| Paper | Title | Page |
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| TUPP001 | Alternating Gradient Operation of Accelerating Modules at FLASH | 1523 |
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| The free electron laser in Hamburg (FLASH) is a user facility providing high brilliant laser light for experiments. It is also an unique facility for testing the superconducting accelerator technology for the European XFEL and the international linear collider (ILC). The XFEL offers several beam lines to users. Within limits given by the beam delivery system the bunch pattern and beam energy should be adjustable independent for each beam line suggesting a time sliced operation. The ILC is focused on the highest gradients possible. FLASH accelerates beam at 5 Hz repetition rate. During accelerator studies the operation of the last accelerating modules with 10 Hz and alternating rf pulses has been established proving the feasibility of a time sliced operation at the XFEL. The rf pulses synchronous to the 5 Hz rf pulses are used for FEL operation whereas the gradient of the remaining rf pulse can be chosen independently and is used for long term high gradient operation gaining experience for the ILC. The operation of two different gradients within a single rf pulse is also available. The paper describes the technical setup, the rf control performance and the operational experience. | ||
| TUPP002 | Uniform Motion Control Solution for Variety of Motion Applications | 1526 |
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| Control solutions for motion applications require high degree of flexibility regarding the use and connectivity. Being fairly simple or highly complex, micro- or millimeter precision, one or multiple axis… the system designer has to tackle specific interfacing issues. One platform should fit different applications and provide cost effective solutions. Flexible software platform is required on one side to satisfy control system (CS) application requirements. On the other side variety of hardware (HW)–controlled by motion controller, i.e., power stages, position feedback–also requires some degree of connection flexibility. Paper presents a design of a motion control platform that offers flexible interfacing both to CS and HW, elegant extendibility options for selection of feedback protocols, low-level direct access for engineering control and enables large distances between controller and motors. | ||
| TUPP003 | Automatic Generation of SEU Immunity for FPGA Based Electronics for Accelerators | 1529 |
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The modern accelerator control systems nowadays are build using digital technology based on FPGA circuits. However, digital circuits working in radioactive environment are exposed to disturbing effects, in particular SEU (Single Event Upset)*. One of the countermeasure is a redundancy in circuit that allow to detect and correct errors caused by radiation**. Unfortunately CAD software provides no support to automatically include required redundancy in the FPGA project. Moreover, optimization procedure removes all redundant parts and special effort must be made to prevent that. The paper presents a software environment to process VHDL description of the circuit and automatically generate the redundant blocks together with voting circuits. The generated redundancy uses Triple Module Redundancy (TMR) scheme. It also supports the VHDL simulation with SEUs in order to enable identification of the most sensitive components***. Since the TMR is costly, the designer can indicate which parts of the circuit should be replicated based on the results of simulation.
*Baumann. Neutron-induced…, Int. Rel. Phys. Symp. 2000. |
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| TUPP004 | Evolution and Status of the Electronic Logbooks at the ESRF | 1532 |
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| In 2004 the ESRF moved to electronic logbooks. Such logbooks should be configurable enough to be used in several situations: document management, exchange of technical information and, in the Control Room, as a powerful tool for storing and retrieving information at a glance. The St James software company developed such a product which met our constraints and which is easy to configure. Moreover, this product can be tailored and evolved with time by its users and allows automatic access to control system parameters. After gaining experience with several logbooks using the old version 4 system, a new more user-friendly version which offers extensive customisation possibilities has been launched. This new version, J5, has already been interfaced to the ESRF control system (Tango) through a Python binding. This allows automatic triggering of records on specific events and the generation of automatic reports from the history database system. J5 can use an LDAP server for security management. | ||
| TUPP005 | Application Programs for the Elettra Booster Commissioning and Operation | 1535 |
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The application programs developed for the commissioning and operation of the new Elettra injector* are all based on the TANGO control system, a new high level framework and a beam optics module named Vicky**. The present paper summarizes the main developed application programs and their successful use during commissioning and operation of the new injector.
*"Overview of the Status of the Elettra Booster Project," these proceedings. |
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| TUPP006 | Beam Test with a New Control System of Acceleration in HIMAC | 1538 |
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| In the present acceleration system in HIMAC, acceleration frequency of a direct digital synthesizer is controlled with B-clock pulses of B+ and B- signals that correspond to 0.2 Gauss increment and decrement of dipole magnetic field. In the tested new control system, we will use only clock pulse whose clock rate is locked to the power line frequency. With this simple system, it is easy to build up the acceleration control system for multiple flat-top pattern. This pattern operation is expexted to use in the next irradiation system of spot-scanning in HIMAC. In this presentation, the used system and its beam tests will be presented. | ||
| TUPP008 | An Automatic Control System for Conditioning 30 GHz Accelerating Structures | 1541 |
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| A software application programme has been developed to allow fast, automatic, conditioning of the accelerating structures to be high-gradient tested at 30 GHz in CTF3. The specificity of the application is the ability to control a high power electron beam which produces the 30 GHz RF power used to condition the accelerating structures. It significantly increases the amount of time useable for high power conditioning. In this paper this fast control system, the machine control system, the logging system, the graphic user control interface and the logging data visualization are described. An outline of the conditioning control system itself and of the feedback controlling peak power and pulse length is given. The software allows different types of conditioning strategies to be programmed. | ||
| TUPP009 | Implementation and Operation of the Elettra Booster Control System | 1544 |
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| A new injector based on a 100 MeV linac and a 2.5 GeV booster synchrotron has been built and commissioned at Elettra to provide full energy and top up injection into the storage ring. The booster replaces the 1.2 GeV linac that will be used for the new 4th generation light source FERMI@Elettra currently under construction at Elettra. A new architecture has been adopted for the booster control system based on the Tango control system software. The implementation of the control system and the tools developed to meet an aggressive commissioning time schedule are presented. The experience gained during the operation of the booster is also discussed. | ||
| TUPP011 | The ESRF Temperature Monitoring System from an Operational Point of View | 1547 |
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| The vacuum control system of the ESRF electron Storage Ring (SR) is in operation since more than ten years now. Apart from difficulties to have appropriate support for the old system, we start facing problems of aging and obsolescence. We have been reviewing our philosophy of data acquisition and remote control in order to upgrade our systems with state of the art technology by taking into account our operational experience. We have installed shielded "intelligent" devices inside the SR and took advantage of the latest developments linked to new communication technologies and standards, such as TCP/IP MODbus protocol and WEB server based instrument control. This presentation outlines our present work dedicated to the ESRF temperature acquisition system based on Programmable Logic Controllers (PLC), and new developments regarding the user interface in the control room. Several examples show the importance of surveying the temperatures in order to identify various mechanical or operational problems which allow us to anticipate later failures and provide us with an additional machine diagnostic tool. | ||
| TUPP012 | Presentation of the New ESRF Vacuum Control Applications from an Operational Point of View | 1550 |
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| The ESRF is in operation since more than ten years. Due to the aging vacuum system, we are faced to different kinds of failures such as air or water leaks, overheating of RF-liners or poor chamber alignment. In order to anticipate these failures and therefore reduce down times, we started to develop new diagnostic tools which allow us to detect much faster and with more precision any possible failures or malfunctioning of our vacuum system. Also driven by the increase of machine performances and the continuous vacuum installations, we search for new tools to safely commission such upgrades. This paper outlines our work on the development of a new vacuum user interface, which not simply reflects the actual status of our vacuum system, but which also provides us with a dynamic survey of computed vacuum signals highlighting unusual vacuum behaviours. | ||
| TUPP013 | Synchronized Data Distribution and Acquisition System Using Reflective Memory for J-PARC 3GeV RCS | 1553 |
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| J-PARC 3GeV RCS inject the different parameter beam to each facilities, which are MLF and MR. Therefore, 3GeV RCS Control System must realize the monitoring and the operation that are distinguished "MLF beam" from "MR beam". And, we have developed the data distribution and acquisition system for "synchronized data" which required the distinguished monitoring and operation. We have designed and developed distribution and acquisition system using Reflective Memory (RM) for BPM data, which is one of synchronized data. There are 54 BPM, and BPM signal is processed by each BPM signal circuit (total 54 circuits). Then, we have designed that RM have 54 virtual ring memories and for a few seconds BPM data pre one virtual ring memory is buffered. And we decide BPM data is written virtual ring memory position based on "beam tag", which distributed from RM of J-PARC Timing System. This "beam tag" is synchronized across J-PARC. Thereby, 54 BPM data that written same virtual ring memory position become BPM data for identical beam. The paper presents the current status of the synchronized data distribution and acquisition system using RM. | ||
| TUPP014 | Control System for a 150 MeV FFAG Complex in KURRI | 1556 |
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| A simple, convenient control system has been developed for a 150 MeV proton FFAG accelerator complex at Research Reactor Institute, Kyoto University(KURRI). This control system is based on conventional PCs and programmable logic controllers (PLC) and these are connected over TCP/IP network. Each PLC is responsible for autonomous control of connected devices such as motors or power supplies, and also responsible for maintaining a parameter database periodic(~100 ms typically) read/written by remote PCs over TCP/IP network. Man-machine interfaces and integrated sequences are developed using LabView environment on these PCs. This control system has been successfully served for the actual operation of the FFAG complex, including the radiation protection control. Further developments, such as portable devices serving man-machine interfaces on site and the integration of SQL server for logging all possible parameters of this accelerator complex, are on the way. | ||
| TUPP015 | Investigations into Cost Reductions of X-band Instrumentation | 1559 |
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| The prohibitive costs of commercial test equipment for making fast and accurate pulsed phase and amplitude measurements at X-band result in decreased productivity due to shortages of shared equipment across the test laboratory. In addition, most current set-ups rely on the use of pulsed power heads which do not allow for the measurement of phase thereby limiting the flexibility of available measurements. In this paper, we investigate less expensive in-house designed instrumentation based upon commercial satellite down converters and widely available logarithmic detector amplifiers and phase detectors. The techniques are used to measure X-band pulses with widths of 50 ns to 10’s of usec. We expect a dynamic range of 30-40 dB with accuracies of less than ± 0.1 dB. We show results of the built and tested systems with particular attention focused on temperature performance and accuracy. Block diagrams of the down conversion scheme, and the architecture of a multi-signal X-band RF monitor and measurement system is illustrated. Measured results, and possible modifications and upgrades are presented. | ||
| TUPP016 | A Flight Simulator for ATF2 - A Mechanism for International Collaboration in the Writing and Deployment of Online Beam Dynamics Algorithms | 1562 |
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| The goals of ATF2 are to test a novel compact final focus optics design with local chromaticity correction intended for use in future linear colliders. The newly designed extraction line and final focus system will be used to produce a 37nm vertical waist from an extracted beam from the ATF ring of ~30nm vertical normalised emittance, and to stabilise it at the IP-waist to the ~2nm level. Static and dynamic tolerances on all accelerator components are very tight; the achievement of the ATF2 goals is reliant on the application of multiple high-level beam dynamics algorithms to align and tune the electron beam in the extraction line and final focus system. Much algorithmic development work has been done in Japan and by colleagues in collaborating nations in North America and Europe. We describe here development work towards realising a 'flight simulator' environment for the shared development and implementation of beam dynamics code. This software exists as a 'middle-layer' between the lower-level control systems (EPICS and V-SYSTEM) and the multiple higher-level beam dynamics modeling tools in use by the three regions (SAD, Lucretia and PLACET). | ||
| TUPP017 | Orbit and Dispersion Tool at FLASH | 1565 |
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| Based on a former MATLAB tool, a java-based application to measure and correct orbit and dispersion has been developed at FLASH. In this paper we discuss the algorithm used in this tool as well as its functionality. First tests on machine operation are also presented. | ||
| TUPP018 | Impact of Electromagnetic Fields in TESLA RF Modules on Transverse Beam Dynamics | 1568 |
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| Transverse electric fields in TESLA rf modules exist on one hand because of deformations of the longitudinal accelerating field in the presence of rf structure misalignments or in the vicinity of asymmetrically machine parts like input couplers. On the other hand, the beam itself induces transverse wake fields if it does not travel through the center of a perfectly rotationally symmetric structure. Transverse deflecting fields deflect beam particles. The average deflection causes a change in the beam trajectory; the phase dependence of the transverse field leads to a variation of the transverse kick along the longitudinal position of the bunch and thus in general to a change in projected emittance. If the strength of the transverse field component varies along the transverse direction itself, slice emittance will be also affected. We will present the amplitudes and spatial variations of transverse fields generated by the mechanisms described above, and discuss their impact on beam trajectories and shape. | ||
| TUPP019 | Wakefield and RF Kicks due to Coupler Asymmetry in TESLA-type Accelerating Cavities | 1571 |
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| In a future linear collider, such as the International Linear Collider (ILC), trains of high current, low emittance bunches will be accelerated in a linac before colliding at the interaction point. Asymmetries in the accelerating cavities of the linac will generate asymmetries in the fields that will kick the beam and tend to degrade the beam emittance and thus the collider performance. In the main linac of the ILC, which is filled with TESLA-type superconducting cavities, it is the fundamental and higher mode couplers that are asymmetric and thus the source of such kicks. The kicks are of two types: one, due to (the asymmetries in) the fundamental RF fields and the other, due to transverse wakefields that are generated even when the beam is on axis. For the ILC configuration we numerically and analytically study both types of kicks and their effect on beam emittance. For the wakefield effect this is quite challenging since the bunches are very short (rms length of 300 microns), the cavity is very long (~1 m), and the distance to steady-state is even longer (~6 m). Finally, we study changes in the coupler design that can greatly reduce the effect. | ||
| TUPP020 | Analysis of Collective Effects at the Diamond Storage Ring | 1574 |
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| The Diamond storage ring has achieved its nominal operating current of 300 mA in multi-bunch mode and up to 10 mA in single bunch mode. Several collective instabilities have been observed and their dependence on machine parameters such as chromaticities, RF voltage and fill pattern have been investigated. We report here the analysis of the observed current thresholds and rise times of the instabilities compared with analytical estimates and tracking simulations. We also present the results of the MAFIA simulations performed with the aim of understanding the main contribution to the impedance of the ring and establishing a machine impedance database. | ||
| TUPP022 | Measurements of Broad Band Impedance Related Longitudinal Properties of Electron Bunches at DELTA | 1577 |
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| DELTA is a 1.5 GeV synchrotron light source which can be operated also at 550 MeV for FEL experiments. Due to interactions with the vacuum chamber, the beam induces wake fields, which act back on the beam and result in a disturbed bunch profile because of potential well distortion and turbulent bunch lengthening. These interactions limit the obtainable bunch length and achievable peak current and therefore strongly affect the FEL-operation. Recent results obtained by streak camera measurements have shown that for short bunches with maximum bunch lengths of 40 ps the longitudinal broad band impedance has to be scaled (SPEAR-scaling) to explain the measurements. The broad band impedance fits well to impedance measurements and calculations performed throughout the last years. The energy spread related to the bunch lengthening has been measured by analysing the undulator spectrum. | ||
| TUPP023 | Direct Detection of the Electron Cloud at ANKA | 1580 |
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| Low energy electrons generated by the interaction of high energy particles with the beam pipe surface can be detrimental for accelerators performances increasing the vacuum pressure, the heat load and eventually producing beam instabilities. The low energy electrons accumulating in the beam pipe are often referred to as electron cloud. In this presentation we report on the direct evidence of the electron cloud in the electron storage ring of the synchrotron light source ANKA (ANgstrom source KArlsruhe). | ||
| TUPP024 | Electron Cyclotron Resonances in Electron Cloud Dynamics | 1583 |
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| We report a previously unknown resonance for electron cloud dynamics. The 2D simulation code “POSINST” was used to study the electron cloud buildup at different z positions in the International Linear Collider positron damping ring wiggler. At magnetic field values, B, for which the bunch frequency is an integral multiple of the electron cyclotron frequency an enhancement of up to a factor of 3 in the electron cloud equilibrium density was found. At low magnetic fields the effects of the resonance are prominent, but when B exceeds ~ (2πme/elb), with lb = bunch length, effects of the resonance disappear. Thus short bunches and low B fields are required for observing the effect. We believe this accounts for the fact that this resonance has not been reported before in the electron cloud literature. The reason for the B field dependence, an explanation of the dynamics, and the results of the 2D simulations and of a single-particle tracking code used to elucidate details of the dynamics will be discussed, along with results from 3D simulations. | ||
| TUPP025 | Preliminary Impedance Budget for the TPS Storage Ring | 1586 |
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| Taiwan Photon Source (TPS) is a new third generation low-emittance synchrotron storage ring which will be built at the present site of the NSRRC in Hsinchu, Taiwan. Preliminary results of the ongoing impedance studies of the TPS are presented in this paper. The overall impedance of the vacuum chamber has been evaluated with focus on the longitudinal broad-band impedance, which can lead to bunch lengthening and microwave instability. Wakepotentials and impedances produced by each component of the storage ring have been evaluated by using 3D electromagnetic code GdfidL. Then longitudinal loss factor, longitudinal broad-band impedance and transverse kick factors were computed. Results are summarized in the table. Numerically obtained data is compared to analytical results for simplified geometries of the vacuum chamber components. | ||
| TUPP026 | Impedance of Ultrarelativistic Charged Distributions in Tapering Geometries | 1589 |
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| We develop a scheme for obtaining the impedance, at any frequency, of a gradually tapered geometry of arbitrary cross-section containing a bunch of arbitrary profile travelling at the speed of light parallel to the axis of the taper. Coordinate-free expressions for Maxwell's equations are 2+2-split in a coordinate system adapted to the particle beam and the taper and, using an asymptotic expansion for a gradual taper, a coupled hierarchy of Poisson equations are obtained. Applications of the scheme are presented. | ||
| TUPP027 | Electron Energy Dependence of Scrubbing Efficiency to Mitigate E-cloud Formation in Accelerators | 1592 |
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Recently built and planned accelerators, base their ability to reach design parameters, on the capability to reduce Secondary Electron Yield (SEY) during commissioning, hence mitigating the potentially detrimental effects of e-cloud driven machine limitations. This SEY reduction (called "scrubbing"), is due to the fact that the electrons of the cloud, hit the vacuum chamber wall, modifying its surface properties and reducing its SEY. This minimise any disturbing effects of the e-cloud to the beam. "Scrubbing" has been studied only as a function of impinging electron dose. In reality SEY modifications are only studied by bombarding surfaces with 300-500 eV electrons, but no scrubbing dependence on the bombarding electron energy has ever been discussed. The actual energy of the electrons of the cloud hitting the wall in real accelerators has never been measured accurately, while simulations predict very low electron energies (<50 eV). For this reason and given the peculiar behaviour observed for low energy electrons*, we decided to study this dependence accurately. Here we present some preliminary results discussing eventual implications to machine commissioning procedures.
*R. Cimino et al. Phys. Rev. Lett 93, 14801 (2004). |
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| TUPP028 | Bunch Length and Impedance Measurements at SPEAR3 | 1595 |
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| A series of bunch length measurements have been made for different lattice configurations in SPEAR3 as a function of single-bunch current. The lattices include achromatic optics, low-emittance optics and short-bunch, low-momentum compaction optics (low-alpha). The streak-camera data clearly demonstrates effects of both resistive and reactive chamber impedance and shows levels of microwave instability threshold. In the low-alpha mode, signs of bunch length ‘bursting’ were observed. Fitted bunch-profile data, impedance calculations and bursting data are presented. | ||
| TUPP029 | Beam Coupling Impedance Measurement and Mitigation for a TOTEM Roman Pot | 1598 |
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| The longitudinal and transverse beam coupling impedance of the first final TOTEM Roman Pot unit has been measured in the laboratory with the wire method. For the evaluation of transverse impedance the wire position has been kept constant, and the insertions of the RP were moved asymmetrically. With the original configuration of the RP, resonances with fairly high Q values were observed. In order to mitigate this problem, RF-absorbing ferrite plates were mounted in appropriate locations. As a result, all resonances were sufficiently damped to meet the stringent LHC beam coupling impedance requirements. | ||
| TUPP030 | A Formula for the Electron Cloud Map Coefficient in the Presence of a Magnetic Field | 1601 |
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The evolution of the electron density during multibunch electron cloud formation can be reproduced using a bunch-to-bunch iterative map formalism. The reliability of this formalism has been proved for RHIC* and LHC**. The coefficients that parameterize the map function are readily obtained by fitting the results of compute-intensive electron cloud simulations. An analytic expression for the linear map coefficient that describes weak cloud behaviour from first principles has been derivied for the case of staight sections of RHIC***. In this paper we generalize the model presented in *** to the case of electron cloud evolution in presence of a dipolar magnetic field and compare the results with numerical simulations.
*U. Iriso and S. Pegg. Phys. Rev. ST Accel. Beams 9, 071002 (2006). |
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| TUPP031 | Electron Cloud Simulations for DAΦNE | 1604 |
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| After the first experimental observations compatible with the presence of the electron cloud effect in the DAΦNE positron ring, a systematic study has been performed regarding the electron cloud build-up. To assess the effects of the electron cloud, simulations of the cloud build up were carried out using ECLOUD. In particular, we discuss modifications to the secondary emission model, build up for various filling patterns and different wiggler magnetic field models. The obtained numerical results are compared with experimental observations. | ||
| TUPP032 | Trajectory Jitter and Single Bunch Beam Break Up Instability | 1607 |
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| This paper addresses stability issues related to control of the beam break up (BBU) instability in the FERMI@Elettra linac using local trajectory bumps. Analytical study and simulations using the Elegant code are presented. Three different parameters have been used to characterize the BBU, i.e. the projected emittance, the bunch head-to-tail deviation, and the Courant-Snyder invariant for the slice centroid. It is shown that shot-to-shot trajectory jitter in the injector affects the efficiency of the control of the BBU. | ||
| TUPP033 | Alternative Scheme of Bunch Length Compression in Linacs for Free Electron Lasers | 1610 |
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| The aim of this paper is to investigate the effect of an alternative scheme of bunch compression on the development of the microbunching instability. Two cases have been considered, one in the presence of a linear energy chirp at the compressor end and another without it. It is shown that after removing the linear energy chirp, a properly tuned R56 transport matrix element is able to dilute the initial energy modulation without affecting the bunch length and to damp the associated current spikes. A by-product of this study indicates that the global compression scheme can be further optimized in the direction of a double compression scheme in which the longitudinal Landau damping is enhanced by increasing the compression factor of the first compressor while reducing that of the second one. The limiting case of such a configuration is the single compression scheme at low energy. The study is based on analytical calculations and on the simulation code LiTrack. | ||
| TUPP034 | Transverse Effects due to Vacuum Mirror of RF Gun | 1613 |
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| The transverse kick due to the vacuum mirror in the RF gun can negatively affect the beam emittance. In this contribution we estimate numerically and analytically the transverse wake function of European XFEL RF gun and apply it in beam dynamics studies of the transverse phase space. | ||
| TUPP035 | Analysis of Intensity Instability Threshold at Transition in RHIC | 1616 |
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| The beam intensity of ion beams in RHIC is limited by a fast transverse instability at transition, driven by the machine impedance and electron clouds. For gold and deuteron beams we analyze the dependence of the instability threshold on beam and machine parameters from recent operational data and dedicated experiments. We fit the machine impedance to the experimental data. | ||
| TUPP036 | "Scrubbing" Process of Cu Surfaces Induced by Electron Bombardment | 1619 |
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| Energy distribution curves of electrons emitted from accelerator used metal surfaces have been measured for electron irradiation with a primary energy from 20 to 400 eV. We separated the contributions of reflected, rediffused and true-secondary electrons out from the spectra and observed significant differences in their incidence angle dependence. These results provide crucial information on the electron cloud formation in particle accelerators and may shed light on the involved physical mechanisms | ||
| TUPP037 | Impedance and Instabilities for the ALBA Storage Ring | 1622 |
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| The geometrical impedance in all 3 planes for most of the vacuum chamber elements of the ALBA storage ring was computed with the 3D-solver GdfidL. Optimisation of some element geometries was carried out in order to reduce dissipative losses and in general the impedance. Resistive wall impedance was calculated analytically. The thresholds of various instabilities were determined on the basis of analytically formulated threshold criteria. The most important are a HOM-driven longitudinal multibunch instability and the transverse resistive wall instability. It is proposed to combat the first one by Landau damping using partial filling and the second one by a transverse feedback system. | ||
| TUPP038 | On the Longitudinal Coupling Impedance and Transmission Coefficient from Uniform and Hollow Ring Sources | 1625 |
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The longitudinal coupling impedance and the transmission coefficient resulting from a thin ring and from a uniform disk are obtained analytically for a resistive cylindrical beam-pipe of finite wall thickness. The impedances are derived and then compared with the well known corresponding expression for perturbations on a uniform, coasting beam. The transmission coefficients from both sources are found to be exactly the same. Differences do appear in the expressions for the electromagnetic fields within the beam region, and therefore leading to different coupling impedances. By applying the results to parameters relevant for the SIS-18 synchrotron at GSI, it is found that the formula from the ring source underestimates the space-charge impedance at all beam energies and it shows a noticeable deviation from the disk formula for all frequencies. Although their mathematical expressions are different, resistive-wall impedances from the two sources are found to be numerically equal. The space-charge impedances become equal asymptotically only in the so called ultra-relativistic limit.
A. Al-Khateeb is on leave from Yarmouk University, Irbid, Jordan |
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| TUPP039 | Wake-field Compensation in Energy Recovery Linacs | 1628 |
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| Problems created by the correlated energy spread that wake fields can produce are strongly enhanced in Energy Recovery Linacs (ERLs), as compared to conventional linacs. This is due to the fact that in ERLs the spent beam is decelerated by a potentially large factor, which increases the relative energy spread proportionally. We show how severe this problem is for the impedance budget of the x-ray ERL that Cornell plans to build, and we analyze several different possibilities to compensate the correlated energy spread involving de-phasing linac components, linear and nonlinear time-of-flight terms in different accelerator sections, or high frequency accelerating cavities. Because of the particular design, which has a turn-around loop between two sections of the linac, there are many options for these techniques which we compare and evaluate. | ||
| TUPP040 | Intra Beam Scattering in Linear Accelerators, Especially ERLs | 1631 |
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| The theories of beam loss and emittance growth by Touschek and Intra Beam Scattering have been formulated for beams in storage rings. It is there that these effects have hitherto been important because of their large currents. However, there are linear accelerators where these effects become important when considering loss rates and radiation damage. Prime examples are high current Energy Recovery Linacs (ERLs), managing these scattering effects can become challenging, and not only because of the large current, but also because the deceleration of the spent beam increases relative energy spread and transverse oscillation amplitudes. In this paper we describe two ways of simulating particle loss by these scattering affects, both implemented in BMAD. One that yields the places where scattering occurs, and another that yields loss rates along the chamber walls. BMAD includes nonlinear beam dynamics, wake effects, and more, which allows a rather complete propagation of scattered particle. For the example of the ERL x-ray facility that Cornell plans to build, we demonstrate that these capabilities are very important for designing a functional radiation protection system. | ||
| TUPP041 | CSR Shielding in the Beam Dynamics Code BMAD | 1634 |
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| Short bunches radiate coherently at wavelengths that are longer than their bunch length. This radiation can catch up with the bunch in bends and the electromagnetic fields can become large enough to significantly damage longitudinal and transverse bunch properties. This is relevant for many accelerators that relies on bunch compression. It is also important for Energy Recovery Linacs, where spent beams are decelerated by a potentially large factor. Because this deceleration increases the relative energy spread, all sources of wake fields, especially Coherent Synchrotron Radiation (CSR), become much more important. In this paper we show how the beam dynamics code BMAD computes the effect of CSR and how the shielding effect of vacuum chambers is included by the method of image charges. We compare the results to established codes: to Elegant for cases without shielding and to a numerical solution of simplified Maxwell equations as well as to analytical csr-wake formulas. Good agreement is generally found, and in cases where numerical solutions of the simplified Maxwell equations do not agree with the csr-wake formulas, we show that BMAD agrees with these analytic formulas. | ||
| TUPP042 | Status of the ORBIT Code: Recent Developments and Plans | 1637 |
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| We report on recent enhancements to the physics modules of the ORBIT Code and on progress toward a new implementation of ORBIT using python. We have developed the capability to track particles through general three dimensional electromagnetic field configurations. This facility has proved essential in modeling beam transport through the complicated magnetic field regions of the SNS injection chicane and injection dump line, where beam losses are high. We have also enhanced the acceleration module to provide more flexibility for synchrotron calculations. Finally, progress continues on the migration of the ORBIT physics models to a python user environment, and we present the status of this work. | ||
| TUPP043 | Computational Beam Dynamics Studies of Collective Instabilities Observed in SNS | 1640 |
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| During the commissioning and early operation of the Spallation Neutron Source, some physcics shifts were set aside for high intensity stability studies. Under certain, especially contrived conditions, a number of beam instabilities were induced. These included both electron cloud and ring impedance driven phenomena. In this paper we apply both simple analytic models and the ORBIT Code to the description and simulation of these observed instabilities. | ||
| TUPP045 | Studies of Beam Breakup in Dielectric Structures | 1643 |
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| Beam breakup (BBU) effects resulting from parasitic wakefields provide a potentially serious limitation to the performance of dielectric structure based wakefield accelerators. We report on experimental and numerical investigation of BBU and its mitigation. The experimental program focuses on BBU measurements in a number of high gradient and high transformer ratio wakefield devices. New pickup-based beam diagnostics will provide methods for studying parasitic wakefields that are currently unavailable at the AWA facility. The numerical part of this research is based on a particle-Green’s function beam breakup code we are developing that allows rapid, efficient simulation of beam breakup effects in advanced linear accelerators. The goal of this work is to be able to compare the results of detailed experimental measurements with the accurate numerical results and to design an external FODO channel for the control of the beam in the presence of strong transverse wakefields. | ||
| TUPP046 | Tunable Ferroelectric Based Technologies for Accelerator Components | 1646 |
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| Low loss ferroelectric materials can be used as key elements in RF tuning and phase shifting components to provide fast, electronic control. These devices are under development for different accelerator applications in X, Ka and L - frequency bands. The exact design of these devices depends on the electrical parameters of the particular ferroelectric material to be used- its dielectric constant, loss tangent and tunability. BST based ferroelectric-oxide compounds have been found to be suitable materials for a fast electrically-controlled tuner for BNL and for high-power fast RF phase shifters to be used for SNS vector modulation applications. We present recent results on the development of BST based ferroelectric compositions synthesized for use in high power technology components. The BST(M) ferroelectrics have been tested using a transverse dc bias field. The tunability factor vs. dc field magnitude has been evaluated and the feasibility of transverse bias tuning for ferroelectric based accelerator components has been demonstrated. | ||
| TUPP047 | Simulation Studies on Coupler Wakefield and RF Kicks for the International Linear Collider with MERLIN | 1649 |
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One of the critical issues in the design of the superconducting cavities or the International Linear Collider (ILC) is the influence of the RF and higher order mode (HOM) couplers on the beam dynamics. Both types of couplers break the rotational symmetry of the cavity and introduce non vanishing transverse wakefields even on the cavity axis. Furthermore the RF input coupler introduces an asymmetry into the accelerating RF field and thereby additional transverse field components. We have implemented both effects following the calculations presented previously* into the MERLIN C++ library**. This allows us to study the influence of wakefield and RF kicks on the beam dynamics, the bunch shape and the overall performance of the ILC for different proposed coupler designs.
*I. Zagorodnov and M. Dohlus, ILC Workshop, DESY 2007; K. Bane and I. Zagorodnov, Wake Fest 07, SLAC 2007. |
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| TUPP048 | Collective Effects in the EMMA Non-scaling FFAG | 1652 |
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| EMMA is an electron machine to study beam dynamics in a linear nonscaling FFAG. We wish to verify that the behavior predicted by the theory and simulation is correct. In particular, we will study, with large emittance beams, a novel accelerating mode outside an rf bucket, and the effects of crossing "resonances." In EMMA, some collective effects become a concern even though the beam stays in the ring for only 10 to 20 turns. We report studies of direct and image space charge, beam loading, and other collective effects with a tracking simulation. Space charge effects, already potentially significant in EMMA, are enhanced by the fact that the beam passes through the beam pipe off-center. There is some possibility of a negative mass instability for some operation modes. We will show several 3D simulation results for space charge and beam loading effects and pure longitudinal simulation for the negative mass instability. | ||
| TUPP049 | Experimental Electron Cloud Studies in the CERN Proton Synchrotron | 1655 |
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| Indications for a beam-induced electron cloud build-up are observed since 2000 for the nominal LHC beam in the PS to SPS transfer line and during the last turns before ejection from the PS. A new electron cloud setup was designed, built, and installed in the PS. It contains shielded button-type pickups, a dipole magnet, a vacuum gauge, and a dedicated stripline electrode to experimentally verify the beneficial effect of electron cloud clearing electrodes. During the 2007 run, the electron cloud effect was also clearly observed in the PS and efficient electron cloud suppression has been obtained for negative and positive bias voltages on the clearing electrode. Here, we present electron cloud measurements with different filling patterns and bunch spacings in the PS. | ||
| TUPP050 | Electron Cloud Mitigation by Fast Bunch Compression in the CERN PS | 1658 |
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| A fast transverse instability has been observed with nominal LHC beams in the CERN Proton Synchrotron (PS) in 2006. The instability develops within less than 1 ms, starting when the bunch length decreases below a threshold of 11.5 ns during the RF procedure to shorten the bunches immediately prior to extraction. An alternative longitudinal beam manipulation, double bunch rotation, has been proposed to compress the bunches from 14 ns to the 4 ns required at extraction within 0.9 ms, saving some 4.5 ms with respect to the present compression scheme. The resultant bunch length is found to be equivalent for both schemes. In addition, electron cloud and vacuum measurements confirm that the development of an electron cloud and the onset of an associated fast pressure rise are delayed with the new compression scheme. Beam dynamics simulations and measurements of the double bunch rotation are presented as well as evidence for its beneficial effect from the electron cloud standpoint. | ||
| TUPP051 | Coupling Impedance of DAΦNE Upgraded Vacuum Chamber | 1661 |
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| The DAΦNE Phi-factory at INFN LNF has been ugraded in the second half of 2007 with a scope to test a recently proposed scheme of crab waist collisions. The vacuum chamber of the collider has been substantially modified: two new low impedance interaction regions have been designed and installed, the new stripline injection kickers have been implemented, the old bellows have been substituted by the new ones and all ion clearing electrodes have been removed. In the paper we present the machine impedance study of these new vacuum chamber components and compare bunch lengthening measurements in the modified DAΦNE with simulation results. | ||
| TUPP053 | Radiolocation of a HOM Source in the PEP-II Rings | 1664 |
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| A signal from the antenna situated in the LER (Low Energy Ring) helped to find a broken shielded bellows in the HER (High Energy Ring) during a single HER bunch operation. | ||
| TUPP054 | A Model of an Electrical Discharge in the Flange Contacts with Omega Seals at High Currents in PEP-II | 1667 |
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| During operation with high currents at HER (High Energy Ring), high temperature elevation was found at almost every location of the vacuum chamber flange contacts. Omega RF seals were strongly damaged or even evaporated by sparks and electrical discharge. We suggest a physical model, which may explain this effect. | ||
| TUPP055 | Loss Factor of the PEP-II Rings | 1670 |
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| RF power balance method is used to measure the synchrotron radiation losses and the wake field losses. We present the history of the loss factor during the last several runs, which reveals many interesting correlations with vacuum chamber improvement and processing. | ||
| TUPP058 | Impedance Estimation of Diamond Cavities | 1673 |
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| The RF straight section of the Diamond storage ring presently consist of two CESR type SCRF cavities with a provision to install a third cavity in the future. The cavities are equipped with HOM loads and are joined to the adjacent storage ring beam pipe using tapered transitions. The RF cavities are simulated with MAFIA, CST Studio and ABCI to estimate their contribution to the total ring impedance. We also measured the resonant frequencies and Q factors of residual HOMs in these cavities. In this paper, we present the results of our measurements and simulations which lead us to an estimation of the impedance of the RF straight. | ||
| TUPP059 | Study of Controlled Longitudinal Emittance Blow-up for High Intensity LHC Beams in the CERN SPS | 1676 |
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| Preventive longitudinal emittance blow-up, in addition to a fourth harmonic Landau damping RF system, is required to keep the LHC beam in the SPS stable up to extraction. The beam is blown-up in a controlled way during the acceleration ramp by using band-limited phase noise targeted to act inside the synchrotron frequency spread, which is itself modified both by the second RF system and by intensity effects (beam loading and others). For a high intensity beam these latter effects can lead to a non-uniform emittance blow-up and even loss of stability for certain bunches in the batch. In this paper we present studies of the emittance blow-up achieved with high intensity beams under different conditions of both RF and noise parameters. | ||
| TUPP061 | Comparison between Laboratory Measurements, Simulations and Analytical Predictions of the Resistive Wall Transverse Beam Impedance at Low Frequencies | 1679 |
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| The prediction of the resistive wall transverse beam impedance at the first unstable betatron line (8 kHz) of the CERN Large Hadron Collider (LHC) is of paramount importance for understanding and controlling the related coupled-bunch instability. Until now only novel analytical formulas were available at this frequency. Recently, laboratory measurements and numerical simulations were performed to crosscheck the analytical predictions. The experimental results based on the measurement of the variation of a probe coil inductance in the presence of i) sample graphite plates, ii) stand-alone LHC collimator jaws and iii) a full LHC collimator assembly are presented in detail. The measurement results are compared to both analytical theories and simulations. In addition, the consequences for the understanding of the LHC impedance are discussed. | ||
| TUPP062 | Beam Coupling Impedance Studies on LHC FP420 Multi-pocket Beam Pipe Prototype | 1682 |
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| The LHC FP420 collaboration is assessing the feasibility of installing forward proton detectors 420m from the ATLAS and/or CMS interaction points. The latest prototype of a FP420 station consists of a modified LHC beam pipe in which two pockets hosting the detectors introduce an abrupt cross-section variation of the pipe. During the FP420 proposed operation, each station is moved towards the beam as close as 3 mm (~ 10 σx). The impact on the LHC beam coupling impedance has been evaluated with a laboratory wire measurement and a suite of numerical simulations. In addition, we describe a proposed modification of the beam pipe design which minimizes the impedance of the resonances without compromising the FP420 detector signal to background ratio. | ||
| TUPP063 | Characterization of the ATLAS Roman Pots Beam Coupling Impedance and Mechanics | 1685 |
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| At the LHC, four Roman Pot (RP) type detectors will be installed on both sides of the ATLAS experiment with the aim of measuring elastic scattering at very small angles and determining the absolute luminosity at the interaction point. During dedicated LHC runs, the detectors will be positioned at about 1 mm from the nominal beam orbit. Numerical simulations and laboratory measurements were carried out to characterize the RP impact on the total LHC beam coupling impedance. The measurement results assess the effectiveness of RF-absorbing ferrite plates that have been mounted in convenient locations in order to damp high Q resonances of the RP structure. In addition, we review the RP mechanics emphasizing the accuracy and reproducibility of the positioning system. | ||
| TUPP065 | Experimental Study of the Electron Cloud Instability in the CERN-SPS | 1688 |
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| The electron cloud instability limits the performance of many existing proton and positron rings. A simulation study carried out with the HEADTAIL code revealed that the threshold for its onset decreases with increasing beam energy, if the 6D emittance of the bunch is kept constant and the longitudinal matching to the bucket is preserved. Experiments have been carried out at the CERN-SPS to study the dependence of the vertical electron cloud instability on the energy and on the beam size. The reduction of the physical transverse emittance as a function of energy is considered in fact to be the main reason for the unusual dependence of this instability on energy. | ||
| TUPP066 | CERN SPS Impedance in 2007 | 1691 |
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| Each year several measurements of the beam coupling impedance are performed in both longitudinal and transverse planes of the CERN Super Proton Synchrotron to keep track of its evolution. In parallel, after the extensive and successful campaign of identification, classification and cure of the possible sources of (mainly longitudinal) impedance between 1998 and 2001, a new campaign (essentially for the transverse impedance this time) has started few years ago, in view of the operation of the SPS with higher intensity for the LHC luminosity upgrade. The present paper summarizes the results obtained from the measurements performed over the last few years and compares them to our predictions. In particular, it reveals that the longitudinal impedance is reasonably well understood and the main contributors have already been identified. However, the situation is quite different in the transverse plane: albeit the relative evolution of the transverse impedance over the last few years can be well explained by the introduction of the nine MKE kickers necessary for beam extraction towards the LHC, significant contributors to the SPS transverse impedance have not been identified yet. | ||
| TUPP067 | Transverse Mode-coupling Instability in the CERN SPS: Comparing MOSES Analytical Calculations and HEADTAIL Simulations with Experiments in the SPS | 1694 |
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| Since 2003, single bunches of protons with high intensity (1.2·1011 protons) and low longitudinal emittance (0.2 eVs) have been observed to suffer from heavy losses in less than one synchrotron period after injection at 26 GeV/c in the CERN Super Proton Synchrotron (SPS) when the vertical chromaticity is corrected. Understanding the mechanisms underlying this instability is crucial to assess the feasibility of an anticipated upgrade of the SPS, which requires bunches of 4·1011 protons. Analytical calculations from MOSES and macroparticle tracking simulations using HEADTAIL with an SPS transverse impedance modelled as a broadband resonator had already qualitatively and quantitatively agreed in predicting the intensity threshold of a fast instability. A sensitive frequency analysis of the HEADTAIL simulations output was then done using SUSSIX, and brought to light the fine structure of the mode spectrum of the bunch coherent motion. A coupling between the azimuthal modes -2 and -3 was clearly observed to be the reason for this fast instability. The aim of the present paper is to compare the HEADTAIL simulations with dedicated measurements performed in the SPS in 2007. | ||
| TUPP068 | Bench Measurements of the Low Frequency Transverse Impedance of the CERN LHC Beam Vacuum Interconnects with RF Contacts | 1697 |
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| The low frequency longitudinal and transverse impedances of the CERN Large Hadron Collider (LHC) have to be specifically minimized to prevent the onset of coherent instabilities. The LHC beam vacuum interconnects were designed as Plug In Modules (PIMs) with RF contacts to reduce their coupling impedances, but the resulting contact resistance is a concern, as this effect is difficult to estimate. High sensitivity measurements of the transverse impedance of a PIM at low frequency using a coil probe are presented. In particular, the increase of the transverse impedance of the PIM when it is elongated to its operating position is discussed in detail. Finally, the issue of non-conforming contact resistance is also addressed. | ||
| TUPP071 | Development of TiN Coating System for Beam Ducts of KEK B-factory | 1700 |
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| A titanium nitride (TiN) coating system for the copper beam ducts of KEK B-factory (KEKB) was developed to reduce the secondary electron yield (SEY) from the inner surface, which would mitigate the electron cloud instability. The coating was done by DC magnetron sputtering of titanium in argon and nitrogen atmospheres. The duct was set vertically, and a titanium cathode rod was hung from the top on the center axis of the duct. A magnetic field was supplied by a movable solenoid coil placed outside of the duct. Preliminary experiments using small copper samples showed that a 200-nanometer-thick TiN film coated at 150 degree is the best from the viewpoints of SEY and adhesion strength. The SEY of the coated sample decreased to 60% of that of non-coated copper after an electron dose of 0.01 C/mm2, and the maximum SEY was 0.84. Using this system, five ducts with a length of up to 3.6 m were successfully coated. Some of them were installed into the KEKB positron ring last summer, and no problem was found in the following beam operation with a beam current of up to 1.6 A. One coated duct with an electron monitor was installed this winter, and the effect of the coating will be checked. | ||
| TUPP073 | Bench-top Impedance Measurements for a Rotatable Copper Collimator for the LHC Phase II Collimation Upgrade | 1703 |
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| The Phase II upgrade to the LHC collimation system calls for complementing the 30 high robust Phase I graphite collimators with 30 high Z, low impedance Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and this design will be discussed here. Simulations have been performed in MAFIA to study both the resistive wall and geometric impedance contributions of our rotatable collimator design. Benchtop stretched coil probe impedance measurements have also been performed on prototype components to directly measure the low frequency impedance contributions. The design also calls for an RF contact interface at the jaw end. This contact resistance must be a small fraction of a milliohm in order to limit transverse impedance. DC resistance measurements in a custom built test chamber have been performed to test the performance of various metal pairs and surface coatings. | ||
| TUPP074 | A New RF Shielded Bellows for the DAΦNE Upgrade | 1706 |
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A new RF shielded bellows, using the technology of omega shaped strip of beryllium copper material, has been developed and tested on the DAΦNE Upgrade*. The RF omega shield is composed by many Be-Cu strips held by an external floating ring**. Thermal power loss on strips can be easily extracted and dissipated allowing high beam current operation. Leakage of beam induced e.m. fields through the RF shield is almost suppressed. Twenty omega bellows were manufactured and installed in the DAΦNE storage rings and showed good properties up to a stored beam current of 700 mA.
*DAΦNE upgrade: A New magnetic and mechanical layout. PAC07. pp. 1466-1468, Albuquerque. |
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| TUPP075 | Numerical Studies of Resistive Wall Effects | 1709 |
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| In this paper we describe a new numerical code to calculate wakefields of resistive wall geometries. Our code is based on conformal implicit scheme. It allows to estimate wakefields of very short bunches taking into account transitive effects neglected in the European XFEL impedance budget so far. | ||
| TUPP076 | Longitudinal and Transverse Impedances of XFEL Kicker Vacuum Chamber | 1712 |
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| In European XFEL project beam delivery system the kicker magnet vacuum chamber design is composed of the ceramic pipe coated with Titanium Stabilized High Gradient Steel. In this paper the results of the study for the longitudinal and transverse impedances for such a laminated vacuum chamber are presented. The field matching technique is used to calculate the vacuum chamber impedances. The loss and kick factors are given. | ||
| TUPP079 | Distortion of Crabbed Bunch due to Electron Cloud with Global Crab | 1715 |
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| In order to improve the luminosity, crab cavities have been installed in the KEKB HER and LER. Since there is only one crab cavity in each ring, the crab cavity generates a horizontally titled bunch oscillating around the whole ring. The electron cloud in LER (positron beam) may distort the crabbed bunch and cause the luminosity drop. This paper briefly estimates the distortion of positron bunch due to the electron cloud with global crab. | ||
| TUPP081 | Longitudinal Wakefields and Impedance in the CSNS/RCS | 1718 |
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With the more general expressions developed for the wakefield generated by nonrelativistic beam*, the impedances of some main vacuum parts of the Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) are calculated and compared with the relativistic case. An impedance model is then proposed for the ring. With this impedance model, beam instabilities in the CSNS/RCS are investigated.
*N. Wang and Q. Qin, Phys. Rev. ST Accel. Beams 10, 111003 (2007) |
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| TUPP082 | Longitudinal Stability of Flat Bunches with Space-charge or Inductive Impedance | 1721 |
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| We study the loss of Landau damping for the longitudinal plane via the ''Sacherer formalism''. Stability limits are calculated for several longitudinal beam distributions, in particular for two types of flat bunches, which could be of interest to the LHC upgrade. The resulting Landau stability diagrams are computed and displayed for different azimuthal modes. A general recipe is given for calculating the threshold intensity in the case of a capacitive impedance below transition or, equivalently, for a purely inductive impedance above transition. Specific results are finally presented for the case of the PS Booster, as an example of space-charge impedance below transition, and for the SPS, as an example of inductive impedance above transition. | ||
| TUPP084 | Parallel Computation of Integrated Electromagnetic, Thermal and Structural Effects for Accelerator Cavities | 1724 |
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| The successful operation of accelerator cavities has to satisfy both rf and mechanical requirements. It is highly desirable that electromagnetic, thermal and structural effects such as cavity wall heating and Lorentz force detuning in superconducting rf cavities can be addressed in an integrated analysis. Based on the SLAC parallel finite-element code infrastructure for electromagnetic modeling, a novel multi-physics analysis tool has been developed to include additional thermal and mechanical effects. The speedup from parallel computation enables virtual prototyping of accelerator cavities on computers, which would substantially reduce the cost and time of a design cycle. The multi-physics tool will be applied to the LCLS rf gun and a superconducting rf gun cavity. | ||
| TUPP085 | Beam Dynamics Using Graphical Processing Units (GPUs) | 1727 |
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| Simulation of particle beam dynamics in accelerators is computationally expensive, and requires very high particle statistics and accuracy. Conventional beam tracking tools operate sequentially on particle phase space to compute the trajectories of particles through many turns of circular, and linear, machines. Graphical Processing Units (GPUs) utilise stream processing techniques to dramatically speed up parallel computational tasks, and offer considerable performance benefits to particle beam dynamics processing. In this paper, the stream processing beam dynamics code GPMAD is presented, which exploits the NVidia GPU processor, and demonstrates the considerable performance benefits to particle tracking calculations. The accuracy and speed of GPMAD is benchmarked using the Diamond Light Source BTS lattice, and the collimation system is evaluated. | ||
| TUPP086 | Efficient 3D Space Charge Calculations by Self-adaptive Multigrid Methods Using the Chombo Framework | 1730 |
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Current and future accelerator design requires efficient 3D space charge computations for high brightness bunches which should be as precise and fast as possible. One possible approach for space charge calculations is the particle-mesh-method, where the potential is calculated in the rest frame of the bunch by means of Poisson's equation. For an efficient solution of this elliptic PDE an appropriate adaptive discretization of the domain is required. Especially it has to take into account discontinuities in the distribution of the particles. The solution method we investigate in this paper is a self-adaptive multigrid method applying composite grids. To accomplish this, we use the library Chombo* which is being developed as a framework for adaptive multiresolution solvers for elliptic and hyperbolic partial differential equations.
*Developed and distributed by the Applied Numerical Algorithms Group |
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| TUPP087 | Short Range Wakepotentials Computed in a Moving Frame | 1733 |
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| When computing wakepotentials in a frame moving in the same direction as the exciting charge, the relativistic charge is stretched by the factor gamma of the frame's velocity. Because the needed mesh density is proportional to the length of the charge, the moving frame allows a larger gridspacing. The paper presents some implementation details of the handling of the material boundaries moving though the computational volume, and reports some results. | ||
| TUPP088 | Software Components for Electron Cloud Simulation | 1735 |
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| The Synergia2 beam dynamics code is an attempt to incorporate state-of-the-art space charge models from the Impact code into the Chef accelerator tracking code. The need to add new accelerator physics capabilities to the Synergia2 framework has led to software development efforts based on the Common Component Architecture (CCA). The CCA is a specification and a toolset for developing HPC from interchangeable parts, called components. Electron cloud is a potentially limiting effect in the performance of both high-intensity electron and proton machines. The modeling of electron cloud effects is important for the Fermilab main injector. Here, electron cloud effects are expected to play a significant role when the main injector operates in the regime of a high-intensity proton source for the neutrino program. In the ideal case, computational accelerator physicists would like to be able model electron cloud generation and dynamics in a single, self-consistent simulation. As a first step towards creating component-based, electron cloud generation simulations, this work describes a CCA component created from TxPhysics, a library of impact and field ionization routines. | ||
| TUPP089 | Implementation of Fringe Field Dipole Magnets into the V-Code Beam Dynamics Simulation Tool | 1738 |
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| Fast online beam dynamics simulations can advantageously assist the machine operators at various particle accelerator machines because they provide a more detailed insight into the actual machine status. Based on the moment approach a fast tracking code named V-Code has been implemented at TEMF. Within the SFB 634 project the V-Code beam dynamics simulation tool is supposed to be installed at the Superconducting Darmstadt LINear ACcelerator S-DALINAC which is designed as a re-circulating linear accelerator. In order to be able to simulate the entire beam line, an implementation of fringe field dipole magnets is mandatory. Unlike a hard edged field approach the fringe fields influence the beam focusing and its inhomogeneity results in a non-circular bunch motion. For an accurate reproduction of the transverse motion specialized techniques to obtain and to handle the reference path in V-Code together with the 3D-field data along the curved trajectory had to be developed. In the paper a summary of implementation details together with simulation results will be provided. | ||
| TUPP090 | A Kinetic Model of Multipaction for SRF Cavities for Accelerator Driven Sub-Critical System (ADSS) | 1741 |
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| This work simulates multipaction in a 700 MHz elliptical SRF cavity. The cavity design was optimized using SUPERFISH. Then the electromagnetic field was re-computed with FEMLAB, a package using the finite element method, to obtain a more accurate field-mapping, and to make the field values available for computation of multipaction. In the multipacting subroutine, electrons were assumed to be released into the system from various points with different initial parameters. The electrons trajectories were tracked until they hit the cavity surface. Leap-frog scheme was used to solve the Lorentz force equation for primary electrons, as it is easy to use and is accurate up to second order. The position, velocity, phase and kinetic energy of primary electrons at each time step were calculated and stored. An interpolation function was used to calculate secondary emission yield (SEY) at different impact energies. With the emission of secondary electrons, their trajectories too were tracked along with primary electrons, in order to identify parameters responsible for multipaction. By repeating this process for large number of electrons, the multipacting trajectories were identified. | ||
| TUPP091 | WISE: a Simulation of the LHC Optics Including Magnet Geometrical Data | 1744 |
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| The beam dynamics in LHC strongly depends on the field quality and geometry of the magnets. A model of the LHC optics has been built, based on the information available at the end of the production as well as on statistical evaluations for the missing information The pre-processor WISE generates instances of the LHC field errors for the MAD X program, with the possibility of selecting various sources. This paper describes the progress since WISE was presented in EPAC06. The slot allocation in LHC is completed since all magnets are installed and interconnected. Geometric measurements have been added for all magnets. Furthermore, some statistical data is available relative to the precision of magnet installation (alignment) and tunnel movements. In this paper the code and the data are used to update the beta-beating estimate at injection and collision energy. The relevance of misalignments of the different magnets and their impact on beta-beating is compared to the sources that have been previously considered, i.e. the spread in the gradient of the cell quadrupoles and the uncertainty associated to the knowledge of the transfer functions of the stand-alone quadrupoles. | ||
| TUPP093 | Crystalline Beam Simulations | 1747 |
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| A new program code was elaborated for the simulation of crystalline beams on the S-LSR storage ring (Kyoto Univ., Japan) under action of the cooling system. For the investigation of ordered proton beams, which recently were observed in first time on S-LSR, a special molecular dynamics technique was used. This article presents results of the numerical simulation and comparison with experimental data. | ||
| TUPP094 | Recent Improvements in the Tracking Code PLACET | 1750 |
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| The Tracking Code PLACET has recently undergone several improvements. A redesign of its internal data structures and a new user interface based on the mathematical toolbox Octave have considerably expanded its simulation capabilities. Several new lattice elements, optimization algorithms and physics processes have been added to allow for more complete start-to-end simulations. The usage of the AML language and the Universal Parser Library extened its interfacing capability. | ||
| TUPP095 | Computation of Resistive Wall Wakefields with the PBCI Code | 1753 |
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| Both geometric disturbances and resistive wall loss of accelerator cavities contribute to the impedance causing the beam to lose energy. Impedance due to arbitrary three-dimensional (3-D) geometries can be computed with the Parallel Beam Cavity Interaction (PBCI), a parallelized, 3D-wakefield code. However, the contribution of wall loss is often significant. The contribution of this work is to incorporate resistive wall loss into 3-D time-domain simulation. Surface-impedance concept is used to consider wide-band skin-effect loss of metal. In theory, the proposed approach can be extended to consider high-frequency phenomena such as frequency-dependent conductivity of metal and anomalous skin effect. | ||
| TUPP097 | New Formalism in the Spin Tracking Code Spink | 1756 |
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The code Spink*, in use for more than 10 years to track polarized hadrons in a synchrotron, was overhauled with the introduction of a new system of coordinates based on a generalized Frenet-Serret system in all dimensions in space, which allows a better treatment of the curvature of the reference orbit. Two more improvements are (a) treatment of tensor polarization for particles like polarized deuterons, and (b) inclusion of space charge and beam-beam effects, so the code can be used to track spin in synchrotrons with high luminosity like new generation colliders.
*A. U. Luccio. Proc. Adriatico Research Conf. on Trends in Colliders |
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| TUPP098 | The 3D Space Charge Field Solver MOEVE and the 2D Bassetti-Erskine Formula in the Context of Beam - E-cloud Interaction Simulations | 1759 |
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| In this paper the fields computed with our 3D space charge field solver MOEVE are compared to those obtained by means of the Bassetti-Erskine formula, which is a widely used 2D approximation of the electric field of a Gaussian bunch. In particular we are interested in the transversal fields of very flat bunches as the ILC or the KEKB positron bunch. Supposing a longitudinal Gaussian distribution of the bunches, we compare the computed transversal fields for a certain line density of the positron bunch. It turns out that the fields from the 2D and the 3D computation coincide very good. | ||
| TUPP099 | Improvement of RFQSIM | 1762 |
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| RFQSIM has constantly been developed at IAP to simulate multiple particles dynamic of RFQs which include simulations of high current applications, decelerators, debuncher and rebuncher e.g. for the medical application. The latest work to improve RFQSIM include the option to change the modulation and or the aperatur of the simulated RFQ to produce the same acceleration and or focusing efficiency than the two term potential gives for different electrode geometries. Additional work was done to improve the graphical analysis during runtime as well as the change of all routines to be compatible with the Fortran F95 standard. The maximum number of particles to be simulated was increased to 200k. The paper shows examples of results for the high current application like the of the p-linac and the new HLI injector for GSI and for transition sections. | ||
| TUPP100 | A Four-dimensional Vlasov Solver for Microbunching Instability in the Injection System for X-ray FELs | 1764 |
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| The phenomenon of microbunching instabilty arises from small charge-density fluctuations in the electron bunches that are amplified by the combined effect of space charge and coherent synchrotron radiation as the beam travels through magnetic compressors. In order to study the coupled longitudinal and transverse beam dynamics we propose to develop a four-dimensional grid-based Vlasov solver. The goal is to give an accurate characterization of the microbunching instability seeded by the random noise present in the initial bunch distribution. Solving directly the Vlasov equation instead of using macroparticle simulations has the advantage of avoiding the statistical fluctuations due to a limited number of macroparticles. Because a Vlasov solver in a high dimension phase-space tends to be particularly time consuming, to be practical a code implementing this method should run on parallel processors. In this paper we report progress toward the realization of such a 4D Vlasov solver. | ||
| TUPP102 | Beam Transport with Scattering Using SRIM Supporting Software Routines Code | 1767 |
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In many situations a particle beam is transported through matter-containing components separated by ion-optical elements. The matter-containing components scatter the beam and alter its emittance diagram. In order to include accurately the scattering in beam-transport a special beam-transport module was included in the SRIM Supporting Software Modules package (S3M)*. It uses transfer-matrix formalism in ion-optical elements. At the entry to a scattering element a beam-generation routine converts the actual σ-matrix into an ensemble of particles and writes a special SRIM input-file. The beam-transport in the scattering element is then calculated by SRIM MC particle tracking. At the exit of the scattering element, the module imports back the SRIM output data and can either continue with transfer-matrix transformations or generate a modified σ-matrix that can be used by other ion-optical programs. It means the beam transport with scattering can either be fully calculated by S3M, or data exchange between S3M and ion-optical programs can be provided. S3M beam-transport module is described in the paper with some typical application examples.
*M. Pavlovic, I. Strasik. Supporting Routines for the SRIM code, Nucl. Instr. and Meth. B 257 (2007) 601-604. |
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| TUPP103 | The Performance of 3D Space Charge Models for High Brightness Electron Bunches | 1770 |
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| Precise and fast 3D space charge calculations for high brightness, low emittance electron beams are of growing importance for the design of future accelerators and light sources. The program package Astra (A space charge tracking algorithm) has been successfully used in the design of linac and rf photo injector systems. The Astra suite originally developed by K. Flöttmann tracks macro particles through user defined external fields including the space charge field of the particle cloud. In this paper we investigate the performance of the 3D space charge models implemented in Astra. These are the FFT-Poisson solver with the integrated Green's function and the iterative Poisson solver based on the multigrid technique. The numerical tests consider the accuracy of the solvers for model bunches as well as the performance within a typical simulation for the XFEL. | ||
| TUPP105 | Theoretical Field Analysis for Superferric Accelerator Magnets Using Elliptic Multipoles and its Advantages | 1773 |
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| FAIR will build a set of accelerators and storage rings at GSI Darmstadt. Nearly all of them transport beams of elliptical shape (SIS 100, CR, NESR, RESR, SuperFRS). Magnetic field calculations as well as magnetic measurements provide precise field information, which is used to improve the properties of machine using numerical simulations. We had developed elliptical multipoles fulfilling the Laplace equation which enable us to describe the field within the whole aperture consistently. Now the representation of these has been simplified considerably as compared to earlier ones. Meanwhile we found analytical expressions to derive circular multipoles directly from the elliptic multipoles. We illustrate the advantage of this data representation on SIS 100 magnet data and show how a concise set of harmonics can be derived from rotating coil measurements. | ||
| TUPP109 | Meshless Solution of the Vlasov Equation Using a Low-discrepancy Sequence | 1776 |
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| A successful method for solving the nonlinear Vlasov equation is the semi-Lagrangian method, in which the phase space density is represented by its values on a fixed Cartesian grid with interpolation to off-grid points. Integration for a time step consists of following orbits backward in time from initial conditions on the grid, with the collective force frozen during the time step. We ask whether it would be more efficient to use scattered data sites rather than grid points, namely sites from a low-discrepancy sequence as used in quasi - Monte Carlo integration. This requires a technique for interpolation of scattered data, and with such a technique in hand one can try either backward or forward orbits. Here we explore the forward choice, with the data sites themselves following forward orbits. We treat a problem well studied by the backward method, longitudinal motion in the SLAC damping rings. Over one or two synchrotron periods results are encouraging, in that the number of data sites can be reduced by a large factor. Over longer times it appears that the sites must be redistributed or changed in number from time to time, because of clustering. | ||
| TUPP110 | Rotative Systems for Dose Distribution in Hadrontherapy (Gantries) | 1779 |
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| Tumour treatments with high velocity ion beams or protons are characterised by a great depth precision (Bragg pic) and a low divergence for dose delivery in very small volumes. In order to spare normal tissues before and around the tumour it is necessary to have the choice of the beam incidence because the patient cannot be moved. Different devices have been built mainly exocentric and isocentric. Many others are being studied. Cryogenic solutions are analysed to reduce the total mass in rotation. For example it would be very interesting to choose a superconductive solution for the last 90° dipole. | ||
| TUPP111 | Magnetic Design Improvement and Construction of the Large 90o Bending Magnet of the Vertical Beam Delivery Line of CNAO | 1782 |
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| The CNAO (Centro Nazionale di Adroterapia Oncologica) is the medical center dedicated to the cancer therapy, under construction in Italy. Protons with energy ranging from 60 to 250 MeV and carbon ions with energy 120 to 400 MeV/u will be delivered to patients in three different treatment rooms, of which one is served with both horizontal and vertical beams. The vertical line requires a 70 tons 90o bending magnet providing 1.81 T in a good field region of x = ± 100 by y = ± 100 mm2 with an integrated field quality (ΔBL/BL) at all field levels ≤ ± 2×10-4. Starting from the experience matured when constructing the large bending magnet for HICAT gantry, we have developed a design able to meet these more stringent requirements in both 2D and 3D and special attention was paid to the study of manufacturing tolerances | ||
| TUPP112 | The RADIOTHOMX Project | 1785 |
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| The goal of this project is to develop a compact device, which could produce an intense flux of monochromatic X-rays for medical applications. It is based on Compton back-scattering resulting from collisions between laser pulses and relativistic electron bunches. Intense laser beams can be obtained with a high gain Fabry-Perot cavity coupled with a high average power fiber laser. Such a scheme is going to be developed by CELIA and LAL laboratories. The accelerator design to produce high repetition rate electron bunches at 50 MeV is under study. Two possibilities are being investigated: either a linear accelerator combined with a storage ring operating at an injection frequency high enough to preserve the electron beam characteristics or a high average current ERL. Both accelerator configurations aiming at producing X-ray fluxes higher than 1012 photons/s will be presented. | ||
| TUPP113 | Intensity Upgrade Programme for the HIT Injector Linac | 1788 |
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| The Heidelberg Ion Beam Therapy Centre (HIT) is a worldwide unique radiation therapy facility and the first installation of its kind in Europe. It is equipped with three treatment rooms and has the potential to irradiate over 1000 patients per year. To guarantee such a high patient throughput, i.e. based on short irradiation times, and in order to prepare upcoming clinical requirements the currently limited beam intensity (particles per spill) needs to be increased. In an endeavour to provide optimum conditions for the patient treatment an intensity upgrade programme for the injector linac has been initiated. It affects primarily the ion source and the RFQ but also other linac components. The largest influence on the linac transmission is expected by a new RFQ design with optimised electrodes, which is currently commissioned on a test bench. The update programme is accompanied by beam dynamics simulations and machine studies. First improvements are presented and the status of the programme is given. | ||
| TUPP115 | Variable Energy Protontherapy FFAG Accelerator | 1791 |
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| A hadrontherapy accelerator assembly based on an FFAG ring and a variable energy H- cyclotron injector has been designed in the frame of the RACCAM project. The FFAG ring allows 2.1 Tm top rigidity, corresponding to 180 MeV proton top energy and 21.6 cm penetration depth and to 50 MeV per nucleon for carbon ions suitable for biological R&D). Variable energy extraction, bunch to pixel 3D scanning and multiport beam delivery are proposed in this installation. A prototype of a spiral sector scaling type of FFAG dipole is being built for proving the feasibility of the FFAG ring, subject to a second contribution in the conference. This paper will describe the accelerator assembly parameters and the beam properties. | ||
| TUPP116 | Development of Scanning System at HIMAC | 1794 |
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| A new treatment facility project, as an extension of the existing HIMAC facility, has been initiated for the further development of carbon-ion therapy. This new treatment facility will be equipped with a three-dimensional irradiation system with pencil beam scanning. For moving-tumor treatments with high accuracy, the most important part of the design study is how to realize this by scanning irradiation. For this purpose, we have studied a combination of the rescanning technique and the gated irradiation method. In order to avoid hot and/or cold spots even by a relatively larger number of rescannings within the acceptable irradiation time, we studied a fast scanning system. Further, this concept was experimentally demonstrated at the HIMAC. The design and the related study of the scanning system for the HIMAC new treatment facility will be presented. | ||
| TUPP117 | Review of Energy Variation Approaches in Medical Accelerators | 1797 |
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| Most of cancer Radiation Therapy (RT) machines rely on a linac as the source of the treatment beam which can be an electron beam or an X-ray beam. In either case, an approach to vary the energy of the linac’s output beam may be needed to target cancer tumors of different depths. Over the last two decades, multiple approaches for medical linac energy variation were proposed and some of them have been developed and implemented clinically. The most direct and conventional technique is to vary the amount of the RF power delivered to the linac and hence the energy output as required by the treatment plan. A second approach involves keeping the RF power delivered to the linac fixed but varying the power delivered to different sections of the linac by utilizing a mechanical or an electronic switch that controls the power distribution inside the linac. A third approach is to use two separate linac sections. The first section receives a fixed amount of RF power while the RF power delivered to second section is controlled using conventional microwave power splitting techniques. In this paper we will review the above approaches and discuss the advantages and disadvantage of each technique. | ||
| TUPP118 | Update of an Accelerator Control System for the New Treatment Facility at HIMAC | 1800 |
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| Tumor therapy using energetic carbon ions, as provided by the HIMAC, has been performed since June 1994, and more than 3200 patients were treated until now. With the successful clinical results over more than ten years, we started to construct a new treatment facility. The new facility would have three treatment rooms; two of them have both horizontal and vertical fixed-irradiation-ports, and the other has a rotating-gantry-port. For all the ports, a scanning irradiation method is applied. The new facility will be constructed in conjunction with the HIMAC, and heavy-ion beams will be provided by the HIMAC accelerators. To fulfill requirements for the scanning irradiation, we are planning to update the accelerator control system. The proposed control system would enable us to provide heavy ions having variable energies within a single synchrotron-pulse; the beam energy would be changed a few tenth of times within a pulse by an energy step corresponding to a water range of 2 mm. Since the beam range would be adjusted without using range compensators, an excellent irradiation field could be obtained. We will present our project on updating the accelerator control system. | ||
| TUPP119 | Lattice Design of a Carbon Ion Synchrotron for Cancer Therapy | 1803 |
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| A synchrotron accelerator for carbon ion cancer therapy was designed to be compact for a hospital based therapy facility. The circumference of the synchrotron is only 60 meter and the lattice is the FODO structure of 6 cells. Each cell has two dipole magnets with a angle of 30 degree. The lattice satisfies the requirement of Hardt condition for slow beam extraction which is to align the separatrices of different momenta of the particles. | ||
| TUPP120 | Current Status of the IBA C400 Cyclotron Project for Hadron Therapy | 1806 |
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| Compact superconducting isochronous cyclotron C400 has been designed at IBA (Belgium) in collaboration with the JINR (Dubna). This cyclotron will be used for radiotherapy with proton, helium or carbon ions. 12C6+ and 4He2+ ions will be accelerated to 400 MeV/u energy and extracted by electrostatic deflector, H2+ ions will be accelerated to the energy 250MeV/u and extracted by stripping. We describe the parameters of the cyclotron, the current status of development work on the cyclotron systems. Reports on the status of the C400 project have been given regularly. Therefore, we will focus on the progress which has been achieved since recent reports in Cyclotron 2007 and EPAC 2006 conferences. The project will be ready to begin construction in the nearest future. | ||
| TUPP121 | Spatial Resolution and Contrast of the Intensity Modulated Electron Beam by the Photocathode RF Gun for the Radiation Therapy | 1809 |
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| The radiation therapy of cancer is developing to un-uniform irradiation as the Intensity Modulated Radiation Therapy (IMRT), for reduce dose to normal tissue. Toward the IMRT, optical modulation of electron beam is studying by a photocathode RF gun. The photocathode RF gun can generate a low emittance electron beam by laser light. Because of the low emittance beam, the modulated electron beam is able to accelerate keeping shape. Electron beam were monitored by CCD cameras measuring the luminescence of the scintillator. Fundamental data such as the spatial resolution and the contrast of the optical intensity modulated electron beam are necessary. Spatial Resolution and Contrast of the Intensity Modulated Electron Beam by a Photocathode RF Gun will be reported. If the shape of the modulated electron beam is different, it may not keep beam shape from the non-symmetrically of the repulsion of the bunch inside. It will be reported that the relations of the beam-shape and the keeping ability of beam. | ||
| TUPP123 | SCENT300, A Superconducting Cyclotron For Hadrontherapy | 1812 |
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| SCENT300 is a superconducting cyclotron able to deliver proton and C beam at 260 and 300 AMeV respectively. The study of the machine is near to be completed. The mechanical and magnetic design will be presented. The mechanical drawing and size of the cyclotron will be presented. The characteristics of the main coil and magnetic field will be presented. The method to change the magnetic setting for H2 and Carbon acceleration will be described. The acceleration system consisting of 4 RF cavities will be also described. | ||
| TUPP124 | Status of the Particle Therapy Accelerator System Built by DANFYSIK A/S | 1815 |
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Danfysik and Siemens have entered a cooperation to market and build Particle Therapy* systems for cancer therapy. The accelerators will consist of an injector (7 MeV/u proton and light ions) and a compact synchrotron able to accelerate proton beams up to 250 MeV and carbon ions up to 430 MeV/u in less than 1s. These beams can be slowly extracted over a period of up to 10s and delivered to treatment rooms through a choice of fixed-angle horizontal and semi-vertical beamlines and Gantry Systems. The intensity for protons and carbon ions will be sufficient for the needs of scanning beam applications. The design of a particular system, with three horizontal beamlines and one semi-vertical (45°) beamline, will be described. At the time of EPAC08, most components have been manufactured and hardware tested. The detailed layout of the facility will be presented, together with some of the components and their performance.
*Particle Therapy is a work in progress and requires country-specific regulatory approval prior to clinical use. |
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| TUPP125 | New Heavy-ion Cancer Treatment Facility at HIMAC | 1818 |
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| The first clinical trial of cancer treatment with carbon beams generated from the HIMAC was conducted in June 1994. Based on more than ten years of experience with HIMAC, we have proposed a new treatment facility for the purpose of further development of the heavy-ion cancer therapy with HIMAC. This facility, which is connected with the HIMAC synchrotron, consists of three treatment rooms: two rooms equipped with horizontal and vertical beam-delivery systems and one room with a rotating gantry. In both the fixed beam-delivery and rotating gantry systems, a 3D beam-scanning method is employed with gated irradiation with patient’s respiration in order to increase the treatment accuracy. Since the beam control for the size, the position and the time structure plays an essential role in the 3D beam scanning with the irradiation gated with respiration, the R&D study has been carried out with the HIMAC synchrotron since 2006. At December 2007, the Japanese government approved this project. We will report the design and R&D studies toward the construction of the new treatment facility. | ||
| TUPP126 | Advanced Concepts for Particle-therapy Accelerators | 1821 |
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| Presently in Europe the first generation of particle-therapy accelerators is on the way from construction into operation. Each layout typically consists of two ion sources, a single injection line, a main synchrotron and beam transfer lines to several treatment rooms, one of them equipped with or foreseen for an ion gantry. The paper presents some possible enhancements for the next facility generation still based on existing layouts and design studies. The focus lies on an improved injection line and gantry concepts. A simplified injection line using a different configuration of ion sources and low-energy beam-transport line is described. It is based on combination of particle species with identical charge-to-mass ratio. Optimized gantry constructions are shown with mechanical designs driven by ion-optical demands, especially by the accuracy of the beam position at the isocentre. The enhancements presented in the paper may influence upgrades of existing centres or may be implemented in the design of newly developed next generation of particle- therapy accelerators. | ||
| TUPP127 | Spill Structure Measurements at the Heidelberg Ion Therapy Centre | 1824 |
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| A specially designed accelerator facility for tumour irradiation located at the Heidelberg University Hospital was built up, the commissioning is still ongoing. Technically the Heidelberg Ion Therapy Center (HIT) fully relies on the three dimensional intensity-controlled rasterscan technique developed at GSI. This method demands for smoothly extracted ion beams (from protons to oxygen) from the HIT synchrotron. For this purpose a RF knock-out system consisting of a RF-exciter in combination with an electrostatic septum, two septum magnets and two sextupoles is used. To characterize the extracted beams scintillators for low intensities and ionization chambers for higher currents are installed in the high energy transport lines. Using a PXI-based DAQ system full spills are recorded with a time bin of 100 μs. Typical raw data will be shown as well as derived statistics like Fourier spectra and maximum-to-average ratios that proof the beam quality for its applicability to produce outstanding dose distributions via beam scanning. In addition, safety aspects like the performance of the spill interrupt procedure will be demonstrated with measured data. | ||
| TUPP129 | Accelerator Development for Advanced Particle Beam Therapy | 1827 |
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| Particle beam therapy has become one of the most effective modalities of cancer treatment. High reliability, high throughput and high precision irradiation are strongly demanded for the therapy system. In order to meet the requirements, we have developed several key technologies of synchrotron-based accelerator system, such as multi-harmonic RF acceleration, extracted beam intensity feedback, respiration-synchronized operation and beam tuning for spot scanning irradiation. Almost all these technologies have already been applied to the proton beam therapy system at M. D. Anderson Cancer Center. Beam specifications required for the spot scanning irradiation have successfully been achieved. In this paper, present status of the accelerator development will be described. | ||
| TUPP130 | Development of 3D Dose Verification System for Scanned Ion Beam at HIMAC | 1830 |
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| A 3D dose imaging system has been developed for a project of a new cancer treatment with 3D pencil beam scanning at HIMAC. This system provides the dose measurements easily and rapidly. this system consists of a water tank, fluorescent screen and charge-coupled device, set at isocentor. The fluorescent screen is directly attached to the downstream side of water tank. One of great advantages of this system is to obtain 2D dose map at once, by correcting LET-dependent quenching. The procedure to verify 3D dose distribution is based on the 2D dose measurement of slice-by-slice under a water depth. We will present the measurement result of 3D dose distribution by the proposed method, and its comparison with that by the ionization chamber. | ||
| TUPP131 | Status of the Linac Components for the Italian Hadrontherapy Centre CNAO | 1833 |
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| The IH-DTL for the Linac in the Italian National Center for Hadron Therapy in Oncology CNAO will accelerate different ion species (C4+, O6+,3He+, H2+) to an energy of 7 MeV/u. The combined rebunching and accelerating beam dynamic concept ("KONUS", "Kombinierte Null Grad Struktur", combined zero degree structure) requires a real voltage distribution in all 56 accelerator gaps (distributed in 4 sections) matching very close to the design voltage distribution. The tuning of the mechanically finished and copper plated cavity started in January 2007, based on the experience from the similar IH-DTL for the HIT linac ("Heidelberger Ionenstrahl-Therapiezentrum", the Heidelberg ion beam therapy center). Very small differences in mechanical measures caused modified starting conditions, resulting in varying number and shape of fixed tuners, but nevertheless accurate field distribution. The CNAO Linac is at presently under commissioning, all linac components except the IH-DTL have been delivered to the center in November 2007. | ||
| TUPP132 | Design, Construction and Low Power RF Tests of the First Module of the ACLIP Linac | 1836 |
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| ACLIP is a 3 GHz proton SCL linac designed as a booster for a 30 MeV commercial cyclotron. The final energy is 62 MeV well suitable for the therapy of ocular tumours or for further acceleration (up to 230 MeV) by a second linac in order to treat deep seated tumours. The possibility of using magnetrons as the source of RF power, to reduce the overall cost of the machine, is under investigation within a collaboration with the company e2v (Chelmsford, UK). ACLIP is a 5 modules structure coupled together. The first one (able to accelerate proton from 30 to 35 MeV) has been machined and completely the brazed. We plan to have the high power test by early fall 2008. In this paper we will review the main features of the linac and discuss the results of the RF measurements carried out on this prototype. | ||
| TUPP133 | Assembly of the Carbon Beam Gantry at the Heidelberg Ion Therapy (HIT) Accelerator | 1839 |
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| The HIT facility comprises the only carbon ion gantry worldwide. This gantry is especially unique in offering fully flexible beam transport to the patient up to a magnetic rigidity of 6.6 Tm, equivalent to an energy of C-ions of 430 MeV/u. It includes a full 3D-beam scanning system and full medical treatment environment. The gantry can be rotated by 360 degree so that the beam may be aimed at the patient from arbitrary directions. Commissioning of the gantry with beam was started in January 2008, when the first beams were transported into the treatment room. The design and assembly of this gantry with a rotating mass on the order of 600 tons was a real challenge to the project partners involved, in particular the supplier MT Mechatronics. Given the tight tolerances for the position of the beam line components the survey and alignment procedure was difficult, since also the elastic deformation for the different rotation angles had to be taken into account. This presentation will report on the experiences and results of the assembly and alignment phases. Furthermore, the final performance reached for precision and reproducibility of the beam line components will be presented. | ||
| TUPP134 | Commissioning of the Carbon Beam Gantry at the Heidelberg Ion Therapy (HIT) Accelerator | 1842 |
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| The HIT facility comprises the only carbon ion gantry worldwide. This gantry is especially unique in offering fully flexible beam transport to the patient for carbon ions up to an energy of 430 MeV/u. It includes a full 3D-beam scanning system and full medical treatment environment. The gantry can be rotated by 360 degree so that the beam may be directed at the patient from arbitrary directions. Commissioning with beam of the gantry was successfully started in January 2008 when the first proton and carbons beams were transported into the gantry treatment room. Based on theoretical calculations for rotation independent settings of the beam optics, the beam commissioning aims for an efficient practical way to realize the full variety of required beam properties (2 ion types, 10 intensities, 255 energy steps, and four beam sizes) in the isocenter independent of the gantry angle. The presentation will report on the concept and progress of the beam commissioning process. | ||
| TUPP139 | Variable Energy 2-MeV S-Band Linac for X-ray and Other Applications | 1845 |
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| We will describe the design and operation of a compact, 2-MeV, S-band linear accelerator (linac) with variable energy tuning and short-pulse operation down to 15 ps with 100-A peak current. The design consists of a buncher cavity for short-pulse operation and two coupled resonator sections for acceleration. Single-pulse operation is accomplished through a fast injector system with a 219-MHz subharmonic buncher. The machine is intended to support a variety of applications, such as X-ray and electron beam diagnostic development and, recently, electron diffraction studies of phase transitions in shocked materials. | ||
| TUPP141 | Electron Accelerators for Cleaning Flue Gases and for Oil Liquefaction | 1848 |
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| High-power electron beams can be used to reduce the environmental impact of coal and oil-fired power generating plants by removing harmful materials from flue gases. This technology has been tested in the laboratory and at smaller industrial levels, but to make it economically attractive, the accelerator costs must be reduced and the efficiency must be increased for removing toxic components in low concentrations. We propose a simple electron accelerator with a wide beam to reduce costs. To remove toxic materials we propose a plasma reactor for desulfurization and selective catalytic reduction. The designs of 0.5 to 1.0 MeV accelerators with 20 to 100 kW average power are considered, along with the design of a plasma reactor for flue gas treatment. The design of a pilot facility for the oil industry is also presented. | ||
| TUPP143 | Collective Ionization by Attosecond Electron Bunches | 1851 |
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| Present accelerator technology has realized linac bunch length on the order of femtosecond. If the bunch length becomes onto the order of attosecond, its inverse is comparable to the ionization frequency; ionization potential divided by Plank's constant. The stopping power then becomes proportional to square of the number of bunch electrons. Such a bunch ionizes the target collectively. This collective, or coherent ionization will provide us plenty of applications including unknown ones at the present. This phenomenon has historically been expected in cluster beams, which can be regarded as ultra-short bunches. The present paper adapts formalism of stopping power of a medium characterized by a dielectric function against cluster beams to that against electron bunches. It then describes some numerical calculations on the collective ionization by the attosecond electron bunches. | ||
| TUPP147 | Accelerator Driven Systems for Energy Production and Waste Transmutation | 1854 |
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| Due to their inherent safety features and waste transmutation potential, accelerator driven subcritical reactors (ADSRs) are the subject of research and development in almost all countries around the world. The neutrons needed to sustain fission are generated by the spallation process resulting from high energy protons impacting a target element installed at the centre of the core. In the present paper the possible benefits of FFAGs as accelerator drivers for ADSR systems are analysed. FFAGs afford fast acceleration as there is no need of synchronization between RF and magnets, high average current with large repetition rate and large acceptance. The present study also focuses on the Monte Carlo studies of the reactor core design. The impact of the subcriticallity, target material and proton beam energy on the ADSR performance was also examined. Entirely novel ADSR configurations involving multiple accelerator drivers and associated spallation targets within the reactor core have also been considered. Calculations were carried out using the GEANT4 simulation code. | ||
| TUPP148 | Multigrid Negative Ion Source Test and Modeling | 1857 |
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| Negative ion sources are a fundamental ingredient of neutral ion beam injectors for tokamak, like the ITER project and beyond. While detail of formation of negative ions and meniscus of the plasma beam interface at source extraction at source extraction is still debated, reasonable modelling of the beam extraction is well possible. A project of a small source (up to 9 beamlet of 15 mA each of H-, 60 kV acceleration voltage) is here described, and relevant modeling tools are reviewed. Power load deposition on the extraction grid (about 1.5 kW total) and on the source walls (comparable) need accurate cooling design. The extracted beam is direclty useful for wall damage studies. | ||
| TUPP150 | The Radiatron: A High Average Current Betatron for Industrial and Security Applications | 1860 |
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| The fixed-field alternating-gradient (FFAG) betatron has emerged as a viable alternative to RF linacs as a source of high-energy radiation for industrial and security applications. For industrial applications, high average currents at modest relativistic electron beam energies, typically in the 5 to 10 MeV range, are desired for medical product sterilization, food irradiation and materials processing. For security applications, high power x-rays in the 3 to 20 MeV range are needed for rapid screening of cargo containers and vehicles. In a FFAG betatron, high-power output is possible due to high duty factor and fast acceleration cycle: electrons are injected and accelerated in a quasi-CW mode while being confined and focused in the fixed-field alternating-gradient lattice. The beam is accelerated via magnetic induction from a betatron core made with modern low-loss magnetic materials. Here we present the design and status of a prototype FFAG betatron, called the RadiaTron, as well as future prospects for these machines. | ||
| TUPP151 | A High Intensity Positron Source at Saclay: The SOPHI Project | 1863 |
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| One of the fundamental questions of todays physics concerns the action of gravity upon antimatter. No experimental direct measurement has ever been successfully performed with antimatter particles. An R&D program has been launched at IRFU (CEA/Saclay) to demonstrate the feasibility of the production of antihydrogen (H) with the use of a target of positronium (Ps) atoms. This target, when bombarded with antiprotons, should allow combining its positrons with the incoming antiprotons and create H atoms and H+ ions. This experiment needs a large amount of Ps atoms, thus an intense source of positrons is necessary. We are building the SOPHI experiment in Saclay, based on a small 5 MeV electron linac to produce positrons via pair production on a tungsten target. This device should provide 108 slow e+/s, i.e. a factor 300 greater than the strongest activity Na22 based setups. The SOPHI system has been finalized in 2006 and the main components have been studied and built during 2007. The experiment is currently assembled and first results are expected in June 2008. The Linac, beam production and transport system will be presented, and first positron production rate measurements reported. | ||
| TUPP154 | Proton Energy Measurement Using Stacked Silicon Detectors | 1866 |
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| Proton energy was measured using stacked Si(Li) detectors at the MC-50 cyclotron of KIRAMS (Korea Institute of Radiological and Medical Sciences). The proton energies from the cyclotron were 35 MeV and 45 MeV. Generally, using a single semiconductor detecor it is not available to measure the proton energy above 30 MeV because the maximum thickness of the semiconductor detector was limited to 5mm. We have used a detector consisting of three 2 mm thick Si(Li) detectors and a 5 mm thick one. The active areas of these detectors are 75mm2. In this paper, we report the energy measurement results using the stacked detectors. | ||
| TUPP155 | Compact EUV Source Based on Laser Compton Scattering between Micro-bunched Electron Beam and CO2 Laser Pulse | 1869 |
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| High-power extreme ultra-violet (EUV) sources are required for next generation semiconductor lithography. We start developing a compact EUV source in the spectral range of 13-14 nm, which is based on laser Compton scattering between a micro-bucnhed electron beam and a high intensity CO2 laser pulse. The electron beam extracted from a DC photocathode gun is micro-bunched using laser modulation techinque and a magnetic compressor before the main laser Compton scattering for EUV radiation. We will describe a considerating scheme for the compact EUV source based on laser Compton scattering with micro-bunched electron beam and the result of its numerical studies. A plan of test experiment generating micro-bunched electron beam will be also introduced in this conference. | ||
| TUPP156 | Development of a Compact X-ray Source Based on Laser-Compton Scattering with a Pulsed-laser Super-cavity | 1872 |
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| A compact and high quality x-ray source is required for various fields, such as medical diagnosis, drug manifacturing and biological sciences. Laser-Compton based x-ray source that consists of a compact electron storage ring and a pulsed-laser super-cavity is one of the solutions of a compact x-ray source. Pulsed-laser super-cavity has been developed at KEK-ATF for a compact high brightness x-ray source. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. Recently, 357MHz mode-locked Nd:VAN laser pulses can be stacked stably in a 420mm long Fabry-Perot cavity with 2.5kW average power in our R&D. On the other hand, we have succeeded to stack the pulsed amplified laser in the super-cavity. This indicates that the number of X-ray is multiplied due to the gain in the amplification system to synchronize the pulsed pump to the beam. In view of this successful result, we have started an X-ray generation experiment using a super-cavity and a multi-bunch electron beam at KEK-LUCX. Development of the super-cavity and the results of X-ray generation experiment will be presented at the conference. | ||
| TUPP157 | Commissioning of L-band Electron Accelerator for Industrial Applications | 1875 |
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| An intense L-band electron linear accelerator is under construction at CESC (Cheorwon Electron-beam Service Center) for industrial applications. It is capable of producing 10-MeV electron beams with a 30-kW average beam power. For high-power capability, we adopted 1.3 GHz, and the RF source is a 25-MW pulsed klystron with a 60-kW average RF output power. A pre-buncher is used before the bunching section, which is built-in with the regular accelerating sections. The accelerating structure is a disk-loaded waveguide with a constant-impedance operated in the 2π/3-mode. It is to be operated under the fully beam-loaded condition for high average power with the 6-μs pulse length and the 350-Hz repetition rate. In this paper, we present details of the accelerator system and commissioning results. | ||
| TUPP158 | Development of Laser System for Compact Laser Compton Scattering X-ray Source | 1878 |
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| A compact X-ray source via laser Compton scattering is required for biological, medical and industrial science because it has many benefits about generated X-rays such as short pulse, quasi-monochromatic, energy tunability and good directivity. Our X-ray source is conventionally the single collision system between an electron pulse and a laser pulse. To increase X-ray yield, we have developed a multi-collision system with a multi-bunch electron beam and a laser optical cavity. The multi-bunch beam will be generated from a Cs-Te photocathode rf gun sytem using a multi-pulse UV laser system. The laser optical cavity will be built like the regenerative amplification including the collision point between the electron pulse and the laser pulse to enhance the laser peak power per 1 collision on laser Compton scattering. In this conference, we will describe the results of preliminary experiments for the multi-collision system and future plans. | ||
| TUPP159 | Dual Energy Material Recognition: Preliminary Results Obtained with the Radio-tomographic System Hosted in Messina | 1881 |
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| Dual Energy technique is a very powerful tool for material recognition. It typically involves X-ray energy below 1 MeV, thus limiting to few mm the thickness of the inspected heavy materials. However, it would be interesting to investigate the chance to extend this technique to higher energies, to allow recognition of thick heavy samples too. Encouraging preliminary tests performed by means of the radio-tomographic system based on a 5 MeV electron linac have suggested to develop a dual energy technique for high energy x-ray beams. This can be done because first experimental tests have confirmed the chance to vary the electron beam energy in a continuous way. As a consequence, bremsstrahlung beams with different end points can be produced, thus allowing to work with different x-ray transmissions. The composition of two different energies X-ray transmission results, allows to perform material recognition. By means of the MCNP4C2 code, simulations have been performed to evaluate the theoretical x-ray transmission in different materials and thickness. These results allow us to choose two x-ray energies providing the best results in order to perform material recognition. | ||
| TUPP160 | Superconducting RF Activities at ACCEL Instruments | 1884 |
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| We report on highlights of SRF activities at ACCEL Instruments during the last few years. For example the development of a new hydrofloric and sulphoric acid free electropolishing method for niobium cavities and the construction and installation of a new standard electropolishing plant for 9-cell 1.3 GHz cavities. In addition we have further developed our design for 500 MHz superconducting RF modules for light sources and delivered three such accelerator modules for Shanghai Ligth Source. For SOLEIL we manufactured a 350 MHz twin cavity accelerator module using the technology of sputtering niobium onto copper. | ||
| TUPP161 | 60 keV 30 kW Electron Beam Facility for Electron Beam Technology | 1887 |
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| At the Budker Institute of Nuclear Physics, Novosibirsk, the 60 keV 30 kW electron beam facility for electron beam technology has been developed. The electron gun provides continuous or modulated beam within the current range from 1 mA up to 500 mA. The optical system allows both static and dynamic focusing of the electron beam within the 50/500 mm range of distance from the gun outlet, the beam scanning and its parallel displacement from the optical axis. The electron gun facility is controlled by the computer via the CAN interface. This paper presents the general description of the facility, its block diagram and main parameters. | ||
| TUPP162 | High Heat Load Components in TPS Front Ends | 1890 |
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| National Synchrotron Radiation Research Center (NSRRC) will build a new synchrotron accelerator (TPS, Taiwan Photon Source) with a great heat-load power. Various IDs have been proposed. For instance, at 3.3 GeV, 350 mA, superconductivity wiggler SW4.8 may generate 5.8mrad wide, 57 kW/mrad2 power whereas undulator CU1.8 will be 0.7 mrad, 148 kW/mrad2. The function of the fixed mask in TPS front ends not only to protect the downstream vacuum from being hit by the radiation during miss-steering, but also shadow the unwanted power. More than one fixed masks are introduced in some high heat load front ends. High conductivity, high thermomechaical strength GlidCop® is used; design and thermomechanical analysis is also presented in this paper. |