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As part of the R\&D for the 50 MeV ThomX Compton source project, we have studied the effect of several beam dynamics processes on the evolution of the beam in the ring. The processes studied include among others Compton scattering, intrabeam scattering, coherent synchrotron radiation. We have performed extensive simulations of a full injection/extraction cycle (400000 turns). We show how each of these processes degrades the flux of photons produced and how a feedback system contributes to recovering most of the flux., Submitted to IPAC'14, WEPRO001

The Colorado State University (CSU) Accelerator Facility will include a 6-MeV L-Band electron linear accelerator (linac) with a free-electron laser (FEL) system capable of producing Terahertz (THz) radiation, a laser laboratory, a microwave test stand, and a magnetic test stand. The photocathode drive linac will be used in conjunction with a hybrid undulator capable of producing THz radiation. Details of the systems used in CSU Accelerator Facility are discussed., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

FLUTE, a new linac-based test facility and THz source is currently being built at the Karlsruhe Institute of Technology (KIT) in collaboration with DESY and PSI. It consists of an RF photo gun and a traveling wave linac accelerating electrons to beam energies of ~41 MeV in the charge range from a few pC up to 3 nC. The electron bunch will then be compressed in a magnetic chicane in the range of 1 - 300 fs, depending on the charge, in order to generate coherent THz radiation with high peak power. An overview of the simulation and hardware status is given in this contribution., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Under normal operational conditions in NSLS-II the energy of the beam extracted from the Booster and transferred to and injected into the Storage Ring (SR) is 3 GeV. It was determined that for the commissioning purposes energy range of the beam reaching the SR is allowed to be 2 GeV - 3.15 GeV. While the upper limit of the beam energy is defined by the maximum possible settings of Booster dipoles at the top of the ramp, the lower energy limit has to be provided by magnet interlocks. The constraints of time and resources do not allow providing dynamic interlocks of the Booster dipoles for commissioning stage of NSLS-II. In this paper we find a feasible solution for the static interlock of magnets in the Booster to SR transfer line (BSR) which creates a required “energy filter”., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Future light sources aim at achieving a diffraction limited photon beam both in the horizontal and vertical planes. Small magnet apertures and high magnet gradients of a corresponding ultra-low emittance lattice may restrict physical and dynamic acceptance of the storage ring such that off-axis injection and accumulation may become impossible. We investigate a longitudinal injection, i.e. injecting an electron bunch onto the closed orbit with a time-offset with respect to the circulating bunches. The injected bunch will be merged to a circulating bunch thanks to longitudinal damping., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Ongoing developments in Compton radiation sources are aimed toward a diversity of potential applications, ranging from university-scale compact x-ray light sources and metrology tools for EUV lithography, to positron sources for e⁻e⁺ colliders. Novel conceptual approaches are pursued on different routes: One research direction lies in multiplying the source’s repetition rate and increasing its average brightness by placing the point of Compton interaction inside an optical cavity. High-gradient plasma-wakefield accelerators are fast becoming a practical reality, offering a new paradigm to compact all-optical Compton sources operating in x-ray- and gamma-regions. Continuing improvement in the quality of the beam of plasma accelerators promises the achievement of fully coherent Compton x-rays, thereby prompting the evolution of the Compton source to an all-optical free-electron laser., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Within the scope of a future major upgrade of the SOLEIL storage ring, presently having the energy of 2.75 GeV, the circumference of 354 m and the horizontal emittance of 3.7 nm.rad, towards a Diffraction Limited Storage Ring (DLSR), the present paper presents and discusses the outcomes of a series of studies launched to explore different possible scenarios for the magnet lattice arrangement, under the constraint of making the upgrade in the same existing machine tunnel. Two scenarios were presented earlier in this context, which both preserved all the existing free straight sections for insertions, though the bending magnet positions were not strictly conserved. The purpose of the extended studies is to explore, in particular, the range of horizontal emittance that can be reached by hypothetically removing some of the existing geometric constraints, such as suppressing or shortening partially the straight sections. The emittance range is equally studied by fulfilling rigorously all constraints. The dependence of the nonlinear properties of the magnet lattice on the linear optics is simultaneously investigated., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

This paper reports about aspects of design, manufacturing, and commissioning of the 12 FLASH2 variable gap undulator segments. The accuracy of gap drive and encoder systems was tested by magnetic measurements; changes in the phase error proved to be a highly sensitive probe to verify a reproducibility of 1 μm. After magnetic tuning of the IDs, the remaining gap dependence in the field integrals could be successfully compensated by corrector coils. Inconsiderate handling of components during assembling necessitated an elaborate demagnetisation process before the tuning could start., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The detector of a FEL-THz source at HUST is now in the physical design stage. The electro-optic (EO) sampling method will be employed for the coherent detection. The performances of three widely used EO crystals will be evaluated and compared numerically in the time domain detection: zinc telluride (ZnTe), gallium arsenide (GaAs) and gallium phosphide (GaP). The phase matching properties are analyzed to find the appropriate probe wavelength. The EO detection response is calculated to select the suitable crystal thickness and to discuss the detection ability of each crystal., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

An intense on-axis radiation power from an undulator is a serious problem especially for a low-photon-energy beamline in a facility with high or medium energy storage ring. This problem may be solved by using a Figure-8, a Pera, or a Knot undulator configuration*,**. However, these schemes are useless for variably polarizing undulators such as an APPLE undulator and other similar variations since such devices are not capable for reducing on-axis power density in the linear mode. In these circumstances, we have completed a conceptual magnet design of Knot-APPLE udulator which is capable to generate elliptically polarized radiation as well as linearly polarized radiation. This pure permanent magnet device is equipped with a motion mechanism of APPLE undulator. In this paper, we present detailed magnet design feature, magnetic field distributions, and radiation properties including variations of polarization in comparisons with other exotic devices. In addition, a possibility to introduce a quasi-periodicity in this type of undulator is considered in order to achieve further reduction of second and third harmonic radiation intensities., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

A proposal of a low alpha lattice for the ALBA third generation light source is presented. Opposed to most of other machines, belonging to the same category, ALBA employs an optimized lattice making use of combined function dipoles. This has permitted a very compact design stripped out of all not strictly necessary quadrupoles resulting in a lack of flexibility. For such a reason the common approaches used in many other synchrotrons can not be directly applied to ALBA and a different strategy has to worked out., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The femtoslicing project at SOLEIL is currently under commissioning. It will enable to serve several beamlines with 100 fs FWHM long pulses of soft and hard X-rays with reasonable flux and with a 1 kHz repetition rate. It is based on the interaction of a femtosecond Ti:Sa laser with electrons circulating in the magnetic field of a modulator wiggler, that provides the electron beam energy modulation on the length scale of the laser pulse. The optimization of the interaction is performed using two dedicated diagnostics stations. The first one, operating in the Infra-Red (IR) is installed in the tunnel and allows the adjustment of the temporal, spectral and spatial overlap between the laser and the electron beam. The second one, located in the IR-THz AILES beamline, measures the intensity of the terahertz (THz) radiation emitted by the local dip structure produced in the core electron beam after interaction. This second setup provides refined optimization of the interaction. This paper describes the layout of these diagnostics and gives first results and characterization of the slicing experiment at SOLEIL., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The Photo Injector Test facility at DESY, Zeuthen Site (PITZ) characterizes and optimizes high brightness electron sources for FLASH and the European XFEL. At nominal conditions the electron bunches are created from a photocathode laser with flat-top temporal distribution and sharp rise and fall times. Beam dynamics simulations using a 3D ellipsoidal cathode laser shape yielded to a significant improvement of the electron beam quality compared to the traditionally used cylindrically shaped beams. The 3D ellipsoidal laser system is under development at the Institute of Applied Physics (IAP) and will be used at PITZ soon, to create high quality electron beams. The recent studies of electron beam simulations at PITZ have been devoted to the position optimization of the second accelerating cavity for the 3D ellipsoidal laser profile. Electron beam properties were compared for cylindrical and 3D ellipsoidal beams applying default and optimized booster positions. Beam tolerance studies revealed much better injector performance for the 3D ellipsoidal laser profile case with the optimized booster position. The outcome of such investigations is presented and discussed in this contribution., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

3-D ellipsoidal photo cathode laser pulses are considered as the next step in optimization of photo injectors required for a successful operation of linac based free electron lasers. Significant improvements in electron beam emittance obtained from the beam dynamics simulations using such laser pulses compared to the conventional cylindrical pulses motivated the experimental studies in order to develop a laser system for quasi 3-D ellipsoidal pulses. The Institute of Applied Physics (Nizhny Novgorod, Russia) in collaboration with the Joint Institute of Nuclear Research (Dubna, Russia) and the Photo Injector Test facility at DESY, Zeuthen site (PITZ) is developing such a photo cathode laser system. Experimental tests of the laser system with photoelectron beam production are planned at PITZ. The laser pulse shaping is realized using the spatial light modulator technique. The laser system is capable of pulse train generation. First cross-correlation measurements were done demonstrating in principle the ability to generate and measure quasi ellipsoidal laser pulses. In this contribution the overall set-up, working principle and the actual progress of the development will be reported., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

At the ANKA synchrotron radiation facility measurements in the microwave range (~10 to 12 GHz) employing a LNB (Low Noise Block), which is the receiving part of a Satellite-TV system, have been carried out. Experiments showed that the observed signal depends on the length of the electron bunches. Furthermore the temporal shape of the microwave signal depends on the detector's position along the accelerator. Due the LNB antenna's sensitivity to polarisation it was also possible to measure the polarisation along the several ns long signal, revealing polarised and non-polarised regions. This paper describes the experimental setup and summarises the observations of the systematic studies performed with the LNB system., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

As part of the design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory, a high repetition rate S-band photoinjector RF gun is being developed. This gun will be able to operate at up to 400 Hz repetition rate in single bunch mode. We present the initial cavity design including its optimisation for the beam dynamics of CLARA. We also present the initial cooling design for the cavity which will enable the high repetition rates to be achieved., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The infrared undulator constructed at JINR and installed at FLASH in 2007 is used for longitudinal bunch shape measurements in the range of several tenths of μm. The presented below electromagnetic wiggler is applied for a narrow-band THz radiation for measurements of electron bunch longitudinal structure in FEL with electron energy of several tenths of MeV. This is a planar electromagnetic device with 6 regular periods, each of 30 cm long. The K parameter is varied in the range 0.5- 7.12 corresponding to a range B=0.025- 0.356 T of the peak field on axis. The wiggler is simulated for 19.8 MeV/c FEL. The bunch compression scheme allows the whole wavelength range to be covered by super-radiant emission with a sufficient form factor. The wavelength range corresponds to 126 μm - 5.3 mm for the electron beam momentum of 19.8 MeV/c. The 3D Opera simulations of THz wiggler will be discussed., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Sirius is a 3 GeV synchrotron light source that is being built by the Brazilian Synchrotron Light Laboratory (LNLS). The electron storage ring uses the multi-bend-achromat approach (5BA in this case) to achieve a very low beam emittance of 0.28 nm.rad. The 518 m circumference contains 20 straight sections of alternating 6 and 7 meters in length, to be used for insertion devices as well as injection and RF systems. The 5BA cell is modified to accommodate a thin high field dipole (for 1.4˚ deflection) in the center of the middle bend producing hard X-ray radiation (12 keV critical energy) with a modest contribution to the total energy loss. This high field dipole (2.0 T) will be made of permanent magnet material, whereas the low field (0.58 T) ones, responsible for the main beam deflection, will be electromagnetic. Many challenges are associated with this kind of lattice, including both in beam dynamics and in accelerator engineering, that require R&D on new techniques. In this paper we discuss the main issues and achievements for Sirius during the last year., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The “Linac Coherent Light Source–II” Project, initiated in September 2010, has gone through a radical transformation beginning in August 2013. In its new form, LCLS-II will construct a 4 GeV CW superconducting linac in the first kilometre of the existing linac tunnel. A new undulator, optimized as a soft x-ray (200-1,300 eV) source, will receive electrons from the new SC linac. The existing undulator system will be replaced with a new variable gap device, which will receive electrons from either the new SC linac (providing 1-5 keV photons) or the copper linac presently used by LCLS (providing 1-25 keV x-rays). First light from the new facility is expected in September 2019., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The installations of the In-Vacuum kicker system of the booster injection in TPS are presented in this article. Due to the more than 20 kV operation voltages and precise positioning requirements, the insulations and positioning systems are designed with more attentions. Although increasing the gap between high potential parts and ground could provide enough withstanding voltage, on the other hand, the insufficient space and vacuum requirements limit the sizes of insulators. Therefore, lots of effort have been done to deal with these conflicts. All assembling processes will be described in this paper as well., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The LCLS-II project is a high repetition rate, high average brightness free-electron laser based on the existing facilities at the SLAC National Accelerator Laboratory. The LCLS-II will be driven by a new CW superconducting RF (SCRF) 4-GeV linac replacing the existing Cu-linac in the 1st km of the linac tunnel. The SCRF linac will include chicanes for providing full compression of the electron bunch length. After the linac, the electron beam will be directed into the existing 2-km bypass line connecting to the Beam Switch Yard (BSY), where a new spreader system will allow a high rate bunch-by-bunch deflection into the hard X-ray (HXR) or soft X-ray (SXR) transport lines, or towards the BSY high power dump. The HXR line will include a new variable gap undulator replacing the existing LCLS-I undulator and will reuse the existing LCLS-I linac-to-undulator and dump transport lines. The SXR will require a new transport line sharing the same tunnel with the HXR and will include a new variable gap undulator. Overview of the electron beam transport and the optics design are presented., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

72 out of the 74 girders on which the Diamond Storage Ring magnets are mounted, can in principle be moved along 5 degrees of freedom (sway, heave, yaw,pitch, roll) potentially allowing a thorough re-alignment of the machine. Previously conducted tests improved our knowledge of the system both in terms of simulations and comprehension of the control system we rely upon. In this report we present the results of more detailed tests which now give us full confidence in our ability to predict the results of any given set of girder moves. We also discuss possible ways of increasing the speed of the procedure, and a strategy to mitigate the impact of girder moves involving nearby beam lines., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

A free electron laser (FEL) facility aimed for VUV and THz radiation is being studied at National Synchrotron Radiation Research Center (NSRRC) in Taiwan. Strong consideration has been given to minimize the cost by making maximum use of existing hardware at NSRRC. One unique consideration is to use an existing undulator for the dual functions of the THz radiator and the modulator of a HGHG section. Design emphasizes versatility of operation and beam quality control and compensation of nonlinearities, with a vision that it will allow as much as possible future upgrades as well as later R&D of FEL physics. The polarization control of the THz radiation provides novel application for the users. The facility is to be housed in the existing 38-m by 5-m tunnel of the TPS Linac Test Laboratory., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

In this research, a new K-B mirror system was developed for focusing a microbeam to 1 μm x 1 μm at the 4B beamline of the Pohang Light Source-II. The new K-B mirror system consists of a pair of assemblage having three mechanisms that adjust the position, pitch, and curvature of each vertically and horizontally focusing mirrors and stages that support both the assemblages to enable translations along two orthogonal axes and rotation on the horizontal plane. Both the pitch- and curvature-adjusting mechanisms were designed as flexural mechanisms driven by their respective single actuators to minimize the movement of the mirror center even when the pitch or the curvature of each mirror was adjusted. The K-B mirror system with these features will be robust against possible disturbances and will help promote easy and simple mirror adjustment. This paper describes the whole design of the new K-B mirror system in detail and the structural analysis results of the pitch- and the curvature-adjusting mechanisms, and reports the operation principle of the curvature-adjusting mechanism., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The Canadian Light Source is implementing an elliptically polarizing undulator (EPU) with period 180 mm for the production of soft x-rays with variable polarization. Two issues arise from implementing such a device. First, a long-period EPU can cause significant loss of dynamic aperture due to strong dynamic focusing. Second, to compensate for polarization effects due to beamline optics, the EPU must be able to produce light with an arbitrary polarization at the source point, which is referred to as universal mode. We present a scheme for operating the EPU in universal mode and discuss the use of BESSY-style current strips in order to compensate for dynamic effects. Tracking simulations suggest that dynamic aperture can be sufficiently recovered for all required operating points in universal mode., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

DELTA is a 1.5-GeV synchrotron light source operated by the TU Dortmund University. The beam lifetime, which is a critical issue for user operation of a light source, was studied experimentally and by simulation for different operation modes, i.e. single-bunch and multibunch fill patterns and for different beam currents. The electron loss rate is dominated by residual-gas scattering (Coulomb scattering and Bremsstrahlung) and by electron-electron scattering (Touschek effect). Since these processes depend in different ways on the momentum acceptance of the storage ring, a variation of the RF cavity voltage allows to disentangle their respective contributions to the total loss rate. The experimental results lead to a consistent picture for different operation modes with a characteristic dependence of the residual-gas pressure on the beam current., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

In this study the results of ground vibration measurement for the site of Iranian Light Source Facility (ILSF) has been investigated. Light source buildings are very sensitive to the ground weak motions. Sources for the ground vibrations could be Cultural noise from human activities like traffic and industrial works. In order to satisfy requirements for level of the ground vibrations, a perfect ground vibration survey has been conducted and compared with other same projects. Two broad-band seismometers were utilized for surveying the ground vibration at ILSF site. The raw data were pre-processed as well as analyzed in term of seismology and engineering aspects. Spectrum amplitudes along with powers of the vibration amplitudes were calculated at the time domain. The power spectral density of vibration displacements were extracted from the measurements and were compared with results of other synchrotron projects. The results show that the dedicated site for ILSF is in the appropriate condition in the point view of ground vibration issues., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The Canadian Light Source utilizes two superconducting wigglers for the production of hard x-rays. These superconducting wigglers often quench during beam loss, even though tracking calculations predict that the beam is lost on an aperture far from the wigglers. We present measurements that suggest the tracking simulations are correct and the electron beam indeed strikes the predicted limiting inboard aperture. By simulating the interaction of the beam with the aperture, we find that some scattered electrons can retain sufficient energy to remain inside the storage ring. The simulations show that some of these scattered electrons strike the wiggler vacuum chamber and deposit energy in the superconducting coils, causing the quench., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The Iranian Light Source Facility Project (ILSF) is a 3 GeV third generation light source with a current of 400 mA which will be built on a land of 50 hectares area in the city of Qazvin, located 150 km West of Tehran. ILSF conceptual design report, CDR, was published in October 2012. To have a competitive leading position in the future, 489.6 m storage ring of ILSF is designed to emphasize on small emittance electron beam( 0.93 nm-rad), high photon flux density, brightness, stability and reliability. Moreover, 40% of 489.6 m ring circumference is straight sections (14×8 m+ 14×6 m) which are long enough for the commonly used insertion devices. Some prototype accelerator components such as high power solid state radio frequency amplifiers, LLRF system, thermionic RF gun, Storage ring H-type dipole and quadruple magnets, Hall probe system for magnetic measurement and highly stable magnet power supplies have been constructed in ILSF R&D laboratory., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a LPWA based light source driven by a transverse gradient undulator is being investigated. This report presents the accelerator physics, FEL studies and the performance expected from such a facility., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The 2.75 GeV synchrotron light source SOLEIL delivers photons to 27 beamlines; 2 new ones are under construction together with the FEMTOSLICING project of which commissioning started in January 2014. Five filling patterns are available for the users in Top-up injection mode. The storage ring is running with an upgraded optics less sensitive to insertion device (ID) configurations and giving both better beam lifetime and injection efficiency. The beam position stability remains excellent with a focus on electron vertical beam-size stability for the new very long beamlines. A gating system during Top-up injection improves significantly the quality of the spectrum on an infrared beamline. Several heavy actions of maintenance and upgrades on crucial subsystem equipment are underway. Others accelerator projects are going on such as the design and construction of new IDs, new Multipole Injection Kicker, radiation damage studies as well as R&D on solid-state amplifiers., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Several lattice alternatives have been designed for the 3 GeV storage ring of Iranian Light Source Facility (ILSF). Design of the ILSF storage ring emphasizes an ultra low electron beam emittance, great brightness, stability and reliability which make it competitive in the operation years. In this paper, we give a brief review of the main designed lattice candidates for the ILSF storage ring., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

At the Iranian Light Source Facility (ILSF), two different storage ring options are being studied. The designs differ in emittance. In the first option the calculated emittance is 3.278 nm-rad whereas for the second option emittance is 0.937 nm-rad. In this paper the electron beam emittance effects on the source radiation properties from bending magnet, wiggler and undulator, X-ray optics and the beamline design are carefully studied. The present calculations demonstrate that in the case of 0.937 nm-rad brilliance of undulator is increased by a factor of about 5. For bending magnet, flux is reduced almost 1 order of magnitude for hard x-ray regime. Because of smaller size of the source for undulator at the case of 0.937 nm-rad, we can achieve to a smaller spot size and higher resolution with easier focusing systems and usual kind of monochromator than the emittance of 3.278 nm-rad and for the bending magnet hard x-ray beamline, size of the mirrors reduced 30% in the 0.937 nm-rad emittance case, so its result is shorter mirror, low cost and perhaps more challengeable heat load., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Control of microbunching instability is a fundamental requirement in modern high brightness electron linacs, in order to prevent malfunction of beam optical diagnostics and contamination in the generation of coherent radiation, such as free electron lasers. We present experimental control and suppression of microbunching instability-induced optical transition radiation by means of particles’ longitudinal phase mixing in a magnetic chicane*. In presence of phase mixing, the intensity of the beam-emitted coherent optical transition radiation is reduced by one order of magnitude and brought to the same level provided, alternatively, by beam heating. The experimental results are in agreement with particle tracking and analytical evaluations of the instability gain. A discussion of applications of magnetic phase mixing to the generation of quasi-cold high-brightness ultra-relativistic electron beams is finally given., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Multi-turn energy recovery linac based light sources are candidates for the future 4th generation synchrotron light sources. Using the superconducting linac technology, the Femto-Science-Factory (FSF) will provide its users with ultra-bright photon beams of angstrom wavelength at 6 GeV final beam energy. The FSF is intended to be a multi-user facility and offers a variety of operation modes. An overview of the machine layout and magnetic optics design of the installation will be given in this paper with the focus on high brightness injector design., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The prototype of TPS injection girder system was designed and installed in a temporary factory. As the leakage field of the kicker magnet in the prototype was found to be too large according to both simulation and measurement to be acceptable, the lattice was altered to fit the requirements. In this paper, we present the design modifications of the injection girder system due to the new lattice. The DC septum magnet is replaced by a pre-AC septum magnet, of which its adjustable stage must be redesigned. The positions of vacuum components in the injection girder are also altered; we add some new holes in the prototype girder. The prototype of an injection girder system after modification has been installed in the tunnel of Taiwan Photon Source. The accuracy of position of three girders installed, and the stages for the septum or kicker magnet are within 0.25 and 0.08 mm, respectively., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Total impedance is one of the most effective parameters for proper operation of an accelerator system. This quantity is evaluated with the summation of individual component impedance of the vacuum pipe and is desired to be as low as possible. The bellows have very significant effects on total impedance of the accelerator systems particularly synchrotron light source storage rings. Design of the bellow for Iranian Light Source Facility (ILSF) with a practical approach for fabrication has been down. Minimization of the total impedance budget, loss factor and the resulting wake field due to the passage of 400 mA electron beam is the main goal of our design., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Within last decade a linear accelerating structure with an average loaded gradient of 100 MV/m at 12 GHz has been demonstrated in the CLIC study. Recently, it has been proposed to use the CLIC structure to drive an FEL linac. In contrast to CLIC the linac would be powered by klystrons not by a drive beam. The main advantage of this proposal is achieving the required energies in a very short distance, thus the facility would be rather compact. In this study, we present the conceptual design parameters of a facility which could generate laser photon pulses covering the range of 1-75 Angstrom. Shorter wavelengths could also be reached with slightly increasing the energy., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

An upgrade of the BESSY II ring to a Variable bunch length Storage Ring BESSY^{V}SR has been recently proposed *, by introducing strongly focusing superconducting cavities. This will allow to store simultaneously long and short bunches. In the regular user optics, bunch lengths of 15 ps (rms) and down to 1.5 ps (rms) are expected. Bunches as short as 300 fs (rms), close to the bunch length limit, and a ring current of 3.5 mA at the bunch bursting threshold can be provided by using a modified low-alpha optics. This presentation will discuss the properties of the low-alpha optics and intrinsic bunch length limits, given by coupling effects of the longitudinal and horizontal plane., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

A search for HOMs in Cornell’s ERL main linac cavity installed in a Horizontal Test Cryomodule (HTC) has been carried out using a bunch charge modulation method, as part of the effort towards building an Energy Recovery Linac (ERL). The beam-based HOM measurements offer the significant advantage of being able to detect trapped modes invisible to both the RF pickup probes and HOM damping loads, and allow for measuring the R/Q of the modes. For each HOM detected during the search, measurements were taken to determine its nature (monopole, dipole, etc.), frequency, loaded quality factor and shunt impedance. A selection of the most notable modes found is presented, compared to 3D HOM simulations, and their potential impact on the BBU current of the future Cornell ERL is discussed., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

In the new octant of PETRA~III, there are 14 undulator beamlines covering photon energy range from 0.3keV to 150keV. There are also 80m of damping wigglers in order to achieve a low emittance of 1nmrad. Some of these devices, operating at PETRAIII since 2008, accumulated total radiation doses of about 100kGy. Visible corrosion at the magnet structures of some permanent magnet undulators setting in after a few years and a high dose rate measured regularly by thermoluminescent dosimeters (TLDs) gave reason to inspect the magnetic field of all insertion devices in the PETRA tunnel. This paper presents details of the magnetic field degradation caused by radiation damage to the undulator magnets. For some undulators changes in the spectral properties of the generated light were observed. It was measured with different taper settings in order to partly compensate the nonuniform demagnetization along the structure. The results are compared with the data from the sFLASH undulators and measurements of special 3 pole "sacrificial" undulator, installed in FLASH. Its magnetic field is periodically remeasured and shows field amplitude decrease of 1% per 16kGy accumulated dose., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

An ultimate storage ring (USR) is being designed at synchrotron radiation facilities in the world. USR can generate theoretically minimum synchrotron radiation because emittance of the USR is less than diffraction limit of the radiation. The USR requires high alignment precision of micro-meter order. A vibrating wire method (VWM) has widely been used for such a high precision alignment. An error field of multi-pole magnet is estimated by detecting a vibration of a single wire excited with AC current. The wire position, where no vibration is excited, is defined as the magnetic center. The applied frequency is kept on a resonant frequency, which may drift due to temperature change etc. during the measurement. To trace the resonant frequency at all times, we developed a frequency feedback system. It is necessary to trace the resonance, even when the wire is set in the vicinity of the magnetic center where the magnetic field is nearly zero. Here we propose to install one or two additional wires parallel to the original wire. The additional wires off the center can detect the vibration frequency with enough S/N ratio. We discuss the effectiveness of it for quick and reliable alignment., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

We proposed a torus knot type synchrotron radiation ring in that the beam orbit does not close in one turn but closes after multiple turns around the ring. Currently, we are designing a new ring based on the shape of a (11, 3) torus knot for our future plan ‘HiSOR-II.’ This ring is mid-low energy light source ring with a beam energy of 700 MeV. Recently some light source rings are achieving very low emittance that reaches a diffraction limited light by adopting a multi-bend scheme to the arc section of the ring. It is not difficult for low-mid energy VUV-SX light source ring because the electron beam less than 10 nmrad can provide the diffraction limited light in the energy less than 10eV. However the multi-bend lattice has many families of the magnets, therefore it is not easy to decide the parameters of the lattice. Especially, it is difficult for the torus knot type SR ring because there is a lot of geometric limitation around the cross points of orbits. We present the details of the designing procedure and the specifications of the ultra-low emittance light source ring having innovatively odd shape., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Taiwan Photon Source (TPS) commissioning exercise by using the high-level accelerator physics application programs (HL-APAP) has been performed on the operational 1.5 GeV Taiwan Light Source (TLS) storage ring. It includes steering the injection beam in the first turn to achieve multi-turns and stored beam with the help of the RESOLVE analysis. The orbit correction programs using different algorithms such as SVD, Householder transformation, and local bumps were applied to reduce the closed orbit distortion of the stored beam and to adjust the beam orbit to pass through those field centers of quadrupoles indicated by the corresponding BPMs. The golden orbit defined by the measured data of BPMs corresponding to each quadrupole field center was based on the Beam Based Alignment (BBA). After approach the stored beam orbit to the golden orbit, we save all the BPMs data as the target orbit for machine operation. The lattice calibration is then performed by the LOCO. The detail of the commissioning exercise is described in this report., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a short pulse THz FEL based on a conventional RF accelerator driven by a RF photocathode gun is being investigated. This report presents the concept of the facility, the accelerator physics and FEL studies and engineering integration in the University physics department., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The European X-ray Free Electron Laser (E-XFEL) provides an ultra-short and high-brilliant photon pulses of spatially coherent X-rays with wavelengths down to 0.05 nm by using three undulator systems. Within these undulator systems, the orbit trajectory is required to be straight to a few micron over each gain length, so that the photon beam is capable of overlapping efficiently with the electron beam. However, this requirement is not obtainable with ordinary mechanical alignment methods. For this reason, a beam-based alignment (BBA) method using BPM readings of different beam energies is applied to the E-XFEL SASE1 undulators. In this report, we describe the BBA simulation for SASE1 including alignment errors of quadrupoles and BPMs. After correction, the desired range of the orbit trajectory is attained with high confidence. In addition, to identify the reliability of an aligned orbit trajectory acquired from the BBA simulation, we present here the SASE FEL radiation simulation, in which we observe a slight decrease of radiation energy and power., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Since its 2003 construction, the SPEAR3 synchrotron light source at SLAC has continuously improved its performance by raising beam current, top-off injection, small alpha and smaller emittance. This makes SPEAR3 one of the most productive light sources in the world. Now to further enhance the operation of SPEAR3, we are looking into the possibility of converting SPEAR3 to a multi-bend achromat storage ring within its site constraint., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Turkish synchrotron radiation source named TURKAY, is a part of the TAC (Turkish Accelerator Center) Project , is at conceptual design process. The radiation properties of a SR sources are strongly depends on the magnetic lattice of the storage ring. The storage ring is designed to obtain low emittance electron beam at 3 GeV energy. Optimization of the lattice properties, including the non-linear dynamics, is described in detail. Radiation properties are calculated by the example of some existing undulators from the other SR facilities., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The interest in superradiant THz sources based on the coherent transition, synchrotron or undulator radiation grows continuously and such sources require high-quality electron bunches with low emittance, high charge and sub-picosecond (sub-ps) duration. Since accelerator-based THz sources are usually driven by relatively low energy electron bunches of a few tens of MeV, space-charge makes bunch compression to sub-ps level very challenging. In the present work we investigate the feasibility of ballistic bunching down to sub-ps duration while preserving the transverse phase-space quality. We found that in order to compensate for the nonlinear dependency of the arrival time on the energy as well as bunch deformations induced by space-charge effects, one needs to apply a nonlinear energy chirp. This chirp permits to maximize the bunch compression and can be realized by exciting a cavity with higher harmonics of the fundamental frequency. Issues related to synchronizing the harmonics are discussed and the analytical analysis is complemented by simulations with PARMELA., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Tiny round electron beams of free-electron lasers and relatively new diffraction-limited storage rings make possible utilization of electromagnetic helical undulators based on double-helical windings. It has been understood for a while that a coaxial pair of double-helical windings can generate helical as well as planar magnetic fields*. Such a coil structure can potentially be realized with superconducting windings thus forming the concept of a universal superconducting undulator (Universal SCU). An example of a possible universal SCU for the recently suggested Advanced Photon Source multi-bend achromat storage ring is given in this paper. The results of the magnetic simulation together with initial cryogenic considerations are presented., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany