SINAP, Shanghai
The Shanghai Synchrotron Radiation Facility (SSRF) is an intermediate energy, third generation light source. In December 2007, electron beam was stored and accumulated in the SSRF storage ring. Since then the accelerator commissioning and beam line installation have continued toward the scheduled user operation from May 2009 onwards. This paper presents an overview of the SSRF status and preparations for user operations.
LNLS, Campinas
We present several alternative designs of hybrid bending magnets based on the use of ferrite blocks with steel pole pieces to be used in the new Brazilian storage ring - LNLS2. Their main magnetic and mechanical characteristics are presented. Such models are compared to electromagnet magnets, and some advantages and disadvantages are listed, as well as a cost estimate.
BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
Discrete corrector magnets are used for the 230 horizontal and vertical steering magnets in the NSLS-II storage ring. A unique design incorporates both dipole and skew quad correctors for(DC) steering in the same magnet. Separate AC (orbit feedback) correctors have also been designed. Comparison with alternate designs are presented as well as prototype measurements
BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
The Sextupole magnets for the National Synchrotron Light Source (NSLS-II) have stringent performance requirements. These magnets have a faceted pole profile departing from the classic shape due to constraint imposed by the vacuum tube. Three different geometric features were used as parameters to minimize unallowed harmonics. Prototypes were measured and have confirmed the good field quality.
BINP SB RAS, Novosibirsk
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
BINP has manufactured and measured 243 multipoles of 9 types for the ALBA storage ring. The magnets had severe requirements on the manufacturing tolerances and the alignment of their magnetic axes. The quadrupole magnets are made of 1mm laminated yokes with the bore diameter of 61mm. The sextupole magnets are made of 0.5mm laminated yokes with the bore diameter of 76mm. Rotating coils and Hall probes have been used for the magnetic measurements. The features of manufacturing and magnetic measurements are presented in this paper.
NSRRC, Hsinchu
The highly stable pulsed magnets are designed for injection and extraction the electron beams operation in Taiwan Photon Source. The injection to the booster at 0.15 GeV is performed with septum and kicker devices as well as the extraction from the booster at 3 GeV. There are 5 in-vacuum septum and kicker magnets used for booster injection and extraction processes. For the storage ring, an injection of the electron beam into the storage ring is performed with a septum magnet and four identical kicker magnets. All pulsed magnets are designed for injection into the 3-GeV storage ring. The kicker magnet is excited with a 4.8-μs half-sine current waveform. A prototype of kicker magnet with 0.6 m of length is made and tested for examining the field errors. The field performances of the kicker magnet are presented. All pulsed magnets are fed with special current waveform. Both pulsed magnets are considered with the goal to achieve reliable work.
NSRRC, Hsinchu
The accelerator lattice magnets of the Taiwan Photon Source (TPS) with energy 3 GeV have been designed for the storage and booster ring. The magnetic computation codes of TOSCA and RADIA software packages were used to design the magnet circuits of the accelerator magnets. Meanwhile, the design of a magnet circuit must take into account both the requirements of accelerator physics and practical engineering constraints. The criterion of magnet design is to keep a rise of coil temperature within 10o C and a safety margin greater than 15 %. We apply pole edge shims and end magnet chamfers to enhance the field homogeneity and to decrease multipole components, respectively. The edge shim involves a smaller magnet dimension but maintains the same quality of the field. Use of an end magnet chamfer avoids field saturation. The mechanical engineering design of the storage ring magnets has been completed and the booster ring magnets have started to be designed. The 3D Solidworks package was used to draw and design the mechanical engineering. The prototype magnets of the storage ring have been contracted out to the local company in Taiwan and will be finished before the end of 2009.
ANL, Argonne
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A superconducting planar undulator is under development at the Advanced Photon Source (APS). The initial R&D phase of the project includes intensive magnetic modeling performed with the Opera 2d and 3d software packages. This simulation addresses questions of magnetic design of the undulator including calculation of peak field on the undulator axis and maximum field in the conductor, superconductor load line optimization, and design of the undulator ends and correction coils. Results of the magnetic simulation are presented in the paper.
FZK, Karlsruhe
INFN/LNF, Frascati (Roma)
Max-Planck Institute for Metal Research, Stuttgart
Recent investigations with the cold bore superconducting undulator installed at ANKA indicate that the main contribution to the beam heat load is caused by electron bombardment. For a quantitative understanding of the problem a cold vacuum chamber for diagnostics has been designed. Among other important parameters (heat load, pressure, etc) this device shall monitor the spectrum of the low energy electrons bombarding the wall. In this contribution we report on the measurements of the spectrum of the low energy electrons bombarding the wall of the cold vacuum chamber in a room temperature region of the ANKA storage ring performed using a in house developed retarding field analyzer (RFA). The calibration of the RFA performed at the national laboratories of Frascati is also described.
IMP, Lanzhou
The vacuum system of HIRFL is a large and complex system. HIRFL consists of two ECR ion sources, a sector focus cyclotron (SFC), a separate sector cyclotron (SSC) and a multipurpose cooling storage ring system which has a main ring (CSRm) and an experiment ring (CSRe). Several beam lines connect these accelerators together and transmit various heavy ion beams to more than 10 experiment terminals. According to the requirements of the ion acceleration and ion lifetime, the working pressure in each accelerator is different. SFC is nearly 50 years old. After upgrade, the working pressure in SFC is improved from 10E-6mbar to 10E-8mbar. The pressure in SSC which was built in 1980s reaches the same level. The cooling storage ring system with a length of 500m came into operation in 2007. The average pressure in CSRm and CSRe is 5E-12mbar and 8E-12mbar respectively. Different designs were adopt for vacuum system of dozens beam lines to meet various experiment terminals requirement. For instance, some shockproof measures have to be taken for the heavy ion microbeam facility. A clean and large throughput differential pumping system was built for the Gas-filled Recoil Separator and so on.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The vacuum system of CELLS is in the installation stage. The booster vacuum chambers have been assembled and baked out in a provisional laboratory ex-situ in the ALBA building and in less than two months (starting from February) all the booster vacuum system was installed inside the tunnel and under vacuum. All the storage ring vacuum chambers have been delivered and ready for installation, several chambers were tested at CELLS (tests include vacuum tests, dimensional check, magnetic permeability tests etc). All the tools needed for the assembly of the storage ring vacuum chambers have been delivered and tested at CELLS to validate the assembly procedure. Concerning the standard vacuum components; all the gauges and residual gas analyzers were delivered, all the ion pumps and controllers are at CELLS, the NEG pumps, leak detectors, roughing stations and the UHV valves were delivered too.
NSRRC, Hsinchu
National Synchrotron Radiation Research Center (NSRRC) will build a new 3GeV, 400mA synchrotron accelerator machine. Several different IDs have been proposed and the corresponding front ends are designed. Beam lines of IU20, IU28, SW48 and EPU70 will be the phase I requirement. Due to different power load and density flux, fixed masks, photon absorber, slits, photon absorber and photon beam position monitor will all be customized to meet the beam line user requirements as well as the thermomechanical limits. Overall front end layout, analysis results of the high heat load components are illustrated; experiments of photon beam position monitor, front end pressure distribution due to thermal and photon stimulated desorption outgassing analysis, are also presented in this paper.
NSRRC, Hsinchu
Front End (FE) is the first area shapes radiation power to suit the need not only for protection but also for the beam line uses. About 14m long FE vacuum system will connect the ultra high vacuum (UHV) storage ring and beam line in Taiwan Photon Source (TPS). The Fixed mask (FM), photon absorber (PAB) and slit are the major high gas load components, especially in insertion Devices (ID) front ends, because of the synchrotron radiation. From the P(pressure)=Q(outgas)/S(pump) formula, there are some issues will be concerned to get lower vacuum pressure: The low outgassing rate of the vacuum chamber (Qthermal), the localization of the the pumps (IP and NEG) to pump down the outgassing of the photon simulated desorption(Qpsd), and the arrangement of the aperture and gas load . The basic pressure distribution of the bending magnet (BM) and ID front ends will be discussed.
KUK, Abha
KACST, Riyadh
MPI-K, Heidelberg
Cockcroft Institute, Warrington, Cheshire
At the National Centre for Mathematics and Physics (NCMP), at the King Abdulaziz City for Science and Technology (KACST), Saudi Arabia, a multi-purpose low-energy experimental platform is presently being developed in collaboration with the QUASAR group. The aim of this project is to enable a multitude of low-energy experiments with most different kinds of ions both in single pass setups, but also with ions stored in a low-energy electrostatic storage ring. In this contribution, the injector of this complex is presented. It was designed to provide beams with energies of up to 30 kV/q and will allow for switching between different ion sources from e.g. duoplasmatron to electrospray ion sources and to thus provide the users with a wide range of different beams. We present the overall layout of the injector with a focus on its mechanical and ion optical design.
LAL, Orsay
IN2P3 IPNL, Villeurbanne
HU/AdSM, Higashi-Hiroshima
KEK, Ibaraki
CERN, Geneva
One of the main challenges for the future linear colliders projects (ILC and CLIC) is to design an efficient positron source taking into account the constraints imposed by the target heating. At present, different schemes have been analysed to produce high energy gammas and to convert them in an amorphous target. One of them considers the possibility to boost the energy of the backscattered photons of a laser pulse by Compton effect. This method is very attractive since the source is independent from the main Linac and since the photon helicity is conserved in Compton scattering and subsequently transferred to the produced pairs. This allows the physics experiments disposing of both positron and electron polarised sources. Different schemes have been proposed to provide the electron beam for the Compton collisions. taking into account the constraint imposed by the low value of the Thomson cross section. One of the explored possibilities is to design an ERL with relatively low repetition frequency, high charge per pulse and then to stack the produced positrons in an accumulation ring. Different considerations on this scheme will be illustrated and the main constraints discussed.
BNL, Upton, Long Island, New York
Funding: US DOE Office of Basic Energy Sciences
This paper will describe the requirements, the design and the prototype test results of the magnets for the new synchrotron radiation source NSLS-II now under construction at BNL. Several innovations have been incorporated in the design, in manufacturing and in the alignment procedures of the magnets. Prototypes of these magnets have been built in industry. A dipole design has been developed with a maximized magnetic length which is longer than the mechanical length. The quadrupole and sextupole magnets of NSLS-II must be aligned and positioned to better than 30 microns, a level never achieved before in such accelerators. The paper will present a brief status of the progress made in the techniques developed to measure and achieve these demanding requirements. Another concern has been the distortion of field quality due to the small (150 mm) axial spacing between the iron-yoke of two adjacent magnets. Calculations (in 3-D) and the result of systematic measurements of the field quality in the presence of other magnets and other machine components in close proximity will be presented.
BNL, Upton, Long Island, New York
A new 3rd generation light source (NSLS-II project) is in the early stage of construction at Brookhaven National Laboratory. The NSLS-II facility will provide ultra high brightness and flux with exceptional beam stability. It presents several challenges in the diagnostics and instrumentation, related to the extremely small emittance. In this paper, we present an overview of all planned instrumentation systems, results from research & development activities; and then focus on other challenging aspects.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The Dampy cavity, operating at 500 MHz and up to 160 kW, normal conducting HOM damped, will be used in the ALBA storage ring. The pre-series has shown two problems. First, the HOM damping is very efficient but for one mode. The longitudinal impedance of the E011 mode was found to be around 11 kΩ, slightly above ALBA stability threshold. Second, overheating close to the dampers flanges induces a vacuum leak after several thermal cyclings. The maximum achieved operational dissipated power is 40 kW, if power is further increased a leak opens at one of the dampers flanges. In order to alleviate this latter drawback, two modifications have been implemented in two different cavities. The pre-series has been provided with short-circuits bridging waveguide ridges and cavity body. These are supposed to decrease the current in the area of the flanges. The first production cavity features a reduced thermal impedance between the water cooling channels and the area of overheating by replacing stainless steel by copper in the critical area. Both these cavities are currently under test and this paper will show the results.
ANL, Argonne
Funding: U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
Work is underway to improve the reilability and power handling capability of input couplers used in the Advanced Photon Source single-cell and five-cell cavities. Coupler performance during conditioning in a test cavity suggests that ceramic material defects and field enhancement caused by a mechanical gap in the coupler design may be responsible for past coupler failures at high power. Simulation results and high-power test data will be discussed.
ANL, Argonne
Funding: U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
An investigation into development of a 200-kW CW solid state rf power system design to replace the existing klystron-based 352-MHz rf systems at the Advanced Photon Source has been started. The baseline 352-MHz solid state system design will consist of multiple 1-kW CW modules combined to produce a total output capability of 200-kW CW, sufficient to drive one single-cell storage ring cavity. A description of the 1-kW CW module building block of the solid state power sistem will be presented, along with results from hardware evaluation tests at the 1-kW CW level.
KEK, Ibaraki
Four klystron power supplies that can provide a typical voltage of 40kV (current 8A) are used for the PF storage ring at High Energy Accelerator Research Organization (KEK). The original power suplies were fabricated during 1979-1987. Although the power supplies have been operated well, we anticipate some difficulty in maintaining them in future. Then, we planned to renew them by stages. As the first step, we renewed one of the power supplies in 2003. The renewed power suplly have been operated well without any trouble. As the second step, we updated another power supply in the summer of 2008. The renewed power supply is equipped with a solid-state high-voltage (HV) switch that is made of insulated gate bipolar transistors (IGBT) for klystron protection. The renewed power supply have been operated well from September, 2008. We report the performance of the new power supply.
PAL, Pohang, Kyungbuk
Funding: Supported by the Korea Ministry of Science and Technology mhchun@postech.ac.kr
The RF system for the Pohang Light Source (PLS) storage ring is operating at total maximum RF power of 300kW with four 75kW klystron amplifiers and four PF-type normal conductivity(NC) RF cavities for 190mA at 2.5GeV. The PLS will be upgraded from 2.5GeV/200mA to 3.0GeV/400mA in the near future. Therefore the RF system should be greatly upgraded to supply total 627kW beam power. We are investigated the some upgrade ways with adding NC cavities or new super conductivity(SC) RF cavities. According to the cavity type, the high power RF system will be adjusted the total RF power, and source type and quantity such as klystron or IOT. This paper describes the present operation status and several optional ways of high power RF system for the upgrade project of PLS storage ring
ELETTRA, Basovizza
The full energy injection is now the standard procedure for the Elettra synchrotron radiation light source. The four RF storage ring plants have been benefited by this procedure in terms of reliability and stability of operation. The injector booster RF plant is running well. A new High Order Mode (HOM) diagnostic board has been implemented using the radiofrequency (RF) cavity’s signal to improve the HOM’s detection. The analysis and the performances of the new Inductive Output Tube (IOT)based RF power transmitter are presented.
SESAME, Amman
Funding: SESAME (Synchrotron light-source for Experimental Science and Applications in the Middle-East) Allan, Jordan
The SESAME (Synchrotron light source for Experimental Science and Applications in the Middle-East) accelerator consists of a 22MeV Microtron, an 800MeV booster synchrotron and a 2.5GeV storage ring. Each accelerator has its own RF system. The Microtron RF frequency is 3GHz generated by a 2MW pulsed Magnetron while the booster and storage ring have a common 500MHz CW RF source. The Booster RF system consists of a DORIS cavity fed by a 2kW CW solid-state RF amplifier but the storage ring (SR) RF system has been designed based on four 500 MHz plants, each comprising a normal conducting (NC) single-cell cavity , powered with 140 kW (CW) by two combined 80kW IOTs to have maximum possible RF power in the cavity via a WR1800 waveguide line. In the initial phase, it has been decided to start with two ELETTRA type cavities and in final phase, four cavities will be accommodated in one straight section in the storage ring to have nominal energy and current in the machine. This paper presents status of installed Microtron RF system and modified booster RF system from BESSY I, as well as designed SESAME storage ring high power RF system and low level electronics.
Ankara University, Faculty of Sciences, Tandogan/Ankara
The Turkish Accelerator Complex (TAC) is a project for accelerator based fundamental and applied researches supported by Turkish State Planning Organization (DPT). The proposed complex is consisted of 1 GeV electron linac and 3.56 GeV positron ring for a charm factory and a few GeV proton linac. Apart from the particle factory, it is also planned to produce synchrotron radiation from positron ring. In this study the lattice structure design of the positron storage ring is made to produce the third generation synchrotron light. The parameters of complementary undulators and wigglers are determined. It is shown that the insertion devices with the proposed parameter sets produce maximal spectral brightness to cover 10 eV - 100 keV photon energy range.
BESSY GmbH, Berlin
PTB, Berlin
The Metrology Light Source (MLS)* is in user operation since April 1st, 2008. It is the first storage ring designed and built for operation in the low α mode, which relies on the control of higher order terms of the momentum compaction factor α with respect to the momentum deviation dp/p, α=a0+a1*dp/p+a2*(dp/p)**2. The a0 term is controlled by quadrupoles, a1 by 3 families of sextupoles for controlling the chromaticity in the transverse and longitudinal planes, the a2 term is controlled by an octupole family. The a0 value can be varied by more than a factor of {10}00. The low α mode is also called 'isochronous' operation, it is used for short bunch operation, where intense signals of coherent sub-THz radiation are produced. We report on operation experience of this scheme.
*R. Klein et al., 'Operation of the Metrology Light Source as a primary radiation source standard',
PHYSICAL REVIEW SPECIAL TOPICS - ACCELERATORS AND BEAMS 11, 110701 (2008).
BNL, Upton, Long Island, New York
BESSY GmbH, Berlin
The NSLS-II is a state of the art 3 GeV synchrotron light source that is being developed at BNL. The 9.3 meter long injection straight section of NSLS-II storage ring currently fits a conventional injection set-up that consists of four kickers producing a closed bump together with a DC septum and a pulsed septum. In this paper we analyze alternative options based on: a) injection via a pulsed sextupole and b) injection with a Lambertson septum. We discuss dynamics of the injected and stored beams and, consequently, magnet specifications and tolerances. In conclusion we summarize advantages and drawbacks of each injection scheme.
BNL, Upton, Long Island, New York
Vibration stability in third generation light sources such as the 3 GeV NSLS II under construction at BNL and which are aiming at high brightness and extremely small photon beam sizes is paramount. Movement of the magnetic elements of the accelerator lattice, and in particular when uncorrelated, will induce jitter in the beam and degrade the machine performance. The accelerator lattice response is coupled with the ring structure which in turn interacts with the site and the ground vibration field that characterizes it. Therefore, understanding this dynamic coupling between the accelerator ring structure and the site and the “filtering” effect of the interaction on both the amplitude and the spectral characteristics of the ground vibration is central towards establishing the response of the lattice. In this study, the site-ring dynamic interaction is evaluated based on the NSLS II design and site conditions using a state-of-the-art 3-D wave propagation and scattering analysis model. The study is augmented with an extensive array of measurements at the selected site as well as field studies at similar operating light source facilities.
CLS, Saskatoon, Saskatchewan
Coherent Synchrotron Radiation (CSR) is produced when short bunch lengths are set up in the Canadian Light Source storage ring. To achieve short bunches large negative dispersion is introduced into the straight regions of the lattice such that the momentum compaction can be made to approach zero. In this way CSR has been observed using a few single bunches with currents up to 10 mA per bunch at the nominal operating energy of 2.9 GeV. Attempts produce CSR with low bunch currents in many bunches were unsuccessful at 2.9 GeV. At 1.5 GeV, however, it is possible to achieve CSR with a total of 5 mA stored in over 70 bunches. CSR production is enhanced by operating at a horizontal tune where the chromaticity can be kept near zero. Tracking simulations in longitudinal phase space indicate enhanced stability at tunes lower than the nominal tune. The optimum tune does not depend on the fractional tune but rather there is a tune "window" at the center of which stable longitudinal motion can be maximized.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
ALBA is the first 3rd generation synchrotron light source to be build in Spain. The project is in the process of installation, with the LINAC already commissioned, and the Booster and Storage Ring in the installation phase, and the building already completed. The Booster synchrotron is expected to be finish and commission by the end of summer 2009, and the storage ring commissioning should take place in spring 2010. Most of the major components are already delivered and tested in-house, among those the vacuum system, the magnets, the RF cavities, etc. In this paper, the status of the project and of the most relevant components is reviewed.
CLASSE, Ithaca, New York
Funding: Funding support from the National Science Foundation
X-ray beam production from a linac beam is investigated, especially emphasizing the optical matching flexibility that is possible with an external beam but not with a storage ring. Compared to existing storage ring light sources, a high energy linac (with or without recirculation) can produce monochromatic hard x-ray beams having comparable flux density, and far higher brilliance, than are available with existing storage rings. Full coherence and the possibility of diffraction limited focusing are preserved by avoiding the need for x-ray focusing mirrors.
FZK, Karlsruhe
The ANKA storage ring is filled at 0.5 GeV and then ramped to 2.5 GeV for regular user operation. A full-energy injection of the ANKA storage ring would have several advantages. The damping at a beam energy of 2.5 GeV is stronger, which will more efficiently fight instabilities during the injection, therefore allowing higher beam currents. With constant magnet settings, the orbit stability would improve significantly. The injection time would be reduced and topping- up operation would become possible. As a consequence, the optical elements of the user beamlines would see a constant power as a function of time which further enhances the overall stability. In this paper, a design for a full energy injector is proposed. The injector will be located inside the storage ring tunnel, similar to the SLS and ALBA design. The focusing is mainly provided by combined function magnets. The full energy injector has a design emittance of 40 nmrad and a circumference of 94.8 m. A modification of the existing storage ring is foreseen to house the necessary more powerful injection elements.
FZK, Karlsruhe
Ruhr-Universität Bochum, Bochum
KIT, Karlsruhe
HZB, Berlin
DLR, Berlin
PTB, Berlin
BESSY GmbH, Berlin
Funding: This work has partly been supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320.
In synchrotron radiation sources coherent radiation is emitted when the bunch length is comparable to or shorter than the wavelength of the emitted radiation. A detector system based on a superconducting NbN ultra-fast bolometer with an intrinsic response time of about 100 ps jointly developed by the University of Karlsruhe (Institute of micro- and nanoelectronic systems) and German Aerospace Center (Berlin) was used to resolve the radiation emitted from single bunches. This paper reports the observations made during measurements at the MLS and ANKA storage rings.
FZK, Karlsruhe
Ruhr-Universität Bochum, Bochum
KIT, Karlsruhe
A linac based coherent radiation source in the THz to mid-IR range is proposed. The TBONE machine will deliver pulses of radiation as short as a few fs in the frequency range from 0.1 to 150 THz with up to MW peak power. This combination of parameters will open up unprecedented opportunities in THz and infrared applications, such as e.g. microscopy or spectroscopy. This paper presents the main parameters and design considerations. Special emphasis is put on the study of suitable bunch compression and beam transport schemes.
HZB, Berlin
FhG, Euskirchen
PTB, Berlin
The 0.6 GeV storage ring Metrology Light Source (MLS) is in operation since April 2008. Recently, Cherenkov glass fibers have been installed for a temporal and spatial detection of electron beam losses. Based on this information the loss mechanisms can be studied in detail and the performance of the machine can be optimized. First experiments with this diagnostic tool will be presented.
JASRI/SPring-8, Hyogo-ken
An ultra-low emittance storage ring with an energy of 6 GeV was proposed as a next generation synchrotron radiation source*. The storage ring has the same circumference as that of SPring-8 storage ring so as to be able to replace the existing storage ring, but has not four long straight sections. Accordingly, the storage ring beam line is slightly different from that of 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 designed. The beam line position of the new storage ring is the same as the existing one. 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 less than 100 pm-rad. In the paper, the dynamic aperture problem is discussed and the other ring characteristics are presented.
*K. Tsumaki and N. Kumagai, EPAC’06, 3362.
LBNL, Berkeley, California
Funding: This work was supported by the Director, Office of Science, U. S. Department of Energy under Contract No. DE-AC02-05CH11231.
The upgrade of the Advanced Light Source to enable top-off operation has been ongoing for the last four years. Activities over the last year have centered around radiation safety aspects, culminating in a systematic proof that top-off operation is equally safe as decaying beam operation, followed by commissioning and full user operations. Top-off operation at the ALS provides a very large increase in time-averaged brightness to ALS users (by about a factor of 10) as well as improvements in beam stability. The presentation will provide an overview of the radiation safety rationale, commissioning results, as well as experience in user operations.
FEL/Duke University, Durham, North Carolina
BINP SB RAS, Novosibirsk
Funding: This work is supported by the US DoE grant #DE-FG02-01ER41175
A booster-injector synchrotron has been recently built and commissioned at Duke University to provide for the top-off injection into the storage ring in the energy range of 0.24 - 1.2 GeV. Booster injection kicker was designed with a pulse length of 18 out of 19 booster separatrixes, assuming a long train of electron bunches to be injected from the existing linac. Such scheme required a major linac upgrade from single bunch photo emission mode to a multibunch thermionic mode. A major disadvantage of the latter was much higher radiation levels in the facility. Since commissioning, the booster could only operate with one or two bunches limited by both long kicker pulse and single bunch injection from the linac. The consequent limitation of the injection rate restricted the capability of production of the Compton gamma rays in the loss mode, i.e. production of gammas with energy above 20-25 MeV, to about 5*108 photons per sec. Update of the linac for the repetition rate of up to 10 Hz, and modification of the injection kicker for 15 nS pulse length allowed us to developed an alternative multibunch injection scheme with a significant increase of the injection rate into storage ring.
FEL/Duke University, Durham, North Carolina
Funding: This work is supported by US Air Force Office of Scientific Research medical FEL grant FA9550-04-01-0086.
The paper presents a novel technique of measuring the gain of a storage ring based FEL oscillator. As opposed to the conventional technique of measuring the FEL gain from its macro-pulse envelope, this new technique is based upon the measurement of pass-by-pass FELμpulses. To record the growth of the optical energy in the FEL micro-pulse train, we use fast photo-diodes and photo-multiplier tubes (PMTs). PMTs are usually employed at the very beginning of the FEL lasing development, while the photodiodes are used at the latter stages when the FEL power is fully developed and saturated. This new gain measurement technique provides a powerful tool to study the details of the FEL gain process starting from spontaneous radiation to saturation. It allows us to investigate five to seven orders of magnitude of the FEL energy growth. As fast photo-detectors with a sub-nanosecond time response become available, this new technique can be adopted for many oscillator FELs, including those driven by super-conducting linacs. Special attention is paid to the dynamic non-linearity issues of the photodiodes and PMTs associated with short length of FEL pulses.
FEL/Duke University, Durham, North Carolina
Funding: This work is supported by US Air Force Office of Scientific Research medical FEL grant FA9550-04-01-0086 and US Department of Energy grant DE-FG02-01ER41175.
The Duke Free-Electron Laser Laboratory (DFELL) operates several accelerators as a driver for storage ring based Free-Electron Lasers (FELs) and Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS). The HIGS is the most powerful Compton gamma-ray source in the world below 100 MeV. Since completing a major upgrade of the HIGS in 2007, the Duke storage ring FEL and HIGS gamma source have been operated extensively for user research programs. In 2008, the DFELL was merged with the Triangle Universities Nuclear Laboratory (TUNL) to become a major accelerator facility of the TUNL. 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 light source research and development, in particular, the FEL research and Compton light source 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.
ANL, Argonne
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Circular Polarizing Undulator (CPU) had been used for about 10 years at the APS to generate X-rays with variable polarization (circular and linear) switching at rates up to 10 Hz. The CPU consists of two main coils with maximal currents 1600A (about 30kW power) and 400A (4kW power) and seven additional correcting coils. Aging and obsolescence of some of the CPU PS critical components resulted in deterioration of its performance and elevated maintenance. To resolve the issue and to comply with the new requirements for the beam stability at the APS storage ring, the new PS and control electronics for the CPU have been proposed. The new 8-channel Arbitrary Function Generator generating unique complex waveforms for the correctors to minimize orbit distortion during the main coils PS switching will also be discussed in this paper.
ANL, Argonne
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The APS storage ring uses DC/DC converters to power the magnets. High resolution for current regulation is desired for future improvement. It is calculated that at least 20- to 21-bit digital pulse width modulation (DPWM) is required in the proposed digital control system. This paper proposes a digital control system that adopts a new DPWM topology to achieve 21-bit DPWM without gigahertz system clock. The proposed topology uses a combination of a field-programmable gate array (FPGA) and a serializer chip TLK2541 from TI. The FPGA calculates the desired PWM signals and sends them to the TLK2541 chip. Then, the TLK2541 generates corresponding high-resolution DPWM pulses. An FPGA development board has been used to develop a prototype system to verify the proposed DPWM generation topology. This paper discusses the circuit topology and the experiment results.
ELETTRA, Basovizza
The New Full-Energy Injector at Elettra, based on a 3 Hz, 100 MeV to 2.5 GeV booster has officially started its operations since March 2008*. The time schedule was fully respected notwithstanding the performance problems presented by some of the main magnet power supplies**. The refurbishing plan, formally started at the end of the commissioning phase and carried on together with the manufacturer, has brought positive results in approaching the required specifications. The paper will describe the progress of the refurbishing and the experience with the other magnet power supplies, including the positive performances of the in-house low-current (5A) bipolar power supplies, especially designed for the linac pre-injector***. A new version, fully digitally controlled, of these low-power power supplies will be adopted for some coils and magnets of the FERMI@Elettra project.
*M. Svandrlik, Status of the Elettra Booster Project, EPAC08
**R. Visintini, Magnet power converters for the Elettra Booster, EPAC08
***D. Molaro, A new bipolar PS for the Elettra booster, PCIM08
Fermilab, Batavia
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Since 2005, the Recycler has become the sole storage ring for antiprotons used in the Tevatron Collider. The operational role of the Antiproton Source has shifted exclusively towards producing antiprotons for periodic transfers to the Recycler. The process of transferring the antiprotons from the Accumulator to the Recycler has been greatly improved, leading to a dramatic reduction in the transfer time. The reduction in time has been accomplished with a net improvement in transfer efficiency and an increase in average stacking rate. This paper will describe the software improvements that streamlined the transfer process and other changes that contributed to a significant increase in the number of antiprotons available to the Collider.
NSRRC, Hsinchu
National Tsing Hua University, Hsinchu
The Taiwan Photon Source (TPS) is a new 3 GeV synchrotron light source to be built at the National Synchrotron Radiation Research Center (NSRRC) in Taiwan. The design of TPS is aimed to provide a low-emittance and high-brilliance beam with operation in the top-up mode. In this paper we present the design of the TPS injection section and the transport line from booster to storage ring. The specifications and parameters of the septa, kickers, and ceramic chambers are also described.
FEL/Duke University, Durham, North Carolina
SLAC, Menlo Park, California
Funding: *Work supported by US Air Force Office of Scientific Research medical FEL grant FA9550-04-01-0086 (YKWu).
Touschek scattering is the dominant loss mechanism for the electron beam in a low energy storage ring with a large bunch current. The Duke Free-Electron Laser (FEL) storage ring typically operates in the one-bunch or two-bunch mode with a very high bunch current and a varying electron beam energy as low as 250 MeV. The study of the Touschek lifetime is important for improving the performance of the Duke storage ring based light sources, including the storage ring FELs and a FEL driven Compton gamma source, the High Intensity Gamma-ray Source. This work reports our lifetime measurement results for few-bunch operation of the Duke storage ring. The Touschek loss rate is reduced when an electron beam is polarized in the storage ring. The change of the Touschek lifetime can be used as a method to monitor polarization of the electron beam. In this work, we will also report our preliminary results of the electron beam energy measurements using the resonant depolarization technique.
NSRRC, Hsinchu
The correction power supplies are working in the storage ring of NSRRC. They are required to output high quality and high performance current that is long-term stability and output current ripple are required to be under 100ppm. The storage ring consists of more than one hundred units of independence power supplies working together when beam current in 1.5GeV status. The power supplies also are all working under current mode. We just build a new conduction EMI (Electromagnetic Interference) and EMC (Electromagnetic Compatibility) measurement laboratory to measure and test the switching power supplies. That is AC to DC voltage bus source to supply for the switching correction power supply. Using the LISN to obtain conduction noise, it is high frequency voltage noise generated by the switching mode of power supply conduction noise. The current signal pass AC source impendence stabilize network LISN and spectrum analyzer will obtain the conduction noise. We can use a noise separator to separate common EMI noise and difference-mode EMI noise for EMI filtering design. The measurement result will be illustrated in the paper.
BESSY GmbH, Berlin
HZB, Berlin
The Metrology Light Source (MLS) is in user operation since April 2008 working at energies ranging from {10}5 MeV up to 630 MeV, operating currents from a single electron up to 200 mA and different values for the momentum compaction factor. In parallel to machine commissioning, an automated finite state machine has been developed. This code knows, controls and coordinates a broad manifold of machine states and meanwhile has been evolved to an automated operator acting by itself on demand of a few high level commands. Actions range from plain device I/O to complex transactions including filesystem operations and multiple device I/O. The aim is to always keep machine and control system in a well-defined state. We describe the program and report on the experience with the automated operation using this application.
USTC/NSRL, Hefei, Anhui
FEL/Duke University, Durham, North Carolina
Funding: Work supported by US Air Force Office of Scientific Research medical FEL grant FA9550-04-01-0086 (YKWu), also supported by National Natural Science Foundation of China (No.10175062 and 10575100).
Many modern light source storage rings use a basic magnetic lattice structure consisting of a number of repetitive periodic lattice block, the super periods. The study of one super-period can reveal the dynamical proprieties of the storage ring. Unlike the traditional approach of studying the one-turn map of the storage ring, the work focuses on the study of a super-period lattice, which allows us to gain new insight into the storage ring dynamics using a simpler magnetic structure. In this paper, both analytical and numerical techniques, including Lie Algebra and Normal Form, and particle tracking and frequency analysis, are used to study the nonlinear dynamics of one super-period of a standard double-bend achromat (DBA) and triple-bend achromat (TBA) with two or more nonlinear elements (e.g. sextupoles). The relationship between the super-period dynamics and storage ring dynamics is explored in terms of the global lattice tuning and local lattice selection for straight sections.
H. Hao is currently working as a visiting scholar at Duke University Free Electron Laser Laboratory.
LBNL, Berkeley, California
Funding: Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
ALS has been upgraded by adding Top-Off Mode, a new mode of operation to the existing modes of Fill and Stored Beam. The Top-Off Mode permits injection of 1.9GeV electron beam into the Storage Ring, with the safety shutters open, once certain strict conditions are met and maintained. Top-Off Mode enables User operation without an interruption caused by mode switching between the Stored Beam Mode when safety shutters are open, to the Fill Mode with the safety shutters closed and back. The conditions necessary to permit Top-Off Mode are; stored beam is present, the energies are matched between the injector and storage ring, a select set of storage ring lattice magnets are operating at the correct current levels, and radiation losses are minimized. If certain combinations of these conditions are not met, a potentially dangerous condition of injecting electrons down a users beam line can exist. Therefore a system of mode control, energy match, lattice match and stored beam interlocks are needed to control the injected beam prohibiting potentially dangerous conditions. In this paper we will present the Top-Off Mode Beam Interlock system requirements, design, and operational parameters.
BINP SB RAS, Novosibirsk
RRC, Moscow
The project of upgraded RF System of Siberia-2 Electron Storage Ring / SR Source, Moscow, Russia, is presented. The upgraded RF system will allow to increase the total accelerating voltage up to 1.8MV and ensure operation of the storage ring with new superconducting wiggler at beam currents up to 0.3A. RF system operates at 181MHz. It consists of 3 single bi-metal cavities, 2 power amplifiers based on GU-101A tetrodes with output power of 200kW, power transmission lines and control system. Parameters of the upgraded RF system are given, the design of its main elements is shown.
SINAP, Shanghai
SSRF, Shanghai
RF system for SSRF (Shanghai Synchrotron Radiation Facility) Storage Ring consists of three RF stations, each of which has a klystron, one superconducting RF module and its low level RF feedback control. A 300kW klystron will feed the RF power to the superconducting cavity via a circulator and waveguides. Three CESR type 499.654MHz superconducting modules with tuning range ±150kHz are now in operation. A digitalized I/Q technology based on FPGA is adopted in its low level control. The commissioning and the performance of whole RF system will be described in details in this paper.
ASCo, Clayton, Victoria
RF cavities are routinely detuned slightly from resonance to maintain Robinson stability of the beam as beam loading increases. Detuning the cavities results in a reduction of the overall energy efficiency of the RF and can waste many MW hours of energy per year. It is therefore desirable to only detune as much as required by the beam loading to maintain stability. A new system for monitoring the load impedance of the Storage Ring RF cavities has been developed at the Australian Synchrotron. The system utilises the Analogue devices AD8302 chip to monitor the load impedance of the Cavities and allow for more efficient detuning of the system. An overview and commissioning results of this system will be presented.
NSRRC, Hsinchu
The booster design of Taiwan Photon Source(TPS) has been significantly revised. Therefore, the transfer line from linac to booster(LTB) and the one from booster to storage ring(BTS) have been redesigned accordingly. The design of LTB transfer line has been simplified to reduce the number of magnets. The length of BTS transfer line has been greatly reduced. The design goal of transfer lines is to achieve high efficiency for beam injection. The status of current progress will be reported.
NSRRC, Hsinchu
A superconducting accelerating RF cavity is going to be installed in 3GeV Taiwan Photon Source (TPS). It causes a reduction in bunch length in contrast with operation of normal type of RF cavity. A higher harmonic RF cavity is usually considered as an important tool to control the bunch length in the storage rings. The harmonic cavity in lengthening mode can also be helpful for improving the lifetime which is usually dominated in the storage rings by large angle intrabeam scattering (Touschek). In this paper we study the effects of third active harmonic cavity on bunch length of the TPS ring. We present the procedure, the simulation and the formulae to analyze the effects of third harmonic cavity on the rms bunch length while the main superconducting RF system is operated in 3MV. It is shown that the longitudinal rms electron bunches will lengthen up to 7.9 times for the optimum operation of the harmonic system.
PSI, Villigen
Recently the energy acceptance and Touschek lifetime of the storage ring of the Swiss Light Source (SLS) could be successfully set to values in agreement with simulations for an ideal lattice. This was finally achieved through control of linear coupling and symmetrization of the sextupole pattern. 36 small corrector magnets were installed for this purpose as additional windings on the ring sextupoles: 30 skew quadrupoles (24 at zero and 6 at maximum dispersion) and 6 auxiliary sextupoles. Base for the success of these measures were previous corrections of dipolar and quadrupolar errors, which we will summarize briefly.
PSI, Villigen
CANDLE, Yerevan
Recently tentative top-up operation of the Swiss Light Source (SLS) storage ring at low momentum compaction factor has been started. We will present an analysis of the longitudinal dynamics and simulations of the injection process, and explain our method to ensure closed orbit stability. First experimental results will be shown and compared to the model predictions.
PTB, Berlin
HZB, Berlin
The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute is operating the low-energy electron storage ring Metrology Light Source (MLS) in Berlin-Adlershof in close cooperation with the BESSY GmbH. The MLS is designed and prepared for a special machine optics mode (low-alpha operation mode) based on a sextupole and octupole correction scheme, for the production of coherent synchrotron radiation in the FIR and THz region. At the MLS two bending magnet beamlines dedicated to the use of IR and THz synchrotron radiation were built. An IR beamline optimized for the MIR to FIR is now in operation. First measurements at this beamline showed the potential of the MLS as a source of THz radiation*. However, the propagation of sub-terahertz electromagnetic waves from the source point to the experiment through such a typical IR beamline is strongly affected by diffraction. This is why we decided to build a dedicated THz beamline with larger extraction optics. We present first results from the commissioning of the dedicated THz beamline.
*R. Müller et al., Proc. of EPAC08, 2058 (2008)
SAGA, Tosu
Kyoto IAE, Kyoto
The procedure of accelerator modeling using orbit response matrix fitting is well known and widely adopted at many light sources, we also examined the model fitting to diagnose optics and to restore the periodicity of the storage ring optics. In the modeling procedure we used the tracking code TRACY2, because it can calculate the orbit response matrix including energy offset caused by the dipole kick. The multi-parameter fitting was carried out by using SVD algorism implemented in the Labview mathematical package. In the fitting procedure, we fixed a steering magnet field to the value obtained from the orbit measurement using screen monitor to avoid explicit solution between the steering strengths and the BPM gains. By adopting the orbit response matrix fitting, it was found that the quadrupole strength is about 3-5% larger than the calculated value obtained from magnetic measurement data and output current of the power supply. In the conference, we will report on the result of the modeling procedure and its application to the optics correction.
SAGA, Tosu
SAGA Light Source (SAGA-LS) is a 1.4 GeV synchrotron light source consisting of an injector linac and a storage ring of 75.6 m circumference. The SAGA-LS has been routinely operated with low emittance of 25 nm-rad since its official opening in February 2006. Machine improvements, including upgrades on the control system and grid pulsar for the injector linac, construction of a new septum magnet and beam monitor systems, and current increase from 100 to 200 mA, have been made in the past years. Along with the accelerator improvements, installation and development of new insertion devices have started. The SAGA-LS ring has six 2.5-m long straight sections available for insertion devices. A planar type undulator of Saga University is in operation. In addition, an APPLE-2 type undulator producing variably polarized light has been installed during the winter shutdown of 2008. In order to address user demand for high flux hard x-rays, design of a superconducting wiggler is under discussion. Construction of an experimental setup to produce MeV photons by the laser Compton scattering is in progress, preparing for precise beam energy measurement and user experiments in future.
SLAC, Menlo Park, California
Stanford University, Stanford, California
UCLA, Los Angeles, California
Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
SSRL and SLAC groups are developing a long-range plan to transfer its evolving scientific programs from the SPEAR3 light source to a much higher performing photon source that would be housed in the 2.2-km PEP-II tunnel. While various concepts for the PEP-X light source are under consideration, including ultimate storage ring and ERL configurations, the present baseline design is a very low-emittance storage ring. A hybrid lattice has DBA or QBA cells in two of the six arcs that provide a total ~30 straight sections for ID beam lines extending into two new experimental halls. The remaining arcs contain TME cells. Using ~100 m of damping wigglers the horizontal emittance at 4.5 GeV would be ~0.1 nm-rad with >1 A stored beam. PEP-X will produce photon beams having brightnesses near 1022 at 10 keV. Studies indicate that a ~100-m undulator could have FEL gain and brightness enhancement at soft x-ray wavelengths with the stored beam. Crab cavities or other beam manipulation systems could be used to reduce bunch length or otherwise enhance photon emission properties. The present status of the PEP-X lattice and beam line designs are presented and other implementation options are discussed.
SLAC, Menlo Park, California
Funding: Work sponsored by U.S. Department of Energy Contract DE-AC03-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.
Recent experimental results and advances in the theory of short-bunch dynamics have lead to an improved understanding of the parameters and limitations of short-bunch operation in storage rings. In this paper the measurement and analysis of short bunches under a variety of operational parameters is reported for SPEAR3.
SOLEIL, Gif-sur-Yvette
After two years of operation, the SOLEIL 3rd generation synchrotron light source is delivering photons to 20 beamlines with a current of 250mA in multibunch or hybrid modes, and 60 mA in 8 bunch mode. The radiation control of the beamline hutches is performed at 300 mA, but recently a 455mA current was stored during machine tests following the installation of the second RF cryomodule. It is foreseen to reach the maximum current of 500mA in the early 2009 and to operate in top-up mode from then on. The new transverse feedback loop has enabled to improve the performance of the single bunch and multibunch beams. The beam position stability is in the range of few micrometers thanks to the efficiency of the fast orbit feedback. Fifteen insertion devices are now installed in the storage ring, ten others are under construction, and a cryogenic undulator is under development. A big effort is being taken in order to compensate the effects of these insertion devices on the machine performance. The good operation performance achieved in 2007 (first year) has been improved in 2008 during which ~4 000 hours will have been delivered to the users with a 95.5% availability and a 30 hours MTBF.
SOLEIL, Gif-sur-Yvette
SESAME, Allan
SESAME is a 3rd generation synchrotron light source facility under construction in Allan, Jordan, 30 km North-West of Amman. SESAME consists of a 2.5 GeV storage ring, a 22.5 MeV Microtron and an 800 MeV Booster. The Microtron was installed at its final position and its subsystems have been successfully tested. The commissioning with beam of the Microtron will start in March 2009. The installation of the Booster is expected to take place in summer 2009. Most of the storage ring subsystems are ready for call for tender. The progress of SESAME project including beamlines status will be reported in this paper.
UVSOR, Okazaki
Nagoya University, Nagoya
Sokendai - Okazaki, Okazaki, Aichi
UVSOR, a 750 MeV synchrotron light source of 53m circumference, had been operated for more than 20 years. After a major upgrade in 2003, this machine was renamed to UVSOR-II. The ring is now routinely operated with low emittance of 27 nm-rad and with four undulators. The test run of the top up injection has been started. The latest result will be reported. By utilizing a part of the existing FEL system and an ultra-short laser system, coherent synchrotron radiation and coherent harmonic generation have been extensively studied, under international collaborations. A new program on the coherent light source developments has been started, which includes upgrades of the undulator and the laser system and a construction of dedicated beam-lines.
INFN/LNF, Frascati (Roma)
SLAC, Menlo Park, California
The SuperB collider project aims at the construction of an asymmetric high luminosity B-Factory in the Tor Vergata University campus in Rome (Italy). The engineering aspects of the SuperB design and construction with the aim to reuse at maximum the PEP II components will be presented. Sinergies with the Italian FEL project SPARX, which will start civil construction this year, will be discussed. The two projects can share the Linac tunnel and other facilities. A study of ground motion will also be presented.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
The goal of a Neutrino Factory is to generate intense beams of neutrinos from muon decay inorder to study CP violation in the Standard Model, the mass hierarchy, and the neutrino mixing angle θ13. Intense muon beams are created and accelerated in a system of particle accelerators to energies of 20-50 GeV. They are then allowed to decay in dedicated storage rings with long straight sections aligned on suitably chosen long-range detectors. A variety of geometries are possible, and their design and construction present demanding challenges for accelerator R & D, covering not only beam optics but touching on geological and engineering aspects of constructing almost vertical storage rings several hundred metres below the Earth's surface. The basic ideas are described in this paper and are demonstrated by three possible models developed in recent years.
UMAN, Manchester
The LHC Collimators are designed to remove halo particles such that they do not impinge onto either detectors or other vulnerable regions of the storage ring. However, the very high 7 TeV energy means that their design is critical, as is the modelling of the absorption, scattering and wakefield effects upon the passing bunches. Existing simulations are being performed using Sixtrack and K2. We compare these simulations with results obtained using the MERLIN code, which includes a fuller description of the scattering and wakefield processes.
NSRRC, Hsinchu
The TPS (Taiwan Photon Source) of NSRRC is in the design stage now. The grounding system is crucial to the safety issue, the electrical reference level, the electrical noise and the EMI problems. In order to provide a high quality electrical environment, the grounding system should be designed carefully. The soil resistivity of the construction site was investigated first. Many different configurations of the ground grid layouts were simulated and compared. Beside the horizontal ground-conductors, the vertical ground-electrodes of 30 m are considered to be installed below the ground surface and they will reach the ground water level in hopes of minimizing the resistance of ground grid. The main goal is to obtain a ground grid with resistance lower than 0.2 ohm. A rectangular ground grid will also be installed under the new utility building. It will be connected to the ground grid of TPS to further reduce the resistance of whole grounding system, and also to eliminate the potential difference between them.
NSRRC, Hsinchu
The air conditioning system for the 3.0 GeV Taiwan Photon Source (TPS) is currently under the design phase. This paper presents the latest design of the air conditioning system for the TPS. The capacity of the air handling unit (AHU), the dimension and layout of the wind duct were specified. Numerical analysis was applied to simulate the air flow and temperature distribution in one of 24 sections storage ring. A 1/12 experimental hall was also modelled. The air flow of this area was simulated.
NSRRC, Hsinchu
To cope with increasing power cost and to confront huge power consumption of the Taiwan Photon Source (TPS) in the future, we have been conducting several power saving schemes since 2006 in the National Synchrotron Radiation Research Center (NSRRC). Those power saving schemes include optimization of chiller operation, air conditioning system improvement, power factor improvement and the lighting system improvement.
BNL, Upton, Long Island, New York
For his outstanding contribution to the design and construction of accelerators that has led to the realization of major machines for fundamental science on two continents, and his promotion of international collaboration.
Diamond, Oxfordshire
Diamond Light Source, the UK's 3rd generation synchrotron light facility, became operational in 2007. We report here on a number of important recent developments, aimed at increasing its operational performance. In particular, we present our initial experience with regular top-up injection, which began at the end of October 2008, including its reliability and effect on beam stability. We also discuss the issues that have been faced in increasing the beam current to its design value of 300 mA. Diamond currently operates with 10 in-vacuum undulators with a specified initial minimum operating gap of 7 mm. We report on our efforts to understand and control the distribution of beam losses in the ring, in order to allow operation with gaps as small as the target value of 5 mm.
On behalf of the Diamond Machine Staff
PAL, Pohang, Kyungbuk
The Pohang Accelerator Laboratory (PAL) celebrated its 20th anniversary this year. After the completion of the Pohang Light Source (PLS) construction in 1994, the PLS started user service with two beamlines in 1995. The PLS energy was 2.0 GeV. The first major upgrade of the PLS had been done from 2000 to 2002, in which operation energy of the PLS was increased from 2.0 GeV to 2.5 GeV. The number of beamlines has been steadily increased since the start of user service. The number of beamlines currently in service is 28. Three beamlines are under construction. Number of users and performed experiments in 2007 were respectively 2553 and 837. Average impact factor of published papers is over 3.0, which is one of the best among Korean research institutes. Based on such success, the PAL is pursuing the second upgrade plan, called the PLS-II. The PLS will be upgraded its energy from 2.5 GeV to 3.0 GeV. With the upgrade, it will be possible to construct ten more insertion devices. The brightness of the PLS-II will be more than a order higher compared to the current PLS. In this presentation, details of the PLS-II project will be introduced.
This work was supported by the MEST (Ministry of Education, Science and Technology) and the POSCO (POhang iron and Steel making COmpany) in Korea.
FEL/Duke University, Durham, North Carolina
TUNL, Durham, North Carolina
Funding: This work is supported by US Air Force Office of Scientific Research medical FEL grant FA9550-04-01-0086 and by US Department of Energy grant DE-FG02-01ER41175.
Since 2008, the upgraded High Intensity Gamma-ray Source (HIGS) at the Duke FEL Lab has provided users with gamma beams of unprecedented quality for scientific research. The recently completed accelerator upgrades include a HOM-damped RF cavity, a full-energy top-off booster injector, redesigned storage ring straight sections, and two new FELs. The HIGS facility is now capable of producing a high intensity gamma beam in a wide energy range (1 - 100 MeV) using commercial FEL mirrors. It has achieved an exceptionally high flux, up to ~1010 g/s total (< 20 MeV), making it the world's most powerful Compton gamma source. It produces almost 100% polarized gammas, either linear or circular. At the HIGS, the gamma energy can be changed rapidly within a factor of three in minutes. Operated by Triangle Universities Nuclear Laboratory since summer 2008, the HIGS is a dedicated Compton gamma source, capable of producing more than 2,000 h of gamma beam time per year with a five-day, two-shift schedule. Future development at the HIGS includes higher energy gamma beams toward the pion threshold and a rapid switch of circular polarization.
LBNL, Berkeley, California
Funding: This work was supported by the Director, Office of Science, U. S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Touschek lifetime in low energy or small emittance lepton storage rings strongly depends on the particle density in bunches. In the usual parameter range, this dominates other effects and the lifetime gets shorter with higher the bunch density, i.e. with smaller beam emittance. However, once one gets to extremely small horizontal emittances, this is no longer the case. Since the Touschek scattering process is an energy transfer from the transverse plane to the longitudinal one, the Touschek lifetime actually increases, once the transverse temperature (i.e. emittance) gets small enough. In the usual Touschek lifetime formulas, this is accounted for with a complicated multiparameter function (form factor). This paper presents to our knowledge the first direct measurements of the Touschek lifetime in this region of reversed dependence on horizontal emittance, as well as comparison with theory. The measurements were carried out at the ALS at reduced beam energy and ultrasmall horizontal emittance.
BNL, Upton, Long Island, New York
The outer circumference of a BPM button and the inner circumference of the button housing comprise a transmission line. This transmission line typically presents an impedance of a few tens of ohms to the beam, and couples very weakly to the 50 Ω coaxial transmission line that comprises the signal path out of the button. The modes which are consequently excited and trapped often have quality factors of several hundred, permitting resonant excitation by the beam. The combination of short bunches and high currents found in modern light sources and colliders can result in the deposition of tens of watts of power in the buttons. The resulting thermal distortion is potentially problematic for maintaining high precision beam position stability, and in the extreme case can result in mechanical damage. We present here a simple algorithm that uses the input parameters of beam current, bunch length, button diameter, beampipe aperture, and fill pattern to calculate a figure-of-merit for button heating. Data for many of the world’s light sources and colliders is compiled in a table.
ANL, Argonne
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS), a third-generation synchrotron light source, has been in operation for eleven years. The monopulse radio frequency (rf) beam position monitor (BPM) is one of three BPM types now employed in the storage ring at the APS. It is a broadband (10 MHz) system designed to measure single-turn and multi-turn beam positions, but it suffers from an aging data acquisition system. The replacement BPM system retains the existing monopulse receivers and replaces the data acquisition system with high-speed analog-to-digital converters (ADCs) and a field-programmable gate array (FPGA) that performs the signal processing. The new system has been installed and commissioned in a full sector of the APS. This paper presents the results of testing of the beam position monitor which is now fully integrated into the storage ring orbit control and fast feedback systems.
ANL, Argonne
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) has three circular machines: a 7-GeV electron storage ring (SR), a booster synchrotron (booster) of beam energy 325 MeV to 7 GeV, and a particle accumulator ring (PAR). Their tune measurement systems are based on HP 4396 network and spectrum analyzers (NASA) and HP 89400 vector spectrum analyzers (VSA). The instruments are no longer supported by the vendor and will need replacement in the future. An upgrade of these systems with FPGA-based processors has been implemented. The new systems provided faster tune history and bunch-by-bunch tune reading in addition to the original systems. We present a brief description of the implementation and performance of the new systems.
LNLS, Campinas
We describe the development of a new button-type beam position monitor (BPM) for the Brazilian Synchrotron Light Source (LNLS) electron storage ring. One third of the storage ring stripline BPMs were replaced whit this new model, which counts on bellows, temperature stabilization and new support stands in order achieve improved mechanical stability. Finally, in-vacuum heat absorbers were installed at the upstream vacuum tubes of the bending magnets to minimize the vacuum chamber motion due to the high thermal load. We also present performance results.
LNLS, Campinas
UNICAMP, Campinas, São Paulo
This paper reports on the LNLS experience with the digital electron beam position monitor Libera Brilliance through the realization of several standard accelerator physics experiments, taking advantage mainly of the equipment’s turn-by-turn capabilities.
BNL, Upton, Long Island, New York
The NSLS-II Light Source being built at Brookhaven National Laboratory is expected to provide submicron stability of the electron orbit in the storage ring in order to utilize fully the very small emittances and electron beam sizes. This requires high stability supports for BPM pick-up electrodes, located near insertion device source. Description of the efforts for development of supports including carbon tubes and invar rods is presented.
BNL, Upton, Long Island, New York
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-98CH10886.
With growth of circulating current in the storage rings the heating of the beam position monitor (BPM) buttons due to the induced trapped modes is drastically increasing. Excessive heating can lead to the errors in the measuring of beam position or even catastrophic failures of pick-up assembly. In this paper we present calculations of heat generated in the button for different geometries and materials. The obtained results are used for the optimization of the BPM design for the NSLS-II project.
LANL, Los Alamos, New Mexico
Funding: This work is supported by the United States Department of Energy under contract DE-AC52-06NA25396
Precise measurement of the tunes in the Los Alamos Proton Storage Ring (PSR) is difficult because the beam is normally extracted immediately after accumulation, preventing the use of continuous-wave radio frequency measurements. Presented here is a method that takes advantage of the phase information in the response of the beam to a transverse oscillatory driving voltage. This technique offers much greater precision than using the amplitude spectrum alone.
Ankara University, Faculty of Sciences, Tandogan/Ankara
The Turkish Accelerator Complex (TAC) is a project for accelerator based fundamental and applied researches supported by Turkish State Planning Organization (DPT). The proposed complex is consisted of 1 GeV electron linac and 3.56 GeV positron ring for a charm factory and a few GeV proton linac. Apart from the particle factory, it is also planned to produce synchrotron radiation from positron ring. In this study the lattice structure design of the positron storage ring is made to produce the third generation synchroton light. It has been studied with different lattice structures (DBA, TBA, DDBA etc.) for TAC. It has been compared lattice structures and tried to find the best structure for lowest emittance.
ASCo, Clayton, Victoria
Emittance coupling in the Australian Synchrotron storage ring is currently controlled using a total of 28 skew quadrupoles. The LOCO method was used to calculate the skew quadrupole settings, using measured vertical dispersion and transverse coupling. This information is used to create a calibrated model of the machine, which is then used to calculate the required skew quadrupole settings needed to minimise coupling. This method has thus far achieved encouraging results for achieving ultra low (<2pm) vertical emittance. In this study we seek to explore the validity of the LOCO model based on empirical measurements and possible improvements of this method.
ASCo, Clayton, Victoria
Generating short bunches for time resolved studies or the generation of THz radiation has been done at many other light sources and is of increasing interest in the user community. Light sources not designed with ps bunchs can usually tune the lattice to reduce ps bunchs without much difficulty, sometimes referred to as a Low Alpha mode. At the Australian light source a low alpha configuration has been investigated. The results looking into the 'shaping' of the momentum compaction factor, beam stability and current limitations will be presented.
LNLS, Campinas
The UVX electron storage ring at the Brazilian Synchrotron Light Laboratory (LNLS) was recently equipped with active current shunt circuits that allow for individual variation of the quadrupole magnet strengths. This allows us to apply the widely used technique of beam-based alignment (BBA) to calibrate the electrical center offset of the BPMs with respect to the magnetic center of the closest quadrupole. In this report we present the BBA experimental results and an analysis of the resolution of the method in the case of the LNLS UVX storage ring.
LNLS, Campinas
The synchrotron machine at the Brazilian Synchrotron Light Laboratory (LNLS) is a storage ring for 1.37 GeV electrons composed of six DBA cells whose lengths add up to around 93 meters of circumference. There are 18 horizontal and 24 vertical correctors available in the ring for correcting the orbit as measured at 24 BPMs. In the past, stored beams have been delivered which successfully fulfilled user’s stability and emittance demands. This has been accomplished by fine tuning the machine using mostly measured beam parameters. The ongoing commissioning of the a new undulator beamline, which is expected to become the most demanding one, puts pressure in the direction of improving existing models of the ring optics in order to envisage ways of improving beam quality. In this paper we discuss preliminary tests with LOCO* at the LNLS. We report on the impact of the calibration of the machine based on LOCO calculations through the analysis of standard experiments and optics parameters such as beta-beat reduction, improvement of life-time and so on.
*LOCO in the Beam Dynamics Newsletter, 44, ICFA, December 2007.
Diamond, Oxfordshire
JAI, Oxford
With the aim of generating short pulse radiation, a low momentum compaction lattice has recently been commissioned for the Diamond storage ring. By introducing both positive and negative dispersion in the bending magnets it has been possible to operate the storage ring in a quasi-isochronous state, resulting in a natural electron bunch length of less than 1 pico-second. A description of the techniques used to develop the lattice is given, along with first results obtained during recent machine trials. Operation with both positive and negative momentum compaction factor is also described
BNL, Upton, Long Island, New York
We present a newly developed method to analyze some non-linear dynamics problems such as the Henon map using a linear matrix analysis method in linear algebra. Using the Henon map as an example, we analyze the spectral structure, the tune-amplitude dependence, the variation of tune and amplitude during the particle motion, etc., using the method of analysis of eigenvectors in Jordan spaces which is widely used in conventional linear algebra.
CERN, Geneva
SOLEIL, Gif-sur-Yvette
The successful correction of non-linear resonances in DIAMOND using the BPM turn-by-turn data has motivated testing this approach in SOLEIL in collaboration with CERN. We report on the first experiences towards the correction of non-linear resonances in SOLEIL.
FZK, Karlsruhe
CERN, Geneva
KIT, Karlsruhe
Max-Planck Institute for Metal Research, Stuttgart
Funding: This work has partly been supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320
The status of longitudinal and transverse Schottky observation systems for the synchrotron light source ANKA is presented. ANKA regularly operates in a dedicated low alpha mode with short bunches for the generation of coherent THz radiation. The Schottky measurement results are shown and compared with theoretical predictions for the regular as well as the different stages of the low alpha mode of operation. Special care had to be taken to control and mitigate the impact from strong coherent lines of the short bunches on the signal processing chain. The system setup is shown, expected and unexpected observations as well as applications are discussed.
GSI, Darmstadt
The FAIR Storage Rings (CR, RESR and NESR) are designed for efficient cooling, accumulation, deceleration and performing nuclear physics experiments with antiproton and rare isotopes beams. Tracking studies for all these rings have been performed to estimate the dynamic aperture and other properties of beam stability depending on the low and high field multipole components, fringe fields and field interference. The multipole limits have to be determined in order to provide a reasonable estimate of the stability boundary and needed correction of the low field multipoles. We report on quantitative studies of the effects of multipoles on the dynamic aperture of the rings, and show that the systematic multipole components in the present magnet designs are unlikely to impose a severe limitation.
LBNL, Berkeley, California
Funding: This work was supported by the Director, Office of Science, U. S. Department of Energy under Contract No. DE-AC02-05CH11231.
Frequency map analysis is being widely used, nowadays, both in simulations to design or improve accelerator lattices, as well as in experiments to study the transverse nonlinear dynamics in accelerators. A significant challenge to the use of frequency map analysis in experiments is the usually very fast decoherence of transverse oscillations, caused by the large nonlinearities of state-of-the-art lattices. Due to the decoherence, the center of mass oscillations of bunches often disappear in less than 100 turns. A potential way to get around this limitation is the use of multiple BPMs distributed (symetrically) around the storage ring. The presentation will describe the challenges multi-BPM frequency map analysis poses as well as initial results using the ALS.
USTC/NSRL, Hefei, Anhui
Radial alternating magnetic field is generated to act on polarized beam to give rise to resonant depolarization and calibrate the energy of electron by feeding power to a pair of vertical installed striplines in HLS. In the paper, the relationship between depolarization time and power fed into the striplines is investigated, and spin frequency spread is considered too. As a result, a depolarization time of 60s is acquired with an amplifier power of 15W fed into the striplines.
UW-Madison/SRC, Madison, Wisconsin
The betatron tunes of an electron storage ring may be measured by driving transverse oscillations with an excitation electrode and measuring the resonant beam response with a pickup electrode. We model the damping of coherent betatron oscillations from the tune spread and radiation damping, finding that the tune signal is proportional to the square root of the product of the betatron functions at the excitation and pickup locations. The signal is independent of the betatron phase advance between the two locations. Our results are applied to the Aladdin 800-MeV electron storage ring.
Melbourne
ASCo, Clayton, Victoria
Recently a transverse bunch-by-bunch feedback system was commissioned to combat the resistive-wall instability in the storage ring. The system successfully controls the vertical beam motion so 200 mA can be stored with all in-vacuum undulators at minimum gap and a slightly positive chromaticity setting. The FPGA that comes with the feedback system also provides powerful possibilities for diagnostic measurements. Results will be presented for a) growth/damp measurements to quantitatively characterise the resistive-wall instability, b) bunch-by-bunch diagnostics such as tune chromaticity and c) initial bunch-cleaning attempts in conjunction with a APD bunch purity measurement system.
CLS, Saskatoon, Saskatchewan
I-Tech, Solkan
A high-purity single-bunch operating mode, required for time-resolved experiments, has been introduced into the CLS Storage Ring. The newly deployed Transverse Feedback System, which uses the Libera Bunch-by-Bunch system as the feedback processor, has added features that inherently enable bunch cleaning. The bunch purification mechanism is based on a frequency modulated signal that drives the unwanted bunches into betatron oscillations to remove them from the Storage Ring. Bunch purities of 10-6 are achieved, limited only by the leakage rate from adjacent bunches.
FEL/Duke University, Durham, North Carolina
PAL, Pohang, Kyungbuk
Dimtel, San Jose
Funding: work supported by US Air Force Office of Scientific Research medical FEL grant FA9550-04-01-0086
The coupled bunch mode instabilities (CBMIs) caused by vacuum chamber impedance limit and degrade the performance of the storage ring based light sources. A bunch-by-bunch longitudinal feedback (LFB) system has been developed to stabilize beams for the operation of a storage ring based Free Electron Laser (FEL) and the High Intensity Gamma-ray Source (HIGS) at the Duke storage ring. Employing a Giga-sample FPGA based processor (iGP), the LFB is capable of damping out the dipole mode oscillation for all 64 bunches. As a critical subsystem of the LFB system, kicker cavity is developed with a center frequency of 938 MHz, a wide bandwidth (> 90 MHz), and a high shunt impedance (> {10}00 Ω). First commissioned in summer 2008, the LFB has been operated to stabilize high current multi-bunch operation. More recently, the LFB system is demonstrated as a critical instrument to ensure stable operation of the HIGS with a high intensity gamma beam above 20 MeV with a frequent top-off injection to compensate for the substantial and continuous electron beam loss in the Compton scattering process. In the future, we will perform detailed studies of the impedance effects using the LFB system.
SOLEIL, Gif-sur-Yvette
SOLEIL is the French 2.75 GeV high brilliance third generation synchrotron light source delivering photons to beam-lines since January 2007. Reaching micrometer to sub-micrometer level stability for the photon beams is then necessary but very challenging. Since September 2008, a fast orbit feedback has been running in daily operation. The performances of the system will be presented together with comparison with the ones previously achieved with the slow orbit feedback system. Status of the interaction of both feedback systems will be discussed. Moreover new X-BPMs have been installed on dipole and undulator based beam-lines; a total number of 9 vibration sensors (velocimeters) are now installed in the storage ring tunnel, on the experimental slab and outside the building in order to help to locate the different noise sources. Detailed results will be presented and debated.
USTC/NSRL, Hefei, Anhui
JASRI/SPring-8, Hyogo-ken
Hefei Light Source (HLS) is an 800MeV storage ring with bunch rate of 204 MHz, the harmonics of 45, and circumference of 66 meters. HLS injection works at 200MeV, where the multi-bunch instabilities limit the maximum stored current. A digital transverse bunch-by-bunch feedback system has recently been commissioned at HLS to suppress the multi-bunch instabilities during injection. We employ the SPring-8 FPGA based feedback processor and modified it at NSRL to process horizontal and vertical oscillation signals, independently and simultaneously by one single processor. The design of the digital transverse feedback system and the experiment results are presented in this paper.
ANL, Argonne
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
The Argonne Advanced Photon Source is in the process of developing a short-pulse x-ray (SPX) beamline capable of producing picosecond-scale x-ray pulses for use in time-resolved studies. To accomplish this, transverse deflecting cavities (crab cavities) operating at eight times the storage ring rf will be installed to enable production of short x-ray pulses at a selected beamline. Analysis reveals demanding phase and amplitude stability requirements for the cavity fields. The common-mode cavity field phase error relative to bunch arrival time is ± 10 degrees at the 2815-MHz cavity frequency while the cavity-to-cavity phase difference must be held to ± 0.07 degrees. The phase differential between the cavity phase and beamline timing must be held to ± 1 picosecond. A phase stabilized link* is being developed to transport a phase stable 351.9-MHz reference to the LLRF located at the beamline end. The delivered phase-stable reference will be used to develop rf references for the cavity LLRF, beamline laser, and streak camera. This paper will discuss the details of the design and report measured performance of the prototype.
* J. Frisch, D. Bernstein, D. Brown, E. Cisnerso, “A High Stability, Low Noise RF Distribution System,“ Proceedings of PAC2001, pp 816-818.
ELETTRA, Basovizza
Elettra is the third generation light source in operation in Trieste since 1993,upgraded with a full energy booster injector last year. Top-up operation is on schedule in the near future but already the new timing system and gun are ready to operate in this mode. The paper describes all tasks and requirements needed to satisfy top-up injection include custom made hardware, interaction with controls and radiation protection system.
GSI, Darmstadt
CERN, Geneva
The FAIR storage ring complex comprises three storage rings with a magnetic rigidity of 13 m. Each of the rings, CR, RESR, and NESR, serves specific tasks in the preparation of secondary beams, rare isotopes and antiprotons, or for experiments with heavy ion beams. The CR is optimized for fast stochastic pre-cooling of secondary beams. The RESR design includes optimization of antiproton accumulation. The design of the NESR for experiments with heavy ions, deceleration of ions or antiprotons for a subsequent low energy facility, and the accumulation of rare isotope beams is proceeding. This report summarizes various new concepts conceived in the design process of this new storage ring facility.
Omega-P, Inc., New Haven, Connecticut
Columbia University, New York
Yale University, Beam Physics Laboratory, New Haven, Connecticut
NSC/KIPT, Kharkov
Funding: US Department of Energy, Office of High Energy Physics, Advanced Accelerator R & D.
A rectangular two-beam dielectric wakefield accelerator (DWA) module is described which, when energized by a 14 MeV, 50 nC drive bunch moving in one channel, is shown to deflect a test bunch which originates from an independent source moving in a parallel channel. We show that such a module, 30 cm in length, can deflect transversely a 1 GeV electron by ~ 1 mrad in 1 ns, after which a following bunch can pass undeflected. Apparatus required to accomplish this task consists of a laser-cathode RF gun and an optional linac to generate the drive bunch. The associated DWA components could be used for kicker applications in a storage ring or a more energetic electron linear accelerator. An example we describe is tailored to a DWA demonstration project underway at the Argonne Wakefield Accelerator, but the design can be altered to allow for changes including a lower-energy but still relativistic drive bunch. The kicker, through appropriate design, can deflect one out of several bunches in a storage ring, leaving the remaining bunches essentially unaffected by the structure.
LANL, Los Alamos, New Mexico
IUCF, Bloomington, Indiana
Funding: US DOE #DE-AC52-06NA25396
Orbit response matrix techniques have been used in numerous electron storage rings to elucidate various optical properties of the machines. Such measurements in a long-pulse accumulator ring have unique complications. We present here the techniques and results of such a measurement at the Los Alamos Proton Storage Ring*. We also show the deficiencies in previous models of the ring and a comparison of the beta-functions as fit by the orbit response method to direct measurements by quadrupole magnet variations.
*LA-UR- 08-07694
MPI-K, Heidelberg
Cockcroft Institute, Warrington, Cheshire
Funding: Work supported by the Helmholtz Association of National Research Centers (HGF) under contract number VH-NG-328 and GSI Helmholtzzentrum für Schwerionenforschung GmbH
In the future Facility for Low-energy Antiproton and Ion Research (FLAIR) at GSI, the Ultra-low energy electrostatic Storage Ring (USR) will provide cooled beams of antiprotons and possibly also highly charged ions down to energies of 20 keV/q. A large variety of the envisaged experiments demands a very flexible ring lattice to provide a beam with variable cross section, shape and time structure, ranging from ultra-short pulses to coasting beams. The preliminary design of the USR worked out in 2005 was not optimized in this respect and had to be reconsidered. In this contribution we present the final layout of the USR with a focus on its “split-achromat” geometry, the combined fast/slow extraction, and show the different modes of operation required for electron cooling, internal experiments, or beam extraction. We finally give a summary of the machine parameters and the layout of the optical elements.
SLAC, Menlo Park, California
BNL, Upton, Long Island, New York
Funding: US DOE
Unlike an electron storage ring with radiation damping, resonance excitation is unsuitable to a proton storage ring for turn-by-turn betatron orbit data. However, one may consider modified betatron motion driven by ac dipoles oscillating at frequencies near the betatron tunes. With a matrix formulation for adding ac-dipole effects on 2-D coupled one-turn map, we concatenate the ac-dipole effects and the one-turn map to obtain a modified linear map. The ac-dipole effects are equivalent to inserted symplectic linear maps at the ac-dipole locations. If the maps are normalized through decoupling similarity transformation, the decoupled maps for the ac-dipole effects are equivalent to 1-D thin quads inserted at the corresponding locations, the same conclusion for the 1-D driven oscillation*. For optics modeling with MIA technique**, one must make sure that there are, simultaneously, two transverse ac-dipole driven betatron oscillations along with one longitudinal synchrotron oscillation. Once the optics model for the modified betatron motion is obtained, one can then obtain the proton storage ring model by de-concatenating the inserted ac-dipole linear maps.
* R. Miyamoto, S.E. Kopp, A. Jansson, and M.J. Syphers, PRSTAB 11, 084002 (2008).
** Y.T. Yan, ICFA Beam Dynamics Newsletter, No. 42, pp. 71-87 ( 2007), Y. Cai, W. Chou, Eds.
SSRF, Shanghai
Funding: SSRF
The ssrf is a 3rd generation light source under commissioning. The commissioning of the storage ring has progressed very well so far. The periodicity and symmetry of the linear optics in a real storage ring is important, however maybe be broken by various errors, such as field errors, manufactured errors. A distorted linear optics can excite stronger nonlinear resonances, which will reduce the storage ring dynamic aperture and make the storage ring suffer from low injection efficiency and short beam lifetime. Therefore, it is necessary to restore the designed periodicity or symmetry of the linear optics based on measured closed orbit distortion. The calibration procedure can be done by using LOCO (the Linear Optics from Closed Orbit). After fitting the measured response matrix by the model one, the linear optics of the storage ring is calibrated. And different operation modes have been also measured and calibrated.
SLRI, Nakhon Ratchasima
For the SIAM Photon Source, we propose to establish a storage ring model based on quadrupole fitting of the measured betatron functions. By fitting of quadrupole field strength parameters to measured values of the betatron function, a series of problems at the SIAM Photon Source could be determined. For example, the problem of turn-to turn electrical coil shorts was detected and solved by replacing the new quadrupole coils. Subsequently, we could identify a quadrupole calibration error due to conflicting information on the number of turns per coil. Other causes regarding the beam dynamics model such as high field saturation effects, power supply calibration error, and proximity to nearby magnets have been taken into account to establish accurate quadrupole calibration factors. The establishment of an accurate model is essential for beam dynamics predictions, closed orbit correction, response matrix determination for LOCO, low emittance operation, and optics correction for high filed insertion devices.
TUB, Beijing
Funding: This work is supported by National Natural Science Foundation of China (Project 10735050) and National Basic Research Program of China (973 Program) (Grant No. 2007CB815102).
The feasibility study of optical stochastic cooling (OSC) utilizing a compact storage ring is presented in this paper. We present the general layout of the scheme, as well as the lattice design of the storage ring. The results of beam dynamics simulation are likewise presented.
USTC/NSRL, Hefei, Anhui
In order to meet the increasing requirements of synchrotron radiation users, a new plan of VUV and soft X-ray light source, named Hefei Advanced Light Source (HALS), is brought forward by National Synchrotron Radiation Laboratory (NSRL). This 1.5GeV storage ring with ultra low emittance 0.2nmrad consists of 18 combined FBA cells and the circumference is 388m. Strong enough quadrupoles and sextupoles must be needed for getting such low emittance lattice, which will lead beam close orbit distortions’ (COD) sensitivity to the field and alignment errors in magnets. Estimation of the COD from various error sources is investigated. Using orbit response matrix and singular value decomposition method, the distribution of beam position monitors and the location of correctors are reported in the paper. Simulation proves that COD can be corrected down to 60 microns level. In the same time the corrector strengths are weaker enough in the correction scheme.
UMD, College Park, Maryland
Funding: *This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office
The University of Maryland Electron Ring (UMER) is designed for operation over a broad range of beam intensities, including those normally achieved only in linacs. This is possible thanks to a combination of low-energy (10 keV) electrons and a high density of magnetic quadrupoles (72 over an 11.5 m circumference) that allow operation from 0.5 mA to 100 mA; that is, from the emittance dominated to the highly space charge dominated regimes. We present results of basic centroid-motion characterization, including measurements of closed-orbit distortion, momentum compaction factor, and natural chromaticity and dispersion. These are compared with results from computer simulations employing the code ELEGANT. We discuss the techniques and challenges behind the measurements with fast beam-position and wall-current monitors, and also the special role of the background ambient magnetic field for beam steering.
YSU, Yerevan
CANDLE, Yerevan
PSI, Villigen
An online measurement of the beam energy spread is based on the analysis of the decoherence/recoherence signals obtained from the beam position monitors after a single turn beam excitation by a pinger magnet. Furthermore the analysis allows calibration of the model in terms of higher order chromaticities and amplitude dependant tune shifts. An analytical model including 1st and 2nd order chromaticities and amplitude dependant tune shift will be presented.
BNL, Upton, Long Island, New York
Impedance of two vacuum chamber components, Bellows and BPM, is considered in some detail. In order to avoid generation of Higher-Order Modes (HOM’s) in the NSLS-II bellows, we designed a new low-impedance RF shielding consisting of 6 wide and 2 narrow metal plates without opening slots between them. The short-range wakepotential has been optimized taking into account vertical offset of RF fingers from their nominal position. The results were compared with data of bellows designed at other laboratories. Narrow-band impedance of the BPM Button has been studied. TE-modes in the BPM button were suppressed by a factor of 8 by modification of existing housings. Two new types of housings are shown. The total impedance of the NSLS-II storage ring is discussed in terms of the loss factor and the vertical kick factor for a 3mm-Gaussian bunch.
CANDLE, Yerevan
PSI, Villigen
The longitudinal and transverse impedances of CPMU (cryogenic permanent magnet undulators) of the SLS storage ring are evaluated. The study takes into account the walls frequency dependent conductivity and the electrical and magnetic properties of the material at low temperature.
HZB, Berlin
Bursts of coherent synchrotron radiation (CSR) in the far IR and down to the μ-wave region have been observed in many synchrotron light sources. At BESSY II the temporal structure of these pulses in the THz-region was observed as a function of the bunch length which was varied by changing the momentum compaction factor and as a function of the number of electrons in the single bunch. It was found, that for a bunch length between 3 and 15 ps the first signs of time dependent CSR occur at a frequency which is a multiple of the zero current synchrotron frequency. This frequency increases with the bunch length and indicates that higher azimuthal modes become unstable first. Slower bursts, with repetition rates on the time scale of mill seconds and much slower than the synchrotron period, show up slightly above this threshold. These bursts possess the much faster initial temporal structure and are probably the result of longitudinal mode mixing. The experimental observations are presented and compared to calculations.
JAI, Oxford
Diamond, Oxfordshire
Diamond is a third generation synchrotron light source built to generate infra-red, ultraviolet and X-ray synchrotron radiation (SR) of exceptional brightness. The operation of the Diamond storage ring with short electron bunches for generation of Coherent THz radiation and short X-ray pulses for time-resolved experiments is limited by the onset of microbunch instabilities. We have started a project to investigate the longitudinal electron beam dynamics and microbunch instabilities in the Diamond storage ring. In the first experiment we used an ultra-fast (time response is about 250 ps) Schottky Barrier Diode sensitive to the radiation within the 3.33-5 mm wavelength range. When the single bunch current exceeded 1.9 mA we observed a set of sub-THz bursts appearing quasi-periodically while the beam was circulating in the ring. The fast response allowed us to detect the signal turn-by-turn, which gives us an opportunity to study the bursts’ structure and evolution. It also allows us to study the effect in a multi-bunch mode when bunches are only 2 ns apart. In this report we will present our first preliminary results and also discuss future plans.
LBNL, Berkeley, California
Funding: Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Uneven beam fill patterns in storage rings, such as gaps in the fill patterns, leads to periodic, or transient loading of the modes of the RF cavities. We show that an analogous effect can occur in the loading of a dipole cavity mode when the beam passes off the electrical center of the cavity mode. Although this effect is small, it results in a variation of the transverse offset of the beam along the bunch train. For ultralow emittance beams, such as optimized third generation light sources and damping rings, this effect results in a larger projected emittance of the beam compared with the single bunch emittance. The effect is particularly strong for the case when a strong dipole mode has been purposely added to the ring, such as a deflecting, or ‘‘crab'' cavity. We derive an approximate analytic solution for the variation of the beam-induced deflecting voltage along the bunch train. We also show via a tracking simulation the combined effect of the periodic loading of the fundamental and dipole modes.
BNL, Upton, Long Island, New York
Funding: Work performed under auspices of the U.S. Department of Energy under Contract No. DE-AC02-98CH10886 with Brookhaven Science Associates, LLC.
The role of relational database (RDB) technology plays in accelelerator control and operation continues to grow in such areas as electronic log books, machine parameter definitions, and facility infrastructure management. RDBs are increasingly relied upon to provide the official 'master' copy of these data. The services provided by the RDB have traditionally not been 'mission critical'. The availability of modern RDB management systems is now equivalent to that of standard computer file-systems, and thus RDBs can be relied on to supply (pseudo-)realtime response to operator and machine physicist requests. This paper describes recent developments in the IRMIS RDB (1) project. Generic lattice support has been added, serving as the driver for model-based machine control. Abstract physics name service, with introspection has been added. Specific emphasis has been placed both on providing fast response time to accelerator operators and modeling code requests, as well as high (24/7) availability of the RDB service.
BNL, Upton, Long Island, New York
LBNL, Berkeley, California
Funding: U.S. Department of Energy
A new approach to embedded device control is being developed by Lawrence Berkeley Laboratory (LBNL) and Brookhaven National Laboratory (BNL). Synchronous device interface (SDI) will be implemented in NSLS-II project as a key communication protocol. This paper describes the design motivation and principles of SDI. It also discusses SDI in fast orbit feedback system and its extension in power supply control system.
MPI-K, Heidelberg
Weizmann Institute of Science, Physics, Rehovot
Funding: This work is supported by the Max Planck Society.
An electrostatic Cryogenic Storage Ring (CSR) is currently being built in Heidelberg, Germany. The current status and final design of this ring, with a focus on the precision chamber suspension, optimized 2K chamber cooling, and the cryogenic pumping down to extremely low pressures will be presented. This ring will allow long storage times of ion beams with energies in the range of keV per charge for highly charged ions and polyatomic molecules. Combined with vacuum chamber temperatures approaching 2K, infrared-active molecular ions will be radiatively cooled to their rotational ground states. Many aspects of this concept were experimentally tested with a cryogenic trap for fast ion beams (CTF), which has already demonstrated the storage of fast ion beams in a large cryogenic device. An upcoming test will investigate the effect of pre-baking the cryogenic vacuum chambers to 600K on the cryogenic vacuum and the ion beam storage.
MPI-K, Heidelberg
Cockcroft Institute, Warrington, Cheshire
Funding: Work supported by the Helmholtz Association of National Research Centers (HGF) under contract number VH-NG-328 and GSI Helmholtzzentrum für Schwerionenforschung GmbH.
One of the central goals of the Ultra-Low energy Storage Ring (USR) project within the future Facility for Low-energy Antiproton and Ion Research (FLAIR) is to provide very short bunches in the 1-2 nanosecond regime to pave the way for kinematically complete measurements of the collision dynamics of fundamental few-body quantum systems for the first time on the level of differential cross sections. The “short pulse” operation mode may be split up in two steps: First, the cooled coasting beam of low energy ions will be adiabatically captured by a high harmonic RF cavity (20 MHz) into ~50 ns buckets. Second, the beam will be compressed to very short pulses with a desired width of only 1-2 ns by an RF buncher located 2 m in front of the so-called reaction microscope. To efficiently limit the beam energy spread, RF decompression is then done at after the experiment to avoid beam losses. In this contribution, we present numerical investigations of this very particular operation mode.
KUK, Abha
KACST, Riyadh
MPI-K, Heidelberg
Cockcroft Institute, Warrington, Cheshire
A state-of-the-art fixed energy electrostatic storage ring that will allow for precision experiments with most different kinds of ions in the energy range of up to 30 keV will be constructed and operated at the National Center for Mathematic and Physics (NCMP) at the King Abdulaziz City for Science and Technology (KACST). The ring is planed to be the central machine of a unique and highly flexible experimental platform. The lattice design therefore has to cover the different experimental techniques that the ring will be equipped with, such as e.g. electron-ion crossed-beams and ion-laser/ion-ion/ion-neutral merged-beams techniques. This paper presents the technical and particle optical design of this novel machine, explains the particular challenges in its layout, and reports on the general project status.