| Paper | Title | Other Keywords | Page | ||
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| MOP008 | Design and Performance of Optics for Multi-Energy Injector Linac | optics, electron, linac, quadrupole | 46 | ||
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Injector linac provides injection beams for four storage rings, KEKB high energy electron ring (HER), KEKB low energy positron ring (LER), PF-AR electron ring, and PF electron ring. The injection beams for these rings have different energies and intensities. Recently, a requirement of simultaneous injection among these rings arises to make a top-up injection possible. Magnetic fields of DC magnets to confine the beam to the accelerating structures can not be changed between pulse to pulse, although the beam energy can be controlled by fast rf phase shifters of klystrons. This implies that common magnetic fields of bending magnets and quadrupole magnets should be utilized to deliver beams having different characteristics. Therefore, we have designed multi-energy optics for KEKB high energy electron ring (8 GeV, 1 nC/pulse) and PF electron ring (2.5 GeV, 0.1 nC/pulse) and present a performance of the multi-energy injector linac.
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| MOP030 | An Upgrade to NSCL to Produce Intense Beams of Exotic Nuclei | cyclotron, linac, ion, acceleration | 103 | ||
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A substantially less costly alternative to the Rare Isotope Accelerator (RIA) project has been developed at Michigan State University (MSU). By upgrading the existing facility at the National Superconducting Cyclotron Laboratory (NSCL), it will be possible to produce stable beams of heavy ions at energies of greater than 180 MeV/u with beam power in excess of >80 kW. The upgrade will utilize a cyclotron injector and superconducting driver linac at a base frequency of 80.5 MHz. Radioactive ion beams will be produced in a high-power target via particle fragmentation. A charge-stripping foil and multiple-charge-state acceleration will be used for the heavier ions. The 9 MeV/u injector will include an ECR source, a bunching system, and the existing K1200 superconducting cyclotron with axial injection. The superconducting driver linac will largely follow that proposed by MSU for RIA, using cavities already designed, prototyped, and demonstrated for RIA. The existing A1900 Fragmentation Separator and experimental areas will be used, along with a new gas stopper and reacceleration system.
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| MOP039 | The SPL (II) at CERN, a Superconducting 3.5-GeV H- Linac | linac, proton, target, simulation | 127 | ||
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A revision of the physics needs and recent progress in the technology of superconducting (SC) RF cavities have triggered major changes in the design of a SC H- linac at CERN. With 4 - 5 MW beam power, the SPL can be the proton driver for a next generation ISOL-type radio-active beam facility ("EURISOL") and/or supply protons to a neutrino facility (conventional superbeam + beta-beam or neutrino factory). Furthermore the SPL can replace Linac2 and the PS booster, improving significantly the beam performance in terms of brightness, intensity, and reliability for the benefit of all proton users at CERN, including LHC and its luminosity upgrade. Compared with the first conceptual design, the beam energy is almost doubled (3.5 GeV instead of 2.2 GeV) while the length is reduced by 40%. At a repetition rate of 50 Hz, the linac re-uses decommissioned 352.2 MHz RF equipment from LEP in the low-energy part. Beyond 90 MeV the RF frequency is doubled, and from 180 MeV onwards high-gradient SC bulk-niobium cavities accelerate the beam to its final energy of 3.5 GeV. This paper presents the overall design approach, together with the technical progress since the first conceptual design in 2000.
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| TUP016 | BPM DAQ System Using Fast Digital Oscilloscope | linac, controls, feedback, factory | 280 | ||
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The KEK injector linac is planned to be upgraded to perform the simultaneous injection for four rings (KEKB e-/ e+, PF and PF-AR rings). In this operation mode, each rf pulse accelerates the beam with different charge and energy by controlling the low-level rf phase. For this purpose, it is strongly required to improve the BPM DAQ system. In the current system, maximum DAQ rate is strictly limited by the oscilloscope performance, and it should be improved for the 50-Hz measurement. We made decision to replace the current DAQ system by the fast digital oscilloscope. In this presentation, the system description of the new DAQ system and the result of the performance test will be presented.
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| TUP020 | The J-PARC L3BT Monitor System for RCS Injection | linac, electron, beam-losses, pick-up | 290 | ||
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The J-PARC linac-3GeV rapid cycling synchrotron (RCS) beam transport line (L3BT) monitor system will be used to tune the intensity of 5mA-50mA linac beam. The monitor system is composed of BPMs and multi wire profile scanners (MWPS) in L3BT line and RCS injection area. A non-destructive beam momentum spread monitor using a 4-stripline pickups is also developed in order to measure and control the momentum spread of linac beams. The spatial resolution of less than 0.3mm and momentum spread of less than 0.1% is required for RCS injection to avoid uncontrolled beam losses. In this paper, beam position monitor, profile monitor and momentum spread measurement for J-PARC linac is described. Preliminary results of beam size and m value measurement with quadrupole mode of the signal of 4-stripline BPMs in the KEK MEBT1 are also discussed.
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| TUP046 | Experimental Studies of Electrostatic and Solenoidal Focusing of Low-Energy, Heavy-Ion ECRIS Beams at the NSCL/MSU | emittance, dipole, focusing, ion | 352 | ||
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Replacement of the focusing solenoids between both ECR Ion Sources and the beam analysis dipoles with electrostatic triplets has resulted in a large increase in net accelerator output. 2D emittance scans explain some but not all of this increase. Further improvement is anticipated with a new optical device consisting of an electrostatic quadrupole doublet-octupole-doublet-magnetic sextupole arrangement, which has been built and is being tested in place of a triplet. Motivations and results of measurements and operating experience are discussed.
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| TUP053 | Initial Tests of an Elemental Cs-System for the SNS Ion Source | ion, SNS, ion-source, plasma | 364 | ||
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The ion source employed in the Spallation Neutron Source* (SNS) is an RF-driven, Cs-enhanced, multi-cusp H- source. To date, the source has been successfully utilized in the commissioning of the SNS accelerator producing 10–40 mA. Presently, Cs is dispensed within the source using Cs2CrO4 cartridges located in an air heated/cooled cylindrical collar surrounding the outlet aperture. The temperature of the collar is elevated to release Cs into the source. Typically, this process can only be repeated 2-3 times before the Cs is depleted and the source needs to be replaced. In addition, the dispensers are subject to poisoning by the residual gases in the source leading to beam decay. This is especially problematic at high duty-factor. This report describes the design of an elemental Cs system incorporating an external reservoir based on the proven Fermilab system. Source performance is characterized and compared for both the original and the elemental Cs systems.
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| TUP060 | Status of the EBIS Project at Brookhaven | ion, rfq, electron, linac | 385 | ||
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The EBIS Project at Brookhaven National Laboratory will replace the Tandem Van de Graaff accelerators with an Electron Beam Ion Source, an RFQ, and short linac, as the heavy ion preinjector for RHIC. This project, jointly funded by DOE and NASA, will provide a modern preinjector which will have increased flexibility in providing beams to the various programs running simultaneously, will be capable of providing beams not presently available for RHIC and the NASA Space Radiation Laboratory, and will be simpler and less costly to operate. Presently in the first year of the four-year project, the detailed design is nearly complete, and some major procurements have been placed. The overall status of the project will be presented, as well as some unique features in the design, and results from the R&D using the prototype EBIS.
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| TUP067 | Tune-up Scenario for Debuncher System in J-PARC L3BT | simulation, monitoring, linac, target | 406 | ||
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We plan to start beam commissioning of J-PARC linac and the succeeding beam transport line in December 2006. The beam transport line, to which we refer as L3BT, has two key functionalities to satisfy the requirements for the succeeding ring injection. One is to reduce the momentum jitter and momentum spread, and the other is to scrape off the transverse tail. To realize the former functionality, a debuncher system is installed in L3BT which enables longitudinal gymnastics of the beam to reduce the momentum spread at the ring injection. In this presentation, the tune-up scenario for the debuncher system is presented together with simulation results on the effects of debuncher system.
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| TUP068 | Tuning Strategy for Transverse Collimator in J-PARC L3BT | collimation, beam-losses, monitoring, linac | 409 | ||
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We plan to start beam commissioning of J-PARC linac and the succeeding beam transport line in December 2006. The beam transport line, to which we refer as L3BT, has two key functionalities to satisfy the requirements for the succeeding ring injection. One is to reduce the momentum jitter and momentum spread, and the other is to scrape off the transverse tail. To realize the latter functionality, a transverse collimator system is installed in L3BT which consists of four horizontal and four vertical collimators. In this presentation, the tuning strategy for the transverse collimator system is presented together with the main features of the collimator system.
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| THP009 | Performance of RF Reference Distribution System for the J-PARC Linac | controls, linac, klystron, feedback | 583 | ||
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Installation of the J-PARC linac machines (Phase I) has been almost completed and the beam commissioning will be started in December this year. The error of the accelerating field must be within ±1 degree in phase and ±1% in amplitude. Thus, high phase stability is required as an RF reference. Our objective concerning the phase stability of the reference aims at less than ±0.3 degrees. Last year the installation of the RF reference distribution system was completed. The reference signal is optically distributed to all of the low-level RF control systems by using E/O, O/E, Optical Amplifier and Optical Couplers and so on. The performance of this system was evaluated. The phase stability of ±0.06 degrees was obtained.
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| THP073 | High-Current Elliptical Cavity Design and Prototyping | pick-up, vacuum, simulation, linac | 752 | ||
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Beam instabilities due to undamped higher-order modes (HOMs) in the cavities can limit the performance of high-current superconducting accelerators, such as energy recovery linacs. If the accelerator is designed such that the bunch frequency is equal to the accelerating mode frequency and the beam pipe radius is chosen such that the cutoff frequency is less than twice that of the accelerating mode, all of the monopole and dipole HOMs that can be driven by the beam can be well-damped. A 6-cell elliptical cavity for speed-of-light particles and a 2-cell elliptical injection cavity have been designed for high-current accelerator applications. Both cavities have an aperture 29% larger than the TeSLA cavity, at the expense of peak surface fields about 10% higher for the same gradient. The injection cavity has a geometric β of 0.81 and was designed to accelerate electrons from 50 keV to 1 MeV, and the 6-cell cavity has a geometric β of 1 for further acceleration. Both cavities are designed for the purpose of accelerating hundreds of milliamps without HOM-induced beam breakup and to operate at 2.45 GHz. The cavity designs and prototype injection cavity results will be presented.
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| THP084 | Design of an 8-Gev H- Transport and Multiturn Injection System | linac, lattice, proton, dipole | 779 | ||
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The baseline design of the transport and multiturn injection of 8 GeV H- to the FNAL Main Injector from a proposed 8 GeV superconducting linac will be discussed.
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| THP092 | Control System for a Limitation of an Integrated Amount of Beam Charges Delivered from the KEKB Injector Linac | controls, linac, electron, positron | 800 | ||
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A new control system is under construction for radiation safety at the KEKB injector linac. The control system restricts the integrated amount of the beam charges delivered from an electron gun in order to keep the radiation safety with high reliability in a daily operation of the linac. The old control system of the radiation safety has been working based on a software control implemented on a UNIX-based workstation. However, this control system is not possible to be implemented for the long-term linac operation with high reliability. The new control system comprises a charge-integration-type analog circuit mounted along with a CPU chip and a data acquisition system based on programmable logic controllers. The fast analog circuit can detect the beam-charge signals delivered from a wall-current monitor, and control the beam-abort trigger pulses pulse-by-pulse. The new hardware-based control system may stabilize the radiation safety control for the long-term linac operation. In this report the design of the new control system is described along with preliminary test results.
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| THP094 | GeV Laser Wakefield Acceleration and Injection Control at LOASIS | laser, electron, plasma, simulation | 806 | ||
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Experiments at the LOASIS laboratory of LBNL have demonstrated production of GeV electron beams with low energy spread and divergence from laser wakefield acceleration. The pondermotive force of a 40 TW laser pulse guided by a 3 cm capillary discharge plasma density channel drove an intense plasma wave (wakefield), producing acceleration gradients on the order of 50 GV/m. Electrons were trapped from the background plasma and accelerated. Beam energy was increased from 100 to 1000 MeV*, compared to earlier experiments**, by using a longer guiding channel at low density, demonstrating the anticipated scaling to higher beam energies. Particle simulations are used to understand the trapping and acceleration mechanisms. Other experiments and simulations are also underway to control injection of particles into the wake, and hence improve beam quality and stability further. Recent experimental and simulation results from channel guided laser acceleration, and initial injection results, will be presented.
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*W. P. Leemans et al, submitted. |
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