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| MPPE045 | Accelerator Physics Issues at the 2.5 GeV PLS Storage Ring | lattice, insertion, emittance, undulator | 2854 | ||
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Over the past decade, PLS has served the synchrotron light source with the 2.0 GeV to 2.5 GeV electron beam. Accelerator physics issues at the present 2.5 GeV storage ring have been investigated in order to improve the performance of the light source. We present the issues of the low-beta lattice, low-emittance lattice, effects of six insertion devices on the lattice and low-alpha lattice, and show their effects on the beam dynamics in the storage ring.
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| MPPE069 | Optics for the ALBA Lattice | lattice, insertion, vacuum, synchrotron | 3777 | ||
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ALBA will be a third generation synchrotron light source built in Spain near Barcelona. The lattice chosen for ALBA consists in an extended DBA-like structure with finite dispersion in the straight sections, providing low emittance (under 5nmrad), small beam cross sections at the source points (σ x ~ 150 micrometers and σ y ~ 10micrometers), and a large number of straight sections (4 times 8m, 12 times 4.2m and 8 times 2.6m). The small circumference (268 meters) and medium energy (3GeV) makes it challenging to provide the desired emittance while preserving a large enough dynamic aperture and energy acceptance. This paper reviews the main beam dynamics issues (dynamic aperture, energy acceptance, closed correction, lifetime, influence of insertion devices, and higher multipoles of magnets) and the solutions adopted.
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| MPPP003 | FALSE BPM READINGS AFFECTING ORBIT FEEDBACK | feedback, vacuum, insertion, synchrotron | 847 | ||
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Funding: Ministry of Science and Technology, Korea. |
A slow global orbit feedback (SOFB) is routinely operating in the usual user service operation at PLS. The orbit feedback uses 22 correctors in each plane which have 20-bit capability for the vertical plane and 16-bit capability for the horizontal plane, and the feedback speed is 4 seconds. The orbit stability in RMS was maintained below 1 mm in both planes for one hour and 3 mm for a 12-hour operation. The BPM chamber movement due to the change of synchrotron radiation heat load mainly limits the SOFB performance. The intensity dependence of BPM electronics is well compensated by a look-up table of BPM. |
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| MPPP018 | Correction of Insertion Device Induced Orbit Distortions at the SLS | photon, feedback, undulator, insertion | 1584 | ||
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Corrections of insertion device (ID) induced orbit distortions at the SLS are performed by means of feed forward schemes down to the micron level at the corresponding photon beam position monitors (XBPMs). The remaining orbit fluctuations are suppressed by XBPM feedbacks which are an integral part of the fast orbit feedback system. As a result, sub-um RMS stability at the XBPMs is achieved while the ID settings are varied.
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| MPPT023 | A New Magnetic Field Integral Measurement System | photon, acceleration, insertion, multipole | 1808 | ||
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Funding: Work supported by U.S. Department of Energy Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
In order to characterize the insertion devices at the Advanced Photon Source (APS) more efficiently, a new stretched-coil magnetic field integral measurement system has been developed. The system uses the latest state-of-the-art field programmable gate array (FPGA) technology to compensate the speed variations of the coil motions. Initial results demonstrate that the system achieves the system measurement accuracy of 0.15 Gauss centimeter (G-cm) in a field integral measurement of 600 G-cm, probably the world’s best accuracy of its kind. |
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| MPPT026 | Insertion Device Upgrade Plans at the NSLS | undulator, impedance, insertion, vacuum | 1949 | ||
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This paper describes plans to upgrade insertion devices at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory, U.S.A. The aging wiggler (W80) at X25 is being replaced by a 1 m long in-vacuum mini-gap undulator (MGU-18) optimized for a dedicated macromolecular crystallography program. A new, 1/3 m long, in-vacuum undulator (MGU-13.5), will be installed between a pair of RF cavities at X9, and will serve a new beamline dedicated for small angle x-ray scattering (SAXS). Both MGU’s will have provision for cryocooling the NdFeB hybrid arrays to 150K to raise the field and K-value and to obtain better spectral coverage. Design issues of the devices and other considerations, especially magnetic measurement methods in low temperature will be discussed.
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| MPPT079 | Commissioning of an APPLE-II Undulator at Daresbury Laboratory for the SRS | undulator, electron, photon, insertion | 4051 | ||
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A new variable polarisation undulator of the APPLE-II type has been designed and constructed at Daresbury Laboratory. Initial magnet testing of the 56mm period device was followed by an intensive period of shimming to improve the field quality. After this was successfully completed the undulator was installed into the SRS and tests made of the effect of the device upon the electron beam. This beam commissioning was completed in a very short space of time with the beamline being given full control of the gap and phase of the magnet within a few weeks of installation. This paper summarises the measurement of the magnet and the shimming techniques employed to improve the field quality. It also describes the effect of the device upon the stored 2 GeV electron beam and the measures taken to minimise these effects during user operations.
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| RPAE004 | Parametric Mechanical Design of New Insertion Devices at the APS | undulator, insertion, brilliance, radiation | 889 | ||
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Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. W-31-109-ENG-38. |
Three permanent-magnet, planar, hybrid ID designs have recently been completed at the APS. The periods of the devices are 2.7 cm, 3.0 cm and 3.5 cm with nominal lengths of 2.4 m. Several design studies were performed for the initial 2.7 cm period device to investigate the utility of various design features. Then a parametric solid model for the initial device was developed and value engineered to minimize manufacturing, assembly and tuning costs. The model allowed the very rapid design of subsequent devices of similar periods and allowed commonality of several components of the IDs. This design family incorporates a low-cost method of pole retention and registration. Poles are secured by screws in two holes tapped into each pole. Pole location is registered by means of two small dowel pins for each pole in mating holes reamed into each pole and a base plate common to the poles and magnets. This base plate is flexible in bending along its length so shimming behind it can be used to accurately change the height of a pair of poles for tuning. Another feature of the design is modular construction to allow each device to be used full-length or shortened to a nominal 2.1 m length for use in APS "canted undulator" sectors. |
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| RPAE040 | COD Correction at the PF and PF-AR by New Orbit Feedback Scheme | feedback, insertion, dipole, electron | 2613 | ||
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The eigen-vector method with a constraint condition is a new COD correction method that enables us to combine the local orbit correction at the insertion devices with the global COD correction by integrating the local one into the global one as the constraint condition using the Lagrange’s undetermined multiplier method. In order to achieve this method, we only use the new contrived response matrix for the global COD correction where the local correction is involved and done simultaneously. We have tested this correction scheme at the PF ring and the PF-AR. In the machine studies, the new orbit correction method is successfully demonstrated. The RMS COD of the constraint BPMs are sufficiently suppressed and, on the other hand, there is almost no large difference in the RMS COD of all the other BPMs between the new and ordinary methods.
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| RPAE054 | Beam Stability at the Advanced Photon Source | photon, insertion, vacuum, instrumentation | 3268 | ||
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Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
The Advanced Photon Source has been in operation since 1996. Since that time, extensive incremental improvements to orbit stabilization systems have been made. This includes the addition of 80 channels of narrowband rf beam position monitors (bpm's), 40 channels of bending magnet photon bpm's, and most recently the inclusion of 36 insertion device photon bpm's into the orbit correction response matrix. In addition, considerable improvements have been made in the area of power supply regulation, both for the main multipole magnets and the steering corrector magnets. The present status of overall performance will be discussed, including long term pointing stability, reproducibility, and AC beam motion. |
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| RPAE056 | NSLS II: The Future of the NSLS | synchrotron, brightness, insertion, photon | 3345 | ||
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Funding: Under Contract with the United States Department of Energy Contract Number DE-AC02-98CH10886 |
The National Synchrotron Light Source at BNL was the first dedicated light source facility and it has now operated for more than 20 years. During this time the user community has grown to more than 2400 users annually. To insure that this vibrant user community has access to the highest quality photon beams, the NSLS is pursuing the design of a new ultra-high brightness (~10E21) electron storage ring, tailored to the 0.3-20 KeV photon energy range. We present our preliminary design and review the critical accelerator physics design issues. |
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| RPAE070 | Recent Developments at Aladdin | emittance, insertion, undulator, linac | 3813 | ||
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Funding: Work supported by the U.S. NSF under Award No. DMR-0084402. |
Following on the success of lower emittance operation at 800 MeV, SRC is pursuing a number of additional enhancements to the performance of the Aladdin storage ring. Work on Aladdin has included development of low emittance lattices at 1 GeV, which will maximize the capabilities of a recently installed spectromicroscopy beamline and a proposed high-resolution keV beamline. Installation of one-meter long insertion devices in the short straight sections within the quadrant arcs of the four sided storage ring is being considered to increase the number of undulator beamlines from four to possibly eight. Studies have been made to determine what is the minimum insertion device gap that does not interfere with nominal ring operation (injection, ramping, and lifetime at full energy), and indicate that smaller-gapped devices for higher photon energy are reasonable. Lifetime increases or further emittance reductions appear possible with modest aperture increases at a small number of points on the ring. Finally, planning is under way for long term projects such as a new injector or a next generation VUV/soft-xray source for the Midwest. Details will be presented. |
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| RPAE077 | A Magnetic Field Model for the Undulator in HLS | undulator, wiggler, storage-ring, insertion | 3994 | ||
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It is important to understand the influence of wigglers and undulators on the beam dynamics in design and optimization of a storage ring, especially when the storage ring runs on a low emittance mode. We present an analytic model of the undulator field in HLS, which can be used in the tracking study to evaluate the effects of it. Coefficients needed by the model are generated by fitting to the results of a numerical field caculation. Fringe fields are included in this model. Then we use three different methods to track particles through the undulator, and compare the results.
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| RPAE082 | The New Undulator Based fs-Slicing Beamline at the ALS | undulator, insertion, wiggler, laser | 4096 | ||
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Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-AC03-76SF00098. |
The existing Femtoslicing beamline at the ALS employs a femtosecond laser beam interacting resonantly with the electron beam in a wiggler (modulator). The induced energy spread over the femtosecond duration is converted to a transverse displacement by exploiting the storage ring dispersion. The displaced femtosecond pulse radiates and produces femtosecond synchrotron radiation. Up to now a regular bending magnet was used as radiator. To improve the flux, a significant upgrade was implemented, replacing the modulator, installing an in-vacuum undulator as new radiator, and installing a higher repeptition rate laser system. The new beamline will provide 100-200 fs long pulses of soft and hard x-rays with moderate flux and with a repetion rate of 10-40 kHz for experiments concerning ultrafast dynamics in solid state physics, chemistry and biology. To achieve the necessary spatial separation of the energy modulated slice from the rest of the bunch, a sizeable local vertical dispersion bump in the radiator is required. All accelerator physics aspects of the upgrade including challenging issues like the impact on the transverse single particle dynamics will be discussed together with initial results of the commissioning. |
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| ROAD005 | Status of NEG Coating at ESRF | vacuum, insertion, quadrupole, storage-ring | 422 | ||
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The ESRF non-evaporable getter (NEG) coating facility is in operation since two years now. A large part of the insertion device straight sections of the electron storage ring has been equipped with in-house coated 5m long aluminum vacuum chambers with an inner vertical aperture of 8 mm. Operational experience with different coating parameters leading to different film thicknesses will be given and compared to bremsstrahlung data. The paper deals also with improvements of the coating production and chamber preparation, and describes some aspects of NEG coating data acquisition, visualization, and remote control. The R&D program leading to a more powerful DC solenoidal coating tool to further improve the NEG coating production throughput and quality aspects is also discussed.
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| RPPE040 | Development of Copper Coated Chamber for Third Generation Light Sources | vacuum, impedance, insertion, feedback | 2633 | ||
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For the 3rd generation light sources, it is essential to reduce the beam instability in order to produce the highly bright synchrotron light much stably. Especially, to avoid the coupled bunch instability, the resistive wall impedance must be reduced. The copper-coating inner surface of the chamber(especially in insertion device section)is much effective method for the reduction of the resistive wall impedance, whose method was already proposed by our group (N.Nakamura et.al., EPAC 1998 p984). We have already produced the copper coated chamber. In this paper, we describe the measurement of the outgassing from the copper coated chamber to evaluate if this chamber is valid on the ultra-low high vacuum condition.
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| RPPE058 | Successful RF and Cryogenic Tests of the SOLEIL Cryomodule | electron, insertion, coupling, synchrotron | 3438 | ||
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In the Storage Ring (SR) of the Synchrotron SOLEIL light source, two cryomodules will provide the maximum power of 600 kW required at the nominal energy of 2.75 GeV with the full beam current of 500 mA and all the insertion devices. A cryomodule prototype, housing two 352 MHz superconducting single-cell cavities with strong damping of the Higher Order Modes has been built and successfully tested in the ESRF. Even though the achieved performance (3 MV and 380 kW) does meet the SOLEIL requirement for the first year of operation, it was decided to upgrade the cryomodule prototype before its implementation in the SR. Modifications of the internal cryogenic system as well as the input power and dipolar HOM couplers required complete disassembling, reassembling and testing of the cryomodule, which were carried out at CERN. This refurbishment program, which was achieved in the framework of a collaboration between SOLEIL, CEA and CERN, is reported in this paper. A second cryomodule, similar to the modified prototype, is under manufacturing and will be implemented in the SR by the end of 2006.
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| RPPT044 | Design, Construction and Commissioning of a NEG Coated Wiggler Vacuum Chamber for the LNLS Storage Ring | vacuum, wiggler, photon, insertion | 2807 | ||
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Funding: MCT - CNPQ - FAPESP |
We present the design of the vacuum chamber for the LNLS 2 T Hybrid Wiggler. The chamber is a 3 m long, 1.2 mm thick 316 SS tube, which was mechanically pressed into an elliptical shape from an originally round tube. In order to provide the necessary mechanical tolerances, the rather flexible tube is welded to lateral supports that run the complete length of the chamber. Special care has been given to the mechanical and magnetic characterization of the chamber and the inner surface of the chamber was NEG-coated at the ESRF. We present the installation procedure as well the vacuum conditioning charge evolution. |
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