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| MPPP015 | Operational Performance of a Bunch by Bunch Digital Damper in the Fermilab Main Injector | antiproton, proton, damping, injection | 1440 | ||
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We have implemented a transverse and longitudinal bunch by bunch digital damper system in the Fermilab Main Injector, using a single digital board for all 3 coordinates. The system has been commissioned over the last year, and is now operational in all MI cycles, damping beam bunched at both 53MHz and 2.5MHz. We describe the performance of this system both for collider operations and high-intensity running for the NuMI project.
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| MPPP019 | Beam Orbit Diagnostics and Control in CANDLE Storage Ring | photon, electron, closed-orbit, storage-ring | 1655 | ||
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Stability requirements for the CANDLE light source are the consequence of a small electron beam size and a tolerable photon beam parameters. In a real machine, the components of the storage ring have static and dynamic imperfections, which cause disturbance of the electron beam and consequently photon beams parameters. In the present paper the basic approaches to the beam diagnostics, control and correction issues for the CANDLE facility are given. The algorithms, electronics and processing hardware are described.
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| MPPT055 | The LANSCE Switchyard Kicker Project | kicker, vacuum, injection, power-supply | 3310 | ||
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Until 2003, the existing configuration of the LANSCE switchyard did not allow simultaneous delivery of the H- beam to Lines D and X. In the late 1990’s, with increased activities in Areas B and C, which serve the ultracold neutron experiments (UCN) and proton radiography (PRad), respectively, planning began to increase beam availability to all areas by installing a kicker system, dubbed the "Switchyard Kicker." The Switchyard Kicker is a system of two pulsed and two direct current magnets that enables simultaneous, uninterrupted beam delivery to Line D for the Lujan Center and the Weapons Neutron Research (WNR) Facility and, on request, a tailored H- beam pulse to Line X for the pRad and UCN research areas. The project received funding in July 2001 for design and implementation. During the 2003 Extended Maintenance Period this upgrade was installed in the Switchyard and commissioned during the Accelerator Turn-On period in the summer of 2003. With the commissioning successful, LANSCE now routinely operates in "Kick" mode, delivering simultaneous beam to Line X and Line D, increasing beam availability to all areas and simplifying production scheduling.
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| MOPB008 | Temporal E-Beam Shaping in an S-Band Accelerator | laser, electron, emittance, linac | 642 | ||
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Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contracts DE-AC02-98CH10886 and DE-AC03-76SF00515. |
New short-wavelength SASE light sources will require very bright electron beams, brighter in some cases than is now possible. One method for improving brightness involves the careful shaping of the electron bunch to control the degrading effects of its space charge forces. We study this experimentally in an S-band system, by using an acousto-optical programmable dispersive filter to shape the photocathode laser pulse that drives the RF photoinjector. We report on the efficacy of shaping from the IR through the UV, and the effects of shaping on the electron beam dynamics. |
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| TPAE025 | Field Ionization of Neutral Lithium Vapor using a 28.5 GeV Electron Beam | plasma, electron, acceleration, radiation | 1904 | ||
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The E164/E164X plasma wakefield experiment studies beam-plasma interactions at the Stanford Linear Acceleration Center (SLAC). Due to SLAC recent ability to variably compress bunches longitudinally from 650 microns down to 20 microns, the incoming beam is sufficiently dense to field ionize the neutral Lithium vapor. The field ionization effects are characterized by the beam’s energy loss through the Lithium vapor column. Experimental results are presented.
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| TPAE031 | Simulations of Laser Pulse Coupling and Transmission Efficiency in Plasma Channels | laser, plasma, simulation, coupling | 2179 | ||
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Funding: Work supported by U.S. DOE under contracts DE-FG03-02ER83557, DE-FC02-01ER41178, DE-AC03-76SF00098, DE-FG03-95ER40926 and use of NERC supercomputer facilities. |
Optical guiding of the laser pulse in a laser wakefield accelerator (LWFA) via plasma channels can greatly increase the interaction length and, hence, the maximun energy of trapped electrons.* Energy efficient coupling of laser pulses from vacuum into plasma channels is very important for optimal LWFA performance. We present 2D particle-in-cell simulations of this problem using the VORPAL code.** Some of the mechanisms considered are enhanced leakage of laser energy transversely through the channel walls, enhanced refraction due to tunneling ionization of neutral gas on the periphery of the gas jet, ionization of neutral gas by transverse wings of the laser pulse and effect of the pulse being off axis of the channel. Using power spectral diagnostics,*** we are able to differentiate between pump depletion and leakage from the channel. The results from our simulations show that for short (≈λp) plasma ramp, very little leakage and pump depletion is seen. For narrow channel walls and long ramps, leakage increases significantly. *C. G. R. Gedes et al., Nature 431 (2004), p. 538. **C. Nieter and J. R. Cary, J. Comp. Phys. 196 (2004), p. 448.***D. A. Dimitrov et al., Proc. Advanced Accel. Concepts Workshop (2004). |
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| TPAE058 | Plasma Dark Current in Self-ionized Plasma Wake Field Accelerators (PWFA) | plasma, electron, radiation, space-charge | 3444 | ||
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Particle trapping is investigated with experiment, theory and simulations for conditions relevant to beam driven Plasma Wake Field Accelerators. Such trapping produces plasma dark current when the wakefield aplitude is above a threshold values and may place a limit on the maximum acceleration gradient in a PWFA. Trapping and dark current are enhanced when in an ionizing plasma, that is self-ionized by the beam as well as in gradual density gradients. In the E164X conducted at the Stanford Linear Accelerator Center by a collaboration of USC, UCLA and SLAC, evidence of trapping has been observed. Here we present experimental results and a simplified analytical model of the particle trapping threshold which is compared to simulations done with an object oriented fully parallel 3-D PIC code OSIRIS.
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| TPAP010 | Reliability Analysis of the LHC Beam Dumping System | dumping, extraction, kicker, collider | 1201 | ||
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The design of the LHC Beam Dumping System is aimed at ensuring a safe beam extraction and deposition under all circumstances. The system adopts redundancy and continuous surveillance for most of its parts. Extensive diagnostics after each beam dumping action will be performed to reduce the risk of a faulty operation at the subsequent dump trigger. Calculations of the system’s safety and availability are presented, considering the detailed design of the trigger generation system and the power converters of the beam dumping kickers and septa magnets.
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| TPAP011 | Reliability Assessment of the LHC Machine Protection System | beam-losses, dumping, collider, hadron | 1257 | ||
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A large number of complex systems will be involved in ensuring a safe LHC operation, such as beam dumping and collimation, beam loss and position detection, quench protection, power interlock controller and beam interlock system. The latter will monitor the status of all other systems and trigger the beam abort if necessary. While the overall system is expected to provide an extremely high level of protection, none of the involved components should unduly impede machine operation by creating physically unfounded dump requests or beam inhibit signals. This paper investigates the resulting trade-off between safety and availability and provides quantitative results for the most critical protection elements.
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| TPAT004 | Strongly Asymmetric Beams at the University of Maryland Electron Ring (UMER) | focusing, electron, quadrupole, emittance | 892 | ||
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Funding: This work is funded by U.S. Dept. of Energy under grants DE-FG02-94ER40855 and DE-FG02-92ER54178. |
The standard operation of the University of Maryland electron ring employs symmetric strong focusing with magnetic quadrupoles, i.e., a FODO scheme whereby the zero-current betatron phase advances per period in the two transverse planes are equal or nearly so. Asymmetric focusing, on the other hand, employs quadrupoles with different strengths in a FODO cell. Typically, a small focusing asymmetry is implemented in most accelerators to set the operating point (horizontal and vertical zero-current tunes) in order to avoid resonances and/or compensate for edge focusing of bend magnets. Extreme asymmetry, however, is rarely, if at all, used. We review the motivation and theory of beam transport with general focusing asymmetry. We also present results of preliminary experiments and simulations with highly asymmetric focusing of a space-charge dominated electron beam in UMER. |
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| TPAT005 | Start to End Error Study for the SPIRAL2 Linac | linac, quadrupole, emittance, beam-losses | 934 | ||
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Funding: CEA |
The possibility of a high intensity accelerator at GANIL, producing secondary beams of unprecedented intensity, is considered. The proposed driver for the SPIRAL2 project aims to accelerate a 5 mA deuteron beam up to 20 A.MeV and a 1 mA ion beam for q/A = 1/3 up to 14.5 A.MeV. It is a continuous wave regime linac, designed for a maximum efficiency in the transmission of intense beams and a tunable energy. This paper presents the error sensitivity study which has been performed for this linac in order to define the tolerances for the construction. The correction scheme and the expected losses are described. |
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| TPAT039 | Wavelet-Based Poisson Solver for Use in Particle-in-Cell Simulations | simulation, vacuum, plasma, electron | 2601 | ||
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Funding: Work of B.T., D.M. and C.L.B. is supported by Air Force contract FA9471-040C-0199. Work of I.V.P. is supported by the U.S. Department of Energy contract DE-AC03-76SF00098. |
We report on a successful implementation of a wavelet-based Poisson solver for use in 3D particle-in-cell simulations. One new aspect of our algorithm is its ability to treat the general (inhomogeneous) Dirichlet boundary conditions. The solver harnesses advantages afforded by the wavelet formulation, such as sparsity of operators and data sets, existence of effective preconditioners, and the ability simultaneously to remove numerical noise and further compress relevant data sets. Having tested our method as a stand-alone solver on two model problems, we merged it into IMPACT-T to obtain a fully functional serial PIC code. We present and discuss preliminary results of application of the new code to the modelling of the Fermilab/NICADD and AES/JLab photoinjectors. Corresponding author: B.T. (bterzic@nicadd.niu.edu) |
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| TOPC001 | Visualizing Electron Beam Dynamics and Instabilities with Synchrotron Radiation at the APS | undulator, electron, storage-ring, photon | 74 | ||
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Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. W-31-109-ENG-38. |
The Advanced Photon Source (APS) is a third generation hard x-ray source serving a large user community. In order to characterize the high-brilliance beams, the APS diagnostics beamlines have been developed into a full photon diagnostics suite. We will describe the design and capabilities of the APS visible light imaging line, the bend magnet x-ray pinhole camera, and a unique diagnostics undulator beamline. Their primary functions are to support the APS user operations by providing information on beam sizes (20 - 100 micrometers), divergence (3 – 25 microradians), and bunch length (20 – 50 ps). Through the use of examples, we will show how these complementary imaging tools are used to visualize the electron dynamics and investigate beam instabilities. Special emphasis will be put on the use of undulator radiation, which is uniquely suitable for time-resolved imaging of electron beam with high spatial resolution, and for measurements of longitudinal beam properties such as beam energy spread and momentum compaction. |
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| TOPC003 | Beam Measurements and Upgrade at BL 7.2, the Second Diagnostics Beamline of the Advanced Light Source | radiation, synchrotron, synchrotron-radiation, emittance | 281 | ||
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Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. |
Beamline BL 7.2 of the Advanced Light Source (ALS) at the Lawrence Berkeley National Laboratory is a beam diagnostics system that uses the synchrotron radiation (SR) emitted by a dipole magnet. It consists of two branches, in the first one the x-ray portion of the SR is used in a pinhole camera system for measuring the transverse profile of the beam. The second branch is equipped with a x-ray BPM system and with a multipurpose port where the visible and the infrared part of the SR can be used for various applications such as bunch length measurements and IR coherent synchrotron radiation experiments. The pinhole system has been commissioned at the end of 2003 and since then is in successful operation. The installation of the second branch has been completed recently and the results of its commissioning are presented in this paper together with examples of beam measurements performed at BL 7.2. |
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| TPPT003 | Development of a Normal Conducting CH-DTL | linac, proton, impedance, injection | 883 | ||
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Funding: GSI, EU (CARE, contract number RII3-CT-2003-506395). |
The normal conducting "Crossbar H-Type" (CH) accelerating structure is a good candidate for pulsed, high intensity linac application, covering the energy range from 3 to 100 MeV. H Mode cavities are outstanding in the low-beta range with respect to shunt impedance, high acceleration fields, and compact design, That's why we propose to base the 70 ma, 70 MeV, 352 MHz proton linan for GSI FAIR project on that structure. The actual design consists of 11 CH-DTL's for a total length of around 25 m. Latest results from beam dynamics optimisation will be discussed. Moreover, this paper describes the CH-DTL cavity design with enphasis on the optimisation with MacroWave Studio (single cell cross section, as well as multi cell cavity simulation), and on the achieved progress in the development of mechanical design concepts. A stainless steel multicell model cavity is presently fabricated by our institute in collaboration with GSI, in order to investigate manufacturing and assembly details. Based on this experience, the design of a CH prototipe power cavity will be optimised. |
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| TPPT040 | X-Band Dipole Mode Deflecting Cavity for the UCLA Neptune Beamline | resonance, dipole, vacuum, simulation | 2627 | ||
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Funding: This work was funded by the Department of Energy under Grant No. DE-FG03-92ER40693. |
We report progress on the design and construction of a nine-cell dipole (TM 110 mode) cavity for use as a temporal diagnostic of the 14 MeV 300 pC electron bunches generated at the UCLA Neptune Laboratory linear accelerator, with an anticipated temporal resolution of 150 fs at a peak input power of 50 kW. The cavity is a center-fed standing-wave pi-mode structure, operating at 9.6 GHz, and incorporating a knife-edge and gasket assembly which minimizes the need for brazing or welding. Results of initial RF tests are discussed and compared with simulation results obtained using the commercial code HFSS. |
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| TOPA005 | Left-Handed Metamaterials Studies and their Application to Accelerator Physics | radiation, electron, dipole, plasma | 458 | ||
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Funding: DOE grant NSF grant |
Recently, there has been a growing interest in applying artificial materials, known as Left-Handed Metamaterials (LHM), to accelerator physics. These materials have both negative permittivity and permeability and therefore possess several unusual properties: the index of refraction is negative and the direction of the group velocity is antiparallel to the direction of the phase velocity (along k). These properties lead to a reverse Cherenkov effect, which has potential beam diagnostic applications, in addition to accelerator applications. Several LHM devices with different configurations are being experimentally and theoretically studied at Argonne. In this paper, we describe permittivity and permeability retrieval techniques that we have developed and applied to these devices. We have also investigated the possibility of building a Cherenkov detector based on LHM and propose an experiment to observe the reverse radiation generated by an electron beam passing through a LHM. The potential advantage of a LHM detector is that the radiation in this case is emitted in the direction reversed to the direction of the beam, so it could be easier to get a clean measurement. |
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| WOAA004 | The ILC Beam Delivery System–Conceptual Design and R&D Plans | extraction, optics, instrumentation, photon | 390 | ||
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The Beam Delivery System of the ILC has many stringent and sometimes conflicting requirements. To produce luminosity, the beams must be focused to nanometer size. To provide acceptable detector backgrounds, particles far from the beam core must be collimated. Unique beam diagnostics and instrumentation are required to monitor parameters of the colliding beams such as the energy spectrum and polarization. The detector and beamline components must be protected against errant beams. After collision, the beams must also be transported to the beam dumps safely and with acceptable losses. An international team is actively working on the design of the ILC Beam Delivery System in close collaboration. Details of the design, recent progress and remaining challenges will be summarized in this talk.
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| WPAE041 | Development of a New Beam Diagnostics Platform | laser, vacuum, SNS, ion | 2669 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. |
The Spallation Neutron Source Project (SNS) is an accelerator-based neutron source currently under construction at Oak Ridge National Laboratory (ORNL). The availability of space along completed portions of the accelerator for the addition of beam diagnostic is limited. A new platform for mounting a variety of instruments has been created by replacing part of the Medium Energy Beam Transport (MEBT) section of the accelerator developed by Lawrence Berkeley National Laboratory. The design and current capabilities of this instrument platform will be presented along with plans for future enhancements. |
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| WPAE065 | Jefferson Lab's Trim Card II | power-supply, feedback, controls, impedance | 3670 | ||
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Funding: This work was supported by DOE contract DE-AC05-84ER40150 Modification No. M175, under which the Southeastern Universities Research Association (SURA) operates the Thomas Jefferson National Accelerator Facility. |
Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF) uses Trim Card I power supplies to drive approximately 1900 correction magnets. These trim cards have had a long and illustrious service record. However, some of the employed technology is now obsolete, making it difficult to maintain the system and retain adequate spares. The Trim Card II is being developed to act as a transparent replacement for its aging predecessor. A modular approach has been taken in its development to facilitate the substitution of sections for future improvements and maintenance. The resulting design has been divided into a motherboard and 7 daughter cards which has also allowed for parallel development. The Trim Card II utilizes modern technologies such as a Field Programmable Gate Array (FPGA) and a microprocessor to embed trim card controls and diagnostics. These reprogrammable devices also provide the versatility to incorporate future requirements. |
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| WPAT037 | LANSCE RF System Refurbishment | klystron, linac, proton, SNS | 2476 | ||
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The Los Alamos Neutron Science Center (LANSCE) is in the planning phase of a refurbishment project that will sustain reliable facility operations well into the next decade. The LANSCE accelerator was constructed in the late 1960s and early 1970s and is a national user facility that provides pulsed protons and spallation neutrons for defense and civilian research and applications. We will be replacing all the 201 MHz RF systems and a substantial fraction of the 805 MHz RF systems and high voltage systems. The current 44 LANSCE 805 MHz, 1.25 MW klystrons have an average in-service time in excess of 110,000 hours. All 44 must be in service to operate the accelerator. There are only 9 spares left. The klystrons receive their DC power from the power system originally installed in 1960. Although this power system has been extremely reliable, gas analysis of the insulating oil is indicating age related degradation that will need attention in the next few years. This paper will provide the design details of the new RF and high voltage systems.
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| WPAT063 | Design and Status of the BPM RF Reference Distribution in the SNS | linac, SNS, beam-transport, Spallation-Neutron-Source | 3615 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. |
The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built at Oak Ridge National Laboratory. The BPMs (Beam Position Monitors) requires RF reference signals to measure the phase of the beam with respect to the RF. In the MEBT (Medium Energy Beam Transport) Line and in the DTLs (Drift Tube Linac Cavities) are cavities that accelerate and bunch the beam at 402.5 MHz. In the CCLs (Coupled Cavity Linac) and SCLs (Superconducting Linac) accelerate the beam at 805 MHz. To mitigate effects of RF leakage into the BPM electrodes it is required to measure the phase in the MEBT and DTLs at 805 MHz and in the CCL and SCL at 402.5 MHz. We are directly connected to the RF group MO (master oscillator) and send these signals along the entire linac using fiber optic technology. Schematics, measurements, and installation update are discussed. |
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| WPAT074 | In Depth Diagnostics for RF System Operation in the PEP-II B Factory | klystron, monitoring, feedback, beam-losses | 3931 | ||
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Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515. |
The PEP-II RF systems incorporate numerous feedback loops in the low-level processing for impedance control and operating point regulation. The interaction of the multiple loops with the beam is complicated, and the systems incorporate online diagnostic tools to configure the feedback loops as well as to record fault files in the case of an RF abort. Rapid and consistent analysis of the RF-related beam aborts and other failures is critical to the reliable operation of the B-Factory, especially at the recently achieved high beam currents. Procedures and algorithms used to extract diagnostic information from time domain fault files are presented and illustrated via example interpretations of PEP-II fault file data. Example faults presented will highlight the subtle interpretation required to determine to root cause. Some such examples are: abort kicker firing asynchronously, klystron and cavity arcs, beam loss leading to longitudinal instability, tuner read back jumps and poorly configured low-level RF feedback loop. |
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| RPAE016 | Smith-Purcell Radiation from a Charge Moving Above a Finite-Length Grating | radiation, resonance, electron, coupling | 1496 | ||
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Funding: This work was supported by the Department of Energy, High Energy Physics, under contract DE-FG02-91ER40648. |
Smith-Purcell radiation (SPR), emitted when a bunch is passing above a periodic structure, is characterized by a broadband radiation spectrum in which the wavelength depends on the observation angle. While various theoretical models agree on this dependence, a significant difference is introduced for the calculated radiated energy by the different approaches. We present two theoretical calculations of the SPR from a 2D bunch of relativistic electrons passing above a finite length grating. The first one uses the finite-difference time-domain approach and the second one uses an electric-field integral equation (EFIE) method. Good agreement is obtained between these two calculations. The results of these calculations are then compared with a formalism based on an infinite length grating in which a periodic boundary condition is rigorously applied. For gratings with less than approximately 50 periods, a significant error in the strength of the radiated field is introduced by the infinite grating approximation. This error disappears asymptotically as the number of periods increases. We are currently working on extending the EFIE model to the case of a three dimensional bunch moving above a finite-length grating. |
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| RPAE035 | Orbit Stability at BESSY | feedback, electron, dipole, insertion | 2366 | ||
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Funding: Funded by the Bundesministerium für Bildung und Forschung and by the Land Berlin. |
Traditionally intrinsic component stability as well as perturbation source identification and suppression (like set-up modifications or feed-forward compensations) have been the preferred methods used to guarantee beam orbit stability for user operation at BESSY. Second focus of activity is the reliability of slow drift control and the high degree of beam position reproducibility maintained under frequently changed operation conditions. Along these lines an overview of the measures taken, the available diagnostic means as well as the achievements and shortcomings of the existing slow orbit feedback is given. Diagnostic capabilities of a fast BPM read-out and data distribution system give insight into the demands on a fast orbit feedback that could provide better operation flexibility and improved performance. |
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| RPAE050 | Status of the CAMD Light Source | quadrupole, lattice, wiggler, emittance | 3103 | ||
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With the increasing diversity of its research program, the CAMD Light Source has improved its beam brightness and quality. Using a well calibrated model of the lattice, the ring optic has been refined to generate a lower beam emittance of 150 nm.rad and this has been confirmed by measuring the beta values with the modulated quadrupole shunt system. The beam sizes have also been measured with an X-ray pinhole camera and compared to the calculated emittance. The beam orbit is corrected to a standard position referenced to the quadrupole centers to a precision better than 0.5 mm, using a suite of well localized bumps which can also flexibly steer the user photon beams to their requirements. Beam reliability has been improved by bringing into use a VME control system for the energy ramp.
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| RPAE080 | Diagnostic Systems Plan for the Advanced Light Source Top-Off Upgrade | injection, kicker, betatron, monitoring | 4066 | ||
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Funding: This work was supported by the Director, Office of Energy Research, Office of Basic Energy Sciences, Materials Science Division, of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. |
The Advanced Light Source (ALS) will soon be upgraded to enable top-off operation,* in which electrons are quasi-continuously injected to produce constant stored beam current. We will upgrade our injector from 1.5GeV to full-energy 1.9GeV, and top-off operation will also require more precise injector beam characterization and control than we are capable of using our current diagnostics system. Therefore, a diagnostics upgrade will be crucial for the success of top-off, and our plan for it is described in this paper. Among the improvements will be the integration of all existing beam current monitors along the accelerator chain into an injection efficiency monitoring application. New booster ring diagnostics will include a tune kick and monitoring system, updated beam position monitor electronics, and a new scraper. Two new synchrotron light monitors and a beam stop will be added to the booster-to-storage ring transfer line, and a dedicated bunch purity monitoring system will be installed in the storage ring. Together, these important diagnostic upgrades will enable smooth commissioning of the full energy injector and a quick transition to high quality top-off operation at the ALS. *Please see the ALS Top-off Upgrade presentation at this conference. |
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| RPAP018 | Identification of Nano-Objects in Substances by Using of X-Ray Electron Radiation | electron, radiation, photon, polarization | 1610 | ||
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Funding: Russian Foundation for Basic Researches, grant 03-02-16587. |
Using opportunity of X-ray emission, arising at process of fast charge interaction with media atomic electrons, for nano-object discovery and diagnostics in substances is discussed. This kind of of X-ray emission termed as polarization bremsstrahlung radiation (PB) depends very strongly on media structure. As result spectra of PB in a media containing nano-inhomogeneities (as fullerenes, nanotubes, composite structures as fullerites) reflex structural characteristics of last ones. Fullerenes in carbon soot as example of an amorphous substance with mentioned structure inhomogeneities are considered. It is shown that spectra of PB on fullerenes contain a series of oscillations which give the valuable information about single- ore multilayers fullerene structures. The main peak of emission is placed in energy area of PB photons less than 1-1.5 keV. Here PB obtains a coherent character due to which one PB intensity is very high because it becomes to proportional square of all fullerene electrons number. Due to PB intensity depends weakly enough on observation angle, that permits to pick up PB signal from traditional bremsstrahlung radiation, and to facilitate measurement conditions. |
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| RPAP040 | Design of a Fast Neutral He Beam System for Feasibility Study of Charge-Exchange Alpha-Particle Diagnostics in a Thermonuclear Fusion Reactor | ion, ion-source, extraction, plasma | 2630 | ||
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For alpha-particle diagnostics in a thermonuclear fusion reactor, neutralization using a fast (~2 MeV) neutral He beam produced by the spontaneous electron detachment of a He- is considered most promising. However, the beam transport of produced fast neutral He has not been studied, because of difficulty for producing high-brightness He- beam. Double-charge-exchange He- sources and simple beam transport systems were developed and their results were reported in the PAC99* and other papers.** To accelerate an intense He- beam and verify the production of the fast neutral He beam, a new test stand has been designed. It consists of a multi-cusp He+ source, alkali metal gas cell for double charge exchange, a stigmatic 90 degree bending magnet as an ion separator, an accelerating tube and a free-flight tube to produce fast neutral He beam by autodetachment. The beam parameters of the He- beam are planed to be 150 keV of the beam energy and 10 uA of the beam current. A He+ beam of about 10 mA is extracted from the ion source and accelerated up to 15~25 keV for the effective charge exchange. Details of the design of the test stand and the brief result of the beam optics will be presented.
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*M. Sasao et al., Proc. of PAC99, pp. 1306-1308. **M. Sasao et al., Rev. Sci. Instr. Vol.69, pp.1063-1065 (1998). |
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| RPAP045 | Development of Laser-Induced Fluorescence Diagnostic for the Paul Trap Simulator Experiment | ion, ion-source, laser, background | 2878 | ||
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Funding: Research Supported by the U.S. Department of Energy. |
The Paul Trap Simulator Experiment (PTSX) is a cylindrical Paul trap whose purpose is to simulate the nonlinear dynamics of intense charged particle beam propagation in alternating-gradient magnetic transport systems. For the in-situ measurement of the transverse ion density profile in the PTSX device, which is essential for the study of beam mismatch and halo particle production, a laser-induced fluorescence diagnostic system is being developed. Instead of cesium, which has been used in the initial phase of the PTSX experiment, barium has been selected as the preferred ion for the laser-induced fluorescence diagnostic. The installation of the barium ion source and the characterization of the tunable dye laser system are discussed. The design of the collection optics with an intensified CCD camera system is also discussed. Finally, initial test results using the laser-induced fluorescence diagnostic will be presented. |
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| RPAP048 | SNS Diagnostics Timing Integration | SNS, controls, Spallation-Neutron-Source, target | 3001 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. |
The Spallation Neutron Source (SNS) accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The SNS diagnostics platform is PC-based running Windows XP Embedded for its OS and LabVIEW as its programming language. Coordinating timing among the various diagnostics instruments with the generation of the beam pulse is a challenging task that we have chosen to divide into three phases. First, timing was derived from VME based systems. In the second phase, described in this paper, timing pulses are generated by an in house designed PCI timing card installed in ten diagnostics PCs. Using fan-out modules, enough triggers were generated for all instruments. This paper describes how the Timing NAD (Network Attached Device) was rapidly developed using our NAD template, LabVIEW’s PCI driver wizard, and LabVIEW Channel Access library. The NAD was successfully commissioned and has reliably provided triggers to the instruments. This work supports the coming third phase where every NAD will have its own timing card. |
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| RPAT002 | Production of Inorganic Thin Scintillating Films for Ion Beam Monitoring Devices | proton, monitoring, ion, background | 808 | ||
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In this work we present the development of beam monitoring devices consisting of thin CsI(Tl) films deposited on Aluminium support layers. The light emitted by the scintillating layer during the beam irradiation is measured by a CCD-camera. In a first prototype a thin Aluminium support layer of 6 micron allows the ion beam to easily pass through without significant energy loss and scattering effects. Therefore it turns out to be a non-destructive monitoring device to characterize on-line beam shape and beam position without interfering with the rest of the irradiation process. A second device consists of an Aluminium support layer which is thick enough to completely stop the impinging ions allowing to monitor at the same time the beam profile and the beam current intensity. Some samples have been coated by a 100 Å protective layer to prevent the film damage by atmosphere exposition. In this contribution we present our experimental results obtained by irradiating the samples with proton beams at 8.3 and 62 MeV. We also propose some innovative applications of these beam monitoring devices in different nuclear sectors such as cancer proton therapy and high intensity beam accelerators.
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| RPAT007 | Status of Beam Diagnostic Systems for the PEFP | proton, instrumentation, pick-up, linac | 1090 | ||
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Funding: Supported by the PEFP (Proton Engineering Frontier Project). |
A proton linear accelerator is currently the construction at the KAERI (Korea Atomic Research Institute) to the PEFP (Proton Engineering Frontier Project) in Korea. We are accomplished the technique development of beam diagnostic system to be currently the construction. We treat beam diagnostics for the high power proton linear accelerator. Prototype beam position & phase monitor (BPPM) electronics was made and tested successfully in one of the beam diagnostic systems. The beam position monitor pickup electrode is a capacitive type (electrostatic type) which has a button form. Button form electrode, in common use around electron synchrotrons and storage rings, are a variant of the electrode with small button form (e.g., sub mm diameter). However, we are designed button form electrode to measure beam position of proton beam. The BCM (Beam Current Monitor) is developed Tuned CT (Current Transformer) for collaborate with Bergoz Instruments. This paper describes the status of beam diagnostic systems for the PEFP. |
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| RPAT009 | FPGA-Based Instrumentation for the Fermilab Antiproton Source | antiproton, instrumentation, proton, controls | 1159 | ||
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We have designed and built low-cost, low-power, ethernet-based circuit boards to apply DSP techniques to several instrumentation upgrades in the Fermilab Antiproton Source. Commodity integrated circuits such as direct digital synthesizers, D/A and A/D converters, and quadrature demodulators enable digital manipulation of RF waveforms. A low cost FPGA implements a variety of signal processing algorithms in a manner that is easily adapted to new applications. An embedded microcontroller provides FPGA configuration, control of data acquisition, and command-line interface. A small commercial daughter board provides an ethernet-based TCP/IP interface between the microcontroller and the Fermilab accelerator control network. The board is packaged as a standard NIM module. Applications include Low Level RF control for the Debuncher, readout of transfer-line Beam Position Monitors, and narrow-band spectral analysis of diagnostic signals from Schottky pickups.
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| RPAT022 | Optical Faraday Cup for Heavy Ion Beams | ion, heavy-ion, target, radiation | 1805 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy by the university of California, Lawrence Berkeley National Laboratory under Contract No. DE-AC03-76F00098. |
We have been using alumina scintillators for imaging beams in heavy-ion beam fusion experiments in 2 to 4 transverse dimensions.* The scintillator has limitations on lifetime, linearity, and time response. As a possible replacement for the scintillator, we are studying the technique of imaging the beam on a gas cloud. A gas cloud for imaging the beam may be created on a solid hole plate placed in the path of the beam, or by a localized gas puff. It is possible to image the beam using certain fast-quenching optical spectral lines that closely follow beam current density and are independent of gas density. We describe this technique and show experimental data using a nitrogen line at 394.1 nm. This approach has promise to be a new fast beam current diagnostic on a nanosecond time scale. *FM Bieniosek, L Prost, W Ghiorso, Beam imaging diagnostics for heavy ion beam fusion experiments, Paper WPPB050, PAC 2003. |
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| RPAT038 | Diagnostic for Electron Clouds Trapped in Quadrupoles | electron, quadrupole, simulation, proton | 2547 | ||
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Funding: Work supported by a DOE SBIR Phase I grant DE-FG02-04ER84105. |
Simulations have indicated that electron clouds generated by beam-induced multipactor can be trapped in the mirror-like fields of magnetic quadrupoles and thereby contribute significantly to the electron cloud buildup in high intensity accelerators and storage rings. This could be the most important source of electrons driving the two-stream (e-p) instability at the Los Alamos PSR and may also play a significant role in electron cloud effects at some of the new high intensity accelerator projects. We will describe the physics design and optimization of an electron-sweeping detector designed to measure the trapped electrons at various times after the beam pulse has passed. The instrument can also serve as an electro-magnetically shielded detector providing a signal obtained from electrons striking the wall during the passage of beam bunches. |
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| RPAT048 | An X-Ray BPM and Accompanying Electronics | photon, synchrotron, feedback, synchrotron-radiation | 3019 | ||
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Recent experiments at the LNLS Ultra Violet and X-Ray beam lines are pushing on the Synchrotron Radiation beam position stability requirements. In the direction of having photon Beam Position Monitor integrated to the orbit closed loop control system, we developed a staggered blades XR BPM and a four channel current measurement electronics. The BPM mechanical design was based on the SR masks previously developed and currently in use at the beam lines front end. By this design reuse, in addition to using an already available and well-tested, low cost construction technique, we expect to have a simple replacement of the SR masks by the XR BPMs in most of the beam lines, shortening the downtimes and the number of line parts to be replaced. We describe the design and the resulting performance of the XR BPM and the accompanying electronics.
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| RPAT059 | The SRI Beam Size Monitor Developed at NSRRC | photon, synchrotron, radiation, synchrotron-radiation | 3465 | ||
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A beam size monitor based on the synchrotron radiation interferometer (SRI) was installed in the NSRRC TLS. This monitor consists of a simple diagnostic beamline with a water-cooled beryllium mirror inside and a detecting optical system for both vertical and horizontal beam size measurement. The beam sizes measured are 48 micron and 160 micron respectively and are more close to the theoretical values than the synchrotron image monitor. Comparing with other monitors, at least 1 micron beam size variation is detectable. To minimize the thermal effect, the mirror is located far away from the source point and closed to the detecting optical system. The thermal distortion of the mirror is quite small measured by a portable long trace profiler (LTP) and agrees with the simulating analysis. The detailed monitor system design and testing results are presented in this paper.
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| RPAT068 | Proposed Diagnostics for the NSLS-II | electron, injection, radiation, synchrotron | 3760 | ||
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Funding: The U.S. Department of Energy under contract No. DE-AC02-98CH10886. |
The National Synchrotron Light Source is performing R&D of a new 3 GeV electron storage ring to be used for the facility upgrade. To satisfy the demands for the brightness and stability of the future light source a state-of-the-art diagnostics system is a necessity. We present our preliminary design with focus on the requirements for instrumentation and technical solutions to achieve them. |
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| RPAT074 | PEP-II Transverse Feedback Electronics Upgrade | feedback, pick-up, coupling, kicker | 3928 | ||
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Funding: Supported by the U.S. Department of Energy under contract No. DE-AC03-76SF00098 (LBNL) and DE-AC03-76SF00515 (SLAC). |
The PEP-II B Factory at the Stanford Linear Accelerator Center (SLAC) requires an upgrade of the transverse feedback system electronics. The new electronics require 12-bit resolution and a minimum sampling rate of 238 Msps. A Field Programmable Gate Array (FPGA) is used to implement the feedback algorithm. The FPGA also contains an embedded PowerPC 405 (PPC-405) processor to run control system interface software for data retrieval, diagnostics, and system monitoring. The design of this system is based on the Xilinx® ML300 Development Platform, a circuit board set containing an FPGA with an embedded processor, a large memory bank, and other peripherals. This paper discusses the design of a digital feedback system based on an FPGA with an embedded processor. Discussion will include specifications, component selection, and integration with the ML300 design. |
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| RPAT086 | Dual-Sweep Streak Camera Measurements of the APS User Beams | storage-ring, electron, emittance, single-bunch | 4185 | ||
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Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences under Contract Number W-31-109-ENG-38. |
The Advanced Photon Source (APS) is a hard x-ray user facility based on a 7-GeV storage ring (SR). To accommodate the requests of the diverse user community, the APS normally runs with a 24-singlets fill pattern, a hybrid fill with a singlet and eight septuplets, or a 324-singlet fill pattern. In all cases the total stored beam current is 100 mA, with the lattice providing a natural emittance of about 2.5 nm rad. The first two patterns are used with a top-up mode that involves injection of one pulse of ~2.5 nC every two minutes into the designated SR bucket. Since the partition of bunch current varies for the different fills as well as the loading of the rf cavities, dual-sweep streak camera measurements (Hamamatsu model C5680) have been performed to characterize the average and individual bunch lengths in the fill patterns and the phase slew that occurs within the patterns. The bunch lengths vary from 32 ps (σ) within the septuplet to 50 ps (σ) for the singlet in the hybrid fill. The phase slew is significant in the hybrid fill across the eight septuplets. Example streak images of each pattern will be presented and discussed. |
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| RPAT089 | Advances in Optical Transition and Diffraction Radiation Emittance Diagnostics | emittance, electron, simulation, optics | 4224 | ||
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Funding: Office of Naval Research and the DOD Joint Technology Office. |
We have performed a series of experiments using Optical Transition Radiation and Optical Diffraction Radiation Interferometry to measure the two orthogonal (x,y) rms divergences of the Brookhaven National Laboratory’s Advanced Test Facility electron beam operating at an energy of 50 MeV. Measurement of the rms divergences at the (x,y) beam waist conditions, together with corresponding measurements of the rms beam sizes allows a determination of the rms x and y emittances. A comparison of the results using OTRI and ODTRI are presented. |
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| RPAT092 | Conceptual Design of an Insertion Device for Non-Destructive Beam Diagnostics of a Low-Emittance Synchrotron Light Source | electron, undulator, photon, radiation | 4275 | ||
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An insertion device is proposed to measure small vertical angular divergence and energy spread (dE/E) of electron beam in a low-emittance synchrotron light source. In accelerators such as the SPring-8 storage ring operated on the small emittance-coupling ratio, vertical divergence of spectral photon flux produced by electron beam in a conventional undulator of several meters long will be dominated by natural divergence of the undulator radiation. Therefore, the divergence of spectral flux is not useful for vertical emittance diagnostics. The proposed insertion device consists of N short undulator sections as x-ray radiators cascaded through vertical deflective sections to make a half-period cosine-like electron trajectory. Two radiation parts of the upper and lower sides are formed due to up-and-down electron orbit by the deflective sections. X-rays emitted from the two radiation parts interfere at observation point far from the insertion device. It was numerically studied that the vertical angular divergence in the sub-micro radian range and the energy spread of the 1·10-3 order could be measured by visibility and envelope width of an observed interference pattern, respectively.
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| RPAT095 | Time Resolved X-Ray Spot Size Diagnostic | target, alignment, electron, shielding | 4302 | ||
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Funding: This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48. |
A diagnostic was developed for the determination of temporal history of an X-ray spot. A pair of thin (0.5 mm) slits image the x-ray spot to a fast scintillator which is coupled to a fast detector, thus sampling a slice of the X-Ray spot. Two other scintillator/detectors are used to determine the position of the spot and total forward dose. The slit signal is normalized to the dose and the resulting signal is analyzed to get the spot size. The position information is used to compensate for small changes due to spot motion and misalignment. The time resolution of the diagnostic is about 1 ns and measures spots from 0.5 mm to over 3 mm. The theory and equations used to calculate spot size and position are presented, as well as data. The calculations assume a symmetric, Gaussian spot. The spot data is generated by the ETA II accelerator, a 2kA, 5.5 MeV, 60ns electron beam focused on a Tantalum target. The spot generated is typically about 1 mm FWHM. Comparisons are made to an X-ray pinhole camera which images the XRay spot (in 2D) at four time slices. |
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| ROPB002 | Experiments Studying Desorbed Gas and Electron Clouds in Ion Accelerators | electron, ion, quadrupole, simulation | 194 | ||
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Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California, LLNL under contract No. W-7405-Eng-48, and by LBNL under Contract DE-AC03-76F00098. |
Electron clouds and gas pressure rise limit the performance of many major accelerator rings. We are studying these issues experimentally with ~1 MeV heavy-ion beams, coordinated with significant efforts in self-consistent simulation and theory.* The experiments use multiple diagnostics, within and between quadrupole magnets, to measure the sources and accumulation of electrons and gas. In support of these studies, we have measured gas desorption and electron emission coefficients for potassium ions impinging on stainless steel targets at angles near grazing incidence.** Our goal is to measure the electron particle balance for each source – ionization of gas, emission from beam tubes, and emission from an end wall – determine the electron effects on the ion beam and apply the increased understanding to mitigation. *J-L. Vay, Invited paper, session TICP; R. H. Cohen et al., PRST-AB 7, 124201 (2004). **M. Kireeff Covo, this conference; A. W. Molvik et al., PRST-AB 7, 093202 (2004). |
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| RPPE015 | Diagnostics and Protection Control for IREN Linac Test Facility | linac, electron, monitoring, instrumentation | |||
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The diagnostic and protection control systems for the full-scale test facility of the linear electron accelerator are constructed according to the project on pulsed neutron source IREN. Combined control schemes of timed diagnostics of a duty cycle and real-time protection control are created for the linac test facility. Applicability of the diagnostics systems of cycle parameters and deviations of a status for control of the mode of protection is shown. Multichannel control modules of the protection system have been developed for logging and diagnostics of a status change, the alarms and control of a mode of operation. The applied multiway controllers for duty protection with fast locking of cycles of the IREN linac are presented.
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| RPPE021 | The SNS Machine Protection System: Early Commissioning Results and Future Plans | SNS, injection, beam-losses, power-supply | 1727 | ||
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The Spallation Neutron Source under construction in Oak Ridge TN has commissioned low power beam up to 187 Mev. The number of MPS inputs is about 20% of the final number envisioned. Start-up problems, including noise and false trips, have largely been overcome by replacing copper with fiber and adding filters as required. Initial recovery time from Machine Protection System (MPS) trips was slow due to a hierarchy of latched inputs in the system: at the device level, at the MPS input layer, and at the operator interface level. By reprogramming the MPS FPGA such that all resets were at the input devices, MPS availability improved to acceptable levels. For early commissioning MPS inputs will be limited to beam line devices that will prohibit beam operation. For later operation, the number of MPS inputs will increase both software alarms and less intrusive MPS inputs such as steering magnets are implemented. Two upgrades to SNS are on the horizon: a 3 MW upgrade and a second target station. Although these are years away the MPS system as designed should easily accommodate the increase in power and pulse-to-pulse target switching at 120 Hz.
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Work supported by the U.S. Department of Energy under contract DE-AC05-00OR22725. |
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| RPPE064 | Development of a Cryogenic Radiation Detector for Mapping Radio Frequency Superconducting Cavity Field Emissions | radiation, shielding, radio-frequency | 3627 | ||
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Funding: Work supported by: U.S. DOE Contract No. DE-AC05-84er4015. |
There is a relationship between field emissions in a Super Conducting RF cavity and the production of radiation (mostly X-rays). External (room temperature) detectors are shielded from the onset of low energy X-rays by the vacuum and cryogenic stainless steel module walls. An internal measuring system for mapping field emissions would assist scientists and engineers in perfecting surface deposition and acid washing module surfaces. Two measurement systems are undergoing cryogenic testing at JLab. One is an active CsI photodiode array and the second is an X-ray film camera. The CsI array has operated sucessfully in a cavity in liquid Helium but saturated at higher power due to scattering in the cavity. A shield with an aperature similar to the X-ray film detector is being designed for the next series of tests which will be completed before PAC-05. |
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| RPPP030 | Design of ILC Extraction Line for 20 mrad Crossing Angle | extraction, luminosity, optics, beam-losses | 2134 | ||
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Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515. |
One of the two ILC Interaction Regions will have a large horizontal crossing angle which would allow to extract the spent beams in a separate beam line. In this paper, the extraction line design for 20 mrad crossing angle is presented. This beam line transports the primary e+/e- and beamstrahlung photon beams from the IP to a common dump, and includes diagnostic section for energy and polarization measurements. The optics is designed for a large energy acceptance to minimize losses in the low energy tail of the disrupted beam. The extraction optics, diagnostic instrumentation and particle tracking simulations are described. |
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| RPPT012 | Layout of the Diagnostic Section for the European XFEL | emittance, lattice, electron, radiation | 1285 | ||
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Fourth generation synchrotron light sources, such as the European Free Electron Laser (XFEL) project, are based on an exponential gain of the radiation amplification in a single pass through a long undulator magnet. To initiate the FEL process and to reach staturation, precise monitoring and control of the electron beam parameters is mandatory. Most challenging are the longitudinal compression processes in magnetic chicanes of the high brightness electron bunch emitted from an RF photo-injector. To measure and control the beam properties after compression, careful consideration must be given to the design of a diagnostic section and the choice of beam monitors. In this paper, the proposed layout of the XFEL diagnostics beamline is discussed and emphasis is put on the possibility of monitoring on-line the slice energy spread, slice emittance and longitudinal bunch profile with high accuracy.
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| RPPT029 | Diagnostics for the LCLS Photoinjector Beamline | emittance, gun, cathode, injection | 2089 | ||
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Funding: This work was supported by U.S. Department of Energy, contract No. DE-AC03-76SF00515A06. |
Two spectrometers have been added to the LCLS photoinjector beamline. The first one will be located close to the exit of the Photoinjector RF gun. With this diagnostic, we will measure beam energy, energy spread (correlated and uncorrelated), possibly deleterious structure in the longitudinal phase space induced by longitudinal space charge force, and slice thermal emittance … This extensive characterization of the 5MeV electron bunch will be made possible by combining this spectrometer with other diagnostics (YAG screens and Cerenkov Radiator). A second spectrometer located at the end of the beamline has been designed to characterize the 6 dimensional phase space of the 135MeV beam to be injected in the main accelerator. At that second spectrometer station, we will measure energy, energy spread (correlated and uncorrelated), longitudinal phase space, slice emittances … Those last two measurements require using this spectrometer in combination with the transverse RF deflecting cavity and with the quadrupole scan emittance station. The designs of these two spectrometers have been supported by simulations from MAD and PARMELA. |
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| RPPT031 | Recent Results from and Future Plans for the VISA II SASE FEL | radiation, electron, simulation, undulator | 2167 | ||
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As the promise of X-ray Free Electron Lasers (FEL) comes close to realization, the creation and diagnosis of ultra-short pulses is of great relevance in the SASE FEL (Self-Amplified Spontaneous Emission) community. The VISA II (Visible to Infrared SASE Amplifier) experiment entails the use of a chirped electron beam to drive a high gain SASE FEL at the Accelerator Test Facility (ATF) in Brookhaven National Labs (BNL). The resulting ultra-short pulses will be diagnosed using an advanced FROG (Frequency Resolved Optical Gating) technique, as well as a double differential spectrum (angle/wavelength) diagnostic. Implementation of sextupole corrections to the longitudinal aberrations affecting the high energy-spread chirped beam during transport to the VISA undulator is studied. Start-to-end simulations, including radiation diagnostics, are discussed. Initial experimental results involving a highly chirped beam transported without sextupole correction, the resulting high gain lasing, and computational analysis are briefly reported.
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| ROPA001 | XAL Application Programming Structure | SNS, linac, injection, lattice | 79 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. |
XAL is an application programming framework used at the Spallation Neutron Source (SNS) project in Oak Ridge. It is written in Java, and provides users with a hierarchal view of the accelerator. Features include database configuration of the accelerator structure, an online envelope model that is configurable from design or live machine values, an application framework for quick-start GUI development, a scripting interface for algorithm development, and a common toolkit for shared resources. To date, about 25 applications have been written, many of which are used extensively in the SNS beam commissioning activities. The XAL framework and example applications will be discussed. |
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| ROPC009 | First Acceleration with Superconducting RF Cavities at ISAC-II | simulation, acceleration, ion, vacuum | 662 | ||
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We have demonstrated the first acceleration of ions with superconducting rf at TRIUMF/ISAC. Alpha particles from a radioactive source were accelerated from 2.8MeV through the ISAC-II medium beta cryomodule to a maximum energy of 9.4 MeV. The four 106 MHz quarter wave cavities (beta_o=7%) were set to the ISAC-II specified gradient of 6 MV/m (Leff=18cm, Ep=30MV/m and Veff=1.08MV) with a cavity power of about 6W per cavity. The final particle energy spectra was measured with a silicon detector. The initial alpha energy corresponds to a velocity of beta=3.9% giving an expected T/To efficiency of 0.48, 0.76, 0.92 and 0.99 for the four cavities respectively and an expected final energy of 9.6MeV. The experimental set-up including details of the source and diagnostic boxes and the detector electronics are described. Beam simulations of the unbunched, uncollimated beam indicate a unique spectral fingerprint that can be used to unambiguously determine each cavity voltage.
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| FPAE033 | Operational Availability of the SNS During Commissioning | linac, SNS, ion-source, ion | 2289 | ||
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Funding: This work was supported by SNS through UT-Batelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. The SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. |
The SNS Front End, Drift Tube Linac and most of the Coupled Cavity Linac have been operated during commissioning. Operating statistics were taken and used by system owners to target developments to improve accelerator availability. This progression will be shown along with the overall availability goals of the SNS and a RAM calculation showing the system and subsystem availability required to meet these goals. |
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| FPAE071 | Initial Results on Neutralized Drift Compression Experiments (NDCX-IA) for High Intensity Ion Beam | plasma, ion, simulation, induction | 3856 | ||
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Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. |
Ion beam neutralization and compression experiments are designed to determine the feasibility of using compressed high intensity ion beams for high energy density physics (HEDP) experiments and for inertial fusion power. To quantitatively ascertain the various mechanisms and methods for beam compression, the Neutralized Drift Compression Experiment (NDCX) facility is being constructed at Lawrence Berkeley National Laboratory (LBNL). In the first compression experiment, a 260 KeV, 25 mA, K+ ion beam of centimeters size is radially compressed to a mm size spot by neutralization in a meter-long plasma column and beam peak current is longitudinally compressed by an induction velocity tilt core. Instrumentation, preliminary results of the experiments, and practical limits of compression are presented. These include parameters such as emittance, degree of neutralization, velocity tilt time profile, and accuracy of measurements (fast and spatially high resolution diagnostic) are discussed. |
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| FPAE073 | A Free Hg Jet System for Use in a High-Power Target Experiment | target, proton, laser, collider | 3895 | ||
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Funding: Work funded by the U.S. Department Of Energy. |
We describe a mercury jet system that is suitable for insertion into the 15cm diameter bore of a high-field solenoid magnet. The device features a hermetically sealed primary containment volume which is enclosed in a secondary containment system to insure isolation of mercury vapors from the remaining experimental environment. The jet diameter is 1-cm while the jet velocity will be up to 20 m/s. Optical diagnostics is incorporated into the target design to allow observation of the dispersal of the mercury as a result of interaction with a 24 GeV proton beam with up to 20 x 1012 ppp. |
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| FPAE074 | Beam Parameter Measurement and Control at the SNS Target | target, quadrupole, emittance, SNS | 3913 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. |
The spallation neutron production target at the SNS facility is designed for 1.4 MW beam power. Both beam position and profile must be carefully controlled within narrow margins to avoid damage to the target. The position must be within 2 mm of the target center, and 90% of the beam must be within the nominal 70 mm x 200 mm spot size, without exceeding 0.18 A/m2 peak beam current density. This is a challenging problem, since most of the diagnostics are 9 m upstream of the target, and because the high beam power limits the lifetime of intercepting diagnostics. Our design includes a thermocouple halo monitor approximately 2 m upstream of the target face, and a beam position monitor, an insertable harp profile monitor, and a beam shape monitor approximately 9 m upstream. In this paper we will discuss our strategy to commission the beam delivery system and to meet target requirements during nominal operation. |
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| FPAP033 | Beam Energy Scaling of Ion-Induced Electron Yield from K+ Ions Impact on Stainless Steel Surfaces | electron, ion, target, heavy-ion | 2287 | ||
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Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California, LLNL under contract No. W-7405-Eng-48, and by LBNL under Contract DE-AC03-76F00098. |
The cost of accelerators for heavy-ion inertial fusion energy (HIF) can be reduced by using the smallest possible clearance between the beam and the wall from the beamline. This increases beam loss to the walls, generating ion-induced electrons that could be trapped by beam space charge potential into an "electron cloud," which can cause degradation or loss of the ion beam. In order to understand the physical mechanism of production of ion-induced electrons we have measured impact of K+ ions with energies up to 400 KeV on stainless steel surfaces near grazing incidence, using the ion source test stand (STS-500) at LLNL. The electron yield will be discussed and compared with experimental measurements from 1 MeV K+ ions in the High-Current Experiment at LBNL.* *A.W. Molvik et al., PRST-AB 7, 093202 (2004). |
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| FPAT008 | SDA-Based Diagnostic and Analysis Tools for Collider Run II | proton, collider, acceleration, controls | 1099 | ||
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Funding: Fermilab (Department of Energy). |
Operating and improving the understanding of the Fermilab Accelerator Complex for the colliding beam experiments requires advanced software methods and tools. The Shot Data Acquisition and Analysis (SDA) has been developed to fulfill this need. Data is stored in a relational database, and is served to programs and users via Web-based tools. Summary tables are systematically generated during and after a store. These tables, the Supertable, and the Recomputed Emittances and Recomputed Intensity tables are discussed here. This information is also accesible in JAS3 (Java Analysis Studio version 3). |
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| FPAT014 | Dynamic Visualization of SNS Diagnostics Summary Report and System Status | SNS, beam-losses, emittance, target | 1395 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. |
The Spallation Neutron Source (SNS) accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The SNS diagnostics platform is PC-based running Embedded Windows XP and LabVIEW. The diagnostics instruments communicate with the control system using the Channel Access (CA) protocol of the Experimental Physics and Industrial Control System (EPICS). This paper describes the Diagnostics Group’s approach to collecting data from the instruments, processing it, and presenting live in a summarized way over the web. Effectively, adding a supervisory level to the diagnostics instruments. One application of this data mining is the "Diagnostics Status Page" that summarizes the insert-able devices, transport efficiencies, and the mode of the accelerator in a compact webpage. The displays on the webpage change automatically to show the latest and/or most interesting instruments in use. |
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| FPAT017 | SNS Diagnostics Tools for Data Acquisition and Display | SNS, target, beam-losses, scattering | 1544 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S Department of Energy. |
The Spallation Neutron Source (SNS) accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of a 1.0 GeV linear accelerator, an accumulator ring and associated transport lines. The SNS diagnostics platform is PC-based and will run Windows for its OS and LabVIEW as its programming language. The diagnostics platform as well as other control systems and operator consoles use the Channel Access (CA) protocol of the Experimental Physics and Industrial Control System (EPICS) to communicate. This paper describes the tools created to evaluate the diagnostic instrument using our standard programming environment, LabVIEW. The tools are based on the LabVIEW Channel Access library and can run on Windows, Linux, and Mac OS X. The data-acquisition tool uses drop and drag to select process variables organized by instrument, accelerator component, or beam parameters. The data can be viewed on-line and logged to disk for later use. A drag and drop display creation tool supports the quick creation of graphical displays to visualize the data produced by the instruments without the need for programming. |
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| FPAT036 | An Induction Linac Test Stand | induction, pulsed-power, linac, electron | 2455 | ||
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Funding: This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. 7405-Eng-48. |
A single-cell test stand has been constructed to facilitate study and guide improvements of the induction electron linac at the FXR radiographic facility at LLNL.* This paper will discuss how modifications in pulse compression and shaping, pulse power transmission, initial ferrite state, and accelerator cell loading have been performed on the test stand and can be applied to the entire accelerator. Some of the specialized diagnostics being used will be described. Finally, the paper will discuss how computer modeling and judicious timing control can be used to optimize accelerator performance by making only selective changes that can be accomplished at minimal cost. *"Test Stand for Linear Induction Accelerator Optimization," Ong et al., Pulsed Power Conference, June 16, 2003, Dallas TX. |
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| FPAT045 | Upgrade of the ESRF Vacuum Control System | vacuum, monitoring, storage-ring, radiation | 2857 | ||
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The temperature acquisition as well as the whole vacuum control system of the electron storage ring of the ESRF is in operation since more than ten years now. Apart from difficulties to have appropriate support for the old systems we start facing problems of aging and obsolescence. We have been reviewing our philosophy of data acquisition and remote control in order to update our systems with state of the art technology, taking into account our operational experience. We have started installing shielded “intelligent” devices inside the storage ring tunnel taking benefit from the availability of ethernet connections. Like this we can take advantage of the latest developments linked to these technologies, such as OPC Server, Webpage instrument control, and more.
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| FPAT046 | RF Control System for the DESY VUV-FEL Linac | feedback, electron, linac, klystron | 2899 | ||
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In the RF system for the Vacuum Ultraviolet Free Electron Laser (VUV-FEL) Linac each klystron supplies RF power to up to 32 cavities. The superconducting cavities are operated in pulsed mode and high accelerating gradients close to the performance limit. The RF control of the cavity fields to the level of 1·10-4 for amplitude and 0.1 degree for phase however presents a significant technical challenge due to the narrow bandwidth of the cavities which results in high sensitivity to perturbations of the resonance frequency by mechanical vibrations (microphonics) and Lorentz force detuning. A digital RF control system has been developed for the VUV-FEL which will demonstrate the required control performance. Presently the Linac is being commissioned, and this effort provides the first full integrated test in the accelerator, including cryogenics, RF, beam transport, and beam diagnostics. The RF control system design and objectives are discussed and compared to the measured performance during the first stage of the VUV-FEL Linac - TESLA Test Facility. Hardware/software design and operational challenges experienced for RF control are presented.
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| FPAT053 | LabVIEW Library to EPICS Channel Access | SNS, Spallation-Neutron-Source, target, scattering | 3233 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. |
The Spallation Neutron Source (SNS) accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The SNS diagnostics platform is PC-based and will run Windows for its OS and LabVIEW as its programming language. Data acquisition hardware will be based on PCI cards. There will be about 300 rack-mounted computers. The Channel Access (CA) protocol of the Experimental Physics and Industrial Control System (EPICS) is the SNS control system communication standard. This paper describes the approaches, implementation, and features of LabVIEW library to CA for Windows, Linux, and Mac OS X. We also discuss how the library implements the asynchronous CA monitor routine using LabVIEW’s occurrence mechanism instead of a callback function (which is not available in LabVIEW). The library is used to acquire accelerator data and applications have been built on this library for console display and data-logging. |
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| FPAT056 | RF Control System Upgrade at CAMD | impedance, klystron, resonance, monitoring | 3339 | ||
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A description is given of the new control system for the RF system of the CAMD light source. The new design being implemented brings all RF signals into the data acquisition system via a modular, custom made, RF detector and renders the amplitude and tune control loops in the VME computer. On line calculations ensure monitoring of proper operation and display the information to the user in an efficient way. In addition, an advanced load impedance monitoring diagnostic has been implemented, being displayed as a Smith Chart, which is based on the system used at the SRS in Daresbury, England.
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| FPAT075 | Using a Control System Ethernet Network as a Field Bus | SNS, vacuum, target, cryogenics | 3961 | ||
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A major component of a typical accelerator distributed control system (DCS) is a dedicated, large-scale local area communications network (LAN). The SNS EPICS-based control system uses a LAN based on the popular IEEE-802.3 set of standards (Ethernet). Since the control system network infrastructure is available throughout the facility, and since Ethernet-based controllers are readily available, it is tempting to use the control system LAN for "fieldbus" communications to low-level control devices (e.g. vacuum controllers; remote I/O). These devices may or may not be compatible with the high-level DCS protocols. This paper presents some of the benefits and risks of combining high-level DCS communications with low-level "field bus" communications on the same network, and describes measures taken at SNS to promote compatibility between devices connected to the control system network.
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Work supported by the U.S. Department of Energy under Contract DE-AC05-00OR22725. |
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