Paper | Title | Page |
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THPC001 | Progress Towards Implementation of Top-up at the Australian Synchrotron | 2904 |
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The Australian Synchrotron Light Source has enjoyed several years of stable operations with a high degree of availability. It is now time to move towards top-up operations to improve the stability and integrated flux of the photon beam. This paper describes the steps that have been taken and what remains to be done in order to implement top-up injection as the normal operation mode for the first user runs of 2012. | ||
THPC002 | Implementation of a Low-Emittance Optics for the LNLS UVX Storage Ring | 2907 |
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In this report we describe the theoretical optimization and implementation of a low-emittance optics for the LNLS UVX storage ring. The emittance is reduced by letting the dispersion be distributed everywhere while keeping the low vertical beta feature. The optimization strategy is based on a series of quadrupole strength scans and selection of points satisfying a number of criteria. The new mode reduces the emittance from 100 nm.rad to 40 nm.rad, including the effects of the already installed insertion devices, and keeps the working point in the same quadrant as the present operation BBY6T mode. Tests have shown a reduction of approximately 20% in the horizontal and vertical beam sizes in the middle of the dipoles, in agreement with the theoretical emittance reduction. | ||
THPC003 | Installation of the ASTRID2 Synchrotron Light Source | 2909 |
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ASTRID2 is the new 10 nm UV and soft x-ray light source being built at Aarhus University, to replace the aging source ASTRID. ASTRID2 is now in the middle of its installation. An update of the design will be presented. Almost all components have now been acquired and received. Several choices and solutions of hardware will be described, and future commissioning plans outlined. Commissioning is expected to take place in the winter 2011/2012. | ||
THPC005 | First Measurements with a Kicked Off Axis Bunch for Pseudo Single Bunch Mode Studies at SOLEIL | 2912 |
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At SOLEIL, the time resolved French community benefits of single bunch operation few weeks a year. Meanwhile most of the multi-bunch filling pattern based experiments are not possible due to the low photon flux. Following the pioneer work performed at ALS*, a new operation mode is under study at SOLEIL where the storage ring is filled up with a special hybrid mode: ¾ multibunch filling pattern and a single bunch with higher current in the last ¼. The so-called pseudo single bunch-filling pattern is obtained if the closed orbit of the single bunch is not the same as the one of the other bunches. Preliminary results are presented where the pinger magnet time impulse response has been significantly reduced while its frequency was increased from 3 Hz up to 1 kHz. This magnet is used as an additional corrector magnet to change only the single bunch closed orbit. First experimental results observed at one interested beamline are also discussed.
* S. Kwiatkowski et al., “'CAMSHAFT' Bunch Kicker Design for the ALS Storage Ring", Proc. of EPAC2006, THPLS114, p. 3547, (2006). |
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THPC006 | Experiments to Measure Electron Beam Energy using Spin Depolarization Method on SOLEIL Storage Ring | 2915 |
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The electron beam energy on SOLEIL storage ring was successfully measured using spin depolarization method after several attempts over the past few years. The experimental results demonstrate that the effective polarization was 91.3%±3% and polarization time was 17±2.3 minutes as expected from the simulation using SLIM code. The beam was depolarized using an AC shaker and the depolarization was monitored using DCCT and beam loss monitors. The beam energy was measured with accuracy up to a few 10-5. | ||
THPC007 | Laser Electron Interaction Simulation for the Femtosecond Bunch Slicing on SOLEIL Storage Ring | 2918 |
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The interaction of an electron bunch and a laser in a wiggler (modulator) to generate a femtosecond slice is simulated for the slicing project on SOLEIL storage ring, using a code based on Monte-Carlo method and GENESIS. The results from these two codes are consistent with the theoretical values. The maximum modulated energy of the electron bunch and the number of electrons above a certain limit are studied for different wiggler and laser parameters. The transport of the 6D distribution of the sliced bunch from the modulator to the radiators are simulated using AT (Accelerator Toolbox) and ELEGANT, with synchrotron radiation on and taking into account the collective effects of the sliced bunch core. | ||
THPC008 | Touschek Lifetime and Momentum Acceptance Measurements for ESRF | 2921 |
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The Touschek lifetime of a synchrotron results from electrons scattering off one another within the bunch and subsequently being lost. We have measured the Touschek lifetime for the major operating modes of the ESRF as a function of RF voltages. This includes multibunch and few bunch filling patterns with correspondingly different chromaticity values. Through calibration of the RF voltage and measurement of the other beam parameters such as bunch length and vertical emittance, we may understand the momentum acceptance in the regime where this is determined by non-linear dynamics effects. | ||
THPC009 | Performance and Upgrade of the ESRF Light Source | 2924 |
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The European Synchrotron Radiation Facility (ESRF) is now fully engaged in a large Upgrade Programme of its infrastructure, beamlines and X ray source. In this context, a first set of 10 insertion device straight sections are being lengthened from five to six metres; a number of them will be operated with canted undulators. The insertion devices are themselves subject to an ambitious development programme to fulfil the scientific requirements. The Radio Frequency system upgrade has started with the replacement of the booster klystron-based transmitter by high power solid state amplifiers, and the development of HOM damped cavities operating at room temperature. A completely new DC-AC orbit stabilization system using 224 BPMs and 96 orbit steerers is currently being commissioned. The upgrade is conducted while keeping, and even improving, routine performance for the user service. In particular the recent installation of new skew quadrupole power supplies allows routine operation with ultra low vertical emittance. This paper reports on the present operation performance of the source, highlighting recent developments and those still to come. | ||
THPC010 | Recent Developments at the Metrology Light Source | 2927 |
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The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute, owns the electron storage ring Metrology Light Source (MLS) which was built and is operated by the Helmholtz-Zentrum Berlin [1, 2]. The MLS has been in regular user operation since April 2008 and supports synchrotron-radiation-based metrology and technological developments in the IR, UV, VUV and EUV spectral range. Here we report on recent progress to develop the MLS into a reliable, flexible and stable user facility. | ||
THPC012 | Mitigating the Pertubations Caused by U 180 at the Metrology Light Source | 2930 |
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The Metrology Light Source is equipped with an electromagnetic undulator with a period length of 180 mm. User requests demand operation of this undulator in a wide energy range from 100 MeV through 629 MeV for user and dedicated low alpha modes. Mitigating the pertubations caused by the undulator to an acceptable level for all user requests, requires each quadrupole in the lattice to be powered individually. To what extend this recently implemented capability allows the restoration of the main properties of the machine optics for various settings of the undulator is presented in this document. | ||
THPC013 | THz Studies at a Dedicated Beamline at the MLS | 2933 |
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The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute is operating the low-energy electron storage ring Metrology Light Source (MLS) in Berlin-Adlershof in close cooperation with the Helmholtz-Zentrum Berlin. The MLS is designed and prepared for a special machine optics mode (low-alpha operation mode) based on a sextupole and octupole correction scheme, for the production of coherent synchrotron radiation in the THz region*. At the MLS two bending magnet beamlines dedicated to the use of IR and THz synchrotron radiation are in operation: the MLS-IR beamline optimized for the NIR to FIR, and a dedicated THz beamline optimized for the FIR/THz spectral range**. Low-alpha operation optic modes for different ring energies, 250 MeV, 350 MeV, 450 MeV and 630 MeV are available. We compare the THz spectra taken in the different low-alpha modes and discuss the results.
* J. Feikes et al., Phys. Rev. ST Accel. Beams 14, 030705 (2011). ** R. Müller et al., J. Infrared Milli Terahz Waves, in press (2011), DOI: 10.1007/s10762-011-9785-6. |
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THPC014 | Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring | 2936 |
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A scheme is discussed, where short and long bunches can be stored simultaneously in the BESSY II storage ring. With recent developments in sc-rf cavity technology it becomes possible, to install high gradient cavities in electron storage rings. With an appropriate choice of these cavities stable fixed points with different rf-voltage gradients are available, leading to different zero current bunch lengths. For BESSY II, we discuss the simultaneously storage of bunches with rms-lengths of 2 ps and 15 ps at high beam intensities. Additionally, in a low alpha optics sub-ps and ps-bunches are possible and a double bucket optics can be set up to store the two types of beams simultaneously on different orbits. Ultra-short and long bunches can be supplied to the users, separated by slightly different orbits. | ||
THPC015 | A Dedicated THz Beamline at DELTA | 2939 |
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Funding: Work supported by DFG, BMBF, and by the Federal State NRW As a consequence of the new radiation source for ultrashort VUV pulses at DELTA, which is based on the interaction of electrons with fs laser pulses, coherent THz radiation is emitted. Simulations of the laser-electron interaction, particle dynamics and radiation spectrum, as well as the optical and mechanical design of a dedicated THz beamline are presented. First experimental results including laser-electron overlap diagnostics and characterization of the THz radiation are discussed. |
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THPC016 | Ultrashort VUV and THz Pulse Generation at the DELTA Storage Ring | 2942 |
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Funding: Supported by DFG, BMBF, and the Federal State NRW The optical klystron (two undulators, separated by a dispersive section) at DELTA, formerly operated as storage-ring FEL, is seeded with ultrashort pulses from a Ti:Sapphire laser. The thus induced energy modulation of an electron bunch in the first undulator is converted to a density modulation within the dispersive chicane. In the second undulator, the micro-bunched electrons emit ultrashort pulses coherently at harmonics of the fundamental laser wavelength. Additionally, coherent ultrashort THz pulses are generated several meters downstream of the optical klystron by the laser-induced gap in the electron bunch. First results are presented. |
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THPC017 | Temporal and Spatial Alignment of Electron Bunches and Ultrashort Laser Pulses for the CHG Experiment at DELTA | 2945 |
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Funding: Supported by DFG, BMBF, and the Federal State NRW The generation of ultrashort VUV pulses by CHG (Coherent Harmonic Generation) requires achieving and maintaining the longitudinal and transversal overlap of femtosecond laser pulses and electron bunches. We present the techniques and the experimental setup applied at the DELTA storage ring. For the longitudinal analysis, both a streak camera and a fast photo diode are used. Transversely, two CCD cameras acquire images of laser and synchrotron light at different positions inside of the undulator. A feedback system utilizes the intensity of a THz signal generated several meters downstream of the undulator to optimize and maintain the overlap. |
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THPC020 | PETRA III Upgrade | 2948 |
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PETRA III, the new third generation light source at DESY, has been running as a user facility since middle of 2010. All 14 undulator beam lines have been commissioned and up to 12 of them are currently in operation. However, already during the planning phase of PETRA III it turned out that the number of beamlines will not be sufficient to fulfill the request for beam time. The pressure to add more beamlines to PETRA III even increased after the decision to shut down DORIS III at the end of 2012. To increase the number of experimental stations two additional halls will be built each housing 5 additional beam lines and about 100 m of the accelerator close to each of the new buildings will be completely remodeled to install additional undulators. The upgrade has been formally approved and at present should be accomplished during a 6 month shut down in 2013. In this paper the layout of the upgraded accelerator will be shown. The impact of the upgrade on machine performance has been studied both theoretically and experimentally and the results of these studies will be presented. | ||
THPC021 | Status of Bunch Deformation and Lengthening Studies at the ANKA Storage Ring | 2951 |
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Funding: This work has been supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320. At the ANKA storage ring (Karlsruhe, Germany) we use a Hamamatsu synchroscan streak camera to study the current dependent bunch lengthening and deformation effects . Previously the camera was used at an IR port, being available only occasionally. In October 2010, a dedicated “beam line” for the streak camera became operational. It is designed to have minimum dispersion and sufficient flux in the optical range at which the camera is most sensitive. This allows us to measure bunch profiles for a single bunch with a charge of less than 15 pC (40 μA), previously more than 55 pC were required to obtain a comparable signal. Along with the design and built-up, we present further measurements of bunch length and shape for different momentum compaction factors, RF voltages, beam energies and bunch charges to provide a complete bunch length map of the low alpha mode at ANKA. |
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THPC023 | Third Generation Light Source Project in Iran | 2954 |
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The Institute for Research in Fundamental Sciences (IPM) is in charge of the establishing the Iranian Light Synchrotron Source Facility (ILSF). This facility will be a 3rd generation 3 GeV storage ring with a circumference of roughly 300 m. The injector will consist of a 150 MeV Linac and a full energy booster synchrotron. The storage ring has a four-fold symmetry with 4 long (7.88m), 16 medium (4.0 m) and 12 short (2.8 m) straight sections. Within the medium straight section there are mini beta values in order to get an optimized flux density for the users. The emittance is in the range of 3 nmrad. The booster synchrotron has a circumference of roughly 192 m with an emittance of roughly 31 nmrad. It is a separated function machine in order to have the maximum flexibility. For both machine it is foreseen to use a 500 MHZ RF-system with normal conducting cavities. The machine will be build in an international collaboration, in which the main components have to be supplied from international market. The conceptual design report should be finished in 2012, the commissioning of the machine is expected to be in 2020. | ||
THPC024 | Lattice Candidates for the ILSF Storage Ring | 2957 |
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Iranian Light Source Facility (ILSF) is a new third generation synchrotron light source which is currently in design and will build in Iran. It will provide a high photon flux density to cover requirements of experimental science in several fields. Regarding to the proposed budget and in order to produce high quality X-ray pulses with several photon beamlines as a request of users, it is decided to design a very low emittance (ε<5nm-rad) storage ring with a typical beam intensity of 400 mA and circumference in the range of 280 m to 320 m. A number of design options with different lattice structure types, circumferences, etc., are explored and we present two designed lattice candidates of the ILSF storage ring. The associated Accelerator Physics issues are discussed. | ||
THPC025 | Booster Design for ILSF | 2960 |
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A full energy 3 GeV booster synchrotron has been designed to boost electron beam to the target energy of 3 GeV for the proposed third generation synchrotron light source (ILSF) that will be constructed in Iran. The primary goal of the ILSF booster is to design a synchrotron which can deliver a small emittance (ε<30 nm-rad), while at the same time has a low cost in construction. In order to design lattice for the booster, two configurations for booster have been considered. In the first configuration, booster is designed based on locating in a separate tunnel as 3 GeV storage ring inside the ring and in the second configuration, the booster is optimized for placing inner to the ring with one shared wall as service area of ILSF storage ring. Several types of lattice with various circumferences have been explored for the booster synchrotron in each configuration and this paper presents results of linear and nonlinear optimization of the main designed lattice for booster in both configurations. | ||
THPC026 | Low Momentum Compaction Optics for Elettra | 2963 |
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The DBA optics lattice of Elettra, the third generation Italian light source is closer to DBA minimum emittance condition than any other similar lattice. At the same time, although the lattice is also optimized for large acceptance, it is very inflexible to any changes like the reduction of the momentum compaction (very desirable to the IR and SR-FEL beam lines). Nevertheless a solution has been found and consists in abandoning the achromat condition and reversing the polarity of some quadrupole and sextupole families. This special optics and its applications to Elettra are presented and discussed. | ||
THPC027 | Top-up Operational Experience at Elettra | 2966 |
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Since May 2010 Elettra, the third generation Italian light source, operates regularly for users at both 2 and 2.4 GeV in top-up. In this paper the experience during more than a year of operation in top-up at both user energies is discussed and the machine up time statistics presented and compared with the before top up period. | ||
THPC028 | A Proposal of Short X-ray Pulse Generation from Compressed Bunches by mm-wave iFEL in the SPring-8 Upgrade Plan | 2969 |
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In the SPring-8 upgrade plan, short pulse options are prepared for time-resolved experiments of pico-second order with high repetition rate. The best scenario is that selected bunches have equilibrium bunch length of 1 ps or less. A mm-wave storage-ring iFEL may be one possible solution for it. If resonant wavelength of the FEL is a few millimeters, which is about ten times longer than typical short bunch length of 0.3 mm corresponding to 1 ps, almost all electrons of a bunch can be confined in one valley of ponderomotive potentials formed by the FEL mechanism. The system consists of a helical wiggler with period length of several meters and a mm-wave resonator. Numerical simulations with coherent synchrotron radiation effect at bunch charge of 479 pC show that an ultra-short injection bunch is trapped in a mm-wave “bucket” and kept shorter than 1 ps (r.m.s.) even after twice the longitudinal damping time from the injection. The ultra-short bunches need to be injected from the XFEL linac. XFEL-to-Storage Ring beam transport line is designed to suppress dispersions which cause bunch lengthening. Tracking calculations show promising results for bunch qualities at the transport line. | ||
THPC029 | Ultra-low Emittance Light Source Storage Ring Consisting of 5-Bend Achromat Cells with Four Long Straight Sections | 2972 |
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The 6 GeV ultimate storage ring (USR) consisting of ten bend achromat cells has been proposed* and applied it to the SPring-8 Storage ring**. It has the same circumference as the SPring-8 storage ring, but does not have four long straight sections, where the SPring-8 storage ring does. The cell length is twice of that of the SPring-8 storage ring and the number of cell is half of the SPring-8. The photon beam line positions would deviate from those of the existing one. To avoid these problems, we designed a storage ring that has four long straight sections and same cell number. The cell is changed from ten bend achromat to five bend achromat and the cell length is shortened to 30 m which is the same length of the SPring-8 storage ring unit cell. The total ring consists of 44 five bend achromat cells and four long straight section cells. The emittance is 104 pm and it will reduce to less than 50 pm by radiation damping of wigglers and undulators. The brightness is expected to be more than 1022 phs/s/mm2/mrad2 in 0.1%BW with 200 mA beam current.
* K. Tsumaki, N. Kumagai, NIM A 565 (2006) 394. ** K. Tsumaki, N. Kumagai, Proc. of EPAC06, THPLS035, p. 3362 (2006). |
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THPC030 | Design of a BeamTransport Line from the SACLA Linac to the SPring-8 Storage Ring | 2975 |
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The SPring-8 Angstrom Compact Free Electron Laser (SACLA) linac has high beam qualities. The normalized emittance is less than 1 mm.mrad and the bunch length is less than 100 fs. If this high quality beam is injected to the SPring-8 storage ring, many interesting experiments can be done. On the other hand, the upgrade of the SPring-8 storage ring is under contemplation. The dynamic aperture of the new storage ring is expected to be so small that the small emittance beam is required to keep high beam injection efficiency. The SACLA linac beam also fulfills this requirement. For these reasons, it was decided to connect the SACLA linac and the SPring-8 storage ring. Since there is already an injection transport line from the SPring-8 synchrotron to the storage ring, the new transport line from the linac to this transport line has been constructed*. We designed the three types of magnet lattice for the new transport line; FODO, Double Bend Achromat and Triple Bend Achromat lattice. Emittance growth and bunch lengthening are calculated for each lattice and the beam qualities are compared. In this paper, lattice design and the comparison of the beam quality for each lattice are described.
* C. Mitsuda et al., this conference. |
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THPC031 | Measurement of Longitudinal Dynamics of Injected Beam in a Storage Ring | 2978 |
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Experimental observation of longitudinal dynamics of injected beam in a storage ring has been demonstrated. Since the injected beam undergoes synchrotron oscillation in a longitudinal phase space, two projected values, i.e., a bunch duration and an energy spread, oscillate at twice the synchrotron frequency. At SPring-8, the initial energy spread (~0.126%) at the injection goes up and down until it reaches the equilibrium energy spread (~0.11%). If the injection timing should not be optimized, an asymmetrically enhanced oscillation could distort the injection efficiency. The observation of such an oscillation helps make sure that no significant injection loss occurs. More importantly, the scheme is expected to enable us to observe non-linear longitudinal dynamics of ultra-short bunches injected from the XFEL linac; the bunches are in near future going to be transferred from the linac to the storage ring via 600-meter long transports, in which strong coherent synchrotron radiation and other high peak-current effects will not be ignorable. Experimental results obtained by a dual-scan streak camera and other devices as well as numerical simulations will be presented. | ||
THPC032 | Current Status of SPring-8 Upgrade Plan | 2981 |
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The SPring-8 upgrade plan has been discussed. The main goal is to replace the storage ring in the existing tunnel so that the resulting emittance will get as close to the diffraction limit in hard x-ray region as possible. For 10 keV photons, for instance, the diffraction limit corresponds to the emittance of as small as 10 pm.rad. For the challenging goal, the new ring features a multi-bend lattice with damping wigglers, which presumably enables us to reduce an emittance by two orders of magnitudes or more compared with the current double-bend lattice without damping wigglers. Up to now, a six-bend lattice has been mainly studied, which is supposed to generate a natural emittance of 60–70 pm.rad for 6 GeV. In addition, damping wigglers and coupling control should assist to reduce the emittance even more for approaching the ultimate goal. The major modification requires not only an advanced lattice design via manipulation of non-linear beam dynamics but also extensive technological developments in almost every component such as magnets, monitors, and RF systems. The overall review of the upgrade plan, including some detailed discussions on the critical issues, will be presented. | ||
THPC034 | Post-earthquake Recovery of PF Ring and PF-AR | 2984 |
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When the unprecedented scale of earthquake occurred in Japan on the afternoon of March 11, 2011, PF ring and PF-AR, two synchrotron light sources in KEK, also suffered various damages. At PF ring, a formed bellows in a wall current monitor was broken, and atmospheric air rushed into the beam duct. At PF-AR, which is installed in the underground tunnel, the alignment of the ring magnets seemed to be disordered to an order of ten mm. At both rings, a lot of electronics racks and toolboxes in the control rooms or in the experimental halls were tilted or tipped over. It was extremely fortunate that the user operation had just been stopped on the morning of that day, and all the gate valves in the rings and to the beam lines had already been closed for the scheduled shutdown. A wide area blackout took place at the big earthquake, and the electric power for the accelerator was interrupted over the next two weeks because of temporal shortage of the electricity in the eastern part of Japan. In April, we could start detailed investigation of machine damages and repair works towards recommissioning of the rings before the summer and resumption of the user operations in the autumn. | ||
THPC037 | Accelerators of the Central Japan Synchrotron Radiation Facility Project (II) | 2987 |
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Central Japan Synchrotron Radiation (SR) Facility Project is making progress for the service from FY2012. The construction of SR building is almost completed in the Aichi area of Japan, and the installs of accelerators will start in a few week. The key equipments of our accelerators are an 1.2 GeV compact electron storage ring that is able to supply hard X-rays and a full energy injector for top-up operation. The beam current and natural emittance of the storage ring are 300 mA and 53 nmrad. The circumference is 72 m. The magnetic lattice consists of four triple bend cells and four straight sections. The bending magnets at the centers of the cells are 5 T superconducting magnets and the critical energy of the SR is 4.8 keV. The injector consists of a 50 MeV linac and a booster synchrotron with the circumference of 48 m. To save construction expenses, the injector is built at inside of the storage ring. More than ten hard X-ray beam-line can be constructed. One variable polarization undulator will be installed in the first phase. The top-up operation will be introduced as early as possible. | ||
THPC040 | Expected Performance Characteristic of Accelerator-based THz Source at Tohoku University | 2990 |
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Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003. Sources of coherent synchrotron radiation at THz wavelength region have been constructed at Tohoku University. Bunch train of extremely shorter electron pulse less than 100 fs will be provided by an injector linac employing thermionic rf gun, where the bunch compression will be performed by means of velocity bunching in an accelerator structure. Radiation source under development are a Halbach type planar undulator and an accumulator isochronous ring. The undulator employs large gap and long period length configuration, so that the resonant frequency of 1 THz is achieved when a lower beam energy of ~ 20 MeV. Since spectrum of coherent synchrotron radiation (CSR) is strongly depending on longitudinal bunch form factor, we have calculated CSR spectra for various conditions of the beam to evaluate the performance of the THz source. Numerical simulation with multi-particle system has been carried out to understand the radiation power and angular distribution as well. The beam transport in the undulator is crucial for quality of the radiation because the beam energy is very much low relative to strong focusing power. Characteristics of THz CSR from the undulator will be discussed. |
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THPC041 | Injector System of Test Accelerator as Coherent Terahertz Source | 2993 |
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Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003. A test accelerator as a coherent terahertz source (t-ACTS) project has been under development at Tohoku University, in which a generation of intense coherent terahertz (THz) radiation from sub-picosecond electron bunch will be demonstrated. We will supply a wide-band coherent radiation from bending magnets in an isochronous ring and a narrow-band coherent THz radiation using an undulator in a linac. Stable generation of very short electron bunch is one of the key issues in the t-ACTS project. The injector system is consists of a thermionic RF gun with two independent cavity cells, an alpha magnet and an accelerating structure. A velocity bunching scheme is employed to produce the very short electron bunch. Components of the t-ACTS injector except the accelerating structure have already been installed and we have started a high power RF processing of the gun cavities. The characteristics of electron bunch extracted from the RF gun are measured by varying phase and amplitude of input RF fields for the gun cavities. The status of t-ACTS project will be presented in the conference. |
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THPC042 | Status and Development of the SAGA Light Source | 2996 |
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The SAGA Light Source (SAGA-LS) is a synchrotron radiation facility consisting of a 255 MeV injector linac and a 1.4 GeV storage ring, and has been stably providing synchrotron light since 2006. The annual failure time is less than 1% of the user time in the recent two years. Three insertion devices are installed in the storage ring: an APPLE-II undulator, a planar type undulator (Saga Univ.) and a 4 T superconducting wiggler (SCW). The SCW contains a hybrid three-pole magnet; the main pole of the magnet is surrounded by superconducting coils while side poles are normal conducting magnets. The main pole of the SCW is cooled by a GM cryocooler, which allows the SCW be operated without liquid helium. Since the installation in March 2010, the SCW has been operated stably. To control the ID parameters during the user time, a feed-forward correction system which minimizes the ID effects on the emittance coupling was developed. The laser Compton Gamma-rays were generated by using a CO2 laser and were used for beam energy measurement. In addition, research works on the beam lifetime and interaction between electron beam and crystal, and development of a multipole magnet are in progress. | ||
THPC043 | Status of SESAME Project | 2999 |
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This paper reports on the progress which has been made on the construction of the SESAME accelerator complex. The construction of the shielding wall has been finished on March 2011. According to plan, the preparation works and tenders of the conventional facilities have been launched such as the cooling system, electrical distribution systems, PSS system and so on. The commissioning of the Microtron at full energy and the installation of the booster are the next millstones to accomplish. The booster upgrade plan has started which consists of replacing all bending magnets vacuum chamber with new one, BPM Libera Electronics, new control system based on EPICS, new timing system, new electronics for tune measurement. The site acceptance test of the new power supplies of the booster with their tracking electronics is planned to take place in July 2011. The magnet system of the storage ring has been reviewed and the manufacturing tendering is foreseen before the end of 2011. | ||
THPC044 | Operation and Performance Upgrade of the Soleil Storage Ring | 3002 |
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SOLEIL delivers photons to 24 beamlines. Up to 22 very diverse insertion devices (IDs) are now installed on the storage ring, and 4 more will come by summer 2011, including a Cryogenic undulator and an electromagnetic/permanent magnet helical undulator, both designed and built at SOLEIL. Work is continuing on beam dynamics and magnetic corrections to reduce the nonlinear effects of all these IDs. A new optics incorporating an additional quadrupole triplet in one long straight section has been successfully tested and will be put in operation by fall 2011. A new coupling correction will also be implemented to maintain the ratio of the vertical to the horizontal emittances at 1% for any IDs configuration. The electron beam orbit stability has been significantly improved reaching a residual noise of 300 nm RMS. Photon LIBERA modules of X-BPM located on the bends, will be integrated soon in the orbit feedback loops. 4905 hours have been delivered in 2010 to the beamlines with an availability of 96.3%. The user operation with the maximum current of 500 mA is foreseen to start by fall 2011, after the completion of the radiation safety tests of the beamlines. | ||
THPC045 | Design of a Compact Storage Ring for the TTX | 3005 |
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We study a compact storage ring with circumference 3-m, 4 dipoles, and two quadrupoles for the Tsinghua Thomson scattering X-ray (TTX) source. The effects of Touschek lifetime, rf system requirement, the Intra-beam scattering (IBS) and coherent synchrotron radiation (CSR) will be addressed. A top-up injection system will be designed to maximize the Photon flux. Conceptual laser cavity to enhance photon flux will be discussed. Expected performance of the compact X-ray source will be presented. | ||
THPC052 | Progress Towards Top-up Operation at SSRF | 3008 |
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The Shanghai Synchrotron Radiation Facility (SSRF) has been in operation for user experiments in decay mode since May 2009. In the meantime various activities to prepare top-up operation at SSRF, including safety analysis and simulation, dedicated instrumentations and interlocks, control software, radiation measurements, injection optimization and top-up operation tests, have been carried out. In this paper, the progress towards top-up operation at SSRF is described together with its achieved performance. | ||
THPC053 | Shanghai Soft X-Ray Free Electron Laser Test Facility | 3011 |
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As a critical development step towards constructing a hard X-ray FEL in China, a soft X-ray FEL test facility (SXFEL) was proposed and will be constructed at the SSRF campus by a joint team of Institute of Tsinghua University and Shanghai Institute of Applied Physics. This test facility, based on an 840MeV electron linear accelerator, aims at generating 9nm FEL radiation with two-stage cascaded HGHG scheme. The project proposal was approved in February 2011 by central government, and the constrction is expected to start in early 2012. This paper describes the preliminary design of this soft X-ray test facility and the R&D progress of the key FEL technologies in the SDUV-FEL test bench. | ||
THPC054 | Project Status of the Polish Synchrotron Radiation Facility Solaris | 3014 |
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Funding: European Regional Development Fund within the frame of the Innovative Economy Operational Program: POIG.02.01.00-12-213/09 The Polish synchrotron radiation facility Solaris is being built at the Jagiellonian University in Krakow. The project is based on an identical copy of the 1.5 GeV storage ring being concurrently built for the MAX IV project in Lund, Sweden. A general description of the facility is given together with a status of activities. Unique features associated with Solaris are outlined, such as infra-structure, the injector and operational characteristics. |
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THPC055 | Front Ends at ALBA | 3017 |
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ALBA is a 3GeV 3rd generation synchrotron radiation source built nearby Barcelona currently under commissioning phase. This paper describes the design and installation of the set of 10 Front Ends that have been manufactured and assembled for day-one operation of the facility. This initial set includes 8 Front Ends devoted to transmit the photons generated by both Insertion Device or Bending Magnet sources to experimental Beamlines, and 2 additional Front Ends for electron beam-diagnostics purposes. The design of each individual Front End has been adapted in order to meet the aperture and power load requirements posed by both the characteristics of the photon sources and the needs of the Beamline users. At the same time, an effort has been made in order to keep a suitable degree of standardization among the components of different Front Ends. With this aim a modular design approach has been adopted. The general layout of the Front Ends as well as the design and function of their main components is described. Finally, a brief summary of their performance during the commissioning period is presented. | ||
THPC056 | Orbit Studies during ALBA Commissioning | 3020 |
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The 3rd generation light source ALBA is in the commissioning stage. This paper review the results of the commissioning concerning the transversal beam behavior, in particular the orbit correction system, results from the beam based alignment (BBA), and coupling. The orbit control system of ALBA consists of 88 horizontal and vertical correctors, mounted as extra coils in the sextupole magnets, up to 104 LIBERA BPMs (brilliance version). The correctors magnets would be used for both static orbit correction and for the fast orbit feedback mode, providing up to 1 mrad of correction in the static case. In phase one of the commissioning, the orbit has been corrected down to values of 50 um rms, with an estimated emittance ratio in the order of 1% . | ||
THPC057 | Operation of the ALBA Injector | 3023 |
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The ALBA injector made of a 100 MeV linac, operating at 110 MeV, and a full energy (3 GeV) booster synchrotron has been routinely in operation since October 2010. The stability of the linac and of the booster on reliability and performance is examined. Also results on the beam performance obtained with the installed diagnostic equipment will be discussed. | ||
THPC058 | The MAX IV Synchrotron Light Source | 3026 |
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The MAX IV synchrotron radiation facility is currently being constructed in Lund, Sweden. It consists of a 3 GeV linac injector and 2 storage rings operated at 1.5 and 3 GeV respectively. The linac injector will also be used for the generation of short X-ray pulses. The three machines mentioned above will be descibed with some emphasis on the effort to create a very small emittance in the 3 GeV ring. Some unconventional technical solutions will also be presented. | ||
THPC059 | Recent Improvements to the Lattices for the MAX IV Storage Rings | 3029 |
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Construction of the MAX IV facility started early this year. The facility will include two storage rings for the production of synchrotron radiation. The 3 GeV ring will house insertion devices for the production of x-rays while the 1.5 GeV ring will serve UV and IR users. Recently, the lattices for the storage rings in the MAX IV facility were updated. In the 3 GeV storage ring the vertical beam size in the long straights has been reduced. The lattice of the 1.5 GeV storage ring has been updated to take into account first results from detailed magnet and vacuum system designs. Additionally, a new injection method to facilitate commissioning of the storage rings has been studied. This paper summarizes the changes made in the lattices and the effect of these modifications. | ||
THPC061 | Comparison of Linear Optics Correction Means at the SLS | 3032 |
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The experimental determination of linear optics is a fundamental prerequisite to achieving a high performance storage ring. In order to further enhance SLS performance and to simulataneously reveal the limitations of the various techniques, we perform a systematic study of linear optics optimization using various independent methods. These include an analysis of the orbit reponse (LOCO), turn-by-turn data, and the response of the tune, whose correction is accomplished using the standard SLS procedure of varying the quadrupole strengths. A comparison of results from these procedures, which use fully independent observables, provides us with a valuable cross-check. For example, the betatron phase advances between BPMs, which is independent of BPM calibration, confirms the optics correction as determined from LOCO. The linear optics are hence better optimized, and these procedures, LOCO in particular, further serve to expose any previously hidden mis-calibration of parameters e.g. from BPMs and corrector magnets. Systematic errors from turn-by-turn data could also be vastly reduced by a better synchronization of the BPM triggers with the electron beam. | ||
THPC062 | SLS Vertical Emittance Tuning | 3035 |
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To establish ultra-small vertical emittances (<1pmrad @2.86GeV) is one important aim of future linear collider damping ring optimization studies* at the SLS. By utilizing various correction techniques the SLS is already close to this goal with emittances of <2pm.rad @2.4GeV under the constraint of maintaining user operation conditions. One of the limiting contributions is the remaining spurious vertical dispersion etay of ~1.4mm which can be reduced by careful re-alignment and the application of dispersion-free steering techniques. The latter require orbit manipulations which are only partially compatible with the user operation mode. A first application of dispersion-free steering techniques demonstrates that etay can be reduced to <1mm at the expense of large orbit excursions which require a simultaneous betatron-coupling correction by means of skew quadrupoles in order to benefit in terms of a further reduction of vertical emittance. Therefore possible girder and magnet misalignments are analyzed in simulation which allows to localize the sources of etay and to eliminate them by re-alignment. Following this path the goal to achieve emittances close to 1pmrad is within reach.
* In January 2011 the EU-project TIARA (Test Infrastructure and Accelerator Research Area) started with contributions from the SLS as part of the SVET (SLS Vertical Emittance Tuning) work package WP6. |
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THPC063 | A 2.9 Tesla Room Temperature Superbend Magnet for the Swiss Light Source at PSI | 3038 |
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The Swiss Light Source (SLS) at the Paul Scherrer Institute (PSI) in Villigen, Switzerland, is a 3rd generation synchrotron light source. With an energy of 2.4 GeV, it provides high brightness photon beams for research in materials science, biology and chemistry. The SLS storage ring contains 36 room temperature bending magnets, all of which produce light for experimental use; at the design energy of 2.4 GeV, they have a maximum magnetic field of 1.4 Tesla. Light is produced along the entire bending arc but can only be transferred to the external experimental facilities from selected short portions of the beam path. In cooperation with the Budker Institute for Nuclear Physics (BINP) in Novosibirsk, Russia, three of these magnets were replaced with new room temperature magnets with short regions of high magnetic field up to 2.9 Tesla. This enabled the production of intense light beams at shorter wavelengths than from the existing magnets. The critical energy of the 2.9 T magnet is 11.1 keV, compared to the 5.4 keV of the normal bend. This paper describes the design, including the multiple restraints, together with the measurement and commissioning of these so-called superbends. | ||
THPC064 | Design Study of Low Emittance Lattice for Taiwan Light Source at 1 GeV | 3041 |
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We explored the possibility that the existing TLS storage ring to be operated at 1 GeV as a high brightness VUV light source after the completion of 3 GeV Taiwan Photon Source. To increase the spectral brightness, we need to reduce the beam emittance in the storage ring as much as possible. We first pursue the lowest emittance which is possible without altering the existing hardware configuration. The theoretical minimum emittance that could be achieved at 1 GeV for non-achromatic lattice is 3.8 nm-rad. However, this could not be achieved without introducing harmonic sextupoles. Preliminary results of low emittance lattice without harmonic sextupoles in TLS storage ring will be presented. | ||
THPC066 | A Study of Emittance Growth in a Photoinjector Linac by using PWT as Pre-accelerator | 3044 |
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The NSRRC high brightness photoinjector for light source R&D is a 2998 MHz split configuration. Our goal is to produce 1 nC bunch charge from a photo-cathode rf gun with normalized emittance of 1 mm-mrad or less. However, limited by the available power from our klystron, previous studies showed that our linac has to be equipped with focusing solenoid to help emittance control during acceleration. In order to omit the bulky focusing solenoid from the booster linac system, we considered to use two high gradient (~26 MV/m) PWT standing-wave structures to accelerate the beam previous to the linac. Studies showed that this configuration can keep the emittance as low as 1 mm-mrad while also decreasing the energy spread to half of its initial amount. The only drawback is the growth of final beam radius, which can be compensated by using a setting of quadrupole magnets. | ||
THPC067 | Tolerance Studies of the Max-IV Linac | 3047 |
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The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (in phase 2). We briefly describe the layout, optics and bunch compression / linearization scheme of the linac. We then investigate the robustness of the design to element errors. | ||
THPC068 | CSR and THz Emission Measurements at the Diamond Light Source | 3050 |
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After the successful implementation of the low alpha optics at Diamond we have started a characterisation of coherent THz emission with the aim of classifying the rich phenomenology of stable and bursting emission and to devise the best operational mode for potential THz users. In conjunction with the Diamond IR beamline B22, THz spectral data were acquired simultaneously with Schottky diode signals in the mm-wave region of the spectrum. We also report the results of comparison with numerical simulations made with the aim of reproducing the measured THz emission spectra and gaining further understanding on the mechanisms of the instability. | ||
THPC069 | Studies to Optimize the Diamond Light Source Booster Synchrotron as a 100 MeV Storage Ring | 3053 |
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The injection chain for the Diamond Synchrotron Light Source consists of a 100 MeV Linac and 3 GeV booster synchrotron. These were commissioned in 2005 and 2006 respectively, and have provided acceptable performance as an injector since then. To advance a programme of work in evaluating and optimizing new control algorithms for orbit stability on the Diamond Storage Ring it was decided to use the booster synchrotron as a test platform by operating it in DC mode at 100 MeV. In support of this work and to improve the operational performance of the booster a series of studies have been carried out to better understand and characterize it. This work and the results will be presented. | ||
THPC070 | An Automated Statistical Analysis Package for the Study of Synchrotron Light Source Operation | 3056 |
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Machine faults and interruptions to user beam at Diamond Light Source are recorded in a Fault Log Database (FLDB) running under Microsoft Access. The scope of numerical analysis in Access is limited, and so an advanced data analysis package has been written in Matlab to exploit the powerful numeric functions available in this environment to automatically analyze machine faults and summarize data for reliability reports. Figures of merit such as mean time between failure (MTBF), mean time to repair (MTTR), total up time and total number of faults over the machine as a whole and by technical group can be calculated, and more advanced Pareto and Weibull analyses can be instantly generated. Data is presented for Diamond Light Source both for the latest year of operation and since user beam began in 2007, and the impact of different technical groups, in particular the storage ring RF, is considered. Failure distributions and the underlying hazard functions are produced and compared with statistical models to highlight deviations from randomly occurring events and to quantify changes in failure probability with time. | ||
THPC071 | Study of the Possibility of Implementing a Superbend in the Diamond Light Source | 3059 |
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We report on recent studies of the feasibility and impact of replacing one of the regular 1.4 T bending magnets in Diamond with a normal conducting 3 T "Superbend" in order to enhance the hard X-ray output for a possible future beamline. We describe the preliminary magnet design, the engineering implications and the effect on beam dynamics, including the additional constraints that arise from implementing a superbend in a DBA lattice, as compared to the more common application in a TBA lattice. | ||
THPC073 | Study of Lower Emittance Lattices for SPEAR3 | 3062 |
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We study paths to significantly reduce the emittance of the SPEAR3 storage ring. Lattice possibilities are explored with the GLASS technique. New lattices are designed and optimized for practical dynamic aperture and beam lifetime. Various techniques are employed to optimize the nonlinear dynamics, including the Elegant-based genetic algorithm. Experimental studies are also carried out on the ring to validate the lattice design. | ||
THPC074 | Dynamic Aperture and Tolerances for PEP-X Ultimate Storage Ring Design | 3065 |
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Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515. A lattice for the PEP-X ultimate storage ring light source[1], having 11 pm-rad natural emittance at a beam energy of 4.5 GeV at zero current, using 90 m of damping wiggler and fitting into the existing 2.2-km PEP-II tunnel, has been recently designed[2]. Such a low emittance lattice requires very strong sextupoles for chromaticity correction, which in turn introduce strong non-linear field effects that limit the beam dynamic aperture. In order to maximize the dynamic aperture we choose the cell phases to cancel the third and fourth order geometric resonances in each 8-cell arc. Four families of chromatic sextupoles and six families of geometric (or harmonic) sextupoles are added to correct the chromatic and amplitude-dependent tunes. To find the best settings of the ten sextupole families, we use a Multi-Objective Genetic Optimizer employing elegant[3] to optimize the beam lifetime and dynamic aperture simultaneously. Then we evaluate dynamic aperture reduction caused by magnetic field multipole errors, magnet fabrication errors and misalignments. A sufficient dynamic aperture is obtained for injection, as well as workable beam lifetime[2]. |
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THPC075 | Lattice Design for PEP-X Ultimate Storage Ring Light Source | 3068 |
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Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515. SLAC expertise in designing and operating high current storage rings and the availability of the 2.2-km PEP-II tunnel present an opportunity for building a next generation light source – PEP-X – that would replace the SPEAR3 storage ring in the future. The "baseline" design for PEP-X, with 164 pm-rad emittance at 4.5 GeV beam energy and a current of 1.5 A, was completed in 2010. As a next step in the study, a so-called "ultimate" PEP-X lattice having another order of magnitude reduction in emittance from the baseline design has been investigated. The beam emittance approaches the diffraction limited photon emittance for multi-keV photons, providing near maximum photon brightness and high coherence. In this design, the ring arcs contain seven-bend achromat cells yielding 29 pm-rad natural emittance and up to 9 insertion device straights per arc. Another factor of two emittance reduction is achieved with an 89.3-m damping wiggler installed in one of the six long straights. Details of the lattice design, the sextupole correction scheme, dynamic aperture simulations, and calculation of the intra-beam scattering effect and Touschek lifetime at a nominal 200-mA current are presented. |
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THPC076 | FEL Performance with Focusing Lattice Magnets Alignment Errors | 3071 |
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At the European XFEL the alignemnet errors of the undulator section quadrupole magnets will be corrected by applying beam based quadrupole alignment methods. Numerical simulations of the SASE process have been conducted to evaluate the FEL power reduction due to residual quadrupole alignment errors. FEL simulations with focusing lattice errors allow choosing an optimal error correction method in terms of FEL performance. | ||
THPC079 | Echo-enabled Harmonic Generation at DELTA | 3074 |
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Funding: Supported by DFG, BMBF, and the Federal State NRW We present conceptual studies of the realization of the echo-enabled harmonic generation (EEHG) technique proposed by G. Stupakov* as an upgrade of the present coherent harmonic generation (CHG) project at the DELTA storage ring**. EEHG allows to reach shorter wavelengths compared to the CHG scheme. In addition to the optical klystron used for CHG, a third undulator is needed for a second energy modulation of the electron bunch, followed by an additional strong dispersive section. Installing these insertion devices requires a new long straight section in the storage ring and a new lattice configuration. * G. Stupakov Phys. Rev. Lett. 102, 074801 (2009) ** A. Schick et al., this conference |
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THPC080 | Making Engineering Data Available at the European XFEL | 3077 |
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One of the essential success factors for the European XFEL is up-to-date, complete and consistent engineering data which is readily accessible throughout the project. Such data include for example civil construction drawings of tunnels and buildings; integrated 3D models of accelerator sections; definitions of fabrication processes and test procedures; inspection sheets, test data, standards, contracts and other technical documentation. The data is kept in the DESY Engineering Data Management System (EDMS). The DESY EDMS is the central information platform for the European XFEL and provides procedures for e.g. review & approvals and change management. The poster presents an overview of Engineering Data Management and its benefits at the European XFEL. | ||
THPC081 | Status of the Free-Electron Laser FLASH at DESY | 3080 |
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The free-electron laser facility FLASH at DESY, Germany has been upgraded in 2010. Now, FLASH delivers an electron beam energy up to 1.25 GeV. The longitudinal phase-space is linearized by 3.9 GHz superconducting cavities. The facility delivers to users ultra-short laser like radiation pulses in the range of less than 50 fs to 200 fs in the soft X-ray wavelenth range from 44 down to 4.1 nm. FLASH provides hundreds to thousands pulses per second to users with unprecedented peak brilliance. FLASH will be upgraded with a second undulator beam line and an additional experimental hall. Construction starts Autumn 2011. We summarize the operational status of the ongoing 3rd user period. | ||
THPC082 | Properties of the Radiation from the European X-ray Free Electron Laser | 3083 |
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Recent success of the Linac Coherent Light Source (LCLS) demonstrated feasibility for reliable production, compression, and acceleration of electron beams with emittances significantly smaller than original baseline parameters. The same scenario can be applied to the European XFEL as well. Experimental results from the Photo Injector Test Facility in Zeuthen (PITZ) demonstrated the possibility to generate electron beams with small charge and emittance. Computer modeling of the beam formation system also indicate on the possibility to preserve electron beam quality during acceleration and compression. Recently these trends have been analyzed, and baseline parameters of the European XFEL have been revised. Parameter space has been significantly extended in terms of the bunch charge. As a result, different modes of FEL operation become possible with essentially different properties of the radiation. In this paper we present an overview of radiation properties of SASE FEL radiators driven by electron beam with new baseline parameters. | ||
THPC083 | Analysis of Parameter Space of a Kilowatt-scale Free Electron Laser for Extreme Ultraviolet Lithography Driven by L-band Superconducting Linear Accelerator Operating in a Burst Mode | 3086 |
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The driving engine of the Free Electron Laser in Hamburg (FLASH) is an L-band superconducting accelerator. It is designed to operate in a burst mode with 800 microsecond pulse duration at a repetition rate of 10 Hz. The maximum accelerated beam current during the macropulse is 10 mA. In this paper we analyze the parameter space for optimum operation of the FEL at the wavelength of 13.5 nm and 6.7 nm. Our analysis shows that the FLASH technology holds great potential for increasing the average power of the linear accelerator and an increase of the conversion efficiency of the electron kinetic energy to the light. Thus, it will be possible to construct a FLASH like free electron laser with an average power up to 3 kW. Such a source meets the requirements of the light source for the next generation lithography. | ||
THPC084 | Optical Afterburner for a SASE FEL: First Results from FLASH | 3089 |
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Radiation Pulse from a Self-Amplified Spontaneous Emission Free Electron Laser (SASE FEL) consists out of spikes (wavepackets). Energy loss in the electron beam (averaged over radiation wavelength) also exhibits spiky behaviour on a typical scale of coherence length, and follows the radiation pulse envelope. These modulations of the electron beam energy are converted into large density (current) modulations on the same temporal scale with the help of a dispersion section, installed behind the x-ray undulator. Powerful optical radiation is then generated with the help of a dedicated radiator (afterburner). Envelope of the optical afterburner pulse is closely resembles the envelope of the x-ray pulse. We have recently demonstrated this principle at the Free Electron Laser in Hamburg (FLASH). We use THz undulator that is installed after the main X-ray as both dispersive element and radiator simultaneously. We characterize properties of the optical pulse using standard laser diagnostics techniques (i.e. FROG). Main result comes from the pulse duration measurement that we use to derive envelope of the x-ray radiation pulse duration which is in sub-100 fs range. | ||
THPC085 | Effect of mirror-tilt on the mode-structure in an oscillator FEL | 3092 |
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In an oscillator free-electron laser (FEL) the power coupled out depends strongly on the mode configuration at the out-coupling mirror. This mode configuration is affected by many parameters such as the resonator configuration, FEL wavelength, etc. In addition, mirror alignment also plays an important role in determining the mode structure. In this paper we use three-dimensional simulations (GENESIS+OPC), to study the effect of mirror tilt on the out-coupled power. We find that mirror-tilt can severely distort the mode, and can introduce non-Gaussian, non-axisymmetric modes. In this regard the confocal configuration is more robust compared to the concentric. | ||
THPC086 | Status Report on FERMI@Elettra Project | 3095 |
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Funding: This work was supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3 FERMI@Elettra, a single-pass FEL user-facility covering the wavelength range from 100 nm (12 eV) to 3 nm (413 eV) located next to the third-generation synchrotron radiation facility Elettra in Trieste, Italy is actually under completion and will start user operation next year. The first seeded lasing was observed in December 2010 and the first experiments have started this year. In this paper an overview of the present status of machine and beamlines systems will be given as well as a status about operation and future upgrade. |
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THPC087 | Saturation Effect on VUV Coherent Harmonic Generation at UVSOR-II | 3098 |
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Light source technologies based on laser seeding are under development at the UVSOR-II electron storage ring. In the past experiments, we have succeeded in generating coherent harmonics (CHs) in deep ultraviolet (UV) and vacuum UV (VUV) region and also in generating CH with variable polarizations in deep UV*. In previous conference, we reported an introduction of new-constructed spectrometer for VUV and results of spectra measurement, undulator gap dependence, and injection laser power dependence on VUV CHs**. This time we have successfully observed saturation on CHs intensities and have found some interesting phenomena in different harmonic orders. In this conference, we will discuss the results of some systematic measurements and those analytical and particle tracking simulations***.
*M. Labat et al., Phys. Rev. Lett. 101 (2008) 164803. **T. Tanikawa et al., Proc. IPAC'10, TUPE029, p. 2206 (2010). ***T. Tanikawa et al., Appl. Phys. Express 3 (2010) 122702. |
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THPC088 | Performance of RF System for XFEL/SPring-8 Injector | 3101 |
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In the XFEL/SPring-8 accelerator, the RF processing of an injector for the 8-GeV accelerator were carried out during two months after the installation of all the main components of the accelerator was completed in January 2011. To realize stable bunch compression process without the emittance growth, the injector adopts the combination of an extremely low emittance thermionic gun and multi-stage RF cavities for velocity bunching. In addition, in order to reduce the emittance growth occurring at the transition from the velocity bunching to acceleration, the newly developed L-band APS type accelerating structures and a waveguide system were introduced in the injector. Since an intensity of beam current is affected by the slight variations of RF power and phase of these RF equipment, we have carried out thorough countermeasures to complete highly-stabilized RF systems. Consequently, the stability of RF power and phase in rated operating condition of each RF cavity achieved 20 ppm (std.) and 0.06˚ (std.), respectively. In this paper, we describe the stability performances and RF processing of these RF systems in the injector. | ||
THPC089 | Study of a Modified Quasi-periodic Undulator | 3104 |
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To suppress high-order harmonic radiation effectively while maintain comparatively higher fundamental radiation intensity, a modified quasi-periodic undulator (QPU) which the magnet blocks have different size is studied in this paper. Then the paper also compares the radiation spectrum of various structural schemes. It is shown that the higher harmonic radiation of this new scheme will be suppressed more effectively than the conventional QPU. | ||
THPC093 | Beam Dynamics Simulations for the SwissFEL Injector Test facility | 3107 |
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The SwissFEL under study at PSI will produce 0.1 nm to 0.7 nm wavelength coherent x-ray. The design of the injector is based on the invariant envelope matching scheme, developed for other photoinjectors in the past years. According to this technique the emittance at the exit of the injector can be minimized if some conditions at the entrance of the booster are satisfied. A campaign of simulations has been carried out to verify the impact of the errors of the machine components (RF and magnetic) and laser shaping (transverse and longitudinal) on the final SwissFEL injector emittance. These results have to be used to define the tolerances on the machine and laser. | ||
THPC095 | Commissioning Status of the SwissFEL Injector Test Facility | 3110 |
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The SwissFEL injector test facility at the Paul Scherrer Institute has been in operation since August 2010. Its primary goal is the demonstration of a high-brightness electron beam as it will be required to drive the SwissFEL main linac. The injector further serves as a platform for the development and validation of accelerator components needed for the SwissFEL project. We give an overview of recent commissioning activities at about 130 MeV beam energy, with particular emphasis on results from optics matching studies and emittance measurements, the latter obtained with different optics-based methods. A five-cell transverse-deflecting cavity allows studies of the longitudinal bunch charge distribution and slice emittance. Bunch length measurements will become the focus of interest after the installation of a magnetic compression chicane, currently scheduled for the summer of 2011. | ||
THPC096 | Soft X-ray Free-electron Laser with a 10-time Reduced Size | 3113 |
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Funding: This work is supported by National Science Council under Contract NSC 99-2112-M-007 -013 -MY3. We present a 30-m long soft x-ray FEL consisting of a 5-MeV photoinjector, a 150 MeV linac, a magnetic chicane compressor, and a 3-m long undulator. We employ both the 3rd and the 4th harmoincs of a Nd laser at 355 and 266 nm, respectively, to illuminate the cathode of the photoinjector. Owing to the beating of the two lasers, the emitted electron beam is modulated at 282 THz. The electrons are further accelerated to 150 MeV and, after acceleration, compressed by 33 times in a magnetic chicane. The temporal compression of the electron macropulse increases the electron bunching frequency to 9.3 PHz, corresponding to a soft x-ray wavelength of 32.2 nm. We adopt a solenoid-derived staggered array undulator* with a 3-m length, 5 mm undulator period, and 1.2 mm gap. With a solenoid field of 10 kG, we estimate an undulator parameter of 0.4 and a corresponding radiation wavelength of 32.2 nm for a 150 MeV driving beam. With 3.3-kA peak current, 0.03% energy spread, 2 mm-mrad emittance, and 80-micron beam radius at the undulator entrance, the GENESIS code predicts 0.2 GW radiation power from the 3-m long undulator for an initial bunching factor of merely 10 ppm. * Y.C. Huang, H.C. Wang, R.H. Pantell, and J. Feinstein, "A staggered-array wiggler for far infrared, free-electron laser operation," IEEE J. Quantum Electronics 30 (1994) 1289. |
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THPC097 | Transverse Alignment Tolerances for the European XFEL Laser Heater | 3116 |
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Funding: Supported by the KTH-SU-UU FEL Center. We study the impact of misalignments between a laser beam and an electron bunch on the energy distribution function of the electron bunch in the laser heater. Transverse position and angular misalignment as well as different spot size of the laser and electron beam are considered. We find that the transverse misalignment makes the energy distribution function narrower compared to the case of ideal adjustment and a distinct peak in the distribution around the initial mean value of the energy appears. We demonstrate that despite these misalignments a uniform heating in terms of the energy spread can be achieved by appropriately adapting the transverse size and power of the laser beam such that the energy distribution function of the electron bunch at the end of the laser heater can be made similar to a Gaussian, thus providing more effective Landau damping against the micro-bunching instability. The laser power mainly determines the local energy spread while the laser spot size governs the shape of the energy distribution function. The transverse oscillations of electrons induced by the magnetic field in the laser heater are found to be non-essential for typical operation parameters. |
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THPC100 | Full Temporal Reconstruction using an Advanced Longitudinal Diagnostic at the SPARC FEL | 3119 |
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The Production of ultra-short (sub 100 fs) single-spike radiation possessing full longitudinal coherence from a free-electron laser (FEL) has been the subject of intense study. A Frequency-Resolved Optical Gating (FROG) diagnostic has been developed and tested at UCLA, which has the capability of providing a longitudinal reconstruction of these ultra-fast pulses. This paper reports the results of the application of the diagnostic at the SPARC FEL facility. | ||
THPC101 | Fitting Formulas for Space-charge Dominated Free-electron Lasers | 3122 |
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A simple power-fit formula for calculating the gain length of the fundamental Gaussian mode of a free-electron laser having strong space-charge effects in the 3D regime has been obtained. This tool allows for quick evaluation of the free-electron laser performance in the presence of diffraction, uncorrelated energy spread, and longitudinal space-charge effects. Here, we use it to evaluate the performance of high-gain FEL amplifiers considered candidates as high average power light sources. Results are compared with detailed numerical particle simulations using the free-electron laser code Genesis. | ||
THPC102 | Production of Coherent Optical \vCerenkov Radiation in Silica Aerogel | 3125 |
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As a demonstration of the apposite properties of silica aerogel as an electron beam diagnostic we intend to use it to produce coherent optical Cˇ erenkov radation (COCR). In this paper we propose an experiment and provide details of the challenges to be overcome in producing COCR. | ||
THPC103 | Beam Dynamics Study of X-band Linac Driven X-ray FELs | 3128 |
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Funding: Work supported by the DOE under Contract DE-AC02-76SF00515 Several linac driven X-ray Free Electron Lasers (XFELs) are being developed to provide high brightness photon beams with very short, tunable wavelengths. In this paper, three XFEL configurations are proposed that achieve LCLS-like performance using X-band linac drivers. These linacs are more versatile, efficient and compact than ones using S-band or C-band rf technology. For each of the designs, the overall accelerator layout and the shaping of the bunch longitudinal phase space are described briefly. |
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THPC104 | Optimization for Single-Spike X-Ray Fels at LCLS with a Low Charge Beam | 3131 |
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The recently commissioned Linac Coherent Light Source is an x-ray free-electron laser at the SLAC National Accelerator Laboratory, which is now operating at x-ray wavelengths of 20-1.2 Angstrom with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources. At the low charge operation mode (20 pC), the x-ray pulse length can be <10 fs. In this paper we report our numerical optimization and simulations to produce even shorter x-ray pulses by optimizing the machine and undulator setup. In the soft x-ray regime, with the help of slotted-foil or undulator taper, a single spike x-ray pulse is achievable with peak FEL power of 30 GW. | ||
THPC105 | An Electron Bunch Compression Scheme for a Superconducting Radio Frequency Linear Accelerator Driven Light Source | 3134 |
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Funding: Support by US DoE contract #DE-AC05-060R23177. We describe an electron bunch compression scheme suitable for use in a light source driven by a superconducting radio frequency (SRF) linac. The key feature is the use of a recirculating linac to perform the initial bunch compression. Phasing of the second pass beam through the linac is chosen to de-chirp the electron bunch prior to acceleration to the final energy in an SRF linac ("afterburner"). The final bunch compression is then done at maximum energy. This scheme has the potential to circumvent some of the most technically challenging aspects of current longitudinal matches; namely transporting a fully compressed, high peak current electron bunch through an extended SRF environment, the need for a RF harmonic linearizer and the need for a laser heater. Additional benefits include a substantial savings in capital and operational costs by efficiently using the available SRF gradient. |
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THPC106 | Commissioning Status of the Fritz Haber Institute THz FEL | 3137 |
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The THz Free-Electron Laser (FEL) at the Fritz Haber Institute (FHI) of the Max Planck Society in Berlin is designed to deliver radiation from 3 to 300 microns using a single-plane-focusing mid-IR undulator and a two-plane-focusing far-IR undulator that acts as a waveguide for the optical mode. A key aspect of the accelerator performance is the low longitudinal emittance, < 50 keV-psec, that is specified to be delivered at 200 pC bunch charge and 50 MeV from a gridded thermionic electron source. We utilize twin accelerating structures separated by a chicane to deliver the required performance over the < 20 - 50 MeV energy range. The first structure operates at near fixed field while the second structure controls the output energy, which, under some conditions, requires running in a decelerating mode. "First Light" is targeted for the centennial of the sponsor in October 2011 and we will describe progress in the commissioning of this device to achieve this goal. Specifically, the measured performance of the accelerated electron beam will be compared to design simulations and the observed matching of the beam to the mid-IR wiggler will be described. | ||
THPC108 | Commissioning of the 50 MeV Preinjector Linac for the BESSY II Facility | 3140 |
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A turn key 50MeV linac manufactured by Thales has been installed in the BESSY II facility. This linac will replace the existing Microtron injector in the near future to provide more flexible bunch population patterns for the femto-slicing operation mode and a higher single bunch intensity for top-up injection. This paper describes the essential problems which have been faced during commissioning and presents the main results obtained in the site acceptance tests including the measurement of beam emittance and energy spread. | ||
THPC109 | First Demonstration of Electron Beam Generation and Characterization with an All Superconducting Radio-frequency (SRF) Photoinjector* | 3143 |
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Funding: Work supported by Bundesministerium für Bildung und Forschung und Land Berlin. The work on the Pb cathode film is supported by EuCARD Grant Agreement No. 227579 In preparation for a high brightness, high average current electron source for the energy-recovery linac BERLinPro an all superconducting radio-frequency photoinjector is now in operation at Helmholtz-Zentrum Berlin. The aim of this experiment is beam demonstration with a high brightness electron source able to generate sub-ps pulse length electron bunches from a superconducting (SC) cathode film made of Pb coated on the backwall of a Nb SRF cavity. This paper describes the setup of the experiment and first results from beam measurements. |
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THPC111 | Operation of an L-band RF Gun with Pulses Inside the Burst Mode RF Pulse | 3146 |
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The Free-Electron Laser in Hamburg (FLASH) is a user facility since 2005, delivering femtosecond short radiation pulses in the wavelength range between 4.1 and 44 nm using the SASE principle. In FLASH, the electron beam is accelerated to 1.25 GeV with L-band superconducting cavities. The electron source is a normal conducting RF-gun photoinjector. The L-band standing wave RF gun has one and a half cells. The gun is operated in burst mode with an RF pulse length of up to 900 microseconds and a repetition rate of 10 Hz. Several hundreds to thousands of bunches are accelerated per second. With 5 MW of pulsed forward power, the dissipated power inside the RF gun is 45 kW. In this paper we propose an operational mode which allows us to reduce the dissipated power to ease operation or to increase the effective duty cycle in the gun by pulsing the gun within one burst. We report on first experimental results at FLASH, where an RF burst of 46μRF-pulses with a length of 10 microseconds separated by 10 microseconds has been successfully generated reducing the dissipated power by a factor of 2. | ||
THPC113 | Slice Emittance Measurements for Different Bunch Charges at PITZ | 3149 |
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The successful operation of the Free electron LASer in Hamburg (FLASH) at DESY brings up the interest in further broadening the spectrum of possible applications also for the upcoming European XFEL. Hence the electron beam properties required for lasing should be tested and optimized for a broad range of values already on the level of the injector. The Photo Injector Test facility in Zeuthen (PITZ) at DESY characterizes the photo injectors for FLASH and the European XFEL. The main study involves the transverse projected emittance optimization for different beam conditions. Beside the projected emittance, the PITZ setup allows to measure the transverse emittance with a sub-bunch longitudinal resolution. This slice emittance diagnostics is based on the usage of bunches with an energy correlation of the longitudinal phase space components induced by the booster. Then the bunch is swept vertically with a dipole magnet. Part of the bunch that corresponds to a longitudinal slice is cut out by means of a vertical slit and the horizontal emittance is measured. This report presents the results of recent slice emittance measurements for different bunch charges. | ||
THPC114 | High Brightness Photo Injector Upgrade and Experimental Optimization at PITZ | 3152 |
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The photo injector test facility at DESY in Zeuthen (PITZ) develops and optimizes electron sources for linac driven free electron lasers. The main goal of PITZ is to demonstrate a small electron beam emittance by tuning several main parameters of the injector - photo cathode laser pulse, rf gun with solenoids and booster cavity parameters. A slit scan technique is used to measure the transverse phase space of the electron beam and the projected normalized emittance. The photo injector is capable of pulse train production which can be measured with dedicated diagnostics at PITZ. This enables optimization of the beam emittance for a wide range of bunch charges from tens of pC to several nC while keeping high resolution of beam measurements. The results of the experimental optimization will be presented yielding a new benchmark of photo injector performance. | ||
THPC115 | Emittance Optimization for Different Bunch Charges with Upgraded Setup at PITZ | 3155 |
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The Photo Injector Test facility at DESY, Zeuthen site, (PITZ) has the aim to develop and optimize high brightness electron sources for Free Electron Lasers like FLASH and the European XFEL. Photo electrons emitted from the Cs2Te cathode are accelerated by a 1.6-cell L-band RF gun cavity operated at 60 MV/m maximum accelerating gradient at the cathode. Cylindrically shaped laser pulses with a flat-top temporal profile of about 20 ps FWHM and 2 ps rise and fall time are used to produce electron beams with extremely low emittance. The PITZ beam line was upgraded in 2010. The new gun cavity (prototype number 4.1) was installed January 2010. The new booster cavity (CDS) with well-defined field distribution was installed in July 2010. The diagnostic system for characterization of the laser hitting the photocathode was upgraded in October 2010. Emittance measurements results for different charges: 2 nC, 1 nC, 0.25 nC, 0.1 nC and 0.02 nC, will be presented. The optimization was done for different parameters, e.g. gun solenoid current, gun phase, laser spot size on the cathode, booster gradient. | ||
THPC116 | Surface Analysis of a Degraded NEA-GaAs Photocathode by Temperature Programmed Desorption Technique | 3158 |
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A GaAs photocathode activated the surface to negative electron affinity (NEA) is an important device for high-average-current electron accelerators, such as a next-generation light source based on an energy recovery linac. It is well known that the quantum efficiency of the NEA-GaAs photocathode is decaying with time elapsing, even if the electron beam is not extracted. The degradation is mainly caused by adsorption of residual gases in a vacuum chamber. Previously a few investigators reported that the quantum efficiency of the photocathode was rapidly degraded by water or carbon dioxide vapor. In order to analyze such surface states, we have measured desorption of gases from the degraded NEA-GaAs photocathode by using of temperature programmed desorption (TPD) technique with a quadrupole mass spectrometer. The desorption peaks of hydrogen, carbon oxide and carbon dioxide from the degraded NEA surface were observed, while that of water was not observed. | ||
THPC117 | Analysis Quantum Efficiency Spectrum of NEA-GaAs Photocathode | 3161 |
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ERL is a future project of synchrotron light source with high brightness and partial coherence. ERL is based on super conducting linear accelerator providing the high brightness electron beam to insertion devices continuously. One of the most difficult technical challenge is the electron source for ERL. A photo-cathode DC biased gun is assumed, but several issues should be solved. One of the issue is the operational lifetime of cathode material, NEA GaAs. NEA stands for Negative electron affinity made by artificial treatment on clean GaAs surface. Emission from the cathode is decreased in time and extracted beam current. In order to research the phenomena, the surface potential is studied by measuring the QE (Quantum Efficiency) spectrum. Observing temporal evolution of QE, we found that the photon energy threshold did not change during the decay. The spectrum shape was changed suggesting that the surface potential barrier becomes thicker. | ||
THPC118 | Present Status of Quantum Radiation Sources on the Basis of the S-band Compact Electron Linac | 3164 |
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We have developed quantum radiation sources such as a laser Compton scattering (LCS) X-ray and a coherent THz radiation sources on the basis of the S-band compact electron linac at AIST in Japan. The S-band linac consists of the laser-driven photocathode rf gun and two 1.5 m-long acceleration tubes and can accelerate the electron beam up to about 42 MeV. The LCS X-ray source can generate a quasi-monochromatic hard X-ray with variable energy of 12 - 40 keV for medical and biological applications. Now, the multi-collision LCS system has been developed with the regenerative amplifier type laser storage cavity and the multi-bunch electron beam to increase the X-ray yield. On the other hand, the high-power coherent THz radiation source has been also developed and its peak power is estimated to be more than 1 kW in frequency range between 0.1 - 2 THz. The high-power THz radiation was applied to the scanning transmission imaging. Now, the high power THz time domain spectroscopy (TDS) has been developed for the material science. In this conference, we will report the present status of the S-band compact electron linac, our quantum radiation sources and applications. | ||
THPC120 | Experimental Investigation of Photocathode Thermal Emittance Components with a Copper Cathode* | 3167 |
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With progress of photocathode RF gun technology, thermal emittance has become the primary limitation of electron beam brightness*. Extensive efforts have been devoted to study thermal emittance, but experiment results diverge between research groups and few can be well interpreted**. One possibility is the undefined online cathode surface conditions, which may cause difference of work functions, field enhancement factor and surface roughness, and lead to thermal emittance divergence. In this paper, we report an experiment of characterizing online photocathode work function, field enhancement factor and surface roughness effect by measuring electric field dependence of photoemission quantum efficiency (QE) and thermal emittance in a Cu-cathode RF gun. Preliminary experiment results reveal huge thermal emittance contributed by surface roughness for the first time, and are in reasonable consistency with theoretical model prediction***.
*Ivan V. Bazarov et al., Phys. Rev. Lett. 102, 104801(2009) ** D.H. Dowell et al, Nucl. Instrum. Methods Phys. Res., Sect. A 622, 685 (2010). ***D. Xinag et al, PAC’07, 1049 (2007) |
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THPC121 | Design and Cold Tests of a Prototype photocathode RF Gun for Shanghai SXFEL Facility | 3170 |
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A soft X-ray (~9 nm) FEL (SXFEL) facility is going to be constructed in Shanghai, China, which requires high charge (>500 pC) electron beam with low transverse emittance (<1.5 mm-mrad) at photoinjector exit. One of the keys to achieve a low emittance with high charge is high gradient on the photocathode, so an S-band photocathode RF gun modified from BNL type gun is designed, which aims running 100 MV/m peak gradient at 10 Hz. By changing the cathode seal technique, removing the insertion RF tuner, and reducing the peak surface field, RF breakdown possibility is reduced. Besides, RF pulse width is also considered to be reduced to lower the RF breakdown possibility. Since zero mode and multipole field degrades the beam emittance, they are also suppressed in the new gun design. Design details and cold testing results are presented in this paper. | ||
THPC123 | Injector Layout and Beam Injection into Solaris | 3173 |
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Funding: European Regional Development Fund within the frame of the Innovative Economy Operational Program: POIG.02.01.00-12-213/09 The Solaris synchrotron radiation storage ring to be built in Krakow, Poland is based on the MAX IV 1.5 GeV design. The injector will be a linear accelerator and its components identical to those for the MAX IV project, however, injection is not at full energy and the injector layout is different. The linac and transfer line layout, optics and injection scheme into the storage ring is presented and an analysis of accumulation before energy ramping is discussed. |
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THPC125 | Study of some Design Concepts and Collective Effects in the MAX IV Linac | 3176 |
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The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (phase 2). Compression is done in two double achromats with positive R56. The natural second order momentum compaction, T566, from the achromats is used together with weak sextupoles to linearise longitudinal phase space, leaving no need for a harmonic cavity for linearization of longitudinal phase space. In this proceeding we present the design of the achromat compressors and results from particle tracking through the MAX IV linac in high brightness mode. We also investigate emittance dilution due to CSR, in the achromat compressors, and transverse wakefields in a high beta function lattice. | ||
THPC126 | RF Gun Studies for the SwissFEL Injector | 3179 |
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The Paul Scherrer Institut (PSI) is planning a compact, high brightness hard X-ray free electron laser. For this purpose a new 2.5 cell RF gun has been designed at PSI and is now in production. The RF gun plays an important role in preserving beam emittance, and hence delivers a high quality beam to the injector. We present beam dynamic parametric studies on the effect of cell length variations using two different codes OPAL and ASTRA. Furthermore laser and other RF parameters are scanned to find the best working point of the injector. The simulations are showing that the SwissFEL injector requirements (ϵ<0.4 mm mrad normalized projected emittance) are achievable with a smooth dependence on the geometrical variation of the gun cell lengths confirming a robust RF design of the gun is possible. | ||
THPC127 | Recent Results from a Combined Diode-RF Gun | 3182 |
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For the SwissFEL project, a novel combined diode-RF electron gun was tested at PSI, as a possible source for XFELs. Typically, electron bunches of 1-100 pC charge , 1-5 MeV energy and 2-0.3 um-rad emittance were produced and measured. The advantage of the combined gun is that diode geometry and emission surface can be changed readily. An optimum polishing procedure for magnesium photo cathodes was found, and various surfaces such as FEA's were tested in high gradient. Emittance changes for emission surface depression within the cathode, as well as laser spot size and anode hole size, were measured. Finally, the excellent performance of the gun permitted detailed study of the pepperpot EMSY (Emittance Measurement System) behaviour with changing beam parameters. | ||
THPC129 | Gallium Arsenide Photocathode Research at Daresbury Laboratory | 3185 |
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Significant effort has been expended over several years by ASTeC to optimise procedures for preparing GaAs photocathodes for use as high-current electron sources in accelerators. Having established robust chemical and thermal cleaning processes, and carried out lifetime studies on activated photocathodes by deliberately poisoning them*, we present data showing high levels of Quantum Efficiency (QE) for heterostructure photocathodes when activated with Cs-O and Cs-NF3 procedures. We will show that the use of NF3 delivers higher QE, and conveys greater control in that the final QE level can be set more accurately using NF3 than with O. We plan to carry out further experiments on GaAs photocathodes to measure the 2-D energy distribution of the emitted electrons at both room and cryogenic temperatures. We are constructing a retarding-field electron calorimeter which will measure current as a function of retarding voltage. From this, we will establish the 2-D energy distribution in the electron beam, permitting a comparison of these figures for photocathodes at room and low temperatures. The goal is to create an ultra-bright electron source for use with particle accelerators.
* Proc IPAC ’10, TUPEC018, 1752-1754 |
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THPC130 | A 160 keV Photocathode Electron Gun Test Tacility | 3188 |
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The ALICE ERL* at Daresbury Laboratory is a prototype 4th generation free-electron laser light source operating at IR wavelengths. An upgrade to the DC photoinjector gun has been designed and partially-constructed, but due to installation postponement, the system will be used for photocathode physics experiments. The re-designed gun will operate at 160 keV. The gun and photocathode preparation facility (PPF) will be assembled with a diagnostic beamline, supporting research towards high-brightness electron beams based on GaAs technology. Combining an external PPF with a load-lock facility allows the rapid exchange of photocathodes, thus permitting the testing of various different photocathode heterostructures, and fine control of the cleaning and activation processes applied during preparation. The diagnostics beamline will include a transverse kicker to study bunch length, and a dipole magnet for beam energy and energy spread measurements. Various horizontal and vertical slit and screen assemblies allow for emittance measurement, so providing full 6-D characterisation of the electron bunches generated. A current transformer and Faraday cups support bunch charge measurements.
* Accelerators and Lasers In Combined Experiments electron Energy-Recovery Linac |
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THPC131 | MAX-IV Linac Injector Simulations including Tolerance and Jitter Analysis | 3191 |
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The MAX-IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (in phase 2). 100 pC bunches of electrons are created from a 1.5 cell S-band photocathode gun and subsequently accelerated up to 3 GeV by S-band linac sections. Simulations of the dynamics of the space-charge dominated beam up to 100 MeV are presented including an analysis of the tolerances required and the effects of jitter sources. | ||
THPC132 | A Velocity Bunching Scheme for Creating Sub-picosecond Electron Bunches from an RF Photocathode Gun | 3194 |
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Sub-picosecond electron bunches are in demand for various applications including Free Electron Lasers and electron diffraction experiments. Typically, for Free Electron Lasers, a multiple picosecond scale bunch is produced from a photoinjector with compression achieved via one or more magnetic chicanes by providing an appropriate energy chirp to the bunch in the preceding linac sections. This approach is complex, requiring many components, often including a higher harmonic linac section to linearise the longitudinal phase-space, and careful tuning in order to minimise emittance blow-up due to coherent synchrotron radiation. We present a scheme to deliver sub-picosecond electron bunches, based on a normal conducting RF gun and two short linac sections, one for providing velocity bunching and the second to capture the compressed bunch and accelerate to tens of MeV where the beam properties are then essentially frozen. | ||
THPC133 | Pre-Conceptual Design Requirements For The MaRIE Facility At LANL And The Resulting X-Ray Free Electron Laser Baseline Design | 3197 |
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The MaRIE (Matter-Radiation Interactions in Extremes) facility is being proposed to advance materials science by the concurrent utilization of a diverse set of highly penetrating probes. These probes will provide the basis for developing materials that will perform predictably and on demand with currently unattainable lifetimes in extreme environments. The MaRIE facilities, the Multi-Probe Diagnostic Hall (MPDH), the Fission and Fusion Materials Facility (F3), and the Making, Measuring, and Modeling Materials (M4) Facility will each have experimental needs for one or more high-energy x-ray beam probes, but all require a 50-keV coherent source of greater than 1010 photons in less than 1 ps. Because of space considerations at the facility, a high-gradient design is being investigated that will use a X-band RF systems to drive a 20-GeV normal-conducting linac. Experimental requirements drive a need for multiple photon bunches over time durations greater than 1 microsecond, as well as interleaving 0.1 nC very-low-emittance bunches with 2-nC electron bunches. This paper will cover an overview of the scientific requirements for the MaRIE XFEL and the baseline XFEL design. | ||
THPC134 | LCLS RF Gun Copper Cathode Performance | 3200 |
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Funding: Work supported by Department of Energy contract DE-AC03-76SF00515 We report on the performance and the operational experience of the LCLS RF gun copper photocathodes used during the LCLS run I, II, III and IV. We discuss the problems of cathode surface contamination and our experience with methods to remove such contamination. Techniques to obtain high quantum efficiency (QE) while preserving the low emittance quality are discussed. Furthermore, we will present the current status of the installed cathode, its quantum efficiency and the typical injector emittances of the extracted beam. |
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THPC135 | Optimal Parameters of the Photocathode Gun Space Charge to Improve Beam Quality | 3203 |
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Accelerator Test Facility at Brookhaven National Laboratory operates with 5 MeV photocathode gun and 70 MeV linac for different range of experiments with a few picoseconds and a few micrometers emittance electron bunch. Many conducted experiments require beam with good spatial resolution and short length as well. NdYaG laser pulse turns to the electron bunch in the gun with space charge affecting on the own bunch length and transverse profile. Optimal beam loading parameters of the space charge in the photocathode RF gun could be found and used to improve bunch length and emittance. Simple model and experimental results on the Accelerator Test Facility at Brookhaven national Laboratory will be described | ||
THPC136 | High Efficiency Visible Photocathode Development | 3206 |
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Alkali antimonide cathodes are critical both for high average current photoinjectors for energy recovery linacs and for high quantum efficiency photodetectors. These cathodes have historically been plagued by extreme vacuum sensitivity, non-reproducibility and poor lifetime. We report on ongoing efforts to improve the performance of alkali antimonides (principally K2CsSb). Cathodes have been fabricated which have a QE of 7% at 532 nm. The films are much more resistant to oxygen and water exposure than previously thought, with a 50% yield lifetime of 20 hrs at 2 pBar partial pressure of water. Several analysis techniques have been employed in this study, including in-situ x-ray diffraction during growth to measure grain size and texture, measurement of transverse momentum distribution of the emitted electrons, and measurement of the stoichiometry of the films via x-ray fluorescence. An extensive study of the growth parameters, including both transparent and metallic substrates, sputtered and evaporated films, variation of growth time and temperatures and post-growth annealing processes, is currently underway. | ||
THPC137 | Low Emittance Booster Design for CANDLE Storage Ring | 3209 |
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The progress in synchrotron based research made the top up operation mode of storage rings as the most attractive option both from the beam lifetime and the user points of view. To provide reliable operation of the facility at top-up injection mode the full energy low emittance new booster ring for 3 GeV CANDLE storage ring is designed. The compact synchrotron magnets with integrated quadrupole and sextupole components are used. The new design provides 20 nm emittance at the top energy with sufficient dynamic aperture and optimal optical properties at straight section for effective extraction. The complete design of the new booster and beam dynamics issues during the energy ramping are presented. | ||
THPC139 | Study of a Pulsed Sextupole Magnet Injection System for LNLS | 3212 |
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An injection system consisting of a pulsed sextupole magnet (PSM) is being considered for Sirius, the project of a new 3rd generation 3 GeV synchrotron source in development in Brazil. This novel injection scheme will be implemented and tested in the existing UVX ring. This will also serve as an opportunity to get acquainted with the new technology and become ready for Sirius. On this paper we report on the ongoing PSM study at LNLS. In particular, details of injection dynamics calculations, magnet and pulsed power supply designs are described, as well as machine preparations for experimental tests in the UVX storage ring. | ||
THPC140 | Design, Tuning and Results of the Pulsed Magnetic Systems for the Beam Injection in the SOLEIL Storage Ring Operated in ‘Transparent’ Top Up Mode | 3215 |
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From the beginning, the SOLEIL Storage Ring was designed to operate in Top Up injection mode. So all equipments involved have been specified to generate as small as possible beam perturbations of the stored beam during the electron beam injection. This concerns many aspects of the design and realization of the injection pulsed magnets (kickers and septa), their vacuum chambers, pulsed power supplies and timing electronics. Despite quite satisfactory results of pulsed magnetic measurements in labs, a still too large perturbation was observed on the e- beam orbit during the Storage Ring commissioning. Therefore a strong work of systematic measurements, analysis of each phenomena, tuning or modification of each device was led until reaching rather good and acceptable performances. This paper will present the results obtained. At this stage, the Storage Ring beam orbit is sufficiently stable in Top Up injection mode so that it is almost transparent to the 24 beam lines, even for the most sensitive ones. After a summary of the main significant topics, we present the developments foreseen to further improve the performances and make a new step towards a “perfect” Top Up injection. | ||
THPC142 | Burst Pulse Superimposed Electron Beam Acceleration in LEBRA FEL Linac | 3218 |
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The electron beam for free electron laser (FEL) at the Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University had been extracted from a conventional DC triode electron gun system. In conjunction with the renewal of the gun high voltage terminal a Kentech high-speed grid pulser was installed in addition to the conventional grid pulser. The 89.25MHz sine wave frequency-divided from the 2856MHz accelerating RF has been applied to the high-speed grid pulser, generating 64 or 128 frequency-divided grid pulses synchronous with the round-trip time in the FEL optical resonator. The high-speed grid pulses have been applied to the EIMAC Y646B cathode simultaneously with the conventional macropulse through the pulse coupling strip-line circuit; the resultant beam has been the short pulse beam superimposed on the macropulse beam. By reducing the macropulse voltage, only the train of the burst beam with 0.6ns width has been extracted. The peak burst beam current roughly 6 times higher than the conventional macropulse beam has been obtained with the Farady cup at the end of the FEL beamline. The FEL lasing experiment with the burst beam is underway. | ||
THPC143 | Beam-based Alignment for Injection Bump Magnets of the Storage Ring using Remote Tilt-control System | 3221 |
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Stored beam is oscillated in vertical if the injection-bump magnets have alignment error in rotation around the beam-axis (tilt). In addition, even if the tilt is negligibly small, the beam out of the median plane is kicked in vertical direction. Also, there is a small long-term drift of the vertical beam positions in the bump magnets, which causes the gradual increase of the oscillation. We have already developed a remote tilt-control system to make a smooth realignment*. To observe the oscillation, the beam position was measured bunch-by-bunch and turn-by-turn by using a bunch-by-bunch feedback system** with high resolution strip-line type beam position monitor. To obtain responses to the tilts of each magnet, the oscillations were measured under the condition that the magnets were tilted intentionally. Tilt errors were calculated with least-squares method using the responses. In order to confirm the source of the residual oscillation, a frequency analysis was carried out with FFT method using the position data from 1st to 128th turns. We succeeded in suppressing the vertical oscillation to sub-microns order, the value of less than one tenth of the beam size.
* K. Fukami et al., Proc. of EPAC'08, p. 2172 (2008). ** T. Nakamura et al., Proc. of ICALEPCS'05, PO2.022-2 (2005). |
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THPC144 | The Construction Status of Beam Transport Line from XFEL-linac to SPring-8 Storage Ring | 3224 |
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The beam transport line from XFEL-linac to SPring-8 storage ring is now under construction to use the ultra short bunched electron beam at the storage ring. The newly constructed line is about 300 m, which is just a half of the whole path from the XFEL linac to the storage ring. The beam extracted from XFEL-linac is guided to the beam transport tunnel connected to the matching section of booster synchrotron bending by 55.2 degrees horizontally and by 10.0 degrees vertically. A double-bend based lattice was adopted to reasonably suppress emittance growth and bunch lengthening. Supposing a bunch length and horizontal emittance at the exit of the XFEL-linac are estimated about 100 fs and 0.04 nmrad respectively, it is expected that the current beam emittance in storage ring is improved to about 0.4 nmrad and almost same bunch length including coherent synchrotron radiation effect. In 2010, the construction of extracting part from XFEL-linac was completed and we finished the installation and alignment of main components. The conceptual design and construction status of transport line will be presented with the emphasis on the detail magnet design and the fabrication. | ||
THPC146 | The Radiated EMI Isolation for TPS Kicker Magnet* | 3227 |
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Electromagnetic interference is a critical problem for electronic equipment, especially for those sophisticated measuring sensors using in TLS. Therefore, lots of efforts have been made to isolate the EM noise from the kicker magnets. In this article, different thicknesses of aluminum chambers are applied to block the radiated EM noise. Furthermore, the different widths of slits simulate the necessary openings on kicker assembly. According to the results of small-scale experiment, some parameters are obtained to design the enclosure of kicker magnet. Compared the results with the data from the original scale kicker, these parameters provide a believable guideline in the beginning of design status. | ||
THPC147 | TPS SR Kicker Prototype Installation Status* | 3230 |
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The purpose of this paper is to illustrate the installation sequence of TPS SR kicker. Because of adding the rotation function in row direction, the position of every component of kicker must be very precise. The kicker magnet and EMI enclosure were fastened on the rotation motor plate which could rotate ±3.0 mrad. The ceramic chamber remain fixed on the bottom plate in order to let the bellow stress free during rotation. After installation, the inductance measurement and the high voltage breakdown test were also tested. The experimental results showed the good uniformity and reached the expected request. The field mapping and EMI prevention schemes will be tested in the future. | ||
THPC149 | Development of PrFeB Cryogenic Undulator (CPMU) at SOLEIL | 3233 |
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A R&D programme for the construction of a 2 m long 18 mm period CPMU is under progress at SOLEIL. The cryogenic undulator will provide photons in the region of 1.4 to 30 keV. It will be installed in the next few months on the long straight section (SDL13) of the storage ring, and could be used later on to produce photons for the NANOSCOPIUM beamline. The use of PrFeB which features a 1.35 T remanence (Br) at room temperature enables to increase the peak magnetic field at 5.5 mm minimum gap, from 1.04 T at room temperature to 1.15 T at a cryogenic temperature of 77 K. Praseodymium was chosen instead of Neodymium magnetic material, because it is more resistant against the appearance of the Spin Reorientation Transition. Different corrections were performed first at room temperature to adjust the phase error, the electron trajectory and to reduce the multipolar components. The mounting inside the vacuum chamber enables the fitting of a dedicated magnetic measurement bench to check the magnetic performance of the undulator at low temperature. The results of the magnetic measurements at low temperature and the comparison with the measurement at room temperature are reported. | ||
THPC150 | Review of Insertion Device Dedicated to HIgh Energy Photons at SOLEIL | 3236 |
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Producing high energy photons between 10 keV and 70 keV is a challenging topic in a medium energy storage ring. It requires up-to-date measurement techniques and specific Insertion Device (ID) technologies to produce high magnetic fields and short periods. SOLEIL (2.75 GeV) has designed and built eight conventional in-vacuum hybrid undulators operating at high radiation harmonics and also one small gap multipole wiggler to produce high magnetic field. The construction has been progressively improved by the choice of new magnetic materials of better quality and higher magnetization, additional correction techniques and mechanical changes. A 2-m long full scale cryogenic undulator made of PrFeB and vanadium permendur has been built, measured, corrected and is to be tested on the beam. An additional wiggler dedicated for Slicing experiments has been designed. The required magnetic field is high enough to also consider the ID as a good candidate for the production of hard X-ray photons. This paper presents the ID dedicated for the high energy photons and their spectral performances. | ||
THPC151 | The 65 mm Period Electromagnetic/Permanent Magnets Helical Undulator at SOLEIL | 3239 |
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SOLEIL prepares a new 65 mm period Electromagnetic/Permanent Magnets Helical Undulator (EMPHU), with a rapid switching at 5 Hz of the polarization required for dichroïsm experiments. The vertical field Bz is produced by coils fed by a fast switching power supply (designed and built in house), with a maximum current of 350 A and a polarity switching time shorter than 100 ms. The coils consist of 25 stacked copper layers shaped by water jet cutting. The current flows in 16 layers and 9 of them are cooled with thermal drain to a water piping. 4 additional power supplies feed 2 types of correction coils for the dynamic compensation of the field integrals, besides the ones for the termination. 1.28 T remanence NdFeB permanent magnets generate the horizontal field Bx. Peak Bz and Bx in the helical configuration reach 0.24 T at 14.7 mm minimum gap. Thermal modelling and measurements aim at keeping the magnet temperature constant. The static magnetic configuration was optimised using the IDBuilder software and the trajectory were checked for insuring a good reproducibility of the photon beam pointing when sweeping from one helicity to the other. | ||
THPC152 | Measurements of SOLEIL Insertion Devices using Pulsed Wire Method | 3242 |
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SOLEIL permanent magnets insertion devices are usually measured with a Hall probe in order to evaluate the electron angular deflexion, their deviation and the optical phase error, a figure of merit related to the quality of the insertion device radiation. A pulsed wire bench is developed at SOLEIL for reducing the measurement time of an undulator and for providing a measurement method without lateral access. A current pulse injected in a stretched wire inside the magnetic field area generates acoustic wave. The wire motion is detected by optical sensors whose signals are proportional to the local integral value. The signal-to-noise ratio of this method is often reduced due to several effects such as electronic noise, external and wire vibrations. However, following some hardware optimization it was possible to increase it up to almost 26 dB, making the method accurate and reproducible in order to realize efficient corrections. Measurements of first and second integral performed with Pulse wire, with Hall probe and with the electron beam are compared on three different types of insertions: an U18 in-vacuum cryogenic undulator, a HU60 APPLE-II undulator and a WSV50 in-vacuum wiggler. | ||
THPC153 | Recent Progress in Insertion Devices at the ESRF | 3245 |
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Insertion Device activities at the ESRF are presently driven by the upgrade of more than ten beamlines. The concept of canted undulators is part of the requirements in a number of cases. Permanent Magnet Steerers (PMS) will be used to create canting angles of up to 5.4 mrad. The magnetic structure of PMS has been fully optimized to minimise space occupancy and magnetic perturbations induced on neighbouring undulators. The measured field quality of PMS recently constructed will be presented. The development of undulators dedicated to high photon energy is still being pursued. Following on from the successful operation since 2008 of a first Cryogenic Permanent Magnet Undulator (CPMU) installed in the ID6 beamline, a second device has been constructed. This 2 m long device has a period of 18 mm and will be operated at 145 K. The field measurements at cryogenic temperature are discussed hereafter. | ||
THPC154 | Shimming of the Dynamic Field Integrals of the BESSY II U125 Hybrid Undulator | 3248 |
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Within a continuous program the BESSY II undulators are prepared for Topping-Up operation. The BESSY II U125 planar hybrid undulator has a period length of 125 mm and a pole width of only 60 mm. The horizontal defocusing of the 1.7 GeV e-beam may result in a significant reduction of the horizontal dynamic aperture, reducing the injection efficiency when injecting into the closed gap. The dynamic field integrals are derived from a 2D-Fourier decomposition of the 3D-field. An analytic description of the dynamic multipoles based on the Fourier coefficients is presented. Magic fingers have been installed in order to minimize the dynamic field integrals and to enlarge the good field region of the device. | ||
THPC155 | Modification of the BESSY II Optic for the Implementation of a Small Gap Undulator | 3251 |
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At BESSY there is an increasing demand for photons in the range from 60 eV to 8 keV available at the same experimental station. The photons will be produced by a combination of two adjacent undulators, one of them will be a small period cryogenic undulator. Several optics schemes for the 1.7 GeV BESSY II storage ring are discussed to install the undulators. Two types of straight sections exist. A high beta straight with betaxmin=15 m and betaymin=4.5 m and a low beta straight with betaxmin=betaymin=1 m. We discuss the present plan, which clearly favours a small detuning of an existing low beta straight to shift the low beta waist to the centre of the low gap undulator, with only minor impact to the machine. | ||
THPC156 | Performance of the PETRA III APPLE II Undulator | 3254 |
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A 5m-long APPLE II undulator has been built in collaboration between Helmholtz-Zentrum Berlin and DESY Hamburg. Magnetic field measurements after the final shimming in the laboratory are presented. The device has been installed in the storage ring and machine studies have been performed. The tune shifts in the elliptical and the inclined mode are in agreement with predictions from theory. The dynamic field integrals have successfully been minimized in the storage ring with so-called L-shims (rectangular iron sheets) which are placed at the undulator center at the magnet edges. | ||
THPC157 | Hot-/Cold-Side Characterization of Asymmetric Undulator Magnets | 3257 |
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The homogeneity of permanent magnets for use in undulators is dominantly described by small variations in remanence (±1%) and magnetic angles (±1°). The definition and measurement of the so-called hot-/cold-side-effect has proven to be useful as characterization of higher order variations of the local field components. It is measured by a Hall probe at a distance of the half gap width from both magnet pole-surfaces. Typical results for a batch of magnets lie in a range of about ±2% or less. For symmetrical permanent magnet geometries, the distribution is symmetric about the value of zero. In a batch of magnets for a new EPU at LBNL, however, we found an asymmetric distribution of the hot-/cold-side-effect. This asymmetry is attributed to the geometrically asymmetric cut-outs inside the magnets used for fixture on the aluminum keepers. We present a theoretical model which can predict this asymmetric influence on the hot-/cold-side-effect resulting from these small geometric asymmetries. The method may also be used to pre-calculate corrected specification values for the near-field results for future undulator magnets. | ||
THPC158 | Field Optimization for Short Period Undulators | 3260 |
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Undulators dedicated to low energy electron beams, like Laser Wakefield Accelerators, require very short period lengths to achieve X-ray emission. However, at these short period lengths (~5 mm) it becomes difficult to reach magnetic field amplitudes that lead to a K parameter of ~1, which is generally desired. Room temperature permanent magnets and even superconductive undulators using Nb-Ti as conductor material have proven insufficient to achieve the desired field amplitudes. The superconductor Nb3Sn has the theoretical potential to achieve the desired fields. However, up to now it is limited by several technological challenges to much lower field values than theoretically predicted. Alternatives for higher fields would be to manufacture the poles of the undulator body from Holmium instead of iron or to use Nb-Ti wires with a higher superconductor/copper ratio. The advantages and challenges of the different options are compared in this contribution. | ||
THPC159 | Factory Acceptance Test of COLDDIAG: A Cold Vacuum Chamber for Diagnostics | 3263 |
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Superconductive insertion devices (IDs) have higher fields for a given gap and period length compared with the state-of-the-art technology of permanent magnet IDs. One of the still open issues for the development of superconductive insertion devices is the understanding of the heat intake from the electron beam. With the aim of measuring the beam heat load to a cold bore and the hope to gain a deeper understanding in the underlying mechanisms, a cold vacuum chamber for diagnostics was built. It is equipped with the following instrumentation: retarding field analyzers to measure the electron flux, temperature sensors to measure the beam heat load, pressure gauges, and mass spectrometers to measure the gas content. The flexibility of the engineering design will allow the installation of the cryostat in different synchrotron light sources. The installation in the storage ring of the Diamond Light Source is foreseen in November 2011. Here we report about the technical design of this device, the factory acceptance test and the planned measurements with electron beam. | ||
THPC160 | A Superconducting Switch for Insertion Devices with Variable Period Length | 3266 |
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Superconducting insertion devices (IDs) are very attractive for synchrotron light sources since they offer the possibility to enhance the tuning range and functionality significantly by period length switching. Period length switching can be realized by employing two or more individually powerable subsets of superconducting coils and by reversing the current in a part of the winding. So far, the first demonstration mock-up coil allowing period length tripling was fabricated and tested successfully. Here, we report on the feasibility of a superconducting switch operating at 4.2 K, immersed in a liquid Helium bath as well as under conduction cooled conditions. | ||
THPC161 | Possible Superconducting Insertion Devices with Period Length Doubling for Beamlines of Third Generation Light Sources | 3269 |
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The tunability of an insertion device can be increased by period length switching, which in superconducting insertion devices (IDs) can be achieved by reversing the current in separately powered subsets of the superconducting windings. The feasibility of this concept has been experimentally proven. We study here different possibilities to tailor the needs of beamlines of third generation light sources: FEM simulations performed to compute the magnetic field on axis of such devices with different period lengths are reported together with the spectral simulations. | ||
THPC162 | Possible Application of NbTi Wire with Artificial Pinning Centres for Insertion Devices | 3272 |
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Superconductive insertion devices (IDs) allow higher fields for a given gap and period length compared to the classical permanent magnet IDs. This technological concept permits to increase the brilliance and/or the photon energy. The working horse for superconducting magnets are multifilament NbTi wires, which are nowadays also used for superconducting insertion devices. Even higher magnetic fields can be reached by using a conductor with enhanced critical current density. Here, we propose a possible application for superconducting undulators, wound with NbTi wire with artificial pinning centres, developed by SupraMagnetics, Inc. We report the critical current characteristic, Jc(B), of short wire measured in a liquid helium bath, and the load-line of a racetrack coil, designed to simulate the field configuration on the conductor as in a superconducting undulator. Based on the measured load-line we report the simulations of the magnetic field on axis and of the spectrum in a third generation light source of a possible undulator wound with a wire having similar properties of the measured one. | ||
THPC163 | Local and Integral Field Measurement Setup for 2m Long Superconducting Undulator Coils | 3275 |
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The performance of superconducting insertion devices depends strongly on their magnetic field quality. It is of fundamental importance to characterize the magnetic properties of insertion devices accurately before installation in synchrotron light sources. Thus a main part of the R&D program for superconducting insertion devices at the Karlsruhe Institute of Technology focuses on quality assessment. This contribution describes the instrumentation to perform magnetic measurements of the local field, of the field integrals and of the multipole components of superconducting undulator coils in a cold in vacuum (cryogen free) environment. It focuses on the outcome of the factory acceptance test together with results of first field measurements performed with mock-up coils. | ||
THPC164 | Phase Shifters for the FERMI@Elettra Undulators | 3278 |
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The variable gap undulator system in operation at the FERMI@Elettra Free Electron Laser facility requires adjustable phase matching devices between consecutive radiator segments in order to maintain optimal lasing conditions while changing the radiation properties. A permanent magnet phase shifter has been designed to achieve the required electron beam delay in a compact structure that could be installed in close proximity to the undulators. In this paper we present the design of the phasing units and the results of the magnetic measurements performed on the five devices installed so far. We also describe the method used to properly set their field strength for any given electron energy, radiation wavelength and polarization. | ||
THPC165 | Estimations for Demagnetization of ID Permanent Magnets due to Installation of OTR | 3281 |
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Demagnetization due to high energy electron irradiation is one of the crucial issues for stable operation of X-ray free electron laser (XFEL) and Synchrotron radiation (SR) facilities. Especially, during the commissioning, electron beam is scattered and then hits permanent magnets of insertion devices due to installation of some instrumentations such as OTR (Optical Transition Radiation) for beam diagnosis so that the estimation of demagnetization is very important to perform the commissioning smoothly. Fortunately, we found the index of demagnetization of Nd2Fe14B permanent magnets due to high energy electron irradiation. Star density produced by high energy photo-neutron reproduces experimental results of demagnetization. At SPring-8, in-vacuum type undulators have been employed for XFEL so that we estimate the demagnetization of the undulators for various cases such as electron energy in ranging from 2 GeV to 8 GeV and the permanent magnet gap from 2 mm to 40 mm. And we also estimate the allowable time to be able to insert the OTR. | ||
THPC166 | Design Consideration of New Insertion Devices of Hefei Light Source | 3284 |
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To meet the requirements of users for higher brilliance and good transverse coherence VUV and soft X-ray synchrotron radiation, Hefei Light Source(HLS) will be upgraded. After upgrade HLS will have smaller beam emittance and install more insertion devices. In this paper the design considerations of new insertion devices are reported, they include one elliptically polarizing undulator, one quasi-periodic undulator, one in-vacuum undulator and one wiggler. | ||
THPC167 | The Design of Dual Canted In-vacuum Undulators at SSRF | 3287 |
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Funding: National foundation for scientific infrastructure, Development and Reform Commission of China. Five new beamlines are under design and construction at SSRF to supply the synchrotron radiation for the structural biology research in the protein project. Two in-vacuum undulators with canted angle of 6mrad are arranged in a 6.5m long straight section in order to keep the potential to accommodate more beamlines for the future. Limited by the length of the straight section and the angle between two beamlines, the layout design in the straight section is rather difficult to satisfy the required photon flux to the beamline and keep the normal design of the undulator. Many main components will be redesigned in this section on the base of existing ones, including in-vacuum undulator, correction magnet, RF bellows, photon absorbers and so on. In this paper the layout design and the modified design for some key components are described. |
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THPC168 | Field Error Correction for a Superconducting Undulator | 3290 |
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To reach higher photon energies in the region of soft or hard x-rays with high photon beam brightness in low energy storage rings, superconducting undulators with very short period length and high magnetic field strength are required. Because undulator radiation comes in a line spectrum, photons up to the 7th harmonic are desired. The photon brightness in such harmonics is strongly dependent on perfect periodicity of the magnetic field. Such imperfections also appear in conventional permanent material undulators, which can be corrected by well developed and efficient shimming. Unfortunately, this method cannot be applied to superconducting undulators. Therefore, we present a new approach to field corrections by modification of the magnetic field saturation in each pole. In this paper it is shown that this approach can reduce not only the magnetic field error but also greatly improves phase errors from period to period. The proposed method works quite local with only small perturbations in neighboring poles. The tenability is preserved for most of the field excitations and is reduced only at extreme parameters. | ||
THPC169 | Short-Period RF Undulator for a Nanometer SASE Source | 3293 |
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Funding: Sponsored in part by US Department of Energy, Office of High Energy Physics. A room-temperature RF undulator to produce ~1 nm wavelength radiation using a relatively low energy electron beam (0.5 GeV) is considered. The design features include an effective undulator period of 0.45 cm, an undulator parameter of K = 0.4, an effective field length of 50 cm. These parameters could be be realized using a multi-MW RF power amplifier to drive the undulator (e.g., the 34 GHz pulsed magnicon at Yale or a 30 GHz gyroklystron at IAP) with microsecond pulse duration. Two undulator designs were considered that avoid problems with a co-propagating wave: a dual-mode cylindrical cavity [TE01 (counter propagating) - TE02 (co-propagating)] with an off-axis electron beam; and a traveling HE11 mode resonant ring with an on-axis beam. |
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THPC170 | Magnetic Characterization of FEL-2 Undulators for the FERMI@Elettra Free-electron Laser | 3296 |
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Kyma Srl is the spin-off company of Sincrotrone Trieste, Elettra laboratory, set up in 2007 together with the two industrial partners Cosylab d.d. and Euromisure SpA, in order to design and manufacture the undulators for the FERMI@Elettra project in Trieste, Italy. The insertion devices, for FEL-2 line, manufactured and characterized so far are the following: Modulator, 3.2 m linearly polarized undulator, three 55.2 mm APPLE-II variable polarization undulators, each 2.4 m long and six 34.8 mm APPLE-II undulators also each 2.4 m long. All the above devices have been characterized, both from the mechanical and the magnetic point of view. The measured parameters are in good agreement with the design values. This paper presents the most relevant changes in design from FEL-1 to FEL-2 line and results of the magnetic measurements carried out on all the above undulators. | ||
THPC171 | Performance of ID at ALBA | 3299 |
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The new synchrotron light source ALBA is currently being commissioned along with the first phase of beamlines. Up to 6 beamlines are using light produced by Insertion Devices. There are up to four types of IDs: 2 Apple-II undulators (EU62 and EU71) operating at low energies, one conventional wiggler (MPW80) operating in the range of 2 – 20 keV, two in-vacuum undulators (IVU21) operating in the range 5 – 30 keV and a superconducting wiggler (SCW30) operating in the range of 40 keV. Installation of the IDs has been done in two steps. First, the out-vacuum devices (EU62, EU71 and MPW80) have been mechanically installed. Initial commissioning of Storage Ring has been done with their gaps opened to maximum value. Then, their gap has been closed to study the effect in the beam dynamics. In the second step, the in-vacuum devices (both IVU21 and the SCW30) have been installed and tested. In this paper we present the first results and performances of the insertion devices obtained both in Site Acceptance Test and during the first months of commissioning with beam. | ||
THPC172 | Superconducting 119-pole Wiggler for ALBA Light Source | 3302 |
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Budker INP of Siberian Branch of the Russian Academy of Science has designed, manufactured and tested 119-pole superconducting wiggler for ALBA CELLS light source. The period length and maximal field of the wiggler are 30 mm 2.2 Ò correspondingly. Pole gap and vertical aperture for electron beam are 12.6 mm and 8.5 mm, accordingly. The wiggler magnetic structure closely comes nearer to undulator structure as K-value is about 6. The wiggler cryostat is bath cryostat type with use of cryocoolers which provide zero liquid helium consumption for long period. In June, 2010 the wiggler has been successfully tested on ALBA site. Test results of the wiggler including magnetic measurement, quench training, cryogenic system behavior for various mode of operation are presented. | ||
THPC173 | Modelization of Inhomogeneities in Permanent Magnet Blocks | 3305 |
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Nowadays one of the main objectives for insertion devices manufacturers is to reduce the gap of undulators as much as possible while keeping the features of the generated magnetic field. Because of that, the effects of magnetic blocks’ inhomogeneities are playing an increasing role in the quality of the whole device. In this paper we present a modelization of the inhomogeneities of permanent magnet blocks used to build wigglers and undulators. The model is based in splitting individual magnet blocks in different parts which are considered magnetically homogeneous. The model takes into account the relative orientation of magnet blocks assembled into their holders as well as local magnetic properties. We have applied the model to fit magnetic field integrals measured with a fixed stretched wire bench and magnetization data obtained from Helmholtz coils measurements for both single blocks and groups of blocks mounted on a common holder. The results of the model fit with experimental data within an rms error of 6•10-4 mT•m for individual blocks and 1.5•10-4 mT•m in the case of magnet groups. | ||
THPC174 | Manufacturing and Testing of the First Phase Shifter Prototypes Built by CIEMAT for the European-XFEL | 3308 |
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Funding: Work partially supported by the Spanish Ministry of Science and Innovation under SEI Resolution on 17-September-2009. The European X-ray Free Electron Laser (EXFEL) will be based on a 10 to 17.5 GeV electron linac. Its beam will be used in three undulator systems to obtain ultra-brilliant X-ray flashes from 0.1 to 6 nanometres for experimentation. The undulator systems are formed by 5m long undulator segments and 1.1m long intersections in between. They accommodate a quadrupole on top of a precision mover, a beam position monitor, two air coil correctors and a phase shifter. The function of the phase shifter is to adjust the phase of the electron beam with respect to that of the radiation field when the wavelength is changed by tuning the gap. In this context, CIEMAT will deliver 92 phase shifters, as part of the Spanish in-kind contribution to the EXFEL project. This paper describes the engineering design, the manufacturing techniques and the mechanical and magnetic tests realized on the first prototypes. |
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THPC175 | Spectral Analysis of Arbitrary Strength Parameter for Various Insertion Devices | 3311 |
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An insertion device (ID) with medium strength parameter was hard to be defined as a wiggler or an undulator. Usually, this kind of ID was classified according to the user’s definition and to select the spectrum calculation formula of wiggler or undulator. The spectrum calculation formula for wiggler or undulator is quite difference and consequently obtain a big different flux density by using the same strength parameter. So, it is no way that the spectrum calculation of them is consistent. Therefore, a universal formula will be developed for the spectrum analysis for the different kinds of insertion devices that is with large different strength parameter (deflection parameter). Consequently, a modified spectrum calculation formula of ID with medium strength parameter was studied by reviewing the difference of existing spectrum formulas. The familiar formula of calculating undulator spectrum was modified and can be used on ID with arbitrary strength parameter. The algorithm of formula modification was described. Some relative issue, like the effect of phase error and energy spread, and taper undulator were also discussed herein. | ||
THPC176 | Progress in Insertion Devices for TPS in Phase I | 3314 |
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Taiwan Photon Source (TPS) with beam energy 3 GeV and beam current 500 mA is a third-generation synchrotron radiation facility of medium energy. In the initial commissioning stage of TPS, the machine will be equipped with ten insertion devices (ID) and serve seven beamlines in phase I. Of these, three long straight sections configured as a double-minimum betay function lattice design with minimized beam influence of emittance are used for the installation of a pair of insertion devices in a straight section, two undulators of APPLE-II type and four in-vacuum undulators (IU), to produce great brilliance and coherent X-rays with great flux. The details of these insertion devices are explained herein. | ||
THPC177 | Field Correction Results from NSRRC Elliptically Polarized Undulator 46 | 3317 |
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Elliptically polarized undulator (EPU) is a common insertion device to use in storage ring in order to provide circular polarization. The field correction is an essential step for EPU construction, and it can prevent the photon flux reduction from idea case and electron beam trajectory and exit angle from EPU. The conventional field correction method is tedious works and strongly based on experiences. An initial state of NSRRC EPU46 has phase error over 40 degrees, and many difficulties on field correction to reduce the phase error under 5 degrees. This paper will describe the detailed magnetic field correction process and practical results from in NSRRC EPU. | ||
THPC178 | Superconducting Planar Undulator Development in the UK | 3320 |
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Superconducting undulators promise higher peak fields on axis than any other technology but they are still not a mainstream solution for 3rd or 4th generation light sources. A team within the UK is developing the design of a short period, narrow aperture, superconducting undulator that is planned to be installed and tested in the Diamond Light Source (DLS) in 2014. This paper will describe the main parameters of the undulator and the key design choices that have been made. Recent progress is then described in the areas of magnet modelling, mechanical design, cryogenic design, and prototyping. Finally, the next steps are described. | ||
THPC179 | Electron Beam Heating and Operation of the Cryogenic Undulator and Superconducting Wigglers at Diamond | 3323 |
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Diamond Light Source has two superconducting wigglers and one cryocooled undulator installed serving three beam lines. The cryocooled undulator (cpmu) has been operating since August 2010 while the superconducting wigglers have been operating for more than 4 years (SCW-1) and 2 years (SCW-2). We will report on the first year of operation of the cpmu including details of its spectral output and cryogenic performance. Our experience of the cooling system and measures taken to ensure reliability and to minimize the risks of a prolonged downtime are also presented. The two superconducting wigglers are exposed to a high heat load due to the beam heating of the inner liner. Until recently this resulted in a much higher helium consumption than specified and so recently a new liner has been fitted to SCW-1 and new re-condensers to SCW-2. In addition a thermal bridge has been made between the RF tapers and the outer heat shield of both SCW-1 and SCW-2. The results of these improvements will be presented. | ||
THPC183 | Application of the Balanced Hybrid Mode in Overmoded Corrugated Waveguides to Short Wavelength Dynamic Undulators | 3326 |
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Funding: Work Supported by the US Department of Energy Inspired by recent developments in low-loss overmoded components and systems for ultra-high power RF systems, we explored several overmoded waveguide systems that could function as RF undulators. One promising structure is a corrugated waveguide system operating at the hybrid HE11 mode. This is a new application for that mode. Initial calculations indicate that such a system can be operated at relatively low power levels while obtaining large values for the undulator parameters. RF surface fields are typically low enough to permit superconducting operation. This technology could realize an undulator with short wavelengths and also dynamic control of the undulator parameters including polarization. We introduce the scaling laws governing such a structures, and then show with exact simulations an undulator design that have a wavelength of about 1.4 cm with an undulator parameter K~1. This undulator is intended to be powered by a 50 MW source at a frequency of 11.4 GHz. We describe the experimental setup for testing such a technology. |
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THPC184 | Progress of the Coherent Soft X Ray Straight Section at NSLS-II | 3329 |
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The National Synchrotron Light Source II (NSLS-II) is the new light source under construction at Brookhaven National Laboratory (BNL). The Coherent Soft X rays beam line (CSX) is one of the six beamlines included in the baseline project. Following the request of CSX scientists for a source providing adjustable polarized radiation from 160 eV to 1.7 keV, two Advanced Planar Polarized Light Emitter II (APPLE-II)-type undulators will be installed in a 6.6 m long straight section. Each device is 2 m long, the period is 49.2 mm and the minimum gap is 11.5 mm. The different operation modes of the beamline and the layout of the straight section are reviewed here. | ||
THPC186 | Heat Load for the APS Superconducting Undulator | 3332 |
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Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The APS Upgrade calls for the development and commissioning of a superconducting undulator (SCU) at the Advanced Photon Source (APS), a 7-GeV electron synchrotron. The first SCU will be installed in June 2012. Until then, simulations such as SYNRAD3D will be used to understand and reduce the heat load on the cryo-system from primary and secondary photons. Current calculations predict that primary photons will distribute 0.5W/m on the chamber walls of the cryostat. SYNRAD3D will be used to calculate the ratio of primary and secondary photons to calculate the heat load due to secondary photons. Previous simulations were of only one sector of the APS accelerator. Simulated here are multiple sectors, to include photons back scattered from downstream photon absorbers. |
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