minimized positional errors in the installed magnet blocks. In this paper we present measurements taken throughout the shimming process, and compare with predictions from a RADIA model where each magnet block was magnetized uniquely according to individual Helmholtz coil measurements. | ||
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| THPOW038 | First Results from Two Novel In-vacuum Magnetic Field Measurement Devices as Built at HZB | 4028 |
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| The characterization of cryogenic in vacuum permanent magnet undulators with periods less than 20 mm and correspondingly narrow gaps requires new in-vacuum measurement systems. The positioning accuracy of the HZB in-vacuum Hallprobe bench has substantially been improved (a few μm) with appropriate feedback systems. A new in-vacuum cable tray has been developed. Another system for field integral measurements, an in-vacuum moving wire, is under commissioning. Both devices are presented. | ||
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| THPOW039 | Measurements of the Lattice Modifications for the Cryogenic Undulator CPMU17 | 4031 |
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| A 2 mrad-canted double undulator system is in preparation as the wide energy range light source for the Energy Material in-situ Laboratory EMIL at the HZB storage ring BESSY II. The cryogenic undulator CPMU-17 is the hard X-ray device of the double undulator system. The soft X-ray undulator UE-48 is of the APPLE II type. It was installed and commissioned a few months ago, whereas the CPMU-17 is under fabrication. The CPMU-17 will employ a minimum magnetic gap of 5.5mm. Including a CuNi-foil for RF-shielding and geometric tolerances the free aperture is planned to be 5.0 mm. The BESSY II lattice has been modified locally in order to cope with the small gap device. The adapted betatron functions with a shifted vertical beam waist were measured and fitted with LOCO. The new optics agrees with the predicted performance. The free aperture at the installation place of the CPMU-17 was measured with four vertical scrapers. It is compatible with the projected minimum undulator gap. Finally, the measured injection efficiency with the new EMIL optics switched on is compatible with top-up operation (injection efficiency ≥ 90 %). | ||
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| THPOW040 | Insertion Devices for Spring-8 Upgrade Project | 4035 |
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| In the upcoming major upgrade project of SPring-8 (SPring-8-II) planned in the early 2020's, the electron energy will be reduced from 8 GeV to 6 GeV and the straight sections will be shortened by nearly 2 m to accommodate more magnets, for the purpose of reducing the emittance down to around 100 pm.rad. The insertion devices (IDs) currently installed in SPring-8 are not compatible with the above upgrade plan, and thus most of them should be replaced with new ones optimized in the new storage ring, or at least be shortened to fit into the new straight sections. We report the status of R&Ds toward realization of IDs for SPring-8-II, such as shortening the magnetic period, reforming the fundamental structure of IDs to reduce the total cost and manufacturing lead time, and refurbishment of existing IDs for shorter lengths. | ||
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| THPOW041 | Field Error Correction Considerations of Cryogenic Permanent Magnet Undulator (CPMU) for High Energy Photon Source Test Facility (HEPS-TF)* | 4038 |
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| Considerations are made for field error corrections of a 2m-long CPMU in built for HEPS-TF. Field changes in cooling to liquid nitrogen temperature are simulated. 1st field integral of terminal changes by tens of Gauss cm and RMS of phase errors induced by cold contraction is less than 1° when temperature gradient along girder is below 1.5K/m. Field signature of magic finger is unchanged with temperature. Strategy of the field error correction is discussed. | ||
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| THPOW042 | Start-to-End Simulation on Terahertz Superradiation of Ultrashort Electron Bunch in an Undulator | 4041 |
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| The narrowband, intense and frequency-tunable THz radiation can be generated by letting an ultrashort electron bunch pass through an undulator. Start-to-end simulation of terahertz radiation from electron bunch in an undulator is studied in this paper. GPT code is used to track particle distribution from the photocathode RF gun to the entrance of the undulator and Genesis 1.3 is applied to simulate the radiation. The simulation results agree well with theoretical predictions. | ||
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| THPOW045 | Development of PAL-XFEL Undulator System | 4044 |
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| Pohang Accelerator Laboratory (PAL) is developing a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. At the first stage, PAL-XFEL needs two undulator lines for photon source. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator and soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. PAL is developing undulator magnetic structure based on EU-XFEL concepts. In this report, the results of final pole height tuning results, and magnetic measurement results will be presented. | ||
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| THPOW046 | Status of Insertion Device Measurement Systems at MAX IV Laboratory | 4047 |
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| An insertion device lab was setup at MAX IV Laboratory and the production of insertion devices, mainly out-of-vacuum is ongoing and aided by new magnetic measurement systems. A new 5.5 m long Hall probe bench is used for field map measurements and a new hybrid flip coil and stretch wire system will be used for field integrals of full devices as well as individual magnet blocks characterisation. This paper describes these magnetic measurement systems and their achieved and expected performance. | ||
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| THPOW048 | Optimization of a Multipole Wiggler for Tps | 4050 |
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| Taiwan Photon Source (TPS) is a synchrotron radia-tion facility with electron energy 3 GeV that was commissioned in 2015. Taiwan Light Source (TLS) with electron energy 1.5 GeV concurrently provides user time. Three beam lines of TLS supply photons of energy 6-18 keV for user experiments; these beam lines are served with an in-achromatic superconduct-ing wiggler (IASW, 3.1 T). This superconducting inser-tion device has the disadvantages of complicated maintenance and operation. A traditional multipole wiggler (MPW) magnet of hybrid type is hence planned to be installed in TPS to cover the range of photon energy of IASW for user experiments. For the design of the magnetic circuit, the side block and the extreme block are arranged surrounding a Permendur Vanadium cobalt steel pole that enhances the field strength and good field region of a MPW magnet. The dynamic integral field and the demagnetizing field of MPW magnet were estimated. The optimization of the pole dimensions and photon characteristics were simu-lated and are discussed in this work. | ||
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| THPOW049 | Status of Insertion Devices at Taiwan Photon Source | 4054 |
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| The storage ring of Taiwan Photon Source (TPS) has eighteen short straight sections (length 7 m) and six long straight sections (length 12 m). In phase I, three elliptically polarized undulators of type APPLE II and seven in-vacuum undulators, which included four in-vacuum undulators and two elliptically polarized undulators in three double mini-βy sections, were installed. Commissioning of the insertion devices began in 2015 November. The influence of insertion devices on the electron beam and the results after compensation are presented. Problems during the commissioning induced by the electron beam and by radiation, and their solutions, are also explained. For insertion devices in phase II and for devices developed in TPS, the preliminary designs are presented herein, to cover from the VUV to the hard X-ray region. | ||
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| THPOW051 | Design and Construction of Compact Electromagnetic Undulator for THz Radiation Production | 4060 |
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Funding: Chiang Mai University Research Fellowship Program The goal of this research is to design and construct a compact electromagnetic undulator. This insertion device will be installed at the PBP-CMU-LINAC system of Chiang Mai University (CMU), Thailand, to produce THz radiation. The undulator magnet is designed by using 2D POISSON and 3D RADIA computer code to optimize the magnet dimensions. The width of iron pole (W) should be 12 mm. The length of iron pole (L) should be about 80 mm long and the thickness of return yoke (d) should be more than 10 mm. The magnet design, the in-house con-struction of the magnet, and the measurement results will be presented. |
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| THPOW052 | Recent Magnetic Measurement Activities at NSLS-II Insertion Device Laboratory | 4063 |
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| National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory (BNL) is a new 3 GeV third generation electron storage ring designated to provide extremely intense beams of X-ray, ultraviolet, and infrared light for basic and applied research. Insertion devices (IDs) play a significant role in achieving the high performance demands of NSLS-II. An accurate magnetic characterization and proper corrections of these devices are essential activities in the development of a state-of-the-art light source facility. This paper describes the results of the latest magnetic measurement activities at the NSLS-II ID laboratory. | ||
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