| Paper | Title | Page |
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| TUPAN004 | Slow Kicker Magnet System with Energy Recover Pulse Power Supply with Extended Flat Top | 1395 |
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| Danfysik has developed a novel Slow Kicker Magnet Power Supply ERMPPS with associated magnet achieving high stability, long flatness top and low energy consumption. Two Slow Kicker Magnet Systems has been built to RAL, one low and one high energy supply. The magnets are laminated window frame type. The RAL synchrotron produces high energy protons at 50 Hz rate. The Slow Kickers operate at 10 Hz, directing a portion of the extracted protons to a second beam line. The flat top width is 600 μs with a flat top and peak-peak stability better than 100 ppm. The rise and fall time is 12 msec. The power supply has been developed with following highlights: High accuracy with adjustable output current, wide range micro-step set able flattop and rise time width, energy recovery, digital flattop and rise time regulation loop in FPGA and variable repetition frequency down to one shoot operation. The flat top- and rise time width settings are bounded by the actual load and internal component values. The paper describes power supply topology, the digital regulation principia and the magnet construction. Performance measurements electrical as well as magnetic measurements are presented. | ||
| TUPAN052 | New Beam Optics Design of Injection/Fast Extraction/Abort Lines of J-PARC Main Ring | 1508 |
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| J-PARC Main Ring has three straight sections for injection, slow extraction and fast extraction. Injection line has been redesigned so as to give a higher reliability for the thin septa. The magnetic field can be reduced by adding an extra kicker. New optics for the fast extraction with a larger acceptance has been proposed. In this design, the thin septa are replaced by kickers with a large aperture. Beam with an arbitrary energy can be aborted from opposite side from the fast extraction. An external abort line has been designed to deliver the beam aborted with an arbitrary energy to a dump just by using a static quadrupole doublet for the focus. | ||
| TUPAN066 | Half-mini Beta Optics with a Bunch Rotation for Warm Dense Matter Science Facility in KEK | 1541 |
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An all-ion accelerator (AIA) is a quite interesting device as a driver to explore a Warm Dense Matter (WDM) state*. The irradiation onto a target at a small focal spot (< a few mm) with a short pulse duration (< 100 nsec) is required to create an interesting WDM state. The final focus is carried out through a half-mini beta beam line placed after the kickout from the AIA. The half-mini beta beam line should be designed with the space-charge effect due to the high current beam. The design includes effects of a large momentum spread caused by a fast bunch rotation. The beam optics concerned with the effects of space-charge and the large momentum spread during the half-mini beta system is designed for the WDM science in KEK AIA Facility.
* E. Nakamura, et al., "A Modification Plan of the KEK 500MeV Booster to an All-ion Accelerators (An Injector-free Synchrotron)", PAC07. |
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| TUPAN076 | Conceptual Design of the Beam Line for the PEFP User Facility | 1547 |
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Funding: The work was supported by the 21C Frontier R&D program in Ministry of Science and Technology of the Korean Government The Proton Engineering Frontier Project (PEFP) will supply 20-MeV and 100-MeV proton beams from a 100 MeV proton linear accelerator for beam applications. The extracted 20 MeV or 100 MeV proton beams will be simultaneously distributed into the five targets through a dipole magnet equipped with a controllable AC power supply. The most important design criterion is the flexibility of the irradiation conditions in order to meet various user requirements in many application fields. For this purpose, we have designed the beamlines to the targets for wide or focused beams, external or in-vacuum beams, and horizontal or vertical beams. This work includes details of the conceptual design of the beamlines. |
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| TUPAN086 | An Improved Beam Screen for the LHC Injection Kickers | 1574 |
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| The two LHC injection kicker magnet systems must produce a kick of 1.3 T.m with a flattop duration variable up to 7860 ns, and rise and fall times of less than 900 ns and 3000 ns, respectively. Each system is composed of two resonant charging power supplies and four 5 Ω transmission line kicker magnets with matched terminating resistors and pulse forming networks. A beam screen is placed in the aperture of the magnets: the screen consists of a ceramic tube with conductors on the inner wall. The conductors provide a path for the image current of the, high intensity, LHC beam and screen the ferrite against Wake fields. The conductors initially used gave adequately low beam impedance however inter-conductor discharges occurred during pulsing of the magnet: an alternative design was discharge free at the nominal operating voltage but the beam impedance was too high for the ultimate LHC beam. This paper presents the results of a new development undertaken to meet the often conflicting requirements for low beam impedance, shielding of the ferrite, fast field rise time and good electrical behaviour. High voltage test results and thermal measurements are also presented. | ||
| TUPAN094 | PS2 Injection, Extraction and Beam Transfer Concepts | 1598 |
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| The replacement of CERN's existing 26 GeV Proton Synchrotron (PS) machine with a separated-function synchrotron PS2 has been identified as an important part of the possible future upgrade programme of the CERN accelerator complex. The PS2 will require a number of new beam transfer systems associated with injection, extraction, beam dumping and transfer. The different requirements are briefly presented, together with an overview of the conceptual design of these systems, based on the initial PS2 parameter set. The required equipment sub-system performance is derived and discussed. Possible limitations are analysed and the impact on the overall design and parameter set is discussed. | ||
| TUPAN096 | High Intensity Commissioning of the SPS LSS4 Extraction for CNGS | 1604 |
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| The fast extraction in SPS LSS4 serves both the anti-clockwise ring of the LHC and the CERN Gran Sasso Neutrino facility (CNGS). The latter requires 2 fast extractions of 10.5 microsecond long batches per cycle, 50 milliseconds apart. Each batch will consist of 2.4·10+13 protons at 400 GeV, a factor of 10 in energy density above the equipment damage limit in case of beam loss. Active and passive protection systems are in place to guarantee safe operation and to respect the radiation limits close to the extraction region. In summer 2006 CNGS was commissioned including extraction with high intensity. A thorough setting-up of the extraction was performed as part of the CNGS commissioning, including aperture and beam loss measurements, and defining and checking of interlock thresholds for the extraction trajectory, magnet currents, kicker voltage and beam loss monitors. The various systems and the associated risks are discussed, the commissioning results are summarised and a comparison is made with predictions from simulations. | ||
| TUPAN097 | Studies of Beam Losses from Failures of SPS Beam Dump Kickers | 1607 |
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| The SPS beam dump extraction process was studied in detail to investigate the possibility of operation with reduced kicker voltage and to fully understand the trajectory and loss pattern of the mis-kicked beams. This paper briefly describes the SPS beam dump process, and presents the tracking studies carried out for failure cases. The simulation results are compared to the results of measurements made with low intensity beams. | ||
| TUPAN098 | Beam Commissioning of the SPS LSS6 Extraction and TT60 for LHC | 1610 |
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| The new fast extraction system in LSS6 of the SPS and the first 100 m of transfer line TT60 was commissioned with low intensity beam in late 2006. The layout and functionality of the main elements are briefly explained, including the various hardware subsystems and the control system. The systems safety procedures, test objectives and measurements performed during the beam commissioning are described. | ||
| TUPAS007 | The Investigation of Injection Timing for the IPNS RCS | 1667 |
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Funding: This work is supported by the U. S. Department of Energy under contract no. W-31-109-ENG-38. The Intense Pulsed Neutron Source (IPNS) Rapid Cycling Synchrotron (RCS) accelerates 3.2x 1012 protons from 50 MeV to 450 MeV at 30 Hz. During the 14.2 ms acceleration period, the RF frequency varies from 2.21 MHz to 5.14 MHz. In order to improve capture efficiency, we varied the injection timing and the early RF voltage profiles. The experimental results are compared with similar studies at ISIS and calculation done with the 1-D tracking code, Capture-SPC. This allowed us to optimize injection time and the RF voltage profile for better capture efficiency. An optimized injection time and RF voltage profile was found that resulted in raising the capture efficiency from 85.1% to 88.6%. These studies have now also been expanded to included 2nd harmonic RF during the capture and initial acceleration cycle in the RCS. |
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| TUPAS013 | Some Physics Issues of Carbon Stripping Foils | 1679 |
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Funding: Work supported by Universities Research Association, Inc. under contract No. DE-AC02-76CH03000 with the U. S. Dept. of Energy.
Carbon foils are widely used in charge-exchange injection in high intensity hadron accelerators. There are a variety of physics issues associated with the use of carbon foils, including stripping efficiency, energy deposition, foil lifetime (temperature rise, mechanical stress and buckling), multiple Coulomb scattering, large angle single Coulomb scattering, energy straggling and radiation activation. This paper will give a brief discussion of these issues based on the study of the Proton Driver and experience of the Fermilab Booster. Details can be found in Ref*.
* W. Chou et al., "Transport and Injection of 8 GeV H- Ions," Fermilab-TM-2285 (2007). |
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| TUPAS016 | Collimation System Design for Beam Loss Localization with Slipstacking Injection in the Fermilab Main Injector | 1688 |
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| Results of modeling with the STRUCT and MARS15 codes of beam loss localization and related radiation effects are presented for the slipstacking injection to the Fermilab Main Injector. Simulations of proton beam loss are done using multi-turn tracking with realistic accelerator apertures, nonlinear fields in the accelerator magnets and time function of the RF manipulations to explain the results of beam loss measurements. The collimation system consists of one primary and four secondary collimators. It intercepts a beam power of 1.6 kW at a total scraping rate of 5%, with a beam loss rate in the ring outside the collimation region of 1 W/m or less. Based on thorough energy deposition and radiation modeling, a corresponding collimator design was developed that satisfies all the radiation and engineering constraints. | ||
| TUPAS026 | Operation and Performance of the New Fermilab Booster H- Injection System | 1709 |
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Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC02-76CH03000. The operation and performance of the new, 15 Hz, H- charge exchange injection system for the FNAL Booster is described. The new system installed in 2006 was necessary to allow injection into the Booster at up to 15 Hz. It was built using radiation hardened materials which will allow the Booster to reliably meet the high intensity and repetition rate requirements of the Fermilab's HEP program. The new design uses three orbit bump magnets (Orbmps) rather than the usual four and permits injection into the Booster without a septum magnet. Injection beam line modification and compensation for the quadrupole gradients of the Orbmp magnets is discussed. |
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| TUPAS040 | Momentum Spread Reduction at Beam Extraction from the Fermilab Booster at Slipstacking Injection to the Main Injector | 1733 |
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| In order to reduce the momentum spread of the beam at extraction from the Booster to the Main Injector with slip stacking injection, the bunch rotation at the end of the cycle is applied. However, the fast RF voltage reduction often causes beam loading issues to Booster RF cavities, and the reliability of extracted beam becomes a problem. An alternative solution is investigated - modulating the RF voltage with twice of the synchrotron frequency introduces bunch length oscillation, and the beam is extracted at the time when the bunch length reaches maximum and the momentum spread becomes minimal. | ||
| TUPAS041 | Injection Parameters Optimization for the Fermilab Booster | 1736 |
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| The maximal capacitance for the Booster to deliver the 8-GeV beam to downstream accelerators is limited by the beam loss. Most of losses happen at injection due to space charge effect being the strongest at the injection energy. Optimizing the RF voltage ramp in the presence of the space charge effect to capture more beam and simultaneously keep small beam emittance has been numerically investigated using 3-D STRUCT code. The results of simulations agree well with the measurements in the machine. Possibilities, such as beam painting and using the second rf harmonic at injection, for further reductions of beam loss in order to reach the maximum beam intensity delivered from the Booster have been investigated. | ||
| TUPAS042 | Transition Crossing Simulation at the Fermilab Booster | 1739 |
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| The demand in high intensity and low emittance of the beam extracted from the Booster requires a better control over the momentum spread growth and bunch length shortening at transition, in order to prevent beam loss and coupled bunch instability. Since the transition crossing involves both longitudinal and transverse dynamics, the recently modified 3-D STRUCT code provides an opportunity to numerically investigate different transition schemes in the machine environment, and apply the results of simulation to minimize the beam loss and emittance growth operationally. | ||
| TUPAS045 | Microwave Ion Source and Beam Injection for an Accelerator-driven Neutron Source | 1745 |
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Funding: Supported by Office of Science, of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231 and by the U. S. Department of Homeland Security under contract No. HSHQBP-05-X-00033. An over-dense microwave driven ion source capable of producing deuterium (or hydrogen) beams at 100-200 mA/cm2 with an atomic fraction > 90% was designed as a part of an Accelerator Driven Neutron Source (ADNS). The ion source was tested with an electrostatic low energy beam transport section (LEBT) and measured emittance data was compared to PBGUNS simulations. In our design a 40 mA D+ beam is produced from a 6 mm diameter aperture using a 60 kV extraction voltage. The LEBT section consists of 5 electrodes arranged to form 2 Einzel lenses that focus the beam into the RFQ entrance. To create the ECR condition, 2 induction coils are used to generate a ~875 Gauss magnetic field on axis inside the source chamber. To prevent HV breakdown in the LEBT, a magnetic field clamp is necessary to minimize the field in this region. The microwave power is matched to the plasma by an autotuner. A significant improvement in the atomic fracion of the beam was achieved by installing a boron nitride liner inside the ion source |
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| TUPAS063 | A New Bunching Scheme for Increasing the LANSCE WNR Peak Beam Current | 1799 |
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Funding: This work is supported by the U. S. Department of Energy, Contract DE-AC52-06NA25396. The LANSCE linac simultaneously provides both H+ and H- beams to several user facilities. The Weapons Neutron Research (WNR) user facility is configured to accept the H- beam with a typical pulse pattern of one linac micro-pulse every 1.8 microseconds. To produce this pulse spacing a slow-wave chopper located in the 750 keV injector beam transport is employed to intensity modulate the beam. The beam is subsequently bunched at both 16.77 MHz and 201.25 MHz prior to entering the 100 MeV drift tube linac. One downside of the chopping process is that the majority of the beam produced by the ion source during the WNR macro-pulses is discarded. By applying a longitudinal bunching action immediately following the ion source, simulations have shown that some of this discarded beam can be used to increase the charge in these micro-pulses. Recently, we began an effort to develop this buncher by superimposing 16.77 MHz RF voltage on one of the HVDC electrodes in the 80 kV column located inside H- Cockcroft-Walton dome. This paper describes the beam dynamics simulations, design and implementation of the rf hardware and the results of tests performed with the system. |
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| TUPAS073 | New Design of the SNS MEBT Chopper Deflector | 1817 |
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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 chopper system for the Spallation Neutron Source (SNS) provides a gap in the beam for clean extraction from the accumulator ring. It consists of a pre-chopper in the low energy beam transport and a faster chopper in the medium energy beam transport (MEBT). The original "meander line" design of the MEBT chopper deflector was successfully tested with low power beam during the SNS linac commissioning but turned out to be unsuitable for high power beam operation due to poor cooling of the copper strip line through the dielectric substrate. We developed a new deflecting structure, with higher deflection efficiency and with rise and fall time easily customizable to match the available high voltage pulse generator. In this paper we describe design, implementation and beam tests results of the new MEBT chopper deflector. |
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| TUPAS083 | Design and Performance of the Matching Beamline between the BNL EBIS and an RFQ | 1844 |
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Funding: Work performed under the auspices of the U. S. Department of Energy and the U. S. National Aeronautics and Space Administration. A part of a new EBIS-based heavy ion preinjector, the low energy beam transport (LEBT) section between the high current EBIS and the RFQ is a challenging design, because it must serve many functions. In addition to the requirement to provide an efficient matching between the EBIS and the RFQ, this line must serve as a fast switchyard, allowing singly charged ions from external sources to be transported into the EBIS trap region, and extracted, highly charged ions to be deflected to off-axis diagnostics (time-of-flight, or emittance). The space charge of the 5-10 mA extracted heavy ion beam is a major consideration in the design, and the space charge force varies for different ion beams having Q/m from 1-0.16. The line includes electrostatic lenses, spherical and parallel-plate deflectors, magnetic solenoid, and diagnostics for measuring current, charge state distributions, emittance, and profile. A prototype of this beamline has been built, and results of tests will be presented. |