| Paper | Title | Page |
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| MOPAN002 | Active Shunts for the LNLS Storage Ring Quadrupoles | 143 |
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| The quadrupoles of the LNLS storage ring are divided into families with two or six units, each one being supplied by an only current source. Some experiments performed by the accelerator physics team require different currents for quadrupoles of a same family. Moreover, there is an interest in obtaining lower steps in the control of their currents. These were the main reasons that required the development of an active shunt. A prototype was built with range of -3A to +3A, what is approximately 3% of the maximum quadrupole current (200A). It was tested with a two-quadrupole family power supply. The full bridge topology was chosen, where the pulse width for the positive and negative output voltages are not the same, which gives an average output current different from zero. Some waveforms and results are shown, such as the long-term stability and output current ripple. Some measurements made in the storage ring electron beam using the active shunt are also described. | ||
| MOPAN003 | A New Family of Power Supplies for the LNLS Orbit Correctors | 146 |
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| Recently the substitution of the older family of orbit corrector power supplies of the LNLS electron storage ring was proposed and a new family has been developed. The new model incorporates additional features such as natural ventilation, unit power factor and shorter response time to reference changes. Moreover, higher efficiency and lower weight and size were obtained. At the moment eight units are operating with storage ring orbit correctors, with current and output voltage up to 10A/10V. This family has three stages of power processing. The first one is a power factor corrector using the boost topology, which gives to the second stage a DC voltage about 400V with regulation and ripple better than 1%. The second stage is an isolated half-bridge with two symmetric adjustable DC outputs from 0 to 40V. The last stage consists of a bipolar series linear regulator using Bipolar Transistors (BJT). Some results obtained for this power supply were: output current ripple and one day stability better than 150ppm, reference voltage step response better than 500A/s with the existing orbit corrector magnet, efficiency higher than 62% and power factor better than 98.5%. | ||
| MOPAN004 | Commissioning of the LNLS Elliptically Polarizing Undulator | 149 |
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| We present the results of the commissioning of the first Elliptically Polarizing Undulator to be installed at the 1.37 GeV electron storage ring of the Brazilian Synchrotron Light Source. The undulator is designed to provide UV and soft X-ray photons from 100 eV up to 1 keV with full polarization control. It uses the APPLE II design with 50 mm period and 22 mm gap and allows for both parallel and anti-parallel longitudinal motion of its magnet cassettes. We present the commissioning results including the measured orbit and tune perturbations as well as the non-linear effects of the undulator fields on the stored beam and the corresponding impact on the beam lifetime. | ||
| MOPAN005 | Injector Improvements at the Brazilian Synchrotron Light Source | 152 |
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| We present the results of hardware, software and operational improvements implemented at the injector complex of the 1.37 GeV electron storage ring of the Brazilian Synchrotron Light Source (LNLS) with the aim of improving injector stability and reliability, thus reducing the injection time. The improvements include changes to the 120 MeV injector LINAC RF system and high power modulators, injection automation and the implementation of a new procedure for reusing the current at the end of each user's shifts before injection by ramping the energy back down to 500 MeV (the injection energy) without dumping the beam. All of these changes allowed us to significantly reduce the overall time from the end of a shift to the delivery of beam in the following shift with a positive impact on the reduction of injection thermal transients for the storage ring and beamlines. Further improvements are expected in the near future as a result of planned changes to the injection timing system and of the installation of a recently assembled upgrade of the 500 MeV booster synchrotron RF system | ||
| MOPAN007 | A Non-intercepting Beam Current Monitor for the ISAC-II SC-linac | 155 |
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| A personnel protection system will monitor the ion beam current into the experimental hall from the ISAC-II SC-linac. It will use continuous self-test and redundancy and have an accuracy of ±10% from 1 to 200enA. The system, based on an Atlas design, will use capacitive pickups with rf resonators and buffer amplifiers. Ion charge, velocity and bunch width will affect the sensitivity so periodic calibration with dc Faraday cups will be needed. The signal from each 13cm long, 5cm diameter pickup tube will pass through a vacuum feedthrough to a helical resonator. An AD8075 IC with an input impedance of 87kΩ at 35MHz will allow a high coil tap. The ISAC beam, bunched at 11.8MHz, is injected into the ISAC-II SC-linac via a 25m long transfer line. Monitors will be placed in the transfer line and downstream of the linac before the experimental hall. A 35MHz and a 70MHz coil (3 and 6 harmonic) have loaded Q's of 600. A test in the transfer line of the 35MHz coil gave a sensitivity 0.09mV/enA from the unity gain buffer using 20Ne+5 ions at 1.5MeV/u. The background was equivalent to 1enA. The 70MHz coil gave 0.04mV/enA using 22Ne+4 ions. System design and test data will be presented. | ||
| MOPAN008 | A Single Bunch Selector for the Next Low β Continuous Wave Heavy Ion Beam | 158 |
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Funding: Eurisol Project supported by the European Commission under contract N? 515768 RIDS The Eurisol heavy ion post-accelerator and the Spiral2 deuton/ion MEBT should transport a continuous wave (cw) beam from respectively a 88.05 MHz RFQ (β respectively 0.036 and 0.04) to a drift-tube linac. A high frequency chopper is being studied to select only 1 bunch over N, 10 < N < 10000 as asked by the physicists. It requires pulses higher than 3 kV, rising in less than 7 ns at a repetition rate up to 8.8 MHz. These figures are at the border of what can be provided by the travelling wave fast choppers and the capacitive-type chopping technologies. We have reviewed the current fast and slow chopping structures and their associated pulse generator. Some preliminary RF simulations to adapt the present chopping devices to our requirements are presented. The main limitations of these technologies when applied to isolate bunches in ion cw accelerators are also shown. Our first studies and results to solve the arising problems are discussed. |
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| MOPAN009 | Transverse Feedback Development at SOLEIL | 161 |
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| With reduced vertical chamber aperture adopted all around the machine, the transverse impedance for the SOLEIL ring is enhanced both in its resistive-wall and broadband content. The predicted instability threshold currents being significantly low as compared to the nominal current in multibunch and in several single bunch modes, a decision was taken to install a digital bunch by bunch feedback system, with an aim to make it operational since the beginning of the storage ring operation. The system implemented comprises components developed elsewhere, particularly the FPGA processor of SPring-8, chosen among different possible solutions. Using a BPM and a stripline in the diagonal mode, a single unit of the FPGA processor board has shown to successfully suppress resistive-wall and ion induced multibunch instabilities in either one or both transverse planes. On top of the system characteristics, the paper discusses details of the obtained performance, as well as future extensions to overcome the encountered limitations. | ||
| MOPAN011 | Upgrade Plans of the Vacuum System of the ESRF | 164 |
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| The ESRF has been delivering beams to users for well over 12 years. The performance of the storage ring has surpassed the original specifications with respect to many accelerator parameters, such as emittance, beam stability, beam availability and so on. Along the years, many of its sub-systems have been improved in order to cope with these more demanding conditions. Now new experimental techniques and arrangements, such as nanofocusing on the samples, call for a radical upgrade of the machine. Another reason to upgrade is the recent coming into operation of new, more modern machines, and the desire for the ESRF to stay at the forefront of synchrotron radiation research. A study group has been set up, with the aim of producing a conceptual design report for what is called a "Long Term Strategy" for the upgrade of the ESRF. This paper will detail the plans for the LTS upgrade of the storage ring vacuum system. | ||
| MOPAN012 | Development of the Injection- and Extraction Systems for the Upgrade of SIS18 | 167 |
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| SIS18 will serve as booster synchrotron for the proposed International Accelerator Facility FAIR at GSI. The aim is to provide high intensity proton and heavy ion beams of e.g. U28+-ions with a repetition rate of 2.7 - 4 cycles per second for injection into SIS100. The operation with low charge state heavy ions requires modifications of the injection and extraction systems. The goal is to minimize beam losses and thereby ion induced gas desorption during the injection and extraction processes. In order to increase the acceptance and for an injection at the reference energy it is necessary to build and install a new electrostatic inflector septum and a new inflector magnet. The electrostatic injection septum is designed for an operation at high field strength and enables a bake-out temperature of 300°C. This may be achieved by means of new cathode surface treatment procedures, e.g. with pulsed high intensity electron beams. Another technique is also under investigation, the coating of alumina by a plasma spray technique. | ||
| MOPAN013 | Wien Filter as a Spin Rotator at Low Energy | 170 |
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Funding: Work supported by DFG under contract SFB 634 The Wien filter is well known as a common energy analyzer and is also used more and more as a compact variant of a spin rotator at low energy for electrons. The Wien filter based on a homogenous magnetic and electric field that are perpendicular to each other and transverse to the direction of the electrons. The rotation of the spin vector is caused by the magnetic field. If the force equilibrium condition is fulfilled the beam should not be deflected at the Wien filter. Simulations show that in the fringe fields the electrons get a kick. Therefore full 3D simulations of the electromagnetic fields and beam dynamics simulations are studied in detail at the example of the Wien filter at the new polarized 100 keV electron injector at the S-DALINAC. The results of the simulations with CST Design Environment(TM), MAFIA and V-Code are presented. |
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| MOPAN014 | DESY and ILC EDMS: Engineering Data Management for Large Scientific Projects | 173 |
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| DESY is using an Engineering Data Management System (EDMS) for supporting the XFEL and PETRA III projects. The system offers a wide range of applications for managing complexity: It enables 3D CAD design collaboration, supports the manufacturing and preparation processes of s.c. cavities and provides general project documentation. The system is now also adopted by the ILC for the collaborative 3D CAD design of cryomodules in the three regions and for change management of the baseline configuration document. The DESY EDMS is based on a commercial system which has been customized to the specific needs of large scientific projects, making it a unique system. In addition to general engineering requirements, the EDMS supports ad-hoc teamwork, provides mechanisms for process industrialization and offers powerful yet easy-to-use web frontends. The paper gives an overview of the EDMS capabilities and reports experience and benefits of using the EDMS. | ||
| MOPAN015 | Compact Waveguide Distribution with Asymmetric Shunt Tees for the European XFEL | 176 |
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| In the European X-ray FEL 32 superconducting cavities (4 cryomodules with 8 cavities per module) are connected to one 10 MW multibeam klystron through a waveguide distribution system. The XFEL tunnel has limited space for the waveguide system and therefore a new more compact waveguide distribution has been developed. The waveguide distribution is based on a binary cell which consists of two circulators connected to a shunt tee with integrated phase shifters. Four binary cells are combined by three asymmetric pretunable shunt tees. The asymmetric shunt tees allow to change the RF power for each pair of cavities and to reach the maximum cryomodule gradient. In this paper we will present the status of the waveguide distribution system and report on the development of the different new waveguide components. | ||
| MOPAN016 | P3PO: An Information System for Supporting Installation Procedures at PETRA III | 179 |
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| For the PETRA III project, an information system called P3PO has been developed for supporting the logistics of the installation process and for managing the technical infrastructure. P3PO provides a central information access point for the PETRA III installation status. The system registers all the components of the accelerator and provides work lists which list the tasks and their responsible groups for each component. It records the progress of work and provides support for managing the documentation. Users can access P3PO through an easy-to-use web-interface and obtain for example inventory lists, delivery status reports and task lists for groups or individuals. P3PO is based on DESYs inventory management and engineering data management systems and is in production since summer 2006. The paper describes the system capabilities and reports benefits and experience. | ||
| MOPAN017 | Noise and drift characterization of direct laser to RF conversion scheme for the laser based synchronization system for FLASH at DESY | 182 |
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Funding: This contribution is funded by the EUROFEL project. The next generation of FEL's (Free Electron Lasers) require a long and short term stable synchronisation of RF reference signals with an accuracy of 10 fs. For that an optical synchronisation system is developed for FLASH at DESY, that is based on optical pulse train which carry the timing information encoded in its precise repetition rate. The optical pulse train has to be converted into an RF signal to provide a local reference for calibration and operation of RF based devices. The drift and jitter performance of the optical to RF converter influences directly the phase stability of the accelerator. Three different methods for optical to RF converters, namely the direct photodiode detection, injection locking and a sagnac loop interferometer are currently under investigation. In this paper we concentrate on the jitter and drift performance of the direct photodiode conversion and show its limitations from measurement results. |
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| MOPAN018 | Performance of the New Coupled Bunch Feedback System at HERA-p | 185 |
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| A longitudinal broadband damper system to control coupled bunch instabilities (LMBF) has been installed in the 920~GeV proton accelereator HERA-p at the Deutsches Elektronen-Synchrotron DESY in Q4/2005. The Feedback system was fully automated, in order to relieve the operator from manual control during system operation. During comissioning in Q1/2006 it turned out that the performance goals were reached and the noise is not as much a problem as expected. The proton bunch length is significantly reduced as is the stretching of the bunches over runtime. Without additional damping the bunch length is about 1.5~ns (FWHM) at the beginning of a typical luminosity run. With the new feedback system in operation the bunch length could be decreased to 1.0 ns at best. Although the bunches get longer during the luminosity run, the integrated luminosity gain is thus up to 5%. System optimization points were found in automatic gain adjustment during acceleration ramp, oscillation level triggering and timing of kicker pulse to bunch. We describe the commissioning of the multibunch feedback system and the adjustment procedures. A performace overview after one year of operation is given. | ||
| MOPAN019 | Performance of the New Master Oscillator and Phase Reference System at FLASH | 188 |
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| The master oscillator and phase reference system at FLASH must provide several rf reference frequencies to widely spread locations with low phase noise and small long term phase drifts. The phase noise requirements of the 1300 MHz reference is of the order of 0.1 deg. while short and medium term phase stability is of of the order of 0.1 deg. and 1 deg. respectively. The frequency distribution system employs a temperature stabilized coaxial line for rf power distribution and a fiber optic system for the monitoring of phase drifts. Presented are the the concept, design and performance measured in the accelerator environment. | ||
| MOPAN020 | Status of the Laser Master Oscillator System at FLASH | 191 |
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| An optical synchronization system based on the timing-stabilized distribution of ultra-short optical pulses has been proposed for next generation light sources, e.g. the European XFEL. The concept will be implemented and tested at FLASH at DESY. This paper describes the status of the optical master oscillator, which consists of two mode-locked Erbium-doped fiber lasers running in parallel. | ||
| MOPAN021 | Magnetic Field Calculations of the Superconducting Dipole Magnets for the High- Energy Storage Ring at FAIR | 194 |
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| For the High-Energy Storage Ring (HESR) to be established for the FAIR facility, magnetic field calculations have been carried out for the layout of the superconducting dipole magnets. Four configurations have been considered for the 2.72 m long magnets, straight ones and bent ones with a bending radius of 13,889 m, respectively, both for the cos(Θ) layout and for the double helix dipole layout. This contribution will focus particularly on the advantages and disadvantages of the individual configurations in terms of field quality in the diopole regions. | ||
| MOPAN022 | Investigation of Machine Operation and Related Radiation Dose at the ANKA Storage Ring | 197 |
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| A new online network for radiation dose measurements offers the opportunity to register the dose rate at the ANKA storage ring every minute. The network consists of six mobile and two stationary monitors with a gamma and a neutron detector and a central computer. The analysis of the dose rate shows strong correlations between beam energy, current, machine parameters and dose rate. | ||
| MOPAN023 | Superconductive Damping Wigglers for the CLIC Project | 200 |
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| The CLIC damping ring requires wigglers with both high on-axis fields and short periods. The present design foresees a superconductive wiggler with a period length of 5 cm, a peak on-axis field of 2.5 T and a full width aperture of 12 mm. In this paper we explore the performance improvements of the damping ring when these parameters are pushed to 2.7 T at a period length of 2 cm with the expense of a reduced aperture of 5 mm. A design for a prototype for testing the field quality of such a wiggler is presented in this paper and the possibility to test this wiggler with beam in the storage ring ANKA is described. | ||
| MOPAN024 | Commissioning of the ELETTRA Fast Orbit Feedback System | 203 |
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| A fast orbit feedback system has been installed at ELETTRA. It globally corrects the closed orbit at 10 kHz rate using all the BPMs and corrector magnets of the storage ring. The Libera Electron device has been used to upgrade the original detectors in order to provide micrometric accuracy and fast data rate of the beam position measurements. The article reports the experience gained during the commissioning of the system and the first operational results. | ||
| MOPAN025 | The Elettra Booster Magnets | 206 |
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| The third generation light source ELETTRA has been in operation since 1993. A new 2.5 GeV full energy booster injector, that will replace the existing linear injector limited to a maximum energy of 1.2 GeV is now under construction and the commissioning will start this August. The paper reports on the construction of dipole, quadrupole, sextupole and steerer magnets and on the magnetic measurement results with a comparison with the requested specifications. | ||
| MOPAN026 | Critical Issues in Ensuring Reproducible and Reliable Deposition of NEG Coatings for Particle Accelerators | 209 |
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| Non Evaporable getter (NEG) coating technology, developed at CERN in the late 90s, is an effective pumping solution for conductance limited vacuum chambers. It reduces thermal out-gassing and provides distributed pumping ability, allowing the achievement of very low pressure. NEG films do show additional interesting features, like low secondary electron yield and low gas de-sorption rates under ions, electrons and photons bombardment. For these reasons, large scale adoption of NEG coated chambers is now a reality and several leading edge machines will soon benefit from it. A critical issue for the successful application of this technology is the ability to deposit NEG coatings in a reproducible and reliable way all along a pipe. This is particularly important for narrow-gap or specially shaped chambers which pose severe challenges in term of film thickness distribution, chemical composition and sorption properties. A dedicated study was carried out to fully understand the deposition process as a function of the sputtering parameters and the chamber geometry. Results obtained do allow to optimize the coating process and ensure that film requirements in a given application are met. | ||
| MOPAN027 | NEG Coating of Pipes for RHIC : An Example of Industrialization Process | 212 |
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| Non Evaporable Getter (NEG) coated chambers have been used in various accelerators facilities and synchrotrons since some years. Initially, NEG coated chambers were mounted in small amounts in specific locations, covering a minor fraction of the accelerator surfaces exposed to vacuum. More recently, NEG coated chambers have been adopted to a larger degree in several projects, becoming an integral part of the machine design. LHC, whose commissioning is expected in 2007, will use 6 km of coated pipes, to be the largest machine ever using this technology. Other examples are the Soleil synchrotron (50% of the ring is NEG coated), ESRF (ongoing replacement of ID with NEG coated chambers) and RHIC (installation of 600 m of NEG coated pipes ongoing).Coating a large number of chambers poses challenges in term of process industrialization, product inspection and quality assurance. In the present paper we report SAES Getters' experience in the NEG coating of pipes delivered to Brookhaven National Lab for RHIC(120 steel chambers, each 5 m long). Main technological issues faced and procedures adopted to ensure product reproducibility and quality are presented and discussed. | ||
| MOPAN028 | Current Status of Virtual Accelerator at J-PARC 3 GeV Rapid Cycling Synchrotron | 215 |
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| We have developed the logical accelerator called "Virtual Accelerator" based on EPICS for 3 GeV Rapid Cycling Synchrotron (RCS) in J-PARC. The Virtual Accelerator has a mathematical model of the beam dynamics in order to simulate the behavior of the beam and enables the revolutionary commissioning and operation of an accelerator. Additionally, we have constructed the commissioning tool based on the Virtual Accelerator. We will present a current status of the Virtual Accelerator system and some commissioning tool. | ||
| MOPAN029 | XAL Online Model Enhancements for J-PARC Commissioning and Operation | 218 |
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Funding: Work supported by a KEK foreign visiting researcher grant The XAL application development environment has been installed as a part of the control system for the Japan Proton Accelerator Research Center (J-PARC). XAL was initially developed at SNS and has been described at length in previous conference proceedings (e.g., Chu et. al. APAC07, Galambos et. al. PAC05, etc.). The fundamental tenet of XAL is to provide a consistent, high-level programming interface, along with a set of high-level application tools, all of which are independent of the underlying machine hardware. Control applications can be built that run at any accelerator site where XAL is installed. Of course each site typically has specific needs not supported by XAL and the framework was designed with this in mind: each institution can upgrade XAL which then is accessible to all users. We outline the upgrades and enhancements to the XAL online model necessary for accurate simulation of the J-PARC linac. For example, we have added permanent magnet quadrupoles and additional space charge capabilities such as off-centered and rotated beams and bending magnets with space charge. We present the physics models for the upgrades as well as the software architecture supporting them. |
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| MOPAN030 | Analysis of Transverse Beam Oscillation at Photon Factory | 221 |
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| FPGA based bunch by bunch feedback system to cure the transverse instabilities has been in operation stably since Oct. 2005. Specification and performance of the system will be introduced, transient measurement has been done to analyze the instability modes, which helps to understand the instability sources. Bunch by bunch beam oscillation, together with the digital turn-by-turn beam position measurement, injection oscillation damping is recorded and analyzed, transverse beam oscillation with and without the bunch by bunch feedback system will be shown in this paper. Precise tune measurement during this period will be presented. Turn by turn phase space monitor is also available with the data, from which the nonlinear beam dynamics can be revealed. | ||
| MOPAN031 | Design Study of a Very Large Aperture Eddy Current Septum for J-PARC | 224 |
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| An eddy current septum is selected as a backup of injection septum. Due to the high beam intensity and low beam energy, the injection beam size is very large. To accommodate the large size beam, large aperture septum is required. Large end field and large eddy current loss result in degradation of gap field. The paper discusses the eddy current loss effects on field distribution and introduces some correction methods. | ||
| MOPAN032 | Eddy Current Effects in an Opposite-field Septum | 227 |
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| A large aperture, thin septum, high field opposite-field septum magnet has been developed for the injection of 50GeV main ring of J-PARC. Due to the eddy current generated in septum conductor, magnet yoke and magnet end plate, the field distribution was degraded. In the paper, eddy current effects on both transverse field and longitudinal field distribution are calculated. Correction methods and experiment results are introduced. | ||
| MOPAN034 | Development of a Pulsed Sextupole Magnet System for Beam Injection at the Photon Factory Storage Ring | 230 |
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| We proposed a single pulsed sextupole system for beam injection in electron storage rings. Now we are going to design a pulsed sextupole magnet and a ceramic chamber and install them at the Photon Factory storage ring next summer. The required specifications of the magnet and the vacuum chamber are estimated using a multi-particle tracking simulation. In this conference, we describe the design of the hardware for the system and the field measurement of the pulsed magnet. | ||
| MOPAN036 | Longitudinal Feedback System for the Photon Factory | 233 |
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| In the KEK-PF, longitudinal coupled-bunch instabilities are suppressed by means of the RF phase-modulation technique during the users operation. This method is very effective not only to suppress the instabilities but also to enlarge the beam lifetime. Together with the feasibility study for top-up operation, bunch-by-bunch feedback system have been developed. A two-port longitudinal kicker based on dafne-type cavity were designed and installed in the storage ring in the summer of 2006. FPGA-based signal processing part is under development based on the KEKB design. As an preliminary test of the longitudinal kicker, a simple mode-feedback system which suppress a specific coupled-bunch mode were tested successfully. | ||
| MOPAN037 | Acceleration of Cold Emission Beam from Carbon Nanotube Cathode in KEKB/PF Linac | 236 |
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| An electron gun with carbon nanotube cathode has been installed in the KEKB/PF linac, and the beam acceleration tests up to 2.5GeV have been performed successfully. The results and performance are presented in details. | ||
| MOPAN038 | Electric Power Compensation of the Large Scale Accelerator using SMES | 239 |
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| Power supply for the large scale accelerator magnets draws a large amount of power from the utility network. For example, the peak active power and the dissipation power of J-PARC 50GeV synchrotron magnet power are estimated to be about 135MW and 37MW, respectively. Super Conducting Magnetic Energy Storage (SMES) is one of candidates to compensate these large load and line voltage fluctuation. Study on circuit configuration of the power supply with SMES has been continued. Present status of the R & D for the SMES system and small case experiment result will be discussed. | ||
| MOPAN039 | Development of Hybrid Type Carbon Stripper Foils with High Durability at >1800K for RCS of J-PARC | 242 |
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| The Japan Proton Accelerator Research Complex (J-PARC) requires thick carbon stripper foils (250-500 ug/cm2) to strip electrons from the H- beam supplied by the linac before injection into the RCS of J-PARC. For this high-intensity H- beam and circulating bunch beam, which gives much damage to conventional carbon stripper foils. Thus carbon stripper foils with high durability at 1800K produced by energy deposition in the foil are indispensable for this accelerator. Recently, we have successfully developed hybrid type thick boron mixed carbon stripper foils (HBC-foil). Namely, the lifetime measurement of the foils was tested by using a 3.2 MeV, Ne+ DC beams of 2.5 uA, in which a significant amount of energy was deposited in the foils. The maximum lifetime was found to be extremely long, 30-and 250-times longer than those of Diamond and commercially available best carbon foils, respectively. The foils were also found to be free from any shrinkage, and to show an extremely low thickness reduction rate even at a high temperature of 1800K during long beam irradiation. In this conference the foil preparation procedures and lifetime measurements with a 3.2 MeV, Ne+ is presented. | ||
| MOPAN040 | Comparative Study on Lifetime of Stripper Foil using 650keV H- Ion Beam | 245 |
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Funding: This work is supported by the Japan Society for the Promotion of Science, under contract No. 18540303. Thick carbon stripper foils of >300 μg/cm2 will be used as a stripping of H-ion beam for 3GeV Rapid Cycling Synchrotron (3GeV-RCS) of the J-PARC. The carbon foils with long lifetime even at >1800 K are required. For this purpose, we have developed a new irradiation system for the lifetime measurement using high current pulsed and dc H- beams of the KEK Cockcroft-Walton accelerator. These high power 650keV H- Ion beams can simulate the high energy deposition in carbon stripper foils at the J-PARC RCS. An automatic data acquisition system is also developed for recording the data of foil temperature and irradiated beam current. The Hybrid Boron mixed Carbon (HBC) stripper foils, which are developed at KEK are irradiated by high current H- ion beam up to 2000 K. A few SNS-diamond and commercially available carbon (CM) foils are also tested for comparing with HBC-foils. The results of the lifetime measurement of HBC and SNS-diamond including CM stripper foils are reported. |
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| MOPAN041 | Design of a Movable Synchrotron Radiation Mask with SiC Absorber for the Photon Factory Advanced Ring (PF-AR) | 248 |
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| We have six rf cavities in the Photon Factory Advanced ring (PF-AR) at KEK. Three years ago, one of them was seriously damaged by the Synchrotron Radiation (SR) from the upstream of the cavity. In order to protect the cavities from SR, we intend to install SR masks nearby the cavities. The masks have to be positioned as close as possible to the beams in order to block the SR completely during the beam storage, and as far as possible during the beam injection. Therefore SR masks should be movable. Since it is placed under strong HOM power from the cavities, careful design is necessary for power dissipation. The basic structure of the movable masks is a coaxial wave-guide with cylindrical SiC absorber whose power capability is designed to be more than 1kW. We report the design of the movable SR masks and the result of rf power test. | ||
| MOPAN042 | Switching Power Supply for Induction Accelerators | 251 |
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| A new particle acceleration method using pulsed induction cavities was introduced in the super-bunch project at KEK. Unlike conventional RF acceleration, this acceleration method separates functions of acceleration and confinement As a result, this acceleration method can be applied for accelerating a wide mass range of particles. However, it is necessary to give a very fast pulsed-excitation to the cavity to perform the induction acceleration. Switching power supplies of high voltage output with very fast pulse-operation is one of the most important key technologies for this new acceleration method. We have developed 20ns rise time pulse at continuous repetition rate of 1MHz using MOS-FET's. Induction cavities were modulated through the 200m long transmission lines. Further development using SI- thyristor achieved 1MHz and 2kV switching in a burst mode operation. SiC devices are also studied for the application and some promising results were obtained. Faster operation will make this new acceleration technology available for small accelerator projects. | ||
| MOPAN043 | Beam Charge Feedback System for Thermionic Cathode RF-Gun | 254 |
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| A beam current feedback system to stabilize the long-time operation of thermionic cathode RF-Gun has been developed in Kyoto University FEL facility where a 4.5-cell thermionic cathode RF-gun provides electron beam to drive a mid-infrared free electron laser. However, the back-bomberdment effect seriously increases the temperature of the cathode surface, and thus the stable operation was quit difficult without continuous control of the cathode temperature or the beam current. We have tried to stabilize the beam current by using a feedback system. The beam current was monitored with current transformer, which was located at the exit of the gun or at the downstream of the energy analyzer, was read by oscilloscope. The total charge was calculated in a PC and the LabView PID-unit controlled the cathode heater current. As a result, the long term stability of the beam current dramatically improved. | ||
| MOPAN044 | Development of Commissioning Software System for J-PARC LINAC | 257 |
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| Beam commissioning of J-PARC LINAC has been performed since November 2006. A commissioning software framework and a database system have been developed for the commissioning. We first discuss the LINAC control system, and then our commissioning software framework. Then, we discuss our strategy of comparing online/offline data and models in our system with monitors, magnets, and the RF system. Commissioning tools developed during the commissioning will be presented in detail. | ||
| MOPAN045 | Longitudinal Particle Tracking of J-PARC RCS for Synchronization | 260 |
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| We have performed particle tracking simulation of J-PARC RCS to study the synchronization process. A frequency offset is added to the nominal RF frequency pattern to shift the center of the bunch, under the condition of the offset value should be 'adiabatic' with respect to the synchrotron motion. Since the synchrotron frequency of the J-PARC RCS is substantially changed during acceleration, the particle tracking simulation helps to decide upper limit of the frequency offset which can be employed. | ||
| MOPAN047 | Mechanical Design Considerations for Sesame Main Subsystems | 263 |
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| Recent advances in the design and analysis of SESAME vacuum system engineering as well as magnets and girder system mechanical designs are described. Multi objective optimization techniques for the storage ring vacuum chambers design from mechanical design point view and the vibration and stability issues for the magnets will be presented. | ||
| MOPAN048 | Design of Injection Pulsed Magnets for SESAME Ring | 266 |
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| In this paper the SESAME storage ring injection pulsed magnet system is described. The injection process in the SESAME storage ring requires septum and kicker magnets. In this paper we discuss the geometrical and magnetic field requirements for septum and kicker magnets and present the results obtained from magnetic field analysis and also the optimization of titanium coating for the injection kicker chambers. The final specification for thin septum and injection kickers are also presented. | ||
| MOPAN053 | Development of Transverse Feedback System and Instabilities Suppress at HLS | 269 |
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| In order to cure and damp coupled bunch (CB) instabilities, a transverse bunch-by-bunch feedback system is under commission at Hefei Light Source (HLS). In this paper, we introduce the HLS Bunch-by-Bunch measurement system and transverse feedback system. The experiment result in HLS ring is also presented in this paper. | ||
| MOPAN054 | Beam Instabilities Measurement and Cures at HLS | 272 |
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| In Hefei Light Source (HLS), coupled-bunch instabilities are major limiting factors in achieving higher beam intensity while maintaining good beam quality. To Measure and suppress beam instabilities, turn-by-turn (TBT) measurement and bunch-by-bunch(BxB) measurement & feedback system are under commission [1][2]. The design of the two systems and primary experiment results is presented. Measurement and detail analysing results in injection status will also be shown. | ||
| MOPAN055 | Bunch-by-Bunch Measurement and Feedback System of HLS | 275 |
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Funding: Supported by National Natural Science Project (10175063); National Natural Science Key Project (10535040) In this paper, HLS (Hefei light Source) bunch-by-bunch measurement and feedback system will be introduced. This system is integrated with longitudinal oscillation measurement system, fast vector control, fiber notch filter and bunch current detection system. The detail of the two fronts will be shown. Some experimental results by this system are also present in this paper, as phase-space tracing, mode dumping rate, and feedback experiments. |
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| MOPAN056 | Development of Digital Transverse Bunch-by-Bunch Feedback System of HLS | 278 |
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Funding: Supported by "National 211 Project" To promote the transverse feedback system of HLS, we develop the transverse digital feedback system. The scheme of HLS digital feedback system is presented in this paper, and the primitive digital feedback experiment we have done in HLS is also included in the paper. |
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| MOPAN057 | LabVIEW and MATLAB-Based Virtual Control System for Virtual Prototyping of Cyclotron | 281 |
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Funding: This work is supported by National Nature Science Foundation of China under Grant 10435030 A virtual control system designed to control and monitor the process of a cyclotron virtual prototyping is presented in this paper. Based on the feature of cyclotron, a distributed control structure is proposed according to the knowledge of software engineering. LabVIEW is employed to develop human machine interface(HMI), sequential control, safety interlock, and MATLAB is used to implement analysis and simulation. Dynamic data exchange (DDE) supported by Win32 Platform SDK is adopted to process data exchanging by a Server/Client mode. Any additional functions can be extended easily in this system in future. |
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| MOPAN058 | Control System for PEFP Instruments with Modbus Protocol | 284 |
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Funding: This work was supported by the 21C Frontier R&D program sponsored by Ministry of Science and Technology, Korean Government. 20MeV proton linear accelerator of the PEFP(Proton Engineering Frontier Project) has above 10 magnet power supplies and getter pumps to interface with Modbus protocol. VME IOC(Input Output Controller) has been designed and constructed for the control system by using VME serial I/O. The driver support module of the VME IOC has been developed to initialize the IO board and communicate with the instruments through EPICS. Operating console and storage module for operators in the control room has been programmed on PC and SUN of the operator interface. |
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| MOPAN059 | PEFP Monitoring System Through an Analog Input to Ethernet Converter | 287 |
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Funding: This work was supported by the 21C Frontier R&D program sponsored by Ministry of Science and Technology, Korean Government. Proton Engineering Frontier Project (PEFP) has above 40 magnet power supplies for the 20MeV proton linac. Because some power supplies have analog interfaces, we chose ATEC (Analog Input To Ethernet Converter) to monitor their output currents and voltage by supporting the protocol conversion function. Software components of the Experimental Physics and Industrial Control System (EPICS) have been ported to a VME single board computer based on a PowerPC microprocessor (MPC7410). This paper presents the software component and processing of analog input values between EPICS on the PowerPC based board and ATEC operating as Server Mode. |
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| MOPAN060 | Compensation of BPM Chamber Motion in PLS Orbit Feedback System | 290 |
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| The false BPM reading resulting from the BPM vacuum chamber motion due to thermal load change by synchrotron radiation is compensated by the real-time monitoring of the chamber position in the PLS orbit feedback system. The BPM chamber moves up to 20 μm during the beam refill and the chamber motion has a time constant of about one and half hour, which is related to thermal equilibrium of the vacuum chamber. To monitor the BPM chamber motion, LVDTs with 0.2 μm reading accuracy were installed on all BPM chambers, and the measured data are used in the orbit feedback every 1 minute. In this paper, we will describe how serious the BPM chamber motion are and how well it is compensated. | ||
| MOPAN061 | Compact Output Filter for Switching Frequency Elimination at the PLC Linac New Magnet Power Supply | 293 |
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Funding: This work is supported by the Ministry of Science and Technology, Korea. At 2006, PLS Linac magnet power supply (MPS) has been upgraded for the stable beam injection and 4th generation light source research. New MPS are developed new compact MPS of 16-bit resolution and 20ppm stability using four-quadrant switching scheme with 50kHz MOSFET switching device, and consists of main power board, control power board, regulator board and CPU board. Size of each board is only 100mm width and 240mm depth. Output of MPS is 10V, ±10A for the bipolar and 50V, 50A for the unipolar magnet. Main board is consisted four-quadrant FET switch, driver and output filter. Output filter must be perfectly eliminating switch frequency and compact size. In this paper, we report on development and characteristics of compact output filter of the new MPS for PAL linac. |
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| MOPAN063 | Extremely Low-jitter FPGA Based Synchronization Timing System | 296 |
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| Injection-involved synchronization timing system must provide synchronization triggers and clocks with the jitter values in the range of few tens of ps. A well-thought-out system-level design approach was necessary, splitting a design into several sub-modules, each addressing the specific synchronization issue. Tight synchronization between the unrelated RF signal and external trigger is based on a PLL phase-shifted over-sampling technique. Beam-monitoring instrumentation synchronization is also handled. An emphasis was put into a design, offering an installation without calibration. Utilizing state-of-the art FPGA circuits we designed a purely digital system, without analogue components (i.e. delay lines) that would require a time-consuming calibration and lead to increasing jitter for long delay ranges. Finally, regardless of its complexity the timing solution has to provide seamless integration into the accelerator facility. To leverage the performance, offered by a dedicated state-of-the-art HW, with flexibility, offered by a SW solution, we used a standard device for peripheral CS integration, based on an embedded processor running OS - a part of a microIOC family of products. | ||
| MOPAN065 | The Conceptual Design and Thermal Analysis of ALBA Crotch Absorbers | 299 |
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| ALBA is a 3 GeV, 268.8 m storage ring with DBA structure under construction near Barcelona. With the design current of 400 mA, a total power of 407 kW is radiated by the circulating beam from the bending magnets. The design of the vacuum system was done by using the concept of the crotch absorbers which is used in many modern synchrotron light sources. These absorbers are not only going to absorb the power of the unused radiation but also will allow fast vacuum conditioning. 156 absorbers are need all around the machine in order to guarantee that no radiation will hit the chamber walls, the absorbers are grouped into three types, several design criteria have been studied in order to create our own one which is based on the number of allowed cycles before failure with the concept of the strain values. Finite element analysis has been performed to estimate the stress, strain, maximum overall temperature and the maximum cooling temperature for all the types. The results for the critical absorber under conservative conditions: max. overall temperature is 313 C, max. strain is 0.1% and max. stress is 112 MPa. With this strain, the absorber can withstand up to 1.105 cycles of operation. | ||
| MOPAN066 | First Tests of a Precision Beam Phase Measurement System in CTF3 | 302 |
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Funding: This work is supported by the Commission of the European Communities under the 6th Framework Programme -Structuring the European Research Area-, contract number RIDS-011899. High precision beam phase measurements will be vital for synchronization of main and drive beams in CLIC. Development work is underway with the aim to demonstrate 0.1 degree resolution for a wideband 30GHz measurement. In order to be able to test this with a beam exhibiting much higher phase jitter, two prototypes have been built so that the difference in their outputs can be measured. Results of measurements made with bunch trains in CTF3 are presented. |
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| MOPAN067 | Transport and Installation of the LHC Cryo-Magnets | 305 |
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| Eleven years have passed between the beginning of transport and handling studies in 1996 and the completion of the LHC cryo-magnets installation in 2007. More than 1700 heavy, long and fragile cryo-magnets had to be transported and installed in the 27 km long LHC tunnel with very restricted available space. The size and complexity of the project involved challenges in the field of equipment design and manufacturing, maintenance, training and follow-up of operators and logistics. The paper presents the milestones, problems to be overcome and lessons learned during this project. | ||
| MOPAN068 | Performance with Lead Ions of the LHC Beam Dump System | 308 |
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| The LHC beam dump system must function safely with lead ions. The differences with respect to the LHC proton beams are briefly recalled, and the possible areas for performance concerns discussed, in particular the various beam intercepting devices and the beam instrumentation. Energy deposition simulation results for the most critical elements are presented, and the conclusions drawn for the lead ion operation. The expected performance of the beam instrumentation systems are reviewed in the context of the damage potential of the ion beam and the required functionality of the various safety and post-operational analysis requirements. | ||
| MOPAN069 | Ultrasound Diagnostics of the Superconducting Cable Connections Between the Main Ring Magnets of LHC | 311 |
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| As part of the LHC assembly program, the super-conducting magnets are interconnected after installation. Electrical continuity between the magnets is ensured via a specifically designed cable splice box which allows the cables to be electrically joined by an automated low temperature brazing technique. The electrical resistance and mechanical strength of the cable junctions depend on the quality of the brazed joint. An ultrasound diagnostic of the brazed joint has been developed to accompany the visual inspection and reinforce the quality control process. Non-standard ultrasound diagnostic techniques, without using matching liquids or gel in the harsh and congested working environment, applied to the sandwich structure of the cable splice box, which presents high ultra-sonic losses due to multiple scattering, have been developed. The equipment and methods implemented are described in detail, together with results of quality control tests made in the production environment. | ||
| MOPAN070 | Developments in High-precision Aspects of Power Converter Control for LHC | 314 |
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| The initial results from integration testing of the LHC magnet power converters revealed problems of low-frequency noise, settling time, drift with time and temperature, thermal management and EMC. These problems originated in the use of DSP, the A/D converter (ADC), the DC Current Transducer (DCCT) and their respective environments. This paper reports the methods used to improve the performance through hardware and software modifications and the results achieved. | ||
| MOPAN071 | Characteristics of Burden Resistors for High-precision DC Current Transducers | 317 |
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| The DC current transducer (DCCT) and accompanying A/D converter determine the precision of a power converter in accelerator operation. In the LHC context this precision approaches 10-6. Inside the DCCT, a burden resistor is used to convert the current to an output voltage. The performance of this resistor is crucial for the accuracy, temperature behaviour, settling time and long-term drift of the DCCT. This paper reports on evaluations, a new parameter called "power coefficient" (PC) and test results from some different types of resistors available on the market. | ||
| MOPAN072 | High-precision Performance Testing of the LHC Power Converters | 320 |
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| The magnet power converters for LHC were procured in three parts, power part, current transducers and control electronics, to enable a maximum of industrial participation in the manufacturing and still guarantee the very high precision (a few parts in 10-6) required by LHC. One consequence of this approach was several stages of system tests: factory reception tests, CERN reception tests, integration tests, short-circuit tests and commissioning on the final load in the LHC tunnel. The majority of the power converters for LHC have now been delivered, integrated into complete converters and high-precision performance testing is well advanced. This paper presents the techniques used for high-precision testing and the results obtained. It is also hoped to report results from the first sector commissioning. | ||
| MOPAN073 | Parametric Study of Heat Deposition from Collision Debris into the Insertion Superconducting Magnets for the LHC Luminosity Upgrade | 323 |
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| With a new geometry in a higher luminosity environment, the power deposition in the superconducting magnets becomes a critical aspect to analyze and to integrate in the insertion design. In this paper, we quantify the power deposited in magnets insertion at variable positions from the interaction point (IP). A fine characterization of the debris due to the proton-proton collisions at 7 TeV, shows that the energetic particles in the very forward direction give rise to non intuitive dependences of the impacting energy on the magnet front face and inner surface. The power deposition does not vary significantly with the distance to the interaction point, because of counterbalancing effects of different contributions to power deposition. We have found out that peak power density in the magnet insertion does not vary significantly with or without the Target Absorber Secondaries (TAS) protection. | ||
| MOPAN074 | Influence of Varying Tune Width on the Robustness of the LHC Tune PLL and its Application for Continuous Chromaticity Measurement | 326 |
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| Tune and chromaticity measurement is an integral part for safe and reliable LHC operation. Tight tolerances on the maximum transverse beam excursions allow oscillation amplitudes of less than 30 um. This leaves only a small margin for transverse beam and momentum excitations required for measuring tune and chromaticity. This contribution discusses a robust tune phase-locked-loop (PLL) operation in the presence of non-linearities and varying chromaticity. The loop design was tested at the SPS, using the LHC PLL prototype system. The system was also used to continuously measure tune width and chromaticity, using resonant transverse excitations of the tune side-slopes. | ||
| MOPAN075 | Experimental Modal Analysis of Components of the LHC Experiments | 329 |
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| Experimental modal analysis of components of the LHC Experiments is performed with the purpose of determining their fundamental frequencies, their damping and the mode shapes of light and fragile detectors components. This process permits to confirm or replace Finite Element analysis in the case of complex structure (with cables and substructure coupling). It helps solving structural mechanics problems to improve the operational stability and determine the acceleration specifications for transport operations. This paper describes the hardware and software equipments used to perform a modal analysis on particular structures such as a particle detectors and the method of curve fitting to extract the results of the measurements. This paper exposes also the main results obtained for the LHC Experiments. | ||
| MOPAN076 | Remote Inspection, Measurement and Handling for LHC | 332 |
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| Personnel access to the LHC tunnel will be restricted to varying extents during the life of the machine due to radiation, cryogenic and pressure hazards. The ability to carry out visual inspection, measurement and handling activities remotely during periods when the LHC tunnel is potentially hazardous offers advantages in terms of safety, accelerator down time, and costs. The first applications identified were remote measurement of radiation levels at the start of shut-down, remote geometrical survey measurements in the collimation regions, and remote visual inspection during pressure testing and initial machine cool-down. In addition, for remote handling operations, it will be necessary to be able to transmit several real-time video images from the tunnel to the control room. The paper describes the design, development and use of a remotely controlled vehicle to demonstrate the feasibility of meeting the above requirements in the LHC tunnel. Design choices are explained along with operating experience to-date and future development plans. | ||
| MOPAN077 | Geometry of the LHC Short Straight Sections Before Installation in the Tunnel: Resulting Aperture, Axis and BPM Positioning | 335 |
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| The Large Hadron Collider Short Straight Sections (SSS) are currently being installed in their final position in the accelerator tunnel. For all the SSSs, both those in the regular arcs as well as those in the insertion regions, magnetic and geometric measurements are made at different steps of their assembly. These stages range from production in the industry to the cryostating at CERN, as well as during and after cold tests or during installation of the BPM and the cold warm transition for the stand alone magnets. The results of the geometry at the various production stages by means of different procedures and analysis tools are reported and discussed in details in this paper. | ||
| MOPAN079 | Assembly and Quality Control of the LHC Cryostats at CERN. Motivations, Means, Results and Lessons Learned | 338 |
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| In 2001 the project management decided to perform at CERN the final assembly of the LHC superconducting magnets,with cryostat parts and cold masses produced by European Industry in large series. This industrial-like production has required a very significant investment in tooling,production facilities,engineering and quality control efforts, in contractual partnership with a consortium of firms. This unusual endeavour of a limited lifetime represented more than 800'000 working hours spanning over four years,the work being done on a result oriented basis by the contractor. This paper presents the reasons for having insourced this project at CERN,describes the work breakdown structure,the production means and methods,the infrastructure specially developed,the tooling,logistics and quality control aspects of the work performed,and the results achieved, in analytical form. Finally the lessons learned are outlined. | ||
| MOPAN080 | Modeling of Flexible Components for Asserting the Stability of Superconducting Magnets | 341 |
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Funding: Raja Ramanna Centre for Advanced Technology (RRCAT), Indore, INDIA European Organisation for Nuclear Research (CERN), Geneva, Switzerland Superconducting magnets are subjected to various forces during their cool down and alignment. Their construction invariably includes bellows, gimbals, hoses and composite supports. A good estimate of the deformations arising out of the cool down and alignment operations is necessary as these induce relative displacements between the fiducialised external vessel and hidden cold mass of the magnet. The nonlinear and orthotropic behaviour of these elements may make the model complicated and if solved as a nonlinear problem, would entail a large solution time as the overall model size runs into million nodes. Authors developed a unified Finite Element Model of the LHC Short Straight Section and during this process many innovative modeling techniques evolved. The developed model uses isotropic material constitutive laws with linear material properties. The paper is presenting some of the salient features of these modeling techniques. |
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| MOPAN081 | The LHC Collimator Controls Architecture - Design and Beam Tests | 344 |
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| The LHC collimation system will require simultaneous management by the LHC control system of more than 500 jaw positioning mechanisms in order to ensure the required beam cleaning and machine protection performance in all machine phases, from injection at 450~GeV to collision at 7~TeV. Each jaw position is a critical parameter for the machine safety which could cause a beam dump. In this paper, the architecture of the LHC collimator controls is presented. The basic design to face the accurate and real-time control of the LHC collimators and the interfaces to the other components of LHC Software Application and control infrastructures are described. The full controls architecture has been tested off-line in dedicated test benches, and in the real accelerator environment in the CERN SPS during beam tests with a full scale collimator prototype. The results and the lessons learned are presented. | ||
| MOPAN082 | Four Quadrant 120 A, 10 V Power Converters for LHC | 347 |
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| The LHC (Large Hadron Collider) particle accelerator makes extensive use of true bipolar power converters, with a regulated high precision output current requirement. A special design and topology is required to permit high performance throughout the converter operating area, including quadrant transition. This paper presents the 120A 10V power converter, well represented in the LHC (300 units). The design is adapted for a wide range of magnet loads [from 10mH to 4 Henry] with stringent EMC requirements. A quick-connect system was applied to the converter modules to allow easy installation and maintenance operations. Discussion of 4 quadrant control and practical results are presented. | ||
| MOPAN083 | 130 mm Aperture Quadrupoles for the LHC Luminosity Upgrade | 350 |
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Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" program (CARE, contract number RII3-CT-2003-506395) Studies for the LHC luminosity upgrade showed the need for quadrupoles with apertures much larger than the present baseline (70 mm). In this paper we focus on the design issues of a 130 mm aperture quadrupole. We first consider the Nb-Ti option, presenting the magnetic design with the LHC dipole cable. We study the Lorentz forces and we discuss the field quality constraints. For the Nb3Sn option we sketch two designs, the first based on the LARP 10 mm cable, and the second one on a 15 mm cable. The issue of the stress induced by the Lorentz forces, which is critical for the Nb3Sn, is discussed using both scaling laws and finite element models. |
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| MOPAN084 | Estimating Field Quality in Low-beta Superconducting Quadrupoles and its Impact on Beam Stability | 353 |
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Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" program (CARE, contract number RII3-CT-2003-506395) The aim of this analysis is to study if the field quality in a large aperture low-beta superconducting quadrupole for the LHC upgrade limits the beam performances due to increased geometric aberrations. Random field errors in superconducting quadrupoles are usually estimated by computing the effect of a random positioning of the coil blocks around the nominal position with an r.m.s. of 0.05 mm. Here, we review the experience acquired in the construction of 7 superconducting quadrupoles in the RHIC and in the LHC projects to estimate the precision in the block positioning, showing that there is no visible dependence on the magnet aperture. Different magnet models are then used to estimate the expected field quality in quadrupoles with apertures ranging from 50 to 200 mm. The impact on geometrical aberrations and scaling laws for their dependence on the aperture are finally evaluated. |
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| MOPAN085 | Completion of the Series Fabrication of the Main Superconducting Quadrupole Magnets of LHC | 356 |
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| By end of November 2006, the last cold mass of the main superconducting quadrupole cold masses were delivered by ACCEL Instruments to CERN. This comprised 360 cold masses for the arc regions of the machine and 32 special units dedicated to the dispersion suppressor regions. The latter ones contain the same main magnet but different types of correctors and are of increased length with respect to the regular arc ones. The end of the fabrication of these magnets coincided with the end of the main dipole deliveries allowing a parallel assembly into their cryostats and installation into the LHC tunnel. The positioning into the tunnel was optimized using the warm field measurements performed in the factory. On the other hand the correct slotting of the quadrupoles was complicated due to the multitude of variants and by the fact that a number of units needed to be replaced by spares which in some cases required a reshuffling of the positioning. The paper gives some final data about the successful fabrication at ACCEL Instruments and explains the issue of their best positions in the machine. | ||
| MOPAN086 | Final Geometry of 1232 LHC Dipoles | 359 |
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| The 15 m long main dipoles for the Large Hadron Collider are now being installed in their final positions in the accelerator tunnel. Geometric measurements of the magnets after many of the production steps from industry to the cryostating, after cold tests and after preparation of the magnets for installation, have been made, permitting careful control of the shape of the magnet, the positioning of the field correctors, and the final positioning in the tunnel. The result of the geometry control at the different production stages, from industry to CERN, using different kinds of control procedures and analysis, will be reported. | ||
| MOPAN087 | Processing Magnet Geometry Measurements for Better Control of LHC Aperture | 362 |
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| The axis of the Large Hadron Collider superconducting magnets are measured from both ends. These two redundant measurements are combined to get a reliable measurement result. When the two measurements are put together, we observe a 'saw tooth' effect due to the fact that the two measurements are, in general, not identical. This is expected from the accuracy of the two measurements. However the effect observed is larger than expected, in the vertical plane. Effects of temperature gradients in the cold bore tube during measurements have been observed and we show that this effect is the most probable explanation for the observations of the large differences in the measurements between the two sides. This work proposes an algorithmic approach to filter this effect to improve measurement results. Magnets are positioned with an accuracy of 0.1 mm, and the error in positioning coming from measurement errors due to the temperature effects can be up to 0.3 mm. Our analysis shows that by applying this correction we can insure the best positioning of the magnets in the tunnel in the vertical plane. Analysis is done for the 14 m long main dipoles, for which the effect is most visible. | ||
| MOPAN088 | A Large Aperture Superconducting Dipole for Beta Beams to Minimize Heat Deposition in the Coil | 365 |
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| The aim of "beta beams" in a decay ring is to produce highly energetic pure electron neutrino and anti-neutrino beams coming from b-decay of 18Ne10+ and 6He2+ ion beams. The decay products, having different magnetic rigidities than the ion beam, are deviated inside the dipole. The aperture and the length of the magnet have to be optimized to avoid that the decay products hit the coil. The decay products are intercepted by absorber blocks inside the beam pipe between the dipoles to protect the following dipole. A first design of a 6T arc dipole using a cosine theta layout of the coil with an aperture of 80 mm fulfils the optics requirements. Heat deposition in the coil has been calculated using different absorber materials to find a solution to efficiently protect the coil. Aspects of impedance minimization for the case of having the absorbers inside the beam pipe have also been addressed. | ||
| MOPAN089 | Numerical Simulation Applied to the Air Temperature Control and Improvement at the TLS | 368 |
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| This paper presents the numerical simulation studies applied on the air temperature control and improvement at the Taiwan Light Source (TLS). To improve air temperature control and study the flow circulation in air conditioned areas, we had applied the computational fluid dynamic (CFD) scheme to the experimental hall, the storage ring tunnel, a technical zone and the booster area, respectively. We review those studies by examining the governing equations, the model construction, mesh generation, boundary conditions, convergence criterion and validation of simulations. | ||
| MOPAN090 | Logging of Operation Data at TLS | 371 |
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| The Taiwan Light Source had been Top-Up operation in October 2005 and the beam current had increased to 300mA in early 2006. For normal operation, there are some important parameters of Top-up operation, such as beam stability, filling pattern and injection efficiency etc. These data have to be recorded and to be reference for the accelerator operating. Therefore, a LabVIEW-based data logging system had been developed. The system handles communication with other instruments via Ethernet and IEEE-488 interconnections. In this report, the design concept and the current status are described. The planned improvements are carried out in the future. | ||
| MOPAN091 | Design of Mechanical Structure and Cryostat for IASW Superconducting Wiggler at NSRRC | 374 |
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| An in-achromatic superconducting wiggler (IASW) was successfully constructed and installed at the Taiwan Light Source (TLS) in January 2006. The cryostat with a 30 L liquid nitrogen aluminum reservoir shielding surrounds the helium vessel, which comprises the cold mass and 100 L liquid helium. The helium vessel is suspended by eight suspension links, which are thermally intercepted at 80 K and can be adjusted by applying tension, such that the center of the cold mass does not move during cooled to 4.2 K. A three-layered stainless tube was designed to prevent the transfer port from freezing and the steam- electricity separation system is designed to supply electricity and return the helium gas to prevent freezing of the power feedthrough. | ||
| MOPAN092 | Earth Leakage Problem of Superconductor Magnet System at TLS | 377 |
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| Due to the inherent connection structure between the power supplies and the superconducting magnetic coil, the power supplies are seeing each others as loads through the coil. It has been observed in the pilot test at TLS that there is about 300mA earth leakage current flowing through the earth leakage protection circuit, which presented an interlock and halted the whole system down. The existance of earth leakage current may undermine the overall system stability and pose more threat on the electronic system safety. In this paper, the earth leakage mechanisms are throughly examined and measures to conqure the problem are proposed. | ||
| MOPAN093 | Stability Improvement of the Cryogenic System at NSRRC | 380 |
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| Negative gauge pressure appears in the helium suction line during the period of compressor starting up. The negative pressure induces the risk of air leakage into the cryogenic system and the damage to the burst disk of cryostat. A buffer tank is connected to the suction line to avoid the negative gauge pressure. Variation of nitrogen pressure changes the thermal-shielding temperature of the cavity cryostat and thus changes the length and frequency of the cavity. A phase separator with pressure control is installed before the cryostat to isolate the fluctuation of nitrogen pressure at the source side and prevent the trip of electron beam due to the frequency change or the overpressure at the cavity side. The stability improvement after usage of the phase separator shows that variation of the nitrogen pressure to the cavity cryostat is reduced from +0.6/-0.4 bar to ±0.08 bar and the drift of nitrogen pressure is eliminated. The stability after usage of the buffer tank shows that the negative gauge pressure is avoided in the suction line and the peak pressure was reduced from 1.4 bar to 1.2 bar. | ||
| MOPAN094 | Operation Experiences of the Bunch-by-Bunch Feedback System for TLS | 383 |
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| Severe multi-bunch instabilities are bothered the operation of Taiwan Light Source (TLS) during the operation during 2004 just after SRF system upgrade. FPGA-based bunch-by-bunch feedback system was commissioning during late 2005 and early 2006. Multi-bunch instability in both transverse plans and longitudinal are well control. Delivery up to 400 mA stored beam was demonstrated. Transverse feedback system make low chromaticity operation is possible; this is very helpful to improve injection efficiency which are essential for routine top-up operation. Operation experiences of the bunch-by-bunch feedback system will be summary in this report. | ||
| MOPAN095 | Design of the Precise Unit for the Rotating Coil Measurement System | 386 |
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| A precise rotating coil measurement system (RCS) is developed to characterize the magnetic field quality of the quadrupole (QM) and sextupole (SM) magnets in the Taiwan Photon Source (TPS). A measurement bench is designed to install the magnets easily and mount the rotating coil unit with high reproducibility. The Fiberglass Reinforced Epoxy (FRP) measurement unit (F-unit) exhibits a large sag and mechanical error while it is 880mm long. Therefore, a new graphite measurement unit (G-unit) with a printed circuit coil is adopted to reduce these errors. The rotating coil design and testing using a QM are also described. | ||
| MOPAN096 | A Safety Protection Device for Bypass Capacitor of the White Circuit | 389 |
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| This paper presents a new safety protection system for the bypass capacitor in the white circuit. In general, if the operation current of the white circuit deviates too much, the injection efficiency will be deteriorated and the white circuit bypass capacitor will be hurt. In order to detect the dynamic characteristics of the bypass capacitor to achieve protection function, the new protection system is proposed in this paper. The experimental results show that new protection system not only can monitor and detect the dynamic voltage and current of the bypass capacitor of the white circuit, but also prevent this bypass capacitor from being damaged. | ||
| MOPAN099 | Integrated Mechanism of Online Monitor and Archive System | 392 |
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| In the accelerator field, the instrumentation monitor system provides the machine online status to view, control and alert. A novel shared data engine developed by Labview provides the distributed PCs, PDAs, embedded devices, and local controllers to exchange data mutually via Ethernet or wireless Ethernet. The mechanism guarantees delivery with an additional function layer of the raw UDP protocol and usees less network bandwidth than TCP/IP. The system's main function is to introduce a platform with reliable online information about the status of the instrumentation. The users can access data with graphic view and trend view by some complementary software. Also, the users can easily take the online data via binding monitor tags without programming. The mechanism benefits all system maintenance, operation, management and analysis. | ||
| MOPAN100 | Multiple Quadrupole Magnetic Center Alignment on the Girder | 395 |
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| Conventional alignments of quadrupole magnets on the girder based on the theodolite and fiducial was limited by human-eye resolution and fiducial precision. The accumulative error of group of magnetic centers may be more than 100 μm. In this paper, an automatic quadrupole magnetic center aligning method was proposed using pulsed wire method to align group of quadrupole magnets concentrically on one girder to higher precision. In order to increase the alignment precision, a short wire reduced sag problem in long wire, laser and position sensitive detector (PSD) system was to trace the wire position to level of micron. The precision of the alignment of quadrupole magnetic centers could be within 30μm. Descriptions of the setup and test results are presented. | ||
| MOPAN101 | Failure Analysis for Cryogenic System Operation at NSRRC | 398 |
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| Two 450W cryogenic systems were installed on the year 2002 and 2006, respectively at NSRRC. So far, one 450W cryogenic system is cooling two superconducting magnets and one superconducting cavity. The new system will serve for five superconducting magnets on the year 2007. This paper presents the abnormal operation for the system, which induces the fluctuations for pressure, temperature, and flow rate, respectively. Solutions for these failures are shown and discussed. | ||
| MOPAN102 | SMS Alert System at NSRRC | 401 |
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| SMS (Short Message Service) technology has been used extensively today in the wireless world. The Utility Group at NSRRC has developed an SMS alert and notification system with LabVIEW programming language to continuously monitor the critical signals of its utility systems. A short message will be sent immediately to the responsible people in case of critical components failure. Many critical signals in the Instrumentation Division have also been included in this system for monitoring. Since its implementation the maintenance people have been notified many times to restore the faulty system to prevent accelerator from being shutdown or to minimize the damage. The detailed methodology used will be presented here. | ||
| MOPAN103 | New Control System for the 50 MeV Linear Accelerator of TLS | 404 |
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| The preinjector of the Taiwan Light Source(TLS) is consist of a 140 kV themionic gun and a 50 MeV traveling wave type linear accelerator system. In order to improve performance, to decouple the vacuum interlock logic from the linac control system, and to provide a better control functionality for top-up operation and to avoid obsolescence, linac control system have been renew. One VME crate system is dedicated for linac control, new hardware equips with high resolution of analog interface to provide better control. Vacuum interlock logic will be done be a dedicated programmable logic controller(PLC). The remained linac devices have sequential control needed will be done by another PLC, such as door access interlock, klystron warm up, gun warm up, trig interlock, gun high voltage interlock, klystron modulator high voltage interlock, water flow interlock. Both interlock and sequence control PLC will control by the VME crate. All the other functions without interlock or sequence requirement will control by the VME crate directly. New control system expects to provide better control functionality, better performance, easy for maintenance, and useful easy to add new hardware equipments. | ||
| MOPAN104 | Current Monitor for the ISIS Synchrotron RF Cavity Bias Regulator | 407 |
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| The ISIS facility at the Rutherford Appleton Laboratory in the UK is currently the world's most intense pulsed neutron source. The accelerator consists of a 70 MeV H- Linac and an 800 MeV, 50 Hz, proton Synchrotron. The synchrotron beam is accelerated using six, ferrite loaded, RF cavities each having its own high voltage r.f. drive amplifier and bias system. Each of these cavities is driven as a high Q tuned r.f. circuit; the resonant frequency being controlled by passing a current through a bias winding. This current comes from the Bias Regulator system which consists in part of eight banks of 40 transistors. This paper describes the design of a system which will use digital techniques to monitor and display the current of each of the 320 transistors in the Bias Regulator system. | ||
| MOPAN105 | Static VAr Power Factor Correction for the ISIS Main Magnet Power Supply | 410 |
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ISIS sited at the Rutherford Appleton Laboratory (RAL) is the worlds most powerful pulsed neutron source. Intense pulses of neutrons are produced at 50 Hz when a heavy metal target is bombarded with a beam of high energy (800MeV) protons. Energy is imparted to the protons by accelerating them in a synchrotron, the magnets of which are connected in a configuration known as a White Circuit*. This White Circuit suffers from problems arising from drifting values of capacitance and inductance which affect the resonant frequency. This paper focuses on the design, simulation, and implementation of a solution utilising Static VAr technology to regulate the resonant frequency of the White Circuit.
* M. G. White et al., A 3-BeV High Intensity Proton Synchrotron, The Princeton-Pennsylvania Accelerator, CERN Symp.1956 Proc., p525. |
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| MOPAN107 | Quadrupole Magnets for the 20 MeV FFAG, 'EMMA' | 413 |
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| EMMA is a 20 MeV non-scaling Fixed Field Alternating Gradient accelerator (nsFFAG) proof-of-principle prototype, to be built at the Daresbury Laboratory as an accelerator physics experiment to explore the behaviour of such machines. Non-scaling FFAGs have potential applications in charged particle cancer therapy and also for particle physics; however, to date, no such accelerator has been constructed. The magnet designs present major challenges - the lattice is made up of 84 quadrupoles, with different horizontal offsets from the magnet centres in the focusing and defocusing quads. These offsets alone provide the necessary bending fields in the ring. The magnets are also very thin (55mm and 65mm yoke lengths) and end field effects therefore dominate. Careful design, followed by prototype construction and measurement, is essential. The magnets have been designed in 3D from the outset, using the CST EM Studio software. The paper will present the results of the design, showing how the magnets have been optimised to improve the integrated good gradient region, and will report on the progress of the prototyping work. | ||
| MOPAN108 | The FONT4 ILC Intra-train Beam-based Digital Feedback System Prototype | 416 |
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| We present the design of the FONT4 intra-train beam-based digital position feedback system prototype. The system incorporates a fast analogue beam position monitor front-end signal processor, a digital feedback board, and a fast kicker-driver amplifier. The system latency goal is less than 150ns. We report preliminary results of beam tests at the Accelerator Test Facility (ATF) at KEK using electron bunches separated by c. 150ns. | ||
| MOPAN109 | Turnaround Feed-Forward Correction at the ILC | 419 |
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Funding: The Commission of European Communities under 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899, and by the UK Particle Physics & Astronomy Research Council. The RTML turnaround feed-forward correction scheme, as proposed in the ILC Baseline Configuration Document, is considered. Instabilities in the challenging Damping Ring extraction kicker system may give rise to betatron bunch-by-bunch jitter and position drift across the bunch train. A system is outlined in which the bunch trajectory is measured with an upstream pair of BPMs and corrected with a pair of downstream fast kickers. The beam turnaround time allows signal processing and calculation of the correction. A feed-forward algorithm is formulated and expressions are derived for the main system parameters and procedures: dynamic range, maximal kicker voltage, gain compression error, BPM resolution, system zero offset stability, BPM-to-kicker matrix measurement, feed-forward gain adjustment. This analysis will enable further consideration of system tolerances, and provides a basis for an engineering design. |
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| MOPAN110 | A Technique for High-frequency Scanning of High Power Laser Light for Laser-wire Scanners at Electrons Accelerators | 422 |
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Funding: Work supported in part by PPARC LC-ABD Collaboration and the Commission of European Communities under the 6th Framework Programme Structuring the European Research Area, contract number RIDS-011899.
Electro-optic techniques might allow implementing a laserwire scanner for intra-train scanning at the ILC with scanning speed in excess of 100 kHz. A scanner capable of running at such a rate would in fact provide information about the particle beam size in about one hundred different positions along the bunch train (approximately 1ms long for the ILC*). The design of an electro-optic deflector capable to scan within 10-100 microsecond is presented, discussed and analytically treated.
* ILC Baseline Conceptual Design (2006).: http://www.linearcollider.org/. |
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| MOPAN111 | Modbus/TCP Controller for the Power Supplies in ALS BTS Beam Line | 425 |
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| The development, testing and commissioning of a self-contained power supply controller for four 100 KW power supplies for the upgraded Booster to Storage Ring (BTS) beam line at the Advanced Light Source at the Lawrence Berkeley Laboratory, is presented. The power supply controller, is a 3U high, rack-mount chassis, that contains the regulation control-loop amplifiers, 16-bit DAC with microcontroller and aμPLC( Programmable Logic Controller) for power-supply state-machine control. Local control is achieved via push-buttons and a color LCD touch screen. Remote control is mediated viaμPLC using embedded Modbus/TCP. Using a unique, data logging system, the operational parameters of the regulation loop can be safely monitored and recorded while the system is running at full power. The entire design is based on optimum reliability, safety and ease of troubleshooting and repair. A modular design for key control components, allows the power supply to operate in a nominal mode, even if one or two ancillary internal modules fail. This allows for continued beam operation until it is convenient to service the unit, keeping beam availability as high as possible. | ||
| MOPAN112 | Digital Control Interface for Bipolar Corrector Power Supplies for LCLS | 428 |
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| We detail the development, testing and commissioning of a single-board digital interface for modular bipolar corrector magnet power supplies to installed at the Linac Coherent Light Source (LCLS) at the Stanford Linear Accelerator (SLAC). The sixteen-channel VME-form-factor board replaces the passive the control-interface board in the MCOR (Magnet Corrector) Chassis. The board is a self-contained system with both serial and Ethernet connectivity intended for use with an EPICS accelerator control system IOC, however, the ASCII protocol allows generic computer control. The interface card contains 16 independent ADC and DAC channels, each with 16 bits of resolution. Additionally, the interlock, fault, reset and digital control lines are remotely controllable via either the serial or Ethernet connections. The design has been planned so that a mini-IOC can be included on board for direct Channel Access connectivity. | ||
| MOPAN113 | The P0 Feedback Control System Blurs the Line between IOC and FPGA | 431 |
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Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The P0 Feedback System is a new design at the APS with the main intent to stabilize a single bunch in order to operate at a higher accumulated charge. The algorithm for this project required a high-speed DSP solution for a single channel that would make adjustments on a turn-by-turn basis. An FPGA solution was selected that not only met the requirements of the project, but far exceeded the requirements. By using a single FPGA, we were able to adjust up to 324 bunches on two separate channels with a total computational time of ~6x109 multiply-accumulate operations per second. The IOC is a Coldfire CPU tightly coupled to the FPGA, providing a dedicated control and monitoring of the system through EPICS process variables. One of the benefits of this configuration is having a four-channel scope in the FPGA that can be monitored on a continuous basis. |
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| MOPAN114 | A Linear MOSFET Regulator for Improving Performance of the Booster Ramping Power Supplies at the APS | 434 |
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Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357. Due to the circuit topology of ramping power supplies used in the APS Booster ring, they are unable to follow the linear current ramp to the desired accuracy of 0.1%. In addition, those supplies are also sensitive to AC line perturbation. To improve the performance, a linear regulator using paralleled MOSFET devices in series with the power supply is proposed. The control algorithm uses a real-time current feedback loop to force the MOSFETs to work in the linear operation mode. By using this linear MOSFET regulator, the MOSFETs' drain to source voltage, and hence the voltage imposed on magnets can be regulated very quickly. As a result, the regulation of the magnet current can be improved significantly. So far the simulation results show that with the linear regulator the current regulation can be improved to better than 0.1%. Because of the high bandwidth of the linear regulator, it can reduce the harmonic content in the output current as well as the noises due to the AC line disturbance. A sextupole power supply has been set up to verify the proposed topology. This paper discusses the circuit topology, the regulation algorithm, and the experiment results. |
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| MOPAN115 | Aluminum Coating in the Undulator Vacuum Chamber for the LINAC Coherence Light Source | 437 |
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Funding: Work supported by DOE under contract Nos. DE-AC02-06CH11357 and DE-AC03-76SF00515. A prototype vacuum chamber is under development at the Advanced Photon Source for use in the Linac Coherent Light Source at Stanford Linear Accelerator Center. The chamber will be fabricated from the austenite stainless steels. The chamber requires a continuous aluminum coating on the inner surface in order to reduce the wakefield losses to a level within the resistivity budget. The method being presented here is unique in that it can be applied to a fully fabricated chamber 5 mm high, 11.5 mm wide, and 3460 mm long. In existing methods the chamber aperture has been much larger than is used here. This paper describes a method applicable for these smaller cross sections. This process uses a pair of small electrodes, centered in the aperture, where they are attached to a high frequency AC power supply. In this configuration each electrode is connected to the opposite polarity of the other. The chamber cavity is filled with argon gas to facilitate the formation of a glow discharge causing the aluminum electrodes to sputter onto the chamber walls. This paper presents the laboratory test results from small samples up to the full-sized assemblies. |
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| MOPAN116 | An FPGA-Based Bunch-to-Bunch Feedback System at the Advanced Photon Source | 440 |
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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. The Advanced Photon Source storage ring has several bunch fill patterns for user operation. The hybrids fill pattern consists of a single bunch with a charge of 16 mA and a bunch train of 56 bunches. Both horizontal and vertical instabilities are observed. Currently chromaticity correction is the only method available to overcome the instability. Beamlife time and injection efficiency suffer because of high sextupole currents. A bunch-to-bunch feedback system is designed to overcome beam instability and reduce the required chromaticity correction. The feedback system is based on an FPGA DSP processor. The signal filtering algorithm is based on the time-domain-least-square method developed at SPring-8. We have just completed the integration of the system. We report the system design and some test results. |
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| MOPAN117 | Magnet System for Helical Muon Cooling Channels | 443 |
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Funding: Supported in part by STTR Grant DE-FG02-04ER86191. A helical cooling channel consisting of a pressurized gas absorber imbedded in a magnetic channel that provides superimposed solenoidal, helical dipole and helical quadrupole fields has shown considerable promise in providing six-dimensional cooling of muon beams. The analysis of this muon cooling technique with both analytic and simulation studies has shown significant reduction of muon phase space. A particular channel that has been simulated is divided into four segments each with progressively stronger fields and smaller apertures to reduce the equilibrium emittance so that more cooling can occur. The fields in the helical channel are sufficiently large that the conductor for segments 1 and 2 can be Nb3Sn and the conductor for segments 3 and 4 may need to be high temperature superconductor. This paper will describe the magnetic specifications for the channel and two conceptual designs on how to implement the magnetic channel. |
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| MOPAN118 | High Field HTS Solenoid for Muon Cooling | 446 |
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Funding: Work supported by U. S. Department of Energy under Contract DE-AC02-98CH1088 and SBIR Grant DE-FG02-04ER86191 The ability of high temperature superconducting (HTS) conductor to carry high currents at low temperatures makes feasible the development of very high field magnets for uses in accelerators and beam-lines. A specific application of a very high field solenoid is to provide a very small beta region for the final cooling stages for a muon collider. This paper will describe a conceptual design of a 50 Tesla solenoid based on Bi-2223 HTS tape, where the magnet will be operated at 4.2 K to take advantage of the high current carrying capacity at that temperature. A 25 Tesla solenoid has been run using a 5 Tesla Bi-2212 insert. The current carrying capacity of the BSCCO wire has been measured to be 266 Amps/mm2 at 4.2 K at the NHFML. This paper will describe the technical issues associated with building this 50 Tesla magnet. In particular it will address how to mitigate the large Lorentz stresses associated with the high field magnet and how to design the magnet to reduce the compressive end forces. |