Hitachi Ltd., Ibaraki-ken
Hitachi, Ltd., Power & Industrial Systems R&D Laboratory, Ibaraki-ken
SAGA, Tosu
A 4T superconducting wiggler for 1.4GeV synchrotron radiation facility Saga Light Source (SAGA-LS) was developed and manufactured. The wiggler consists of one superconducting magnet as main-pole and two normal conducting magnets as side-poles. The superconducting coils are wound with NbTi wires on iron poles, which are directly cooled by a 2-stage GM cryocooler. The structure of the wiggler is made for compactness and cryogen-free operation. This paper describes its magnet design and manufacturing processes.
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Elektronen-Speicherring BESSY II, Berlin
With a 7T wiggler in operation any attempts to detect the resonant depolarization of the electron spins were unsuccessful at BESSY II. This was attributed to the severely reduced final degree of spin polarization in the alternating fields of the strong wiggler which on the other hand nearly double the radiation loss per turn. The key to a clear detection of the depolarization were the improvement of the sensitivity of the polarimeter based on the spin dependent Touschek scattering cross section and the more effective and thus full depolarization of the beam. In the paper the steps taken will be presented in detail. With these improvements in place the high precision energy determination of the stored beam can be performed once again in parallel to the normal user operation and without any noticeable perturbations to the beam.
LBNL, Berkeley, California
CLASSE, Ithaca, New York
Grove City College, Grove City, Pennsylvania
The CESR Damping Ring Test Accelerator collaboration (Cesr-TA) utilizes the CESR e+/e- storage ring at Cornell University for carrying out R&D activities critical for the ILC damping rings. In particular, various locations have been instrumented for the study of the electron cloud effects and their amelioration. In this paper we present the results obtained using the TE wave propagation method to study the electron cloud evolution and its dependence on several beam and machine parameters. Whenever possible, we have also compared our measurements with those obtained by using retarding field analyzers (RFA) with good agreement. Amongst the results obtained, we were able to detect a strong resonance of the electron cloud with the TE wave in regions of the beampipe where a dipole-like magnetic field is also present. Besides the standard transmission method, we are also developing an alternative procedure, the so-called resonant BPM, which can be used for a more localized measurement of the electron cloud density, which has already yielded promising results.
CLASSE, Ithaca, New York
CERN, Geneva
Carleton University, College of Natural Sciences, Ottawa, Ontario
Purdue University, West Lafayette, Indiana
LBNL, Berkeley, California
Grove City College, Grove City, Pennsylvania
INFN/LNF, Frascati (Roma)
ASCo, Clayton, Victoria
KEK, Ibaraki
Clarkson University, Potsdam, New York
BNL, Upton, Long Island, New York
ANL, Argonne
CalPoly, San Luis Obispo, CA
Cockcroft Institute, Warrington, Cheshire
SLAC, Menlo Park, California
Fermilab, Batavia
Technion, Haifa
Loyola University, Chicago, Illinois
The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. Finally a range of EC mitigation methods have been deployed and tested. Measurements of cloud density and its impact on the beam under a range of conditions will be presented and compared with simulations. The effectiveness of a range of mitigation techniques will also be discussed.
DESY, Hamburg
PETRA III is a new hard x-ray synchrotron radiation source at DESY in Hamburg operating at 6 GeV with an extremely low horizontal emittance of 1 nmrad. The new light source is the result of a conversion of the former storage ring PETRA II. The conversion was carried out from middle of 2007 till March 2009. One eighth of the 2304 m long storage ring was completely rebuild and houses now 14 undulator beam lines as well as the optical and experimental hutches. The remaining seven eighths have been modernized and refurbished and in addition twenty 4 m long damping wigglers have been installed. These are required to achieve the small design emittance. Commissioning of the new light source started at the end of March 2009. In this paper we present the results that have been achieved during commissioning and the experience gained during the first user runs.
INFN/LNF, Frascati (Roma)
Metallic clearing electrodes have been designed to absorb the photo-electrons in the DAΦNE positron ring. They have been inserted in the wigglers and dipoles vacuum chambers and have been connected to external high voltage generators. In the paper we present the design of the devices and the results of the electromagnetic simulations related to both the transfer and longitudinal beam coupling impedances. We also present the results of the RF measurements and the first results with the DAΦNE circulating positron beam.
INFN/LNF, Frascati (Roma)
CERN, Geneva
BINP SB RAS, Novosibirsk
Recently the peak luminosity achieved on the DAΦNE collider has been improved by almost a factor 3 by implementing a novel collision scheme based on large Piwinski angle and Crab-Waist. This encouraging result opened new perspectives for physics research and a new run with the KLOE-2 detector has been scheduled to start by spring 2010. The KLOE-2 installation is a complex operation requiring a careful design effort and a several months long shutdown. The high luminosity interaction region has been deeply revised in order to take into account the effect on the beam caused by the solenoidal field of the experimental detector and to ensure background rejection. The shutdown has been also used to implement several other modifications aimed at improving beam dynamics: the wiggler poles have been displaced from the magnet axis in order to cancel high order terms in the field, the feedback systems have been equipped with stronger power supplies and more efficient kickers and electrodes have been inserted inside the wiggler and the dipole vacuum chambers, in the positron ring, to avoid the e-cloud formation. A low level RF feedback has been added to the cavity control in both rings.
SLAC, Menlo Park, California
The Cornell Electron Storage Ring (CESR) has been reconfigured as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R&D. One of the primary goals of the CesrTA program are to investigate the interaction of the electron cloud with low emittance positron beam, to explore methods to suppress the electron cloud, and to develop suitable advanced instrumentation required for these experimental studies. This paper report the simulation of the electron-cloud formation in the wiggler and quadrupole magnets using 3D code CLOUDLAND. The transverse distribution of electron cloud in a wiggler magnet is similar to a dipole magnet except in the zero vertical field regions where the electrons have complicated trajectories and therefore a longer lifetime. Fortunately, these electrons are dominantly direct-photo-electrons and can be easily reduced by properly arranging photon absorbers. Simulations show that the electron cloud in a quadrupole magnet can be trapped for long time due to the mirror field effect.
CLASSE, Ithaca, New York
Cornell University, Ithaca, New York
LBNL, Berkeley, California
ANL, Argonne
Retarding field analyzers (RFAs) provide an effective measure of the local electron cloud density and energy distribution. Proper interpretation of RFA data can yield information about the behavior of the cloud, as well as the surface properties of the instrumented vacuum chamber. However, due to the complex interaction of the cloud with the RFA, particularly in regions of high magnetic field, understanding these measurements can be nontrivial. This paper will examine different methods for interpreting RFA data via cloud simulation programs. Possible techniques include postprocessing the output of a simulation code to predict the RFA response, and incorporating an RFA model into the program itself.
CLASSE, Ithaca, New York
CERN, Geneva
ANL, Argonne
KEK, Ibaraki
SLAC, Menlo Park, California
Over the course of the CesrTA program, the Cornell Electron Storage Ring (CESR) has been instrumented with several retarding field analyzers (RFAs), which measure the local density and energy distribution of the electron cloud. These RFAs have been installed in drifts, dipoles, quadrupoles, and wigglers; and data have been taken in a variety of beam conditions and bunch configurations. This paper will provide an overview of these results, and give a preliminary evaluation of the efficacy of cloud mitigation techniques implemented in the instrumented vacuum chambers.
Technion, Haifa
Electron cloud confined to move in the vertical direction by either the wiggler field or a dipole field has been investigated extensively. We present results of an analysis demonstrating that electrons may be trapped in the region of zero vertical field of a wiggler. Their characteristic frequency and life-time are established and some of the implications are discussed.
KEK, Ibaraki
SLAC, Menlo Park, California
Grooved surfaces are effective to suppress the secondary electron emission, and can be a possible technique to mitigate the electron cloud instability (ECI) in positron/proton storage rings. Various types of triangular grooved surfaces have been studied in a laboratory, and also using an intense positron beam of the KEKB B-factory. The grooves have vertex angles of 20 ~ 30 degrees, and depths of 2.5 mm. In the laboratory, the secondary electron yield (SEY) of sample pieces were measured using an electron beam in a magnetic-free condition. The maximum SEY well below 1.0 was obtained after some extent of electron bombardment for most of grooved surfaces. To test he groove efficacy in magnetic field regions of particle accelerators, insertions with several types of grooved surfaces were installed into a test chamber in a wiggler magnet of KEKB positron ring. In a dipole-like chamber wit magnetic field (0.78 T), the reduction in the electron density around the beam was observed for a grooved section when compared to the case of a flat surface with TiN coating. An R&D effort is underway to optimize and manufacture the grooved surface in accelerator beam pipes for practical use.
SLAC, Menlo Park, California
PEP-X, a next generation, ring-based light source is designed to run with beams of high current and low emittance. Important parameters are: energy 4.5 GeV, circumference 2.2 km, beam current 1.5 A, and horizontal and vertical emittances, 150 pm by 8 pm. In such a machine it is important that impedance driven instabilities not degrade the beam quality. In this report we study the strength of the impedance and its effects in PEP-X. For the present, lacking a detailed knowledge of the vacuum chamber shape, we create a straw man design comprising important vacuum chamber objects to be found in the ring, for which we then compute the wake functions. From the wake functions we generate an impedance budget and a pseudo-Green function wake representing the entire ring, which we, in turn, use for performing instability calculations. In this report we consider in PEP-X the microwave, transverse mode-coupling, multi-bunch transverse, and beam-ion instabilities.
ISIR, Osaka
KEK, Ibaraki
We have been developing a Terahertz free electron laser (FEL) based on the 40 MeV, 1.3 GHz L-band electron linac at the Institute of Scientific and Industrial Research (ISIR), Osaka University. After the FEL lasing at the wavelength of 70 um (4.3 THz)*, next targets of the FEL development are to extend the available laser wavelength, to increase the FEL power, and to evaluate characteristics of FEL. Since the lowest energy of the linac was restricted by a fixed-ratio power divider between the acceleration tube and the buncher, we have prepared the new one with a different ratio to extend the wavelength longer side. As a result, the wavelength region is able to be extended to 25 - 147 um (12.5 - 2 THz). The maximum output energy of the FEL macropulse so far obtained is 3.6 mJ at 66 um. The peak macropulse power available to user experiments is estimated to be 1 kW or less, given that the pulse duration is 3 us. Three users groups have begun experiments using the FEL. We will report these recent activities on the Terahertz FEL.
* G. Isoyama, R. Kato, S. Kashiwagi, T. Igo, Y. Morio, Infrared Physics & Technology 51 (2008) 371-374.
FEL/Duke University, Durham, North Carolina
The Duke FEL and High Intensity Gamma-ray Source (HIγS) are operated with a wide range of electron beam energies (0.24 - 1.2 GeV) and photon beam wavelengths (190 - 1060 nm). Currently, the HIγS provides users with the gamma beams in the energy range from 1 to about 65 MeV, with a near future extension to about 100 MeV. The maximum total gamma-flux produced at the HIγS facility is up to 1010 gammas per second. Production of high level gamma-ray flux, requiring a very high average FEL intra-cavity power and high electron beam current, can cause significant degradation of the FEL mirrors. To ensure the predictability and stability of the HIγS operation for user research program, we have developed a comprehensive program to continuously monitor the performance of the FEL mirrors. This program has enabled us to use a particular set of FEL mirrors for a few hundreds hours of high gamma-flux operation with predictable performance. In this work, we discuss sources and consequences of the mirror degradation for a variety of wavelengths and present our estimates of the mirror life time as a function of the FEL wavelength, gamma-ray polarization, and total gamma-flux.
JLAB, Newport News, Virginia
Jefferson Lab (JLab) is proposing JLAMP (JLab AMPlifier), a 4th generation light source covering the 10-100 eV range in the fundamental mode with harmonics stretching towards the oxygen k-edge. The new photon science user facility will feature a two-pass superconducting linac to accelerate the electron beam to 600MeV at repetition rates of 4.68MHz continuous wave. The average brightness from a seeded amplifier free electron laser (FEL) will substantially exceed existing light sources in this device's wavelength range, extended by harmonics towards 2 nm. Multiple photon sources will be made available for pump-probe dynamical studies. The status of the machine design and technical challenges associated with the development of the JLAMP are presented here.
KEK, Ibaraki
SLAC, Menlo Park, California
In order to mitigate the electron cloud instability (ECI) in a positron ring, an electron clearing electrode with a very thin structure has been developed. The electrode has been tested with an intense positron beam of the KEKB B-factory using a test chamber. A drastic reduction in the electron density around the beam was demonstrated in a dipole magnetic field (0.78 T). The clearing electrode was then applied to the actual copper beam pipe (94 mm in diameter) with antechambers for wiggler magnets of KEKB. The feed-through was revised to improve reliability, and the length was modified to fit a real magnet. The input power into the electrode was estimated to be approximately 80 W/m. The clear reduction in the electron density was also observed by applying a voltage of +500 V to the electrode. The design of clearing electrodes has now reached a high reliability and it is suitable for accelerator applications.
LNLS, Campinas
The main facility of the Brazilian Synchrotron Light Laboratory is a 93 meters circumference, 1.37 GeV storage ring. Recently, the first superconducting insertion device was installed in the machine. This 4 T ID produces powerful beams that can damage the non-cooled parts of the accelerator vessel in the case of a miss-steered beam, even with a relatively large vacuum chamber cross section. In this paper we present the design details and the first operational results of the electronic beam position interlock system. Topics about redundancy engineering will be discussed as well.
SOLEIL, Gif-sur-Yvette
UPMC, Paris
LIXAM, Orsay
An electron bunch slicing set-up is being installed on the SOLEIL storage ring, based on Zholents and Zolotorev method [1]. This will provide 100 fs long X-ray pulses with reasonable flux to two existing beamlines, working with soft X-rays (TEMPO) and hard X-rays (CRISTAL). The parameters of the laser system and of the wiggler modulator, and the optimisation of the laser focusing optics and beam path, from the laser hutch in the experimental hall to the inside of the storage ring tunnel have been finalised. The construction work will start early 2010, including the ordering of the laser, the construction of the laser hutch, the construction of the wiggler, the installation of a new modified vacuum dipole chamber by which the laser will enter into the ring, and the modifications of some components in the beamlines front-ends to provide the best possible separation of the sliced X-Ray. In this paper, we will report on the status of the installation of the set-up and the expected performances including laser-electron interaction efficiency, halo background effect and the possible operation filling patterns.
DESY, Hamburg
PETRA III is a 3rd generation synchrotron radiation light source which started commissioning in April 2009. Recently, first frequency map measurements have been made using the turn-by-turn capabilities of the beam position monitors and horizontal as well as vertical kicker magnets. The results are in good agreement with expectations from tracking studies performed with SixTrack.
DESY, Hamburg
At DESY the PETRA ring has been converted into a synchrotron radiation facility, called PETRA III. The commissioning with beam started in April 2009. The betatron tune versus beam intensity was measured for different configurations of the wiggler magnets which are installed in PETRA III to achieve the small emittance of 1 nm. These measurements are compared with predictions from the impedance model. The measured tune shift is well within the impedance budget and the design single bunch intensities of up-to 2.5 mA can be stored in PETRA III. The predicted vertical tune shift is about 30 % smaller than the measured one.
JASRI/SPring-8, Hyogo-ken
We indicated that a storage ring with picometer-order emittance is possible with realistic parameters and is promising as a next generation synchrotron radiation source* and applied it to the SPring-8 storage ring**. The storage ring had the same circumference as that of the SPring-8 storage ring, but had not four long straight sections that SPring-8 storage ring has. Accordingly, the storage ring beam line is slightly different from that of the SPring-8 and the positions of photon beam lines are also different from the existing one. To avoid this, a storage ring with four long straight sections has been studied and was found that the storage ring with the same beam line positions as the existing one is possible. The storage ring consists of twenty ten-bend achromat cells, four five-bend achromat cells and four long straight sections. The long straight section length is 34.0 m and the short one is 6.6 m. The natural emittance is 108 pm-rad. The maximum brightness is 2.5×1022 photons/s/mm**2/mrad**2 in 0.1% BW with 200 mA beam current, about 160 times brighter than SPring-8. In the end I mention that this ultra-low emittance storage ring is only a result of personal design study.
* K. Tsumaki and N. Kumagai, Nucl. Instr. and Meth. A 565 (2006) 394.
** K. Tsumaki and N. Kumagai, EPAC'06, 3362.
SAGA, Tosu
Saga Light Source (SAGA-LS) is a synchrotron radiation facility with a 255 MeV linac and a 1.4 GeV storage ring. The spectral range covers from VUV to hard X ray region of about 23 keV. Improvement and development of the accelerator have been achieved from official opening of the facility. Stored current of the storage ring has been increased from 100 mA to 300 mA in these three years. An APPLE-2 undulator was developed and installed to a long straight section LS3. A field correction system for the undulator was developed to compensate precisely betatron tune shift, dipole kick and skew quadrupole. A superconducting wiggler is under construction. The peak field and critical energy are 4 T and 5.2 keV, respectively. The wiggler will provide synchrotron radiation in the 20-40 keV range. The wiggler consists of a superconducting main pole and two normal conducting side poles. The main pole is directly cooled by a small GM cryocooler and liquid helium is not used. In addition, laser Compton scattering experiment is under progress. A port to introduce CO2 laser light was installed as a beam line BL1. First gamma ray was observed in December 2009.
USTC/NSRL, Hefei, Anhui
Hefei Advanced Light Source(HALS) will be a high brightness light source with about 0.2nmrad emittance at 1.5GeV and about 400m circumference. To enhance brilliance, very low beam emittance is required. High brightness demand and relative low energy will make emittance a critical issue in ring design. Intra-beam scattering(IBS) is usually thought a fundamental limitation to achieve low emittance. Here we preliminarily estimate the emittance growth due to IBS for the temporary lattice design of HALS based on Piwinski and Bjorken-Mtingwa theories, and discuss the effect of implementation of damping wiggler and harmonic cavity to lower the emittance.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The new 3rd generation synchrotron radiation source ALBA built nearby Barcelona is planned to start operation in 2010 with several different insertion devices installed in the storage ring either from the beginning or within the first year of operation. The list of first insertion devices includes: 2 planar PPM SmCo in-vacuum undulators with the period of 21.6 mm; 2 Apple-II type PPM NdFeB undulators with the periods of 62.36 and 71.36 mm respectively; 1 superconducting planar wiggler with the period of 30 mm and a maximum field of 2.1 T, and a 1 conventional wiggler with the period of 80.0 mm and a maximum field of 1.74 T. The emitted light of these IDs covers wide spectral range extending from hard X-rays to UV. Pre-design of the IDs was done by ALBA, but manufacturing has been outsourced. Production is now finished and they have been tested with magnetic measurements. The paper will present the final as build magnetic designs as well as the main results of magnetic measurements performed on the manufactured devices.
FEL/Duke University, Durham, North Carolina
The light source research program at the Duke Free-Electron Laser Laboratory (DFELL) is focused on the development of accelerator-driven light sources, including storage ring based free-electron lasers (FELs) and Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS). The HIGS is the most intense Compton gamma-ray source currently available with an energy tuning range from 1 to 100 MeV. The accelerator physics program at the DFELL covers a wide range of activities, from nonlinear dynamics research, to the study of beam instability with advanced feedback systems, to FEL research and development. In this paper, we will report our recent progress in accelerator physics research and light source development to meet new challenges of today's and future accelerators.
CLS, Saskatoon, Saskatchewan
The Canadian Lightsource is a 2.9 GeV 3rd generation lightsource in Saskatoon, Canada. The latest expansion of operations includes adding 4 insertion devices in 2 straight sections. These devices will include a hybrid permanent magnet wiggler, an in-vacuum undulator and 2 APPLE-II type undulators. The 4 m long elliptical APPLE-II IDs will cover overlapping photon energy ranges of 15-200eV and 200-1000eV. These devices will be installed adjacent to one another in the same straight with the magnet arrays mounted on one support structure and a horizontal translation system to allow users to select one device at a time for use on a single beamline. The 2nd straight will include the hybrid wiggler and in-vacuum undulator in a 3 magnet chicane. The wiggler is designed to supply photons for a center beamline and a side beamline accepting radiation 5 mrad off of the centerline of the radiation fan. The critical energy of photons emitted of the sideline are >90% of the critical energy on the centerline. An 8 mrad center chicane magnet separates the photons of the undulator from the wiggler beamlines allowing for 3 beamlines operating with 2 IDs in a single straight section.
SOLEIL, Gif-sur-Yvette
The production of high fluxes in the hard X-rays region is a major issue on medium energy storage rings. It requires the installation of Insertion Devices with high magnetic field and a large number of periods. The construction of a superconducting wiggler has been first envisaged but reveals to be maintenance constraining, much more complex and expensive than the permanent magnet technology. A small gap in vacuum wiggler composed of 38 periods of 50 mm has been preferred. The compact magnetic system allows to produce in a limited space a magnetic field of 2.1 T in a small gap of 5.5 mm, whereas an auxiliary counterforce system based on non-magnetic springs compensate the magnetic forces (up to 8.5 Tons) acting between magnet arrays. The gap between jaws and the mechanical deformations have been controlled and corrected. Magic fingers corrections have been also performed to reduce the integrated multipoles and to minimize the 2nd order integrals resulting from the tight width of the wiggler poles. This paper presents the design of the wiggler, the construction, and the results of the measurements after magnetic corrections.
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Elektronen-Speicherring BESSY II, Berlin
At BESSY II photon energies above 2keV can be produced only with bending magnets, a permanent magnet wiggler, superconducting (SC) wavelength shifters and a SC-wiggler. The wiggler brilliance suffers from the depth of field effect and the bending magnets and wavelength shifters produce the X-rays only with a single pole. Experiments such as HIgh Kinetic Energy photoelectron spectroscopy (HIKE) or microspectroscopy on nanostructured materials demand a high brilliance and flux as it is provided by a small period cryogenic undulator. This paper discusses the requirements for the operation of small gap cryogenic devices at BESSY II. A scheme with two adjacent, vertical low beta sections inside of one of the long straight sections is suggested. The straight is divided into two parts by a quadrupole triple in the center. An optic with an increased, vertical beta tune by 0.5 is presently studied. The optics outside of the low beta section and the horizontal tune are kept unchanged.
KIT, Karlsruhe
Karlsruhe Institute of Technology (KIT), Karlsruhe
CERN, Geneva
In the superconductive undulator SCU14, installed at ANKA, time dependent drifts in the magnetic fields were observed*. Simulations with the software OPERA 3D showed, that the cause of these drifts might be leak and eddy currents in the iron body of the undulator caused by the time-varying currents and fields during current ramps, which slowly decay by ohmic losses. This assumption was crosschecked by measurements at different mockup bodies. This contribution discusses the results of the simulations and measurements and the consequential strategies for avoiding this effect.
* S. Ehlers et. al. "Magnetic field transients in superconductive undulators", in Proceedings of the Particle Accelerator Conference, Vancouver, 2009, to be published.
Karlsruhe Institute of Technology (KIT), Karlsruhe
BNG, Würzburg
One of the advantages of superconducting insertion devices (IDs) with respect to permanent magnet IDs is the possibility to enlarge the spectral range by changing the period length by reversing the direction of the current in a part of the windings. In this contribution we report the first experimental test of this principle demonstrated on a 70mm NbTi mock-up coil with period tripling, allowing to switch between a 15mm period length undulator and a 45mm wiggler.
ISIR, Osaka
KEK, Ibaraki
The edge-focusing (EF) wiggler has been fabricated to evaluate its performance rigorously with the magnetic field measurement. It is a 5-period planar wiggler with an edge angle of 2° and a period length of 60 mm. The magnetic field is measured using Hall probes at four different wiggler gaps. It is experimentally confirmed that a high field gradient of 1.0 T/m is realized, as designed, along the beam axis. The magnetic field gradient of the EF wiggler is derived as a function of the magnetic gap. The field gradient decreases with increasing magnet gap more slowly than the peak magnetic field does for the present experimental model. An analytic formula for the field gradient of the EF wiggler is derived and it is shown that the slope of the field gradient with the magnet gap can be changed by varying the magnet width of the EF wiggler. We analyzed the relation between the orientation errors of the measurement system and the measured magnetic field or field gradient using a model magnetic field of the EF wiggle. We corrected the measurement magnetic field based on this analysis and evaluated the performance of the EF wiggler.
MAX-lab, Lund
The MAX IV light source, presently under construction at MAX-lab in Lund, Sweden, will consist of two separate storage rings and a linac-driven short-pulse facility. The two storage rings are operated at different energies, 3 GeV and 1.5 GeV, to provide synchrotron radiation of high brightness over a broad spectral range. The 3 GeV linac serves as a full-energy injector for the storage rings as well as the driver of the short-pulse facility delivering intense x-ray pulses. The paper describes a selection of possible insertion devices to be installed at the MAX IV 3 GeV ring and the expected heat loads produced by the insertion devices.
CERN, Geneva
IMFD, Freiberg
KIT, Karlsruhe
FZK, Karlsruhe
Two damping rings (e+, e-) are foreseen for the CLIC injection chain. In each damping ring 76 two meter long wigglers will be installed. The short period (40-50 mm), combined with a gap larger than 14 mm and a requested field in the mid-plane BPeak > 2 T requires the usage of superconducting technologies to meet these requirements. To demonstrate the feasibility of this wiggler design a short-model vertical racetrack wiggler (40 mm period; 16 mm gap) was built and successfully tested at CERN. The wiggler carries a current of 730 A and 910 A and reaches a mid-plane peak field of Bpeak = 2 T and Bpeak = 2.5 T at 4.2 K and 1.9 K, respectively. The results show that the wiggler model meets the magnetic requirements of the CLIC damping rings at 1.9 K. The paper will also discuss the improvements we propose to enhance the performance in order to meet the CLIC specifications also at 4.2 K.
NCTU, Hsinchu
NSRRC, Hsinchu
A wiggler with the property of low total radiation power and keeping high photon flux in hard x-ray region, 5-20 keV, which is necessary for the special demand of users, was under investigated for reducing the difficulty of the design of optical components in the beam line and decreasing the load of RF cavity power. Such an insertion devise was called wiggler-like undulator. The spectrum of wiggler-like undulater was investigated with a code, of which the algorithm is based on the compromising between photon flux and radiation power of insertion devices for spectrum optimization. The property of the spectrum of the wiggler-like undulator are discussed herein. Furthermore, the brilliance and the power distribution are somehow also discussed.
NTHU, Hsinchu
NSRRC, Hsinchu
IUCF, Bloomington, Indiana
A novel gradient damping wiggler (GDW) was developed for the ALPHA storage ring in Indiana University. The GDW will be used to change the momentum compaction factor and the damping partition at ALPHA storage effectively. There is one middle pole and two outer poles that they have gradient field were assembled together on the same girder to be a full set of GDW magnet system. The dipole and gradient field strength of the middle (outer) pole is 0.67 T (-0.67) and 1.273 T/m (1.273 T/m), respectively. The magnet gap of the middle and outer pole is 40 mm and 35.87 mm, respectively, that the three combined function of dipole magnet can be charged by the same power supply. There is a trim coil on the three magnets to adjust the first and second integral field to zero. The good field region of middle pole and outer pole in transverse x-axis (deltaB/B=0.1%) are ±50mm and ±40mm separately. A prototype GDW magnet was fabricated and a Hall probe measurement system was set up to measure the magnet field to verify the magnet design and the magnet construction performance. The field cross-talk and the fringe field are also discussed herein by different methods.
Diamond, Oxfordshire
Diamond Light Source is currently operating with two multipole superconducting wigglers, one with 49 poles at 3.5 T and another with 49 poles at 4.2 T. The cryogenic arrangement is similar in both cases; each cryostat contains a liquid helium bath cooled by four cryocoolers. The design goal was to allow up to six months continuous operation in the storage ring between refilling the liquid helium bath. However, the helium boil-off is much higher than expected, necessitating much more frequent refills. As well as having a cost implication, this also currently poses a restriction on the operating beam current. In this report we present the results of measurements carried out under various beam conditions to try to understand the reason for the higher boil-off in terms of heat load seen by the cryostat and effective cryocooler performance. We also present our plans for dealing with the problem in the near and longer term.
BNL, Upton, Long Island, New York
National Synchrotron Light Source-II (NSLS-II) project is now in the construction stage. A new insertion device (ID) magnetic measurement facility (MMF) is being set up at Brookhaven National Laboratory in order to satisfy the stringent requirement on the magnetic field measurement of IDs. ISO-Class7 temperature stabilized clean room is being constructed for this purpose. A state-of-the-art Hall probe bench and integrated field measurement system will be installed therein. IDs in the project baseline scope include six damping wigglers, two elliptically polarizing undulators (EPUs), three 3.0m long in-vacuum undulators (IVUs) and one 1.5m long IVU. Three-pole wigglers with peak field over 1 Tesla will be utilized to accommodate the users of bending magnet radiation at the NSLS. Future plan includes: 1) an in-vacuum magnetic measurement system, 2) use of PrFeB magnet for improved cryo undulator, 3) development of advanced optimization program for sorting and shimming of IDs, 4) development of a closed loop He gas refrigerator, 5) switchable quasi-periodic EPU. Design features of the baseline devices, IDMMF and the future plans for NSLS-II ID activities are described.
RadiaBeam, Santa Monica
Purdue University, West Lafayette, Indiana
Of particular interest to X-ray FEL light source facilities is Enhanced Self-Amplified Spontaneous Emission (ESASE) technique. Such a technique requires an ultrafast (20-50 fs) high peak power, high repetition rate reliable laser systems working in the mid-IR range of spectrum (2μm or more). The approach of this proposed work is to design a novel Ultrafast Mid-IR Laser System based on optical parametric chirped-pulse amplification (OPCPA). OPCPA is a technique ideally suited for production of ultrashort laser pulses at the center wavelength of 2 μm. Some of the key features of OPCPA are the wavelength agility, broad spectral bandwidth and negligible thermal load.
National Technical University of Athens, Zografou
CERN, Geneva
Due to the high bunch density, the output emittances of the CLIC Damping Rings (DR) are strongly dominated by the effect of Intrabeam Scattering (IBS). In an attempt to optimize the ring design and using classical IBS formalisms and approximations, the scaling of the extracted emittances and IBS growth rates is being studied, with respect to several ring parameters including energy, bunch charge, optics and wiggler characteristics. Results from the simulations using a multi-particle tracking code are also presented.
INFN/LNF, Frascati (Roma)
A new baseline parameter set has been proposed for the ILC with a reduction by a factor 2 in the number of bunches. This option will allow for a corresponding factor 2 decrease in the Damping Ring circumference, with significant cost savings. A low emittance lattice for a 3.2 km long damping ring has been designed, with the same racetrack layout of the present reference 6.4 km long lattice and similar straight sections. The technical work done for the longer ring can be easily applied to the shorter one. The lattice is based on an arc cell design adopted for the SuperB collider and allows some flexibility in tuning emittance and momentum compaction.
IHEP Beijing, Beijing
In this paper, we made a new design for ILC 3.2 km damping ring with 2 arcs based on FODO cell and 2 straight sections which are nearly the same as the new version of the 6.4 km ring DCO4. This new lattice uses less dipoles and quadrupoles than the present SuperB like lattice and has an adequate aperture for the large injected emittance of the positron beam. The work of lattice design and DA optimization will be presented in detail.
CERN, Geneva
BINP SB RAS, Novosibirsk
The CLIC damping rings should produce the ultra-low emittance necessary for the high luminosity performance of the collider. This combined to the high bunch charge present a number of beam dynamics and technical challenges for the rings. Lattice studies have been focused on low emittance cells with optics that reduce the effect Intra-beam scattering. The final beam emittance is reached with the help of super-conducting damping wigglers. Results from recent simulations and prototype measurements are presented, including a detailed absorption scheme design. Collective effects such as electron cloud and fast ion instability can severely limit the performance and mitigation techniques have been identified and tested. Tolerances for alignment and technical system design such as kickers, RF cavities, magnets and vacuum have been finally established.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
STFC/DL, Daresbury, Warrington, Cheshire
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
BINP SB RAS, Novosibirsk
A vacuum vessel design of wiggler sections should meet a few challenging specification. The SR power of about 40 kW is generated in each wiggler. Expanding fan of SR radiation reaches the beam vacuum chamber walls in the following wiggler and may cause the following problem: massive power dissipation on vacuum chamber walls inside the cryogenic vessel, radiation damage of superconducting coil, high photo-electron production rate that cause an e-cloud build-up to unacceptable level. Therefore this power should be absorbed in the places where these effects are tolerable or manageable. A few possible solutions for tackling all SR related problems as well as vacuum design are discussed in the paper in details.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
STFC/DL, Daresbury, Warrington, Cheshire
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
BINP SB RAS, Novosibirsk
A 374-m long wiggler section is a key part of ILC damping ring that should alloy reaching a low beam emittance for the ILC experiment. Synchrotron radiation generated by the beam in the wigglers should be absorbed by different components of vacuum vessel, including specially designed absorbers. The optimisation of the mechanical design, vacuum system and anti-e-cloud mitigation requires accurate calculation of the SR power distribution. The angular power distribution from a single wiggler was calculated with in-house developed software. Then the superposition of SR from all wigglers allows calculating power distribution for all components along the wiggler section and the downstream straight section.
SLAC, Menlo Park, California
LBNL, Berkeley, California
CLASSE, Ithaca, New York
INFN/LNF, Frascati (Roma)
ANL, Argonne
Cockcroft Institute, Warrington, Cheshire
KEK, Ibaraki
CERN, Geneva
As part of the International Linear Collider (ILC) collaboration, we have compared the electron cloud effect for different Damping Ring designs respectively with 6.4 km and 3.2 km circumference and investigated the feasibility of a shorter damping ring with respect to the electron cloud build-up and related beam instability. These studies were carried out with beam parameters of the ILC Low Power option. A reduced damping ring circumference has been proposed for the new ILC baseline design and would allow to considerably reduce the number of components, wiggler magnets and costs. We also briefly discuss the plans for future studies including the luminosity upgrade option with shorter bunch spacing, the evaluation of mitigations and the integration of the CesrTA results into the Damping Ring design.
LNLS, Campinas
In this paper we report on recent developments in transverse coupling characterization and compensation in the UVX storage ring at the Brazilian Synchrotron Light Laboratory (LNLS). We have designed and manufactured a compact skew quadrupole with which it was possible to completely compensate coupling introduced by insertion devices (IDs) in the ring.
DESY, Hamburg
PETRA III is a 6 GeV third generation light source located at DESY/Hamburg. The former pre-accelerator of HERA has been converted in 2007/2008 into a high brilliance synchrotron light source with an emittance of 1 nm*rad. The commissioning of PETRA III started in 2009. PETRA III is like other third generation light sources very sensitive to errors of the linear optics. Gradient errors reduce the dynamic aperture, increase the emittance and change the beam size. The correction of the optics is based on orbit response matrix data which were analyzed both with the program LOCO and with a fit of the beta-functions and phase-functions at BPMs and correctors. Initial results of the modelling of the machine and the correction of the linear optics functions will be presented.
DESY, Hamburg
PETRA III is a 6GeV positron light source with a design horizontal beam emittance of 1nm.rad and 1% emittance coupling. This low emittance is achieved with proper correction of horizontal dispersion to its theoretical values in the arcs as well as dispersion free sections. The spurious vertical dispersion, arising due to misalignment and rotational errors of the magnets is also duly corrected as this contributes to the vertical beam size of the photon beam. Here we discuss the method taken to correct the horizontal dispersion using a combined orbit and dispersion correction scheme. In the vertical plane the same procedure can be used as that of horizontal plane or only the dispersion can be corrected using dedicated skew quadrupoles to millimeter level after orbit correction has been done. In this paper we present the methods used and results obtained in correction of dispersions in transverse planes.
CERN, Geneva
LAL, Orsay
KEK, Ibaraki
BNL, Upton, Long Island, New York
SLAC, Menlo Park, California
The current ATF2 Ultra-Low beta proposal was designed to achieve 20nm vertical IP beam size without considering the multipolar components of the FD magnets. In this paper we describe different scenarios that avoid the detrimental effect of these multipolar errors in the FD. The simplest approach consists in modifying the optics but other solutions are studied as the introduction of new higher order magnets or the replacement of the FD with SC technology. The practical aspects of such an upgrade are the tuning performance and the compatibility with existing devices and instrumentation. These are fully addressed in the paper.
Fermilab, Batavia
The Project Management Design Team of the International Linear Collider has recently proposed fundamental changes to the published ILC RDR baseline with the goal of presenting a potential alternate design providing a more cost-effective solution. In this framework a new lattice for the Damping Rings has been presented, shortening the exit bunch length from the RDR value of 9 mm down to 6 mm. The shorter bunch length allowed the adoption of a simpler single-stage bunch compressor, instead of the RDR two-stage compressor. The new single-stage compressor has a compression ratio of 20 and still achieves the nominal RDR value of 0.3 mm bunch length at the Interaction Point. The new design has been optimized to generate the required compression while having a small SR emittance growth, and reduced energy spread. The new lattice and its optimization procedure are presented in this paper.
CERN, Geneva
INFN/LNF, Frascati (Roma)
The wigglers of the DAΦNE main rings have been one of the main sources of the non-linearities in the collider. A method to minimize the odd integrated multipoles around the beam trajectory (the even ones tend to vanish due to the periodicity of the device) is described. It consists in displacing the magnetic axis of each pole towards the position of the beam in such a way that the integrated odd multipoles are minimized in each half period of the wiggler. After a study, including multipolar and tracking analysis, has performed to determine the best position of the axes, the wigglers in the DAΦNE main rings have been modified accordingly. To validate this approach magnetic measurements and tests with beam by means of closed orbit bumps have been performed.
NSC/KIPT, Kharkov
In a 1956 article* Panofsky and Wenzel derived the relation for the net transverse kick experienced by a fast charge particle crossing a closed cavity excited in a single rf mode. Later on this relation, usually referred to the Panofsky-Wenzel theorem, was generalized for cavity containing wake field induced by a driving charge. This theorem has played very important role in the accelerator physics. One well-known conclusion of this paper was that in a TE mode the deflecting impulse of the electric field always cancels the impulse of the magnetic fields. In our presentation we more exactly rederive Panofsky and Wenzel's result and obtain correction terms to the transverse kick. We show that in a TE mode the net transverse kick does not zero but is determined by a ponderomotive force. Using the given approach we find correction terms to wake potentials which are inversely proportional to the relativistic factor. Practical implications of our results are discussed.
* W.K.H. Panofsky and W.A. Wenzel, Rev. Sci. Instrum. 27, 967 (1956).
Diamond, Oxfordshire
JAI, Oxford
Diamond operates with 10 in-vacuum insertion devices at 5 mm gap, two Apple-II, two superconducting and two normal conducting wigglers. We report here the correction of the linear optics of wigglers and measurements of nonlinear effects such as dynamic aperture and frequency maps and their impacts on injection efficiency, lifetime and loss distribution in operation of the storage ring.