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| MOAA004 | RHIC Operational Status | luminosity, electron, polarization, proton | 358 | ||
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Funding: Work was performed under the auspices of the U.S. Department of Energy. |
As the first hadron accelerator and collider consisting of two independent superconducting rings RHIC has operated with a wide range of beam energies and particle species. Machine operation and performance will be reviewed that includes high luminosity gold-on-gold and copper-on-copper collisions at design beam energy (100 GeV/u), asymmetric deuteron-on-gold collisions as well as high energy polarized proton-proton collisions (100 GeV on 100 GeV). Plans for future upgrades of RHIC will also be discussed. |
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| MOPA002 | Performance Limitations in High-Energy Ion Colliders | luminosity, electron, heavy-ion, injection | 122 | ||
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Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886. |
High-energy ion colliders (hadron colliders operating with species other than protons) are premier research tools for nuclear physics. The collision energy and high luminosity are important design and operations considerations. However, the experiments also expect flexibility with frequent changes in the collision energy, lattice configuration, and ion species, including asymmetric collisions. For the creation, acceleration, and storage of bright intense ion beams, attention must be paid to space charge, charge exchange, and intra-beam scattering effects. The latter leads to luminosity lifetimes of only a few hours for heavy ions. Ultimately cooling at full energy is needed to overcome this effect. Currently, the Relativistic Heavy Ion Collider at BNL is the only operating high-energy ion collider. The Large Hadron Collider, under construction at CERN, will also run with heavy ions. |
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| MOPC004 | Dynamics of a High Density Ion-Beam with Electron Cooling in HIMAC Synchrotron | injection, beam-losses, betatron, electron | 416 | ||
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High density circulating-ion beam was obtained with electron-cooling and cool-stacking injection in HIMAC synchrotron. The ion density was saturated at 1.0e9/cm2. Coherent transverse instability was observed when ion- and electron-beam density was high. The dynamics of the cooled ion-beam are described in this report.
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| MPPE023 | Improvement of the Longitudinal Beam Dynamics Tuning Procedure for the MSU RIA Driver Linac | linac, emittance, lattice, focusing | 1826 | ||
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The Rare Isotope Accelerator (RIA) driver linac will use a superconducting, cw linac with independently phased superconducting radio frequency cavities for acceleration and, for the heavier ions, utilize beams of multiple-charge-states (multi-q). Given the acceleration of multi-q beams and a stringent beam loss requirement in the RIA driver linac, a new beam envelope code capable of simulating nonlinearities of the multi-q beam envelopes in the longitudinal phase space was developed. Using optimization routines, the code is able to maximize the linearity of the longitudinal phase space motion and thereby minimizing beam loss by finding values for the amplitude and phase of the cavities for a given accelerating lattice. Relative motion of the multi-q beams is also taken into account so that superposition of the beam centroids and matching of their Twiss parameters are automatically controlled. As a result, the linac tuning procedure has been simplified and the longitudinal lattice performance has been improved. In this paper, the general architecture of the code and the results of using it to determine tuning parameters for the RIA driver linac are presented.
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| MPPE082 | Non-Linear Beam Dynamics in High Resolution Multi-Pass Time of Flight Mass Separator | simulation, extraction, resonance, ion-source | 4105 | ||
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Funding: This work was supported by the UNIRIB collaboration and Oak Ridge Associated Universities. |
A multi-pass time-of-flight (MTOF) mass separator is under development by the UNIRIB collaboration. The MTOF consists of two coaxial electrostatic mirrors, focusing lenses and auxiliary injection, extraction and separation elements. The injected ions having almost the same energy but different masses undergo hundreds or thousands of reflections between the mirrors. In the course of this periodic motion, the ions of different masses and hence velocities are spatially separated in longitudinal direction. The periodic motion in the MTOF has been investigated with a recently developed ray tracing program utilizing the canonical integration technique. Results of the performed numerical simulations are discussed. The simulations displayed nonlinear character of the ion’s behavior both in transverse and longitudinal phase spaces. The ion’s transverse stability and longitudinal isochronicity were the matters of primary attention. It is shown in particular that at transverse tunes of around q=0.75 the system can be adjusted to be isochronous up to at least the 3rd order of the ToF optical aberrations. |
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| MPPP035 | Investigation of APS PAR Vertical Beam Instability | injection, linac, synchrotron, electron | 2393 | ||
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Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
The Advanced Photon Source (APS) particle accumulator ring (PAR) is a 325-MeV storage ring that collects and compresses linac pulse trains into a single bunch for booster injection. A vertical beam instability has been observed when only a single linac bunch is injected and the total beam charge is from 0.15 to 0.7 nC. The instability starts about 80 ms after the injection, lasts about 160 ms, and is highly reproducible. We performed spectral measurement and time-resolved imaging with both a gated-intensified camera and a streak camera in order to characterize this instability. Initial analysis of the data indicates that the instability is due to ion trapping. A stable lattice was established as result of the investigation. This report summarizes the experimental results and gives some preliminary analysis. |
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| MPPT068 | A Compact High Gradient Pulsed Magnetic Quadrupole | quadrupole, multipole, heavy-ion, induction | 3771 | ||
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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. |
A design for a high gradient, low inductance pulsed quadrupole magnet is presented. The magnet is a circular current dominated design with a circular iron return yoke. Features include a five turn eddy current compensated solid conductor coil design which theoretically eliminates the first four higher order multipole field components, a single layer "non-spiral bedstead" coil design which both minimizes utilization of radial space and maximizes utilization of axial space, and allows incorporation of steering and correction coils within existing radial space. The coils are wound and stretched straight in a special winder, then bent in simple fixtures to form the upturned ends, simplifying fabrication and assembly. |
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| MPPT069 | A Pulsed Solenoid for Intense Ion Beam Transport | quadrupole, heavy-ion, beam-transport, acceleration | 3798 | ||
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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. |
A design for a pulsed solenoid magnet is presented. Some simple design formulas are given that are useful for initial design scoping. Design features to simplify fabrication and improve reliability are presented. Fabrication, assembly, and test results are presented. |
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| MOPB002 | High Intensity High Charge State ECR Ion Sources | ion-source, plasma, electron, emittance | 179 | ||
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Funding: This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Nuclear Physics Division of the U.S. Department of Energy under Contract DE AC03-76SF00098. |
The next-generation heavy ion beam accelerators such as the proposed Rare Isotope Accelerator (RIA), the Radioactive Ion Beam Factory at RIKEN, the GSI upgrade project, the LHC-upgrade, and IMP in Lanzhou require a great variety of high charge state ion beams with a magnitude higher beam intensity than currently achievable. High performance Electron Cyclotron Resonance (ECR) ion sources can provide the flexibility since they can routinely produce beams from hydrogen to uranium. Over the last three decades, ECR ion sources have continued improving the available ion beam intensities by increasing the magnetic fields and ECR heating frequencies to enhance the confinement and the plasma density. With advances in superconducting magnet technology, a new generation of high field superconducting sources is now emerging, designed to meet the requirements of these next generation accelerator projects. The talk will briefly review the field of high performance ECR ion sources and the latest developments for high intensity ion beam production. The currently most advanced next-generation superconducting source ECR ion source VENUS will be described in more detail. |
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| MOPB003 | Progress with the 2Q-LEBT Facility for the RIA Project | emittance, ion-source, rfq, simulation | 253 | ||
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Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. W-31-109-ENG-38. |
The Rare Isotope Accelerator (RIA) facility utilizes the concept of simultaneous acceleration of two charge states from the ion source. We are building a prototype two charge-state (2Q) injector of the RIA Driver Linac, which includes an ECR ion source originally built by Berkeley Ion Equipment Corporation, a LEBT and one-segment of the prototype RFQ. The reassembly and commissioning of the ECR source has been completed. During the commissioning process we modified and replaced several major components of the BIE-100 to increase the source performance. A new diagnostic station has been designed and built for accurate measurements of the output beam emittance. The paper will discuss detailed beam dynamics studies together with extensive emittance measurements of various ion beams. The status of the design and fabrication of 100 kV high voltage platform, achromatic bending system, multi-harmonic buncher, and a full power 57.5 MHz RFQ segment will be presented. |
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| MOPB004 | Progress on Test EBIS and the Design of an EBIS-Based RHIC Preinjector | electron, cathode, injection, gun | 363 | ||
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Funding: Work supported under the auspices of the U.S. DOE. |
Following the successful development of the Test EBIS at BNL,* we now have a design for an EBIS-based heavy ion preinjector which would serve as an alternative to the Tandem Van de Graaffs in providing beams for RHIC and the NASA Space Radiation Laboratory. This baseline design includes an EBIS producing mA-level currents of heavy ions (ex. Au 32+) in ~ 10-20 microsecond pulses, injecting into an RFQ which accelerates the beams to 300 keV/amu, followed by an IH linac accelerating to 2 MeV/amu. Some details of this design will be presented, as well recent experimental results on the Test EBIS. *E.N. Beebe et al., Proc. Ninth International Symposium on Electron Beam Ion Sources and Traps, Journal of Physics: Conference Series 2 (2004) 164–173. |
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| MOPB005 | Advances in the Performance of the SNS Ion Source | ion-source, SNS, plasma, linac | 472 | ||
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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 ion source developed for the Spallation Neutron Source* (SNS) is a radio frequency, multi-cusp source designed to produce ~ 40 mA of H- with a normalized rms emittance of less than 0.2 pi mm mrad. To date the source has been utilized in the commissioning of the SNS accelerator, delivering beams of 10-50 mA with duty-factors of typically ~0.1% for operational periods of several weeks and availabilities now ~99%. Ultimately the SNS facility will require beam duty-factors of 6% (1 ms pulse length, 60 Hz repetition rate, 21 day run-period). Over the last year, several experiments were performed in which the ion source was continuously operated at full duty-factor and maximum beam current on a dedicated test stand. Recently, a breakthrough in our understanding of the Cs release process has led to the development of a new source conditioning technique which resulted in a dramatic increase in beam persistence with time. Average H- beam attenuation rates have been improved from ~5 mA/day to ~0.4 mA/day, allowing beams in excess of 30 mA to be delivered continuously at full duty factor for periods of ~20 days. Prior to this development, full duty factor beams could only be sustained for periods of several hours. |
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| TOAC003 | Stochastic Cooling for Bunched Beams | synchrotron, kicker, pick-up, heavy-ion | 310 | ||
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Funding: Work performed under the auspices of the U.S. DOE. |
A longitudinal stochastic cooling system for RHIC is under construction and partial commissioning is planned for the upcoming run. The state of the system and future plans are discussed. |
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| TPAE005 | Generation of Small Energy Spread Electron Beam from Self-Modulated Laser Wakefield Accelerator | electron, plasma, laser, space-charge | 976 | ||
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Funding: The authors are grateful for financial support from the Korean Ministry of Science and Technology through the Creative ResearchInitiatives Program. |
Laser and plasma based accelerators have been studied for a next generation particle accelerator. Still, there are some problems to solve for real applications. For example, it has been observed that the accelerated electron beam from laser and plasma based accelerators has a 100% energy spread. Thus, the generation of small energy spread beam is an important issue in the laser and plasma based accelerator study. In this work, we introduce a method to control the energy spread. From a basic theory and simulation, it is found that the transverse electron distribution is changed from the Gaussian to a Maxwell-Boltzmann distribution and low energy electrons spread out more rapidly than high energy electrons as they propagate in vacuum. Thus, a small size collimator is installed to remove the small energy electrons and it is conformed that the small energy spread can be obtained from an experiment. |
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| TPAE039 | The Effects of Ion Motion in Very Intense Beam-Driven Plasma Wakefield Accelerators | plasma, emittance, electron, collider | 2562 | ||
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Funding: This work is supported by U.S. Dept. of Energy grant DE-FG03-92ER40693. |
Recent proposals for using plasma wakefield accelerators in the blowout regime as a component of a linear collider have included very intense driver and accelerating beams, which have densities many times in excess of the ambient plasma density. The electric fields of these beams are widely known to be large enough to completely expel plasma electrons from the beam path; the expelled electrons often attain relativistic velocities in the process. We examine here another aspect of this high-beam density scenario: the motion of ions. In the lowest order analysis, for both cylindrically symmetric and "flat" beams, it is seen that for the recently discussed "after-burner" scenario the ions completely collapse inside of the electron beam. In this case the ion density is significantly increased, with a large increase in the beam emittance expected as a result. Particle-in-cell simulations of ion-collapse in the nonlinear regime are discussed. |
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| TPAE042 | Beam Matching to a Plasma Wake Field Accelerator Using a Ramped Density Profile at the Plasma Boundary | plasma, synchrotron, emittance, focusing | 2702 | ||
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Funding: DOE Grant No. DE-FG03-92ER40727. |
An important aspect of plasma wake field accelerators (PWFA) is stable propagation of the drive beam. In the under dense regime, the drive beam creates an ion channel which acts on the beam as a strong thick focusing lens. The ion channel causes the beam to undergo multiple betatron oscillations along the length of the plasma. There are several advantages if the beam size can be matched to a constant radius. First, simulations have shown that instabilities such as hosing are reduced when the beam is matched. Second, synchrotron radiation losses are minimized when the beam is matched. Third, an initially matched beam will propagate with no significant change in beam size in spite of large energy loss or gain. Coupling to the plasma with a matched radius can be difficult in some cases. This paper shows how an appropriate density ramp at the plasma entrance can be useful for achieving a matched beam. Additionally, the density ramp is helpful in bringing a misaligned trailing beam onto the drive beam axis. A plasma source with boundary profiles useful for matching has been created for the PWFA experiments at SLAC. |
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| TPAP012 | Luminosity Limit from Bound-Free Pair Production in the LHC | simulation, luminosity, dipole, proton | 1306 | ||
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The luminosity of the LHC as a lead-ion collider is known to be limited by the large cross-sections for electromagnetic processes in ultra-peripheral collisions. In particular, the process of bound-free e-e+ pair production creates secondary beams of Pb81+ ions emerging from the collision points and impinging on the vacuum envelope inside superconducting magnets. New Monte-Carlo simulations, exploiting recent implementations of the physics of ion interactions with matter, are helping us to quantify the relationships among luminosity, energy deposition in the magnet coils and signals on beam loss monitors with a view to predicting and alleviating the quench limit on luminosity.
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| TPAP016 | Energy Calibration of the SPS with Proton and Lead Ion Beams | proton, sextupole, quadrupole, alignment | 1470 | ||
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The momentum of the 450 GeV/c proton beam of the CERN Super Proton Synchrotron was determined by a high precision measurement of the revolution frequencies of proton and lead ion beams. To minimize systematic errors the magnetic cycle of the SPS had to be rigorously identical for both beams, and corrections due to Earth tides had to be taken into account. This paper presents how the beam momentum was determined from the RF frequency for which the beams are centred in the machine sextupoles. The measured beam momentum is 449.16 ± 0.14 GeV/c for a nominal momentum of 450 GeV/c, and the accuracy is limited by systematic errors.
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| TPAP043 | Electron Cooling of RHIC | electron, emittance, linac, simulation | 2741 | ||
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We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.agsrhichome.bnl.gov/eCool/.
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Under contract with the U.S. Department of Energy, Contract Number DE-AC02-98CH10886. |
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| TPAP056 | Electron Beam Stability Requirements for Linac-Ring Electron-Ion Colliders | electron, simulation, emittance, luminosity | 3363 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy. |
In recent years, linac-ring electron-ion colliders have been proposed at a number of laboratories around the world. While the linac-ring approach overcomes the beam-beam tuneshift limitation on the electron beam, it also introduces noise into the ion beam, via the beam-beam interaction with electron bunches of slightly fluctuating intensity and transverse size. The effect of these fluctuations is studied using a linearized model of the beam-beam interaction. Upper limits for the rms jitter amplitudes of electron beam parameters for various linac-ring electron-ion colliders are presented. |
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| TPAT001 | An Ultra-Bright Pulsed Electron Beam with Low Longitudinal Emittance | electron, laser, brightness, emittance | 770 | ||
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Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. |
We describe a novel scheme for an electron source in the 10 - 100 eV range with the capability of approaching the brightness quantum-limit and of lowering the effective temperature of the electrons orders of magnitude with respect to existing sources. Such a device can open the way for a wide range of novel applications that utilize angstrom-scale spatial resolution and ?eV-scale energy resolution. Possible examples include electron microscopy, electron holography, and investigations of dynamics on a picosecond time scale using pump-probe techniques. In this paper we describe the concepts for such a source including a complete and consistent set of parameters for the construction of a real device based on the presented scheme. |
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| TPAT028 | TRACK: The New Beam Dynamics Code | linac, simulation, space-charge, multipole | 2053 | ||
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Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. W-31-109-ENG-38. |
The new ray-tracing code TRACK was developed* to fulfill the special requirements of the RIA accelerator systems. The RIA lattice includes an ECR ion source, a LEBT containing a MHB and a RFQ followed by three SC linac sections separated by two stripping stations with appropriate magnetic transport systems. No available beam dynamics code meet all the necessary requirements for an end-to-end simulation of the RIA driver linac. The latest version of TRACK was used for end-to-end simulations of the RIA driver including errors and beam loss analysis.** In addition to the standard capabilities, the code includes the following new features: i) multiple charge states ii) realistic stripper model; ii) static and dynamic errors iii) automatic steering to correct for misalignments iv) detailed beam-loss analysis; v) parallel computing to perform large scale simulations. Although primarily developed for simulations of the RIA machine, TRACK is a general beam dynamics code. Currently it is being used for the design and simulation of future proton and heavy-ion linacs at TRIUMF, Fermilab, JLAB and LBL. *P.N. Ostroumov and K.W. Shepard. Phys. Rev. ST. Accel. Beams 11, 030101 (2001). **P.N. Ostroumov, V. N. Aseev, B. Mustapha. Phys. Rev. ST. Accel. Beams, Volume 7, 090101 (2004). |
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| TPAT036 | Ferroelectric Plasma Source for Heavy Ion Beam Charge Neutralization | plasma, electron, heavy-ion, focusing | 2452 | ||
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Funding: Research supported by the U.S. Department of Energy. |
Plasmas are employed as a medium for charge neutralizing heavy ion beams to allow them to focus to a small spot size. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length ~ 0.1-1 m would be suitable. To produce 1 meter plasma, large-volume plasma sources based upon ferroelectric ceramics are being considered. These sources have the advantage of being able to increase the length of the plasma and operate at low neutral pressures. The source will utilize the ferroelectric ceramic BaTiO3 to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) will be covered with ceramic. High voltage (~ 1-5 kV) is applied between the drift tube and the front surface of the ceramic by placing a wire grid on the front surface. A prototype ferroelectric source 20 cm long produced plasma densities ~ 5x1011 cm-3. The source was integrated into the experiment and successfully charge neutralized the K ion beam. Presently, the 1 meter source is being fabricated. It will be characterized and integrated into NDCX for charge neutralization experiments. Experimental results will be presented. |
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| TPAT037 | Simulating the Long-Distance Propagation of Intense Beams in the Paul Trap Simulator Experiment | plasma, simulation, focusing, lattice | 2491 | ||
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Funding: Research supported by the U.S. Department of Energy. |
The Paul Trap Simulator Experiment (PTSX) makes use of a compact Paul trap configuration with quadrupolar oscillating wall voltages to simulate the propagation of intense charged particle beams over distances of many kilometers through magnetic alternating-gradient transport systems. The simulation is possible because of the similarity between the transverse dynamics of particles in the two systems. One-component pure cesium ion plasmas have been trapped that correspond to normalized intensity parameters s < 0.8, where s is the ratio of the square of the plasma frequency to twice the square of the average transverse focusing frequency. The PTSX device confines the plasma for hundreds of milliseconds, which is equivalent to beam propagation over tens of kilometers. Results are presented for experiments in which the amplitude of the oscillating confining voltage waveform has been modified as a function of time. A comparison is made between abrupt changes in amplitude and adiabatic changes in amplitude. The effects of varying the frequency are also discussed. A barium ion source and a laser system have been installed and initial measurements made with this system are presented. |
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| TPAT040 | Actual Stationary State for Plasma Lens | plasma, electron, acceleration, heavy-ion | 2619 | ||
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The electrostatic plasma lens (PL) provides an attractive and unique tool for manipulating high-current heavy ion beams. The fundamental concept of the PL is based on the use of magnetically insulated electrons and equipotentialization of magnetic field lines. Rigorous application of PL is, however, limited. The reason is the estimation behaviour of electrons for complicated magnetic fields runs into severe difficults.We show that there are specific conditions that admit steady-state of a longitudinal motion, and consider a question of it stability. These results are needed to develop an optimized PL with minimal spherical aberation, in party by optimization of the magnetic field conficuration in the low-magnetic-field range.
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| TPAT047 | A Space Charge Compensation Study of Low Energy Hydrogen Ion Beams | space-charge, simulation, electron, emittance | 2947 | ||
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Funding: Work supported by the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395). |
High-power accelerators are being studied for several projects including accelerator driven neutron or neutrino sources. The low energy part of these facilities has to be carefully optimized to match the beam requirements of the higher energy parts. The complexity of high intensity beam dynamics in the low energy line is essentially due to the non-linear space charge effects. The PIC code CARTAGO* has been developed in order to simulate the beam transport at low energy including the temporal evolution effects of the space charge compensation. This paper relates the structure and the numerical methods of a 2D (r,z) new version of the code. The effects of the longitudinal space charge, the image charge and external 2D (r,z) magnetic field were included. The results of H+ and H- beam transports using solenoid lenses are discussed. Space charge compensation degrees are given for each studied cases. *A. Ben Ismail et al., in Space Charge Compensation in Low Energy Proton Beams, proceeding of the International Linear Accelerator Conference, Lübeck, 2004. |
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| TPAT051 | Asymmetrical Spectrum Observed at the KEKB High Energy Electron Ring | electron, vacuum, luminosity, feedback | 3176 | ||
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KEKB is a multi-bunch, high-current, electron/positron collider for B meson physics. The two beams collide at one interaction point (IP) with a finite horizontal crossing angle. The luminosity achieved at KEKB is the best in the world. In order to keep up the performance, the tune of a non-colliding bunch, placed just after a colliding bunch-train, is continuously monitored. It was observed that an electron bunch showed an asymmetrical distribution biased to a higher tune in the vertical tune-spectrum. We found that the asymmetrical spectrum was reinforced by the beam-beam interaction, though the electron bunch did not collide. The asymmetry was reinforced moreover, as the electron bunch approached a bunch-train further. These observations suggest that the asymmetry in the spectrum is not related to trapped-ions or fast-ions observed in an electron single beam, but related to ions produced by the beam-beam interaction, which makes the particles scattered and they might yield new ions due to the collision with residual gas. We can imagine that the ions are accumulated along a bunch-train and some ions survive after colliding bunches passed through in the electron ring. A quantitative analysis remains for future study.
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| TPAT067 | Study of Longitudinal Space-Charge Wave Dynamics in Space-Charge Dominated Beams | space-charge, simulation, gun, electron | 3712 | ||
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Funding: Work supported by the U.S. Department of Energy, Office of Science. |
Understanding the dynamics of longitudinal space- charge waves is very important for advanced accelerator research. Although analytical solutions of space-charge wave equations based on the cold fluid model exist in one dimension, there are few results for two-dimensional wave evolution. One-dimensional theory predicts two eigen solutions, given an initial perturbation. One is called the fast wave, which moves toward the beam head in the beam frame and the other is termed the slow wave, which moves backward in the beam frame. In this paper, we report experimental results of space charge wave studies conducted on a 2.3 meter long straight beam line at the University of Maryland. An energy analyzer is used to directly measure the energy of space-charge waves at the end of the transport line, which demonstrates the decomposition of an initial current perturbation into a slow wave and a fast wave. A PIC code, WARP [1], is used to simulate this experiment and the behavior of longitudinal waves in space-charge dominated beams in an R-Z geometry. Simulations shown here also demonstrate if the initial current and velocity perturbation strengths are chosen properly, only fast or slow waves could be selectively generated. |
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| TPAT068 | A Fast Faraday Cup for the Neutralized Drift Compression Experiment | plasma, simulation, electron, target | 3765 | ||
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Funding: Research supported by the U.S. Department of Energy. |
Heavy ion drivers for high energy density physics applications and inertial fusion energy use space-charge-dominated beams which require longitudinal bunch compression in order to achieve sufficiently high beam intensity at the target. The Neutralized Drift Compression Experiment-1A (NDCX-1A) at Lawrence Berkeley National Laboratory (LBNL) is used to determine the effective limits of neutralized drift compression. NDCX-1A investigates the physics of longitudinal drift compression of an intense ion beam, achieved by imposing an initial velocity tilt on the drifting beam and neutralizing the beam's space-charge with background plasma. Accurately measuring the longitudinal compression of the beam pulse with high resolution is critical for NDCX-1A, and an understanding of the accessible parameter space is modeled using the LSP particle-in-cell (PIC) code. The design and preliminary experimental results for an ion beam probe which measures the total beam current at the focal plane as a function of time are summarized. |
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| TPAT070 | Intensity and Bunch-Shape Dependent Beam Loss Simulation for the SIS100 | beam-losses, resonance, space-charge, lattice | 3807 | ||
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We have studied the combined influence of magnet nonlinearities, space charge and bunch shapes consistent with different RF scenarios on the long-term loss in the planned SIS100 synchrotron of the FAIR project. The simulation is a 3D tracking with "frozen-in" space charge calculation employing the MICROMAP code. Comparing a one-harmonic RF scenario with an alternative double-harmonic scenario we find that for the same absolute beam loss roughly twice the number of particles can be stored in the double-RF system. Moreover, a barrier bucket RF scenario is found to be loss free. This is due to the fact that loss is caused here by space-charge induced periodic resonance crossing, which is absent for the strictly flat bunch profile of the barrier case.
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| TPAT087 | The Effect of Magnetic Field Errors on Dynamical Friction in Electron Coolers | electron, simulation, positron, luminosity | 4206 | ||
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Funding: Work supported by US DOE grants DE-FG03-01ER83313 and DE-FG03-95ER40926. |
A proposed luminosity upgrade to the Relativistic Heavy Ion Collider (RHIC) includes a novel electron cooling section,* which would use ~55 MeV electrons to cool fully-ionized 100 GeV/nucleon gold ions. A strong (1-5 T) solenoidal field will be used to magnetize the electrons and thus enhance the dynamical friction force on the ions. The physics of magnetized friction is being simulated for RHIC parameters, using the VORPAL code.** Most theoretical treatments for magnetized dynamical friction do not consider the effect of magnetic field errors, except in a parametric fashion.*** However, field errors can in some cases dramatically reduce the velocity drag and corresponding cooling rate. We present a simple analytical model for the magnetic field errors, which must be Lorentz transformed into the beam frame for use in our simulations. The simulated dynamical friction for the case of a perfect solenoidal field will be compared with results from this new model, for parameters relevant to RHIC. *Fedotov et al., Proc. 33rd ICFA Adv. Beam Dynamics Workshop (2004). **Nieter & Cary, J. Comp. Phys. 196 (2004). ***Parkhomchuk, Nucl. Instr. Meth. Phys. Res. A 441 (2000). |
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| TPAT089 | Cooling Dynamics Studies and Scenarios for the RHIC Cooler | electron, luminosity, emittance, simulation | 4236 | ||
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Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-98CH10886 |
In this paper, we discuss various cooling dynamics studies for RHIC, such as an equilibrium process between intra-beam scattering within ion bunch and electron cooling, critical number of electrons needed, magnetized cooling logarithm and resulting requirements on parameters of electron beam, effects of solenoid errors, etc. We also present simulations of various possibilities of using electron cooling at RHIC, which includes cooling at the top energy, pre-cooling at low energy, aspects of transverse and longitudinal cooling and their impact on the luminosity. Electron cooling at various collision energies both for heavy ions and protons is also discussed. |
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| TPAT090 | Simulations of High-Energy Electron Cooling | electron, luminosity, simulation, emittance | 4251 | ||
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Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-98CH10886. |
High-energy electron cooling of RHIC presents many unique features and challenges. An accurate estimate of the cooling times requires a detailed calculation of the cooling process, which takes place simultaneously with various diffusive mechanisms in RHIC. In addition, many unexplored effects of high-energy cooling in a collider complicate the task of getting very accurate estimates of cooling times. To address these high-energy cooling issues, a detailed study of cooling dynamics based on computer codes is underway at Brookhaven National Laboratory. In this paper, we present an update on code development and its application to the high-energy cooling dynamics studies for RHIC. |
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| TPAT091 | IBS for Ion Distribution Under Electron Cooling | lattice, luminosity, emittance, simulation | 4263 | ||
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Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-98CH10886. |
Standard models of the intra-beam scattering (IBS) are based on the growth of the rms beam parameters for a Gaussian beam distribution. As a result of electron cooling, the core of beam distribution is cooled much faster than the tails, producing a denser core. Formation of such a core is an important feature since it plays dominant role in the luminosity increase. A simple use of standard rms-based IBS approach may significantly underestimate IBS for the beam core. A detailed treatment of IBS, which depends on individual particle amplitudes, was recently proposed by Burov,* with an analytic formulation done for a Gaussian distribution. However, during the cooling process the beam distribution quickly deviates from a Gaussian profile. To understand the extent of the dense core formation in the ion distribution, the "core-tail" model for IBS, based on the diffusion coefficients for bi-Gaussian distributions, was employed in cooling studies for RHIC. In addition, the standard IBS theory was recently reformulated for rms parameters growth of a bi-Gaussian distribution by Parzen.** In this paper, we compare various approaches to IBS treatment for such distribution. Its impact on the luminosity is also discussed. *A. Burov, FERMILAB-TM-2213 (2003). **G. Parzen, Tech Note C-AD/AP/150 (2004). |
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| TPAT092 | Numerical Studies of the Friction Force for the RHIC Electron Cooler | electron, simulation, plasma, space-charge | 4278 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy. |
Accurate calculation of electron cooling times requires an accurate description of the dynamical friction force. The proposed RHIC cooler will require ~55 MeV electrons, which must be obtained from an RF linac, leading to very high transverse electron temperatures. A strong solenoid will be used to magnetize the electrons and suppress the transverse temperature, but the achievable magnetized cooling logarithm will not be large. Available formulas for magnetized dynamical friction are derived in the logarithmic approximation, which is questionable in this regime. In this paper, we explore the magnetized friction force for parameters of the RHIC cooler, using the VORPAL code.* VORPAL can simulate dynamical friction and diffusion coefficients directly from first principles.** Various aspects of the friction force, such as dependence on magnetic field, scaling with ion charge number and others, are addressed for the problem of high-energy electron cooling in the RHIC regime. *C. Nieter & J.R. Cary, J. Comp. Phys. 196 (2004), p. 448. **D.L. Bruhwiler et al., Proc. 33rd ICFA Advanced Beam Dynamics Workshop (2004). |
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| TPAT093 | Operations and Performance of RHIC as a Cu-Cu Collider | luminosity, collider, emittance, background | 4281 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy. |
The 5th year of RHIC operations, started in November 2004 and expected to last till June 2005, consists of a physics run with Cu-Cu collisions at 100 GeV/u followed by one with polarized protons at 100 GeV. We will address here overall performance of the RHIC complex used for the first time as a Cu-Cu collider, and compare it with previous operational experience with Au, PP and asymmetric d-Au collisions. We will also discuss operational improvements, such as a ?* squeeze to 85cm in the high luminosity interaction regions from the design value of 1m, system improvements and machine performance limitations, such as vacuum pressure rise, intra-beam scattering, and beam beam interaction. |
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| TPAT094 | Luminescence Beam Profile Monitor for the RHIC Polarized Hydrogen Jet Polarimeter | proton, target, polarization, monitoring | 4293 | ||
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Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspicies of the US Deparment of Energy. |
This is the second polarized proton run in Relativistic Heavy Ion Collider (RHIC) with a new polarized proton jet target used to provide accurate polarization measurements. The interactions between the stored polarized protons with the polarized jet target will produce, in addition to polarization, optical signals due to exited states of Hydrogen or other molecules, ions, or atoms. Additional lenses, optical window, optical analyzer, and the CCD camera are added to the system to allow transfer and detection of optical signals from the interaction chamber. Oxygen or other elements (impurities) could be mixed within the jet target and affect the accuracy of the polarization measurements. It is important to have continuous information of the jet content without affecting the polarization measurements. The optical signals coming from the exited states of molecules, ions, and atoms from the polarized proton beam interaction with the jet will provide that. In addition, the beam profile might be obtained. |
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| TPAT095 | Beam Induced Pressure Rise at RHIC | electron, background, proton, luminosity | 4308 | ||
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Beam induced pressure rise in RHIC warm sections is currently one of the machine intensity and luminosity limits. This pressure rise is mainly due to electron cloud effects. The RHIC warm section electron cloud is associated with longer bunch spacings compared with other machines, and is distributed non-uniformly around the ring. In addition to the countermeasures for normal electron cloud, such as the NEG coated pipe, solenoids, beam scrubbing, bunch gaps, and larger bunch spacing, other studies and beam tests toward the understanding and counteracting RHIC warm electron cloud are of interest. These include the ion desorption studies and the test of anti-grazing ridges. For high bunch intensities and the shortest bunch spacings, pressure rises at certain locations in the cryogenic region have been observed during the past two runs. Beam studies are planned for the current 2005 run and the results will be reported.
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Work performed under the auspices of the US Department of Energy. |
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| TPAT097 | CLIC Drive Beam and LHC Based FEL-Nucleus Collider | collider, photon, electron, linac | 4320 | ||
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Funding: Ankara University, Ankara, TURKEY. |
Main parameters of CLIC-LHC based FEL-Nucleus collider are determined. The matching of beam structures for maximum luminosity is studied. The advantages of the collider with respect to the traditional Nuclear Resonance Fluorescence (NRF) methods are presented considering (/Gamma-/Gamma(prime)) reactions. Determination of unknown decay width, spin and parity of excited levels is discussed for Pb nucleus. |
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| TPPE003 | Analysis of Multigrid Extraction Plasma Meniscus Formation | plasma, electron, extraction, proton | 862 | ||
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Funding: INFN-LNL, CNR-RFX. |
Effects of plasma meniscus on the emittance in negative ion source proposed for spallation sources or neutral beam injectors (NBI) for tokamaks are particularly interesting to study with fluid models because: 1) at least three different charged fluid can be recognised: the thermalized and fully magnetized electrons; the slightly magnetized and roughly thermalized positive ions; the negative ions, typically formed within few cm from meniscus; 2) different implementation of the magnetic filter system need to be compared; 3) optimization of electron dump and outlet electrode strongly depends on plasma meniscus contact point. With reasonable assumption on system geometry, 2D and 3D charged fluid quation for the selfconsistent electrostatic field can be written and effect of grid aperture is investigated. Moreover, these equations are easily implemented into a multiphysics general purpose program. Preliminary results are described, and compared to existing codes. |
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| TPPE004 | The Production of Negative Lithium Beams by Charge Exchange in Cesium Vapours | target, electron, ion-source, vacuum | 898 | ||
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These measurements were carried out at the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory (ORNL-HRIBF) by researchers from the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), Catania, Italy and local staff. The Charge Exchange Cell (CEC) consisted of a vacuum chamber containing cesium vapours at a variable temperature, T, in which positive ions accelerated from an ion source were transformed into negative ones by collisions with the Cs atoms. The main goal of this test was to measure the production efficiency for 7Li- ions at different operating conditions, such as 7Li+ beam energy (5 to 55 keV) and Cs temperature (190 to 300 °C). Moreover, the efficiency measurements performed with a 6Li+ projectile beam gave clear indications about the isotopic shift effect. These results are useful to estimate the charge exchange efficiency for 8, 9Li, which will be the first radioactive beams to be produced at the EXCYT facility (EXotics with CYclotron and Tandem). The data showed that the charge exchange efficiency at the minimum energy suitable for beam handling (20-25 keV) is around 1%.
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| TPPE005 | 50keV, 50mA Pulsed Proton Injector for PEFP | proton, ion-source, extraction, rfq | 964 | ||
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Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government. |
Duoplasmatron type ion source with 50keV proton beam has been constructed and stably operated as the injector for Proton Engineering Frontier Project(PEFP). In DC operation, the beam current of 50mA with 50kV extraction voltage is routinely obtained. However, the pulsed operation mode of the ion source also has been considered to reduce beam induced damage at the entrance of RFQ. A high voltage pulse switch is connected between accelerating electrode and ground electrode for this purpose. The detailed scheme on the focusing of the pulsed proton beam with space charge compensation is in progress. Beam profile and current in front of RFQ will be measured by DCCT and optical measuring tools. |
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| TPPE006 | Radioactive Beams from 252CF Fission Using a Gas Catcher and an ECR Charge Breeder at ATLAS | shielding, ion-source, linac, beam-transport | 1000 | ||
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Funding: Department of Energy Office of Nuclear Science. |
An upgrade to the radioactive beam capability of the ATLAS facility has been proposed using 252Cf fission fragments thermalized and collected into a low-energy particle beam using a helium gas catcher. In order to reaccelerate these beams an existing ATLAS ECR ion source will be reconfigured as a charge breeder source. A 1Ci 252Cf source is expected to provide sufficient yield to deliver beams of up to ~106 far from stability ions per second on target. A facility description, the expected performance and the expected performance will be presented in this paper. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract W-31-109-ENG-38. |
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| TPPE010 | A Parallel 3D Model for the Multi-Species Low Energy Beam Transport System of the RIA Prototype ECR Ion Source VENUS | simulation, ion-source, beam-transport, extraction | 1183 | ||
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Funding: This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Nuclear Physics Division of the U.S. DOE under Contract DE AC03-76SF00098. |
The driver linac of the proposed Rare Isotope Accelerator (RIA) requires a great variety of high intensity, high charge state ion beams. In order to design and optimize the low energy beam line optics of the RIA front end, we have developed a new parallel three-dimensional model to simulate the low energy, multi-species beam transport from the ECR ion source extraction region to the focal plane of the analyzing magnet. A multi-section overlapped computational domain has been used to break the original transport system into a number of independent subsystems. Within each subsystem, macro-particle tracking is used to obtain the charge density distribution in this subdomain. The three-dimensional Poisson equation is solved within the subdomain and particle tracking is repeated until the solution converges. Two new Poisson solvers based on a combination of the spectral method and the multigrid method have been developed to solve the Poisson equation in cylindrical coordinates for the beam extraction region and in the Frenet-Serret coordinates for the bending magnet region. Some test examples and initial applications will also be presented. |
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| TPPE011 | A Compact High-Brightness Heavy-Ion Injector | emittance, plasma, heavy-ion, extraction | 1263 | ||
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Funding: This work has been performed under the auspices of the U.S. DOE by UC-LBNL under contract DE-AC03-76SF00098 and by UC-LLNL under contract W-7405-ENG-48, for the Heavy Ion Fusion Virtual National Laboratory. |
To provide compact high-brightness heavy-ion beams for Heavy Ion Fusion (HIF) accelerators, we have been experimenting with merging multi-beamlets in an injector which uses an RF plasma source. In an 80-kV 20-microsecond experiment, the RF plasma source has produced up to 5 mA of Ar+ in a single beamlet. An extraction current density of 100 mA/cm2 was achieved, and the thermal temperature of the ions was below 1 eV. More than 90% of the ions were in the Ar+ state, and the energy spread from charge exchange was found to be small. We have tested at full voltage gradient the first 4 gaps of a 61-beamlet injector design. Einzel lens were used to focus the beamlets while reducing the beamlet to beamlet space charge interaction. We will report on a converging 119 multi-beamlet source. Although the source has the same optics as a full 1.6 MV injector system, the test will be carried out at 400 kV due to the test stand HV limit. We will measure the beam’s emittance after the beamlets are merged and have been transported through an electrostatic quadrupole. Our goal is to confirm the emittance growth and to demonstrate the technical feasibility of building a driver-scale HIF injector. |
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| TPPE012 | Using the Orbit Tracking Code Z3CYCLONE to Predict the Beam Produced by a Cold Cathode PIG Ion Source for Cyclotrons under DC Extraction | emittance, plasma, ion-source, cyclotron | 1297 | ||
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Experimental measurements of the emittance and luminosity of beams produced by a cold-cathode Phillips Ionization Guage (PIG) ion source for cyclotrons under dc extraction are reviewed. (The source being studied is of the same style as ones that will be used in a series of 250 MeV proton cyclotrons being constructed for cancer therapy by ACCEL Inst, Gmbh, of Bergisch Gladbach, Germany.) The concepts of 'plasma boundary' and 'plasma temperature' are presented as a useful set of parameters for describing the initial conditions used in computational orbit tracking. Experimental results for r-pr and z-pz emittance are compared to predictions from the MSU orbit tracking code Z3CYCLONE with results indicating that the code is able to predict the beam produced by these ion sources with adequate accuracy such that construction of actual cyclotrons can proceed with reasonably prudent confidence that the cyclotron will perform as predicted.
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| TPPE015 | The Effusive-Flow Properties of Target/Vapor-Transport Systems for Radioactive Ion Beam Applications | target, ion-source, cathode, electron | 1422 | ||
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Funding: Research at ORNL is supported by the U.S. DOE under contract DE-AC05-00OR22725 with UT-Battelle, LLC. |
Radioactive atoms produced by the ISOL technique must diffuse from a target, effusively flow to an ion source, be ionized, be extracted, and be accelerated to research energies in a time commensurate with the lifetime of the species of interest. We have developed a fast valve system (closing time ~100 us) that can be used to accurately measure the effusion times of chemically active or inactive species through arbitrary geometry and size vapor transport systems with and without target material in the reservoir. The effusive flow times are characteristic of the system and thus serve as figures of merit for assessing the quality of a given vapor transport system as well as for assessing the permeability properties of a given target design. This article presents effusive flow data for noble gases flowing through a target reservoir and ion source system routinely used to generate radioactive species at the HRIBF with and without disks of 6 times and 10 times compressed Reticulated Vitreous Carbon Foam (RVCF) with the objective of determining the added delay time associated with each of these target matrices. |
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| TPPE016 | ISOL Targets Prepared with a New Paint Infiltration Coating Method | target, vacuum, electron | 1508 | ||
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Funding: Research at ORNL is supported by the U.S. DOE under contract DE-AC05-00OR22725 with UT-Battelle, LLC. |
A new infiltration paint coating method has been developed for fabricating ISOL targets for radioactive ion beam applications. The technique has been shown to be inexpensive, fast, and almost universal for the uniform deposition of many refractory target materials onto the interior surfaces of complex geometry matrices, such as Reticulated-Vitreous-Carbon-Foam (RVCF). The process yields robust, highly permeable targets with fast diffusion and release properties. We demonstrate the viability of the technique for coating forms of RVCF compressed by factors of 6 and 10 with materials to form targets for use at high energy facilities such as RIA. The use of compressed RVCF, coated with an optimum thickness of target material, reduces target lengths to practical values, while preserving high permeability. We calculate thermal conductivities and diffusion for various targets on 6xRVCF and 10xRVCF. |
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| TPPE017 | A New Broadband Microwave Frequency Device for Powering ECR Ion Sources | ion-source, radiation, injection, electron | 1529 | ||
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Funding: Research at ORNL is supported by the U.S. DOE under contract DE-AC05-00OR22725 with UT-Battelle, LLC. |
The multiple discrete frequency technique has been used to improve the performance of conventional B-field configuration ECR ion sources. However, the practical application of this technique is very costly, requiring multiple independent single-frequency rf power supplies and complicated rf injection systems. Broadband sources of rf power offer a low-cost and more effective method for increasing the physical size of the ECR zone within these ion sources. An Additive White Gaussian Noise Generator (AWGNG) system for injecting broadband rf power into these ion sources has been developed in conjunction with a commercial firm. The noise generator, in combination with an external oscillator and a traveling wave tube amplifier, can be used to generate broadband rf power without modifying the injection system. The AWGNG and its use for enhancing the performance of conventional B-field configuration ECR ion sources will be described. |
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| TPPE018 | Characterization of a Tubular Hot-Cavity Surface Ionization Source | target, ion-source, plasma, emittance | 1581 | ||
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Funding: Managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC05-00OR22725. |
Elements with low ionization potentials can be efficiently ionized by positive surface ionization. It has been experimentally observed and theoretically shown that the ionization efficiency in a hot-cavity can be significantly higher than expected for the surface ionization mechanism. This is explained by the existence of a thermal plasma inside the cavity consisting of surface ionized ions and thermionic electrons. We have investigated the suggested ioniation mechanisms in a tubular hot-cavity surface ionization source where the area of the exit aperture is small compared with the tube inner surface. Thermal analyses of the tubular cavity and calculated mean number of wall collisions of a neutral particle in the cavity before escaping through the exit aperture are presented. Measured emittance and ionization efficiencies of various elements as a function of the cavity temperature for different cavity materials are discussed. |
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| TPPE019 | Laser Ion Source Development for ISOL Systems at RIA | laser, ion-source, target, radiation | 1640 | ||
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Funding: Managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC05-00OR22725. |
The isobaric purity of radioactive ion beams (RIBs) is of crucial importance to many experiments. Laser ion sources based on resonant photoionization have already proved to be of great value at existing ISOL RIB facilities. In these ion sources, ions of a selected isotope are produced by laser radiation via stepwise atomic resonant excitations followed by ionization in the last transition. Because each element has its own unique atomic energy levels, the resonant photoionization process can provide elemental selectivity of nearly 100%. We have initiated a research effort to develop a prototype laser ion source with the potential to achieve the high selectivity and high efficiency required for research with ISOL-generated RIBs at the Rare Isotope Accelerator (RIA). A pilot experiment has been conducted to demonstrate resonant photoionization of three atomic species using all-solid-state tunable Ti:Sapphire lasers. Three Ti:Sapphire lasers were provided by the University of Mainz and used in the experiment for three-photon resonant ionization of the elements. Laser generated Sn, Ni, and Ge ions have been successfully obtained in a hot-cavity laser ion source with overall efficiencies of 22%, 2.7%, and 3.3%, respectively. |
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| TPPE021 | Simulation Studies of Diffusion-Release and Effusive-Flow of Short-Lived Radioactive Isotopes | target, simulation, ion-source, vacuum | 1739 | ||
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Funding: Research supported by the U.S. DOE under contract DE-AC05-00OR22725 with UT-Battelle, LLC. |
Delay times associated with diffusion release from targets and effusive-flow transport of radioactive isotopes to ion sources are principal intensity limiters at ISOL-based radioactive ion beam facilities, and simulation studies with computer models are cost effective methods for designing targets and vapor transport systems with minimum delay times to avoid excessive decay losses of short lived ion species. A finite difference code, Diffuse II, was recently developed at the Oak Ridge National Laboratory to study diffusion-release of short-lived species from three principal target geometries. Simulation results are in close agreement with analytical solutions to Fick’s second equation. Complementary to the development of Diffuse II, the Monte-Carlo code, Effusion, was developed to address issues related to the design of fast vapor transport systems. Results, derived by using Effusion, are also found to closely agree with experimental measurements. In this presentation, the codes will be used in concert to make realistic estimations of intensities of a number of short-lived isotopes that are candidates for use in future nuclear physics and nuclear astrophysics experiments at the HRIBF. |
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| TPPE022 | First Results on the Path Towards a Microwave-Assisted H- Ion Source | ion-source, plasma, electron, SNS | 1784 | ||
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Funding: This work supported by Office of Basic Energy Sciences, U.S. Department of Energy under Contract No. DE-AC03-76SF00098. |
A novel concept for creating intense beams of negative hydrogen ion beams is presented. In this approach, an ECR ion source operating at 2.45 GHz frequency is utilized as a primary plasma generator and coupled to an SNS-type multi-cusp H- ion source. The secondary source is driven by chopped dc power avoiding the use of filaments or of an internal rf antenna. The development of the new ion source is aimed at the future beam-power goal of 3 MW for the Spallation Neutron Source (SNS) that will be pursued after the start of SNS operations, but application to other proton driver accelerators that include an accumulator ring is feasible as well. The first two phases of this development effort have been successfully completed: assembly of a test stand and verification of the performance of an rf-driven SNS ion-source prototype; and extraction of electrons with more than 350 mA current from a 2.45-GHz ECR ion source obtained on loan from Argonne National Laboratory. The next goal is the demonstration of actual H- ion production by this novel, hybrid ion source. This paper describes the source principle and design in detail and reports on the current status of the development work. |
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| TPPE023 | Development and Performance of a Proton and Deuteron ECR Ion Source | proton, ion-source, emittance, simulation | |||
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A 5mA proton and deuteron rf source is under development at ACCEL. This source will provide the front end of our superconducting proton/deuteron linear accelerator. The design of the source is based on the proven AECL design of a 100 mA proton source. The paper will describe the design of the source and the layout of the test bench currently set up at ACCEL to characterize the source. Results of the beam dynamic simulations performed to optimize the source geometry based on KOBRA 3D will be presented and compared with first measurement results.
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| TPPE025 | Separating the Penning and Analysing Fields in the ISIS H- Ion Source | emittance, ion-source, vacuum, extraction | 1910 | ||
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Funding: This work was supported by the European Union High Performance Negative Ion Source (HP-NIS) network, contract number HPRI-CT-2001-50021. |
The development of H- ion sources with performances exceeding those achieved today is a key requirement for the next generation of high power proton accelerators. The Penning surface plasma source development program at ISIS is now well established. To allow different ion source designs to be fully tested, the ability to vary the Penning field is required. Until now the Penning field has been generated by the same magnetic circuit that creates the analyzing field, giving no practical way of altering the Penning field alone. This paper describes the infrastructure changes required to allow the Penning field to be independently varied. The effect the Penning field has on beam current, emittance and discharge stability are discussed. |
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| TPPE027 | Properties of Laser-Produced Highly Charged Heavy Ions for Direct Injection Scheme | laser, plasma, target, rfq | 1976 | ||
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To accelerate highly charged intense ion beam, we have developed the Direct Plasma Injection Scheme (DPIS) with laser ion source. In this scheme an ion beam from a laser ion source is injected directly to a RFQ linac without a low energy beam transport (LEBT) and the beam loss in the LEBT can be avoided. We achieved high current acceleration of carbon ions (60mA) by DPIS with the high current optimized RFQ. As the next setp we will use heavier elements like Ag, Pb, Al and Cu as target in LIS (using CO2, Nd-YAG or other laser) for DPIS and will examine properties of laser-produced plasma (the relationship of between charge state and laser power density, the current dependence of the distance from the target, etc).
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| TPPE028 | In-Situ Electron Cyclotron Resonance (ECR) Plasma Potential Determination Using an Emissive Probe | plasma, electron, ion-source, monitoring | 2035 | ||
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Funding: This research was sponsored by the U.S. DOE under contract No. DE-AC05-00OR22725 with UT-Battelle, LLC. HJY acknowledges support from the Korean Science Education Foundation (KOSEF). |
In this paper, real-time, in-situ, plasma potential measurements are reported for an ECR ion source and correlated with extracted beam characteristics. The local real-time plasma potential of the ORNL CAPRICE ECR ion source was measured using an emissive probe, which was inserted perpendicularly from the plasma chamber wall at the mid-plane of the ECR zone between one of the six radial loss cones of the magnetic field structure, where perturbation of the main ECR plasma is expected to be small. Slots machined through the plasma- and puller-electrodes at the plasma chamber wall radius permitted insertion of the probe from the extraction side of the ECR source without perturbation of the coaxial microwave injection. The emissive probe technique permits plasma potential determination independent of plasma conditions and avoids problems related to probe geometry. The probe loop tip was pointed toward the chamber center in a radial plane and was located about 5 mm outside of the ECR zone. Details of the measurements, and a comparison with an external-beam-deceleration-based plasma potential determination will be presented. |
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| TPPE029 | Measurements of Ion Selective Containment on the RF Charge Breeder Device BRIC | electron, extraction, simulation, vacuum | 2065 | ||
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Funding: Istituto Nazionale Fisica Nucleare. |
The "charge state breeder" BRIC (BReeding Ion Charge) is based on an EBIS source and it is designed to accept Radioactive Ion Beam (RIB) with charge +1, in a slow injection mode, to increase their charge state up to +n. BRIC has been developed at the INFN section of Bari (Italy) during these last 3 years with very limited funds. Now, it has been assembled at the LNL (Italy) where are in progress the first tests as stand alone source. The new feature of BRIC, with respect to the classical EBIS, is given by the insertion, in the ion drift chamber, of a Radio Frequency (RF) Quadrupole aiming to filtering the unwanted elements and then making a more efficient containment of the wanted ions. In this contribution, the measurements of the selective effect on the ion charge state containement of the RF quadrupole field, applied on the ion chamber, will be reported and discussed. The ion charge state analisys of the ions trapped in BRIC seem confirm, as foreseen by simulation results carried out previously, that the selective containment can be obtained. A modification of the collector part to improve the ion extraction of BRIC will be also presented and shortly discussed. |
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| TPPE031 | 60 mA Carbon Beam Acceleration with DPIS | rfq, plasma, laser, injection | 2206 | ||
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We have studied "direct plasma injection scheme (DPIS)" since 2000. This new scheme is for producing very intense heavy ions using a combination of an RFQ and a laser ion source. An induced laser plasma goes directly into the RFQ without an extraction electrode nor any focusing devices. Obtained maximum peak current of Carbon 4+ beam reached 60 mA with this extremely simple configuration. The details of the experimental result will be presented.
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| TPPE032 | Particle-in-Cell Simulations of the VENUS Ion Beam Transport System | simulation, extraction, ion-source, beam-transport | 2236 | ||
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Funding: This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Nuclear Physics Division of the U.S. DOE under Contract DE AC03-76SF00098 |
The next-generation superconducting ECR ion source VENUS serves as the prototype injector ion source for the linac driver of the proposed Rare Isotope Accelerator (RIA). The high-intensity heavy ion beams required by the RIA driver linac present significant challenges for the design and simulation of an ECR extraction and low energy ion beam transport system. Extraction and beam formation take place in a strong (up to 3T) axial magnetic field, which leads to significantly different focusing properties for the different ion masses and charge states of the extracted beam. Typically, beam simulations must take into account the contributions of up to 30 different charge states and ion masses. Two three-dimensional, particle-in-cell codes developed for other purposes, IMPACT and WARP, have been adapted in order to model intense, multi-species DC beams. A discussion of the differences of these codes and the advantages of each in the simulation of the low energy beam transport system of an ECR ion source is given. Direct comparisons of results from these two codes as well as with experimental results from VENUS are presented. |
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| TPPE033 | A Comparison of Electrostatic and Magnetic Focusing of Mixed Species Heavy Ion Beams at NSCL/MSU | sextupole, focusing, cyclotron, quadrupole | 2281 | ||
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Funding: This work has been supported by National Science Foundation under grant PHY-0110253. |
Experience at the National Superconducting Cyclotron Laboratory has shown the first focusing element after the electron cyclotron resonance ion source (ECRIS), before the beam is analyzed by a magnetic dipole, to be critical to subsequent beam transport and matching. Until 2004, both ion sources at the NSCL used a solenoid as this first focusing element. Observation of hollow beam formation led to further analysis and the decision to replace the solenoid with an electrostatic quadrupole triplet on a test basis [1]. Substantial increases in net cyclotron output were achieved, leading us to adopt electrostatic quadrupole focusing as the permanent configuration. In addition, a sextupole magnet was installed in this beam line. Motivations for these changes and results of operating experience are discussed. |
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| TPPE034 | Possible Scheme of the Analyzing Part of a Cyclotron Injection Beamline with Higher Energy | emittance, focusing, injection, vacuum | 2345 | ||
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Funding: This work was supported in part by the National Science Foundation under grant PHY-0110253. |
The ion beam produced with an ECR ion source (ECRIS) with an extraction voltage of 30 kV may be additionally accelerated using a negative voltage of -30 kV applied to the last electrode of the extraction system, connected to the beamline biased to the same -30 kV potential. In this way the kinetic energy of the beam is increased to 60 keV/q, decreasing to half the space charge effect on the beam emittance. Using a large gap analyzing magnet placed right after the ECRIS and no focusing element, the transmission is still close to 100%. The voltage on the beamline must be kept constant from the ECRIS till the image focal plane of the analyzing magnet where the full separation of the beam charge states is achieved. An insulator break separates the biased beamline from the downstream section, which is at zero potential. Passing through this section of the beamline, the ion beam is decelerated to 30 keV/q, the energy necessary for the injection in the cyclotron. In order to prevent the increase of the beam divergence, a focusing solenoid is installed behind the break point. This work will present the results of a simulation of the transport of an argon beam in the proposed beamline. |
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| TPPE037 | Relative Contribution of Volume and Surface-Plasma Generation of Negative Ions in Gas Discharges | plasma, electron, ion-source, cathode | 2482 | ||
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The relative contribution of volume and surface-plasma generation of extracted ?- ions in gas discharge sources will be analyzed. At the present time, it is well known that surface-plasma generation of extracted ?- ion is dominate above volume processes in discharges with admixture of cesium or other catalysts with low ionization potential. We will attract attention to evidences, that surface-plasma generation can be enhanced in high density discharges without cesium after electrode activation by high temperature conditioning in discharge. A diffusion of impurity with a low ionization potential can be a reason of observed enhancement of H- emission. For the effective generation of ?- ion beams in discharge without cesium, it is necessary to optimize surface-plasma generation of extracted ?- ion. Such optimization allows considerable improvement of ?-/D- sources characteristics.
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| TPPP015 | ELIC at CEBAF | electron, collider, luminosity, emittance | 1437 | ||
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Funding: Work supported by DOE Contract DE-AC05-84ER40150. |
We report on the progress of the conceptual development of the energy recovering linac (ERL)-based Electron-Light Ion Collider (ELIC) at CEBAF that is envisioned to reach luminosity level of 1033-1035 /cm2s with both beams polarized to perform a new class of experiments in fundamental nuclear physics. Four interaction points with all light ion species longitudinally or transversally polarized and fast flipping of the spin for all beams are planned. The unusually high luminosity concept is based on the use of the ERL and circulator ring-based electron cooling and crab crossing colliding beams. Our recent studies concentrate on the design of low beta interaction points with crab-crossing colliding beams, the exploration on raising the polarized electron injector current to the level of 3-30 mA with the use of electron circulator-collider ring, forming a concept of stacking and cooling of the ion beams, specifications of the electron cooling facility, and studies of beam-beam interaction and intra-beam scattering. |
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| TPPP019 | Collective Effects in Lepton Ring of eRHIC | electron, lepton, impedance, positron | 1628 | ||
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Funding: Department of Energy. |
The eRHIC is a new generation lepton-hadron collider undergoing design studies by a collaboration of BNL, MIT, DESY and BINP. The collider complex will consist of a hadron machine that is mainly the existing RHIC with necessary upgrades, and a new lepton machine that can provide intense, highly polarized electron and positron beams at energy of 5-10 GeV. The ring-ring option of eRHIC is to build a 5-10 GeV electron ring with a injector chain. In this paper the beam lifetime of lepton beams is calculated. |
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| TPPP022 | The eRHIC Ring-Ring Collider Design | electron, polarization, proton, luminosity | 1766 | ||
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The eRHIC ring-ring collider is the main design option of the future lepton-ion collider at Brookhaven National Laboratory. We report the revisions of the ring-ring collider design features to the baseline design presented in the eRHIC Zeroth Design Report (ZDR). These revisions have been made during the past year. They include changes of the interaction region which are required from the modifications in the design of the main detector. They also include changes in the lepton storage ring for high current operations as a result of better understandings of beam-beam interaction effects. The updated collider luminosity and beam parameters also take into account a more accurate picture of current and future operational aspects of RHIC.
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| TPPP043 | ERL Based Electron-Ion Collider eRHIC | electron, proton, luminosity, collider | 2768 | ||
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Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy. |
We present the designs of a future polarized electron-hadron collider, eRHIC* based on a high current super-conducting energy-recovery linac (ERL) with energy of electrons up to 20 GeV. We plan to operate eRHIC in both dedicated (electron-hadrons only) and parallel(with the main hadron-hadron collisions) modes. The eRHIC has very large tunability range of c.m. energies while maintaining very high luminosity up to 1034 cm-2 s-1 per nucleon. Two of the most attractive features of this scheme are full spin transparency of the ERL at all operational energies and the capability to support up to four interaction points. We present two main layouts of the eRHIC, the expected beam and luminosity parameter, and discuss the potential limitation of its performance. *http://www.agsrhichome.bnl.gov/eRHIC/, Appendix A: Linac-Ring Option. |
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| TPPT022 | The Structure of the High Frequency Focusing Cells in Linear Ion Accelerators | focusing, quadrupole, acceleration, proton | 1796 | ||
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The versions of the high frequency quadrupole doublets (RFQD) for proton and heavy ion linear accelerators are discussed. Advantages of focusing of this type over magnetic quadrupoles lie in the simplicity of the structure and high efficiency and reliability of focusing. In the multi-gap structures, focusing periods contain a sequence of focusing and accelerating cells. The elaborated technique of the local cell adjustment provides the high acceleration rate. Various RFQD versions for the specific peculiarities of accelerating structures are discussed. Application of the RF-quadrupole doublets in the spoke cavity, CCDTL and Crossbar structures will allow the application of superconductive cavities for proton acceleration in the range of intermediate energies of 5-100 MeV. In the interdigital H-structures, the application of RFQDs will allow to increase the efficiency of ion beam focusing and to expand the energy range of the ions being accelerated over 10 MeV/u.
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| TPPT025 | Breakdown in RF Cavities | vacuum, lattice, site, target | 1886 | ||
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Funding: DOE |
We present a simple model of breakdown in rf cavities. For most events this involves tensile stress and tensile strength, however other effects can also contribute. We discuss the effects of different materials, fatigue, high pressure gas, primary and secondary emission sites, local field enhancements, dark currents, secondary emission, work functions, magnetic fields, macro and microscopic fracture mechanisms high current densities, surface and subsurface defects, and astronomical power densities. While primarily devoted to normal conductors, this work also has consequences for superconducting rf surfaces. |
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| TPPT033 | Simulations Using the VORPAL Code of Electron Impact Ionization Effects in Waveguide Breakdown Processes | electron, simulation, plasma, space-charge | 2298 | ||
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Funding: Supported by Department of Energy SBIR Grant No. DE-FG03-02ER83554. |
We present results of three-dimensional simulations using the VORPAL code of power absorbtion by stray electrons in X-band waveguides. These simulations include field emission from the waveguide surfaces, impact ionization of background gas, and secondary emission from the walls. We discuss the algorithms used for each of these electron effects. We show the power abosrbed as a function of background gas density. Finally, we present scaling results for running these simulations on Linux Clusters. |
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| TPPT052 | Cryogenic, Magnetic and RF Performance of the ISAC-II Medium Beta Cryomodule at TRIUMF | alignment, acceleration, target, coupling | 3191 | ||
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The medium beta section of the ISAC-II Heavy Ion Accelerator consists of five cryomodules each containing four quarter wave resonators and one superconducting solenoid. The first cryomodule has been designed, assembled and cold tested at TRIUMF. The cryomodule vacuum space shares the cavity vacuum and contains a mu-metal shield, an LN2 cooled, copper thermal shield, plus the cold mass and support system. The bulk niobium cavities are fitted with an LN2 cooled coupling loop fed in series from the side thermal shield and a tuner plate coupled to an out-of-vacuum linear servo motor. All cavities have been locked at the ISAC-II frequency and gradient for extended periods. This paper will report the cryogenic and rf test results from the three cold tests. Of note are measurements of the magnetic field in the cryomodule and estimations of changes in the magnetic field during the test due to trapped flux in the solenoid and magnetization of the environment.
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| TPPT057 | Quality Control of the Electro Polishing Process at DESY | superconductivity, synchrotron, power-supply | 3369 | ||
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Funding: Supported by the European Community Research activity Care under the FP 6 program(RII3-CT-2003-506395). |
The technology of electro-polishing of super-conducting resonators made from Niobium is foreseen as basic surface preparation technology for the Xfel accelerator project at DESY. Here about 1000 resonators will be build and installed into the accelerator section. For an industrial application of this technique a quality control has to be developed and established.A method to control the acid quality and improve the life time of the acid is under development. We report on the test setup and measurements done on samples and the implementation of this quality control to the DESY electro polishing process. |
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| TPPT061 | Prototyping of a 352 MHz, beta=0.17 Superconducting Coaxial Half Wave Resonator | linac, proton, heavy-ion, vacuum | 3547 | ||
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We have designed a 352 MHz superconducting coaxial half wave resonator with beta=0.17. The cavity has a mechanical design similar to the LNL beta=0.31 one developed in 2004. It is very compact (232 mm real-estate length) and it is equipped with a side tuner not exposed to liquid helium, to make it insensitive to pressure fluctuations. Operation is foreseen at 4.2 K. The beta=0.17 cavity fills the gap from 5 to ~25 MeV between the LNL proton RFQ, under construction, and and the existing beta=0.31 half wave resonator. This allows a 5¸100 MeV proton linac working at 352 MHz with 2 types of coaxial HWR cavities with large velocity acceptance, thus able to accelerate also other ion species (e.g. deuterons). A similar scheme was previously proposed for Spoke resonators; the aim of the HWR choice is compactness and cost reduction. The beta=0.17 cavity is presently under construction in the SPES R&D program at LNL; first test results are expected by the end of 2005.
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| TPPT084 | Surface Study of Nb/Cu Films for Cavity Deposition by ECR Plasma | vacuum, electron, superconductivity, plasma | 4153 | ||
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Funding: This manuscript has been authorized by SURA, Inc. under Contract No. DE-AC05-84ER-40150 with the U.S. Department of Energy. |
Deposition of thin niobium (Nb) films on copper (Cu) cavities, using an electron cyclotron resonance (ECR) plasma appears to be an attractive alternative technique for fabricating superconducting radio frequency cavities to be used in particle accelerators. The performance of these Nb/Cu cavities is expected to depend on the surface characteristics of the Nb films. In this paper, we report on an investigation of the influence of deposition energy on surface morphology, microstructure, and chemical composition of Nb films deposited on small Cu disks employing a metallographic optical microscope, a 3-D profilometer, a scanning electron microscope, and a dynamic secondary ion mass spectrometer. The results will be compared with those obtained on Nb surfaces treated by buffered chemical polishing, electropolishing, and buffered electropolishing. Possible implications from this study for Nb deposition on real Cu cavities will be discussed. |
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| TPPT085 | Niobium Thin Film Coating on a 500-MHz Copper Cavity by Plasma Deposition | plasma, vacuum, superconductivity, power-supply | 4167 | ||
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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. |
A system for the deposition, using an ECR plasma source, of a thin film of niobium inside a copper cavity for superconducting accelerator applications has been designed and is being constructed. The system uses a 500-MHz copper cavity as the substrate and the vacuum chamber. The ECR plasma will be created to produce direct niobium ion deposition. The central cylindrical grid is biased to realize the energy controlled deposition. This report describes the design of several subcomponents including the vacuum chamber, RF supply, biasing grid and magnet coils. Operational parameters are compared between a working small-sample deposition system and this system. Initial plasma simulation also suggested that plasma ignition in this cavity system is feasible. |
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| TPPT100 | Superconducting Triple-Spoke Cavity for Beta = 0.5 Ions | linac, coupling, superconductivity, vacuum | 4344 | ||
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Funding: This work was supported by the U.S. Department of Energy under contract no. W-31-109-ENG-38. |
This paper reports results of cold tests of a 345 MHz, three-spoke-loaded TEM-class superconducting niobium cavity being developed for the RIA driver linac and for other high-intensity ion linac applications. The cavity has a beam aperture of 4 cm diameter, an interior length of 67 cm, and the transit-time factor peaks at beta = v/c = 0.5. In tests at 4.2 K, the cavity could be operated cw above the nominal design accelerating gradient of 9.3 MV/m, which corresponds to peak surface fields of 27.5 MV/m electric and 826 gauss magnetic. At this gradient the cavity provides more than 6 MV of accelerating potential. The cavity Q at 9.3 MV/m exceeded the nominal performance goal of 7.3E8. Operation at the design gradient at 4.2 K causes substantial boiling and two-phase flow in the liquid helium coolant, with the potential for microphonic-induced fluctuations of the rf frequency. Total microphonic eigenfrequency fluctuations were measured to be less than 1 Hz RMS in cw operation at 9.7 MV/m at 4.2 K. |
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| TOPA007 | Proton Acceleration and High-Energy Density Physics from Laser Foil Interactions | proton, target, acceleration, electron | 573 | ||
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Intense laser plasma interactions have long been shown to be a source of very energetic ions - from the first experiments in the 1970's. However, there has been a recent revival of interest in the production of protons and ions from the such plasmas - primarily from the observation of collimated beams of protons and heavier ions which were observed at the rear thin foil targets irradiated by ultra-high intensity laser pulses (such that I > 1018 W/cm2). These ion beams have unique properties which may make them suitable for a variety of applications such as for probing high density plasmas, for fast ignition in inertial confinement fusion, as an ion source for subsequent acceleration stages in a particle accelerator or potentially for medical applications. Recent experimental results will be reviewed and the potential for such future applications will be highlighted.
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| TOPD001 | SC Cyclotron and RIB Facilities in Kolkata | cyclotron, target, linac, rfq | 89 | ||
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The superconducting cyclotron under construction at this Centre has bending limit (K-bend) of 520 and focusing limit (K-foc) of 160. It is being constructed, primarily, for nuclear physics experiments with heavy ion beams at intermediate energies. The 100-ton main magnet is currently in the commissioning phase with the main coil already at 4.2K temperature. Magnetic field measurements will be carried out over the next several months. All other systems of the cyclotron are in an advanced stage of fabrication or development. We plan to start assembly of the complete cyclotron around the end of 2005. In the phase-I of the project one beam line has been provided. Construction of three more beam lines and various experimental facilities for nuclear physics as well as irradiation experiments has also been funded and the work is well on its way. An ISOL type Radioactive Ion Beam (RIB) facility is being built with the existing K=130 room temperature cyclotron, VEC, as the primary beam source. In-beam RIB production as well as release measurements have been initiated using the VEC beam. The two-ion-source charge breeder consists of a surface ion source and a 6.4 GHz ECR source. The latter has been commissioned. A low beta RFQ to accelerate RIBs to 86 keV/u energy is being fabricated and the cold model tests completed. Design of first three linac tanks, for acceleration up to 400 keV/u, has been finalized and cold model for the first tank has been fabricated. In this talk status of both the projects will be presented.
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| TOPD003 | Cooler Storage Ring at China Institute of Modern Physics | dipole, heavy-ion, injection, lattice | 271 | ||
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CSR, a new ion cooler-storage-ring project in China IMP, is a double ring system, and consists of a main ring (CSRm) and an experimental ring (CSRe). The two existing cyclotrons SFC (K=69) and SSC (K=450) of the Heavy Ion Research Facility in Lanzhou (HIRFL) will be used as its injector system. The heavy ion beams with the energy range of 7–30 MeV/nucleus from the HIRFL will be accumulated, cooled and accelerated to the higher energy range of 100–500 MeV/ nucleus in CSRm, and then extracted fast to produce radioactive ion beams or highly charged heavy ions. Those secondary beams will be accepted and stored or decelerated by CSRe for many internal-target experiments or high precision spectroscopy with beam cooling. On the other hand, the beams with the energy range of 100–1000MeV/ nucleus will also be extracted from CSRm by using slow extraction or fast extraction for many external-target experiments. CSR project was started in the end of 1999 and will be finished in 2006. In this paper the outline and the activities of the project will be described.
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| TOPD004 | RIB Facility at VECC Kolkata–A Status Report | target, rfq, linac, ion-source | 395 | ||
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The status of the Radioactive Ion Beam (RIB) facility being built at VECC, Kolkata will be presented. The facility is being built around the existing K=130 cyclotron and will be installed in one of the existing experimental caves. The scheme is to use proton and alpha particles from the cyclotron on a thick production target placed inside an integrated surface ion-source. Radioactive ions with charge state q=1+ extracted from the target-ion-source are to be injected into an on-line ECRIS "charge breeder" for further ionization to q=n+. The 1keV/u, q/A=1/16, RIB of interest will be selected in an isotope separator downstream of the ECRIS and accelerated initially to about 86 keV/u in a Radio Frequency Quadrupole (RFQ) linac and subsequently to about 400 keV/u in three IH-Linac tanks. Since RIB development is R&D intensive, it has been decided to build at first all the basic building blocks and to carry out simultaneously thick target R&D and release measurements using the existing He-jet ISOL facility. Future expansion for further upgradation of energy has been planned. The design of the facility and some recent results will be presented.
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| WPAE010 | Neutron Flux and Activation Calculations for a High Current Deuteron Accelerator | vacuum, target, ion-source, simulation | 1192 | ||
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Neutron analysis of the first Neutral Beam (NB) for the International Thermonuclear Experimental Reactor (ITER) was performed to provide the basis for the study of the following main aspects: personnel safety during normal operation and maintenance, radiation shielding design, transportability of the NB components in the European countries. The first ITER NB is a medium energy light particle accelerator. In the scenario considered for the calculation the accelerated particles are negative deuterium ions with maximum energy of 1 MeV. The average beam current is 13.3 A. To assess neutron transport in the ITER NB structure a mathematical model of the components geometry was implemented into MCNP computer code (MCNP version 4c2. "Monte Carlo N-Particle Transport Code System." RSICC Computer Code Collection. June 2001). The neutron source definition was outlined considering both D-D and D-T neutron production. FISPACT code (R.A. Forrest, FISPACT-2003. EURATOM/UKAEA Fusion, December 2002) was used to assess neutron activation in the material of the system components. Radioactive inventory and contact dose rate were assessed considering the potential operative scenarios.
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| WPAE016 | Development of a Precision Amplifier for the Detector | synchrotron, synchrotron-radiation, radiation, feedback | 1514 | ||
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A high gain trans-resistance amplfier has been developed for measuring the intensity of synchrotron radiation at Pohang Light Source(PLS). This amplifier built with discrete elements and operational amplifiers.It had the capability of measuring range from 1pA to 1 uA with good linearity. A microprocessor was also installed to interface the amplifier with the computer, and controlled the other sub-circuits. The various characteristics of amplifier such as linearity, sensitivity,stability, etc. have been investigated, and its experimental results carried out at the beam line are presented in this paper.
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| WPAE031 | Mechanical Design of a Heavy Ion Beam Dump for the RIA Fragmentation Line | radiation, dipole, heavy-ion, vacuum | 2185 | ||
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The RIA fragmentation line requires a beam stop for the primary beam downstream of the first dipole magnet. The beam may consist of U, Ca, Sn, Kr, or O ions. with a variety of power densities. The configuration with highest power density is for the U beam, with a spot size of 3 cm x 3 cm and a total power of up to 300 kW. The mechanical design of the dump that meets these criteria consists of a 50 cm diameter aluminum wheel with water coolant channels. A hollow drive shaft supplies the coolant water and connects the wheel to an electrical motor located in an air space in the floor above the dump. The beam strikes the wheel along the outer perimeter and passes through a thin window of aluminum where 10% of its power is absorbed and the remainder of the beam is absorbed in flowing water behind the window. Rotation of the wheel at 400 RPM results in maximum aluminum temperatures below 100 C and acceptably low thermal stresses of 5 ksi. Rotating the wheel also results in low radiation damage levels by spreading the damage out over the whole perimeter of the wheel. For some of the other beams, a stationary dump consisting of a thin aluminum window with water acting as a coolant and absorber appears to be feasible.
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| WPAE041 | Development of a New Beam Diagnostics Platform | laser, diagnostics, vacuum, SNS | 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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| WPAE053 | Neutronics Assessments for a RIA Fragmentation Line Beam Dump Concept | multipole, radiation, heavy-ion, proton | 3227 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under Contract W-7405-Eng-48. |
Heavy ion and radiation transport calculations are in progress for conceptual beam dump designs for the fragmentation line of the proposed Rare Isotope Accelerator (RIA). Using the computer code PHITS, a preliminary design of a motor-driven rotating wheel beam dump and adjacent downstream multipole has been modeled. Selected results of these calculations are given, including neutron and proton flux in the wheel, absorbed dose and displacements per atom in the hub materials, and heating from prompt radiation and from decay heat in the multipole. |
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| WPAE054 | Irradiation Effects on RIA Fragmentation Cu Beam Dump | heavy-ion, radiation, target, simulation | 3265 | ||
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Funding: U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under Contract W-7405-Eng-48. |
Within the scope of conceptual R&D activities in support of the Rare-Isotope Accelerator (RIA) facility, high priority is given to the development of high-power fragmentation beam dumps. A pre-study was made of a static water-cooled Cu beam dump that can meet requirements for a 400 MeV/u uranium beam. The issue of beam sputtering was addressed and found to be not a significant issue. Preliminary radiation transport simulations show significant damage (dpa) in the vicinity of the Bragg peak of uranium ions. Experimental data show that defects in Cu following neutron or high-energy particle irradiation tend to saturate at doses between 1 and 5 dpa, and this saturation in defect density also results in saturation of mechanical property degradation. However, effects of swift heavy ion irradiation and the production of gaseous and solid transmutant elements still need to be addressed. Initial calculations indicate that He concentrations on the order of 100 appm are produced in the beam dump after several weeks of continuous operation and He embrittlement should be a concern. Recommendations are made for further investigation of Cu irradiation effects RIA-relevant conditions. |
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| WPAE062 | AC Power Supply for Wobbler Magnet of the MC-50 Cyclotron | power-supply, cyclotron, target, radiation | 3576 | ||
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The MC-50 cyclotron (k=50) produces the ion beam for nuclear physics, chemistry, and applied researches in Korea. It has a small beam diameter with Gaussian beam shape, whereas many users want a beam irradiation on a large target. A wobbler magnet and an AC power supply were designed and constructed to meet the users’ requirement. The power supply has two independently operating channels for the vertical and horizontal coils of the wobbler magnet. The frequency of the AC power supply for both coils is programmable from 1 to 20 Hz in a step of 1 Hz, and the maximum rms output current is 12 A. Various properties of the power supply and experimental results are given in the paper.
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| WPAP023 | Compact Source of Electron Beam with Energy of 200 kEv and Average Power of 2 kW | electron, focusing, power-supply, radiation | 1832 | ||
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The paper describes a compact electron beam source with average electron energy of 200 keV. The source operates with pulse power up to 2 MW under average power not higher than 2 kW, pulsed beam current up to 10 A, pulse duration up to 2 mks, and repetition rate up to 5 kHz. The electron beam is extracted through aluminium-beryllium alloy foil. The pulse duration and repetition rate can be changed from control desk. High-voltage generator for the source with output voltage up to 220 kV is realized using the voltage-doubling circuit which consists of 30 sections. The insulation type - gas, SF6 under pressure of 8 atm. The cooling of the foil supporting tubes is provided by a water–alcohol mixture from an independent source. The beam output window dimensions are 180?75 mm, the energy spread in the beam +10/-30%, the source weight is 80 kg.
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| WPAP042 | Progress on Using NEA Cathodes in an RF Gun | gun, electron, cathode, simulation | 2708 | ||
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Funding: This work was supported by Universities Research Association Inc. under contract DE-AC02-76CH00300 with the U.S. DOE and by NICADD. AES personnel were supported under DOE SBIR contract #DE-FG02-04ER838. |
RF guns have proven useful in multiple accelerator applications, and are an attractive electron source for the ILC. Using a NEA GaAs photocathode in such a gun allows for the production of polarized electron beams. However the lifetime of a NEA cathode in this environment is reduced by ion and electron bombardment and residual gas oxidation. We report progress made with studies to produce a RF gun using a NEA GaAs photocathode to produce polarized electron beams. Attempts to reduce the residual gas pressure in the gun are discussed. Initial measurements of ion flux through the cathode port are compared with simulations of ion bombardment. Future directions are also discussed. |
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| WPAP045 | Ion Back-Bombardment of GaAs Photocathodes Inside DC High Voltage Electron Guns | laser, vacuum, electron, gun | 2875 | ||
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Funding: This work was supported by U.S. DOE Contract No. DE-ACO5-84-ER40150. |
The primary limitation for sustained high quantum efficiency operation of GaAs photocathodes inside DC high voltage electron guns is ion back-bombardment of the photocathode. This process results from ionization of residual gas within the cathode/anode gap by the extracted electron beam, which is subsequently accelerated backwards to the photocathode. The damage mechanism is believed to be either destruction of the negative electron affinity condition at the surface of the photocathode or damage to the crystal structure by implantation of the bombarding ions. This work characterizes ion formation within the anode/cathode gap for gas species typical of UHV vacuum chambers (i.e., hydrogen, carbon monoxide and methane). Calculations and simulations are performed to determine the ion trajectories and stopping distance within the photocathode material. The results of the simulations are compared with test results obtained using a 100 keV DC high voltage GaAs photoemission gun and beamline at currents up to 10 mA DC. |
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| WPAP049 | A High-Gradient CW RF Photo-Cathode Electron Gun for High Current Injectors | cathode, gun, coupling, emittance | 3049 | ||
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Funding: This manuscript has been authored by SURA, Inc. under Contract No. DE-AC05-84ER-40150 with the U.S. Department of Energy. |
The paper describes the analysis and preliminary design of a high-gradient photo-cathode RF gun optimized for high current CW operation. The gun cell shape is optimized to provide maximum acceleration for the newly emitted beam while minimizing wall losses in the structure. The design is intended for use in future high-current high-power CW FELs but the shape optimization for low wall losses may be advantageous for other applications such as XFELs or Linear Colliders using high peak power low duty factor guns where pulse heating is a limitation. The concept allows for DC bias on the photocathode in order to repel ions and improve cathode lifetime. |
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| WPAT014 | Sequence Control System of 1-MW CW Klystron for the PEFP | klystron, power-supply, rfq, proton | 1401 | ||
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Funding: Work support by the PEFP(Proton Engineering Frontier Project), Korea. |
Sequence control system of 1-MW CW klystron for the PEFP (Proton Engineering Frontier Project) has been developed in order to drive the 1-MW klystron amplifier. The system is able to control several power supplies and many environment conditions. The hardware of sequence control and the interlock system are based on the Allen-Bradley's SLC500 Program Logic Controller (PLC). Also the system can be controlled by a touch screen at local mode or Ethernet network with high level HMI at remote mode. |
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| WPAT018 | The LEIR RF System | impedance, resonance, coupling, acceleration | 1619 | ||
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The lead-lead physics program of LHC relies on major changes of the CERN ion injector chain. In this framework, the conversion of LEAR (low energy antiproton ring) into the Low Energy Ion Ring (LEIR) is central and implies a new accelerating system covering a wide frequency range (0.35 - 5 MHz,) with a moderate voltage (4 kV). For this purpose two new wide-bandwidth cavities, loaded with Finemet® magnetic alloy cores, have been built in collaboration with KEK. Two 60 kW RF power amplifiers have also been built and the RF systems are now installed in the LEIR ring. They individually cover the whole frequency range without tuning and allow multi-harmonic operation. The design has been guided by need of safety margins, reliability and ease of maintenance. Some design aspects are presented as well as the performance achieved.
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| WPAT030 | Upgrade of the ATLAS Positive Ion Injector Bunching System | feedback, pick-up, bunching, linac | 2161 | ||
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Over the last few years, significant efforts were concentrated on improving the ATLAS Positive Ion Injector (PII) RF bunching system, consisting of a four-harmonic pre-buncher, Traveling Wave Chopper (TWC) and a single-frequency sinusoidal re-buncher. The primary goal was to improve RF field stability with a redesigned RF system and to improve buncher performance for higher current beams resulting in better bunch stability and time structure at the first PII superconducting resonator. The major parts of the system were redesigned and rebuilt, including the RF 12 – 48 MHz amplifiers for the harmonic pre-buncher and re-buncher, RF driver rack for the TWC, and the RF control chassis for both the pre-buncher and re-buncher. The four-harmonic resonant structure of the harmonic buncher itself was modified, too, mainly for better mechanical stability and better RF matching. These improvements will be described and the performance of the new system presented.
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| WPAT069 | Development of a Solid State RF Amplifier in the kW Regime for Application with Low Beta Superconducting RF Cavities | simulation, booster, insertion, monitoring | |||
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Projects based on the use of low beta superconducting cavities for ions are under operation or development at several labs worldwide. Often these cavities are individually driven by RF power sources in the kW regime. For an ongoing project a modular 2 kW, 176 MHz unconditionally stable RF amplifier for CW and pulsed operation was designed, built, and tested. Extended thermal analysis was used to develop a water cooling system in order to optimize the performance of the power transistors and other thermally loaded components. The paper will outline the design concept of the amplifier and present first results on the test of the amplifier with a superconducting cavity.
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| WPAT082 | An Improved Pneumatic Frequency Control for Superconducting Cavities | vacuum, feedback, pick-up, heavy-ion | 4090 | ||
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Funding: U.S. Department of Energy. |
The ATLAS (Argonne Tandem Linear Accelerator System) superconducting cavities use a pneumatic system to maintain the cavity eigenfrequency at the master oscillator frequency. The present pneumatic slow tuner control has a limitation in the tuning slew rates. In some cases, the frequency slew rate is as low as 30 Hz/sec. The total tuning range for ATLAS cavities varies from 60 KHz to as high as 450 KHz depending on the cavity type. With the present system, if a cavity is at the extreme end of its tuning range, it may take an unacceptable length of time to reach the master oscillator frequency. We have designed a new slow tuner control system that increases the frequency slew rates by at least a factor of ten to a factor of three hundred in the more extreme cases. This improved system is directly applicable for use on the RIA (Rare Isotope Accelerator) cavities. This paper discusses the design of the system and the results of a prototype test. |
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| WOAB008 | CANDLE Project Overview | brightness, storage-ring, photon, impedance | 629 | ||
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CANDLE is a 3 GeV energy synchrotron light facility project in the Republic of Armenia. The main design features of the new facility are given. The results of the beam physics study in the future facility are overviewed including the machine impedance, ion trapping, single and multi-bunch instabilities, beam lifetime etc. The main requirements to the magnetic, RF and vacuum systems are discussed. The report includes the status of the project and the nearest R&D plans.
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| ROAC007 | RF Breakdown in Normal Conducting Single-cell Structures | electron, vacuum, simulation, linear-collider | 595 | ||
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Funding: Work supported by the U.S. Department of Energy contract DE-AC02-76SF00515. |
Operating accelerating gradient in normal conducting accelerating structures is often limited by rf breakdown. The limit depends on multiple parameters, including input rf power, rf circuit, cavity shape and material. Experimental and theoretical study of the effects of these parameters on the breakdown limit in full scale structures is difficult and costly. We use 11.4 GHz single-cell traveling wave and standing wave accelerating structures for experiments and modeling of rf breakdown behavior. These test structures are designed so that the electromagnetic fields in one cell mimic the fields in prototype multicell structures for the X-band linear collider. Fields elsewhere in the test structures are significantly lower than that of the single cell. The setup uses matched mode converters that launch the circular TM01 mode into short test structures. The test structures are connected to the mode launchers with vacuum rf flanges. This setup allows economic testing of different cell geometries, cell materials and preparation techniques with short turn-around time. Simple 2D geometry of the test structures simplifies modeling of the breakdown currents and their thermal effects. |
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| ROAC008 | Atom Probe Tomography Studies of RF Materials | superconducting-RF, target, vacuum, instrumentation | 612 | ||
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Funding: DOE |
We are constructing a facility which combines an atom probe field ion microscope with a multi-element, in-situ deposition and surface modification capability. This system is dedicated to rf studies and the initial goal will be to understand the properties of evaporative coatings: field emission, bonding interdiffusion etc, to suppress breakdown and dark currents in normal cavities. We also hope to use this system to look more generally at interactions of surface structure and high rf fields. We will present preliminary data on structures relevant to normal and superconducting rf systems. |
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| RPAE017 | Radially Polarized Ion Channel Laser | bunching, radiation, betatron, electron | 1526 | ||
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Radially polarized radiation is amplified by a free electron laser (FEL) in which the undulator is an ion channel with uniform density. For long betatron wavelengths and low gain per pass, the gain at a given distance from the axis is three-eighths the gain of a periodic ion channel laser with the same wiggler parameter. For amplification of short wavelengths by an ultrarelativistic electron beam, a uniform-density ion channel requires a much higher ion density than a periodic ion channel laser.
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| RPAP004 | Simulations for the Frankfurt Funneling Experiment | simulation, rfq, beam-transport, linac | 901 | ||
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Funding: BMBF |
Beam simulations for the Frankfurt Funneling Experiment are done with RFQSim and FUSIONS. RFQSim is a particle dynamic program to compute macro particle bunches in the 6D phase space through a RFQ accelerator. Behind the RFQ the simulation software FUSIONS calculates both beam lines through a r.f. funneling deflector. To optimise beam transport of existing and new funneling deflector structures FUSIONS is presently being developed. The status of the development of FUSIONS and the results will be presented. |
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| RPAP008 | The CBS–The Most Cost Effective and High Performance Carbon Beam Source Dedicated for a New Generation Cancer Therapy | extraction, electron, synchrotron, injection | 1108 | ||
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A Carbon ion beam is a superior tool to x-rays or a proton beam in both physical and biological doses in treating a cancer. A Carbon beam has an advantage in treating radiation resistant and deep-seated tumors. Its radiological effect is of a mitotic independent nature. These features improve hypofractionation, typically reducing the number of irradiations per patient from 35 to a few. It has been shown that a superior QOL(Quality Of Life) therapy is possible by a carbon beam.The only drawback is its high cost. Nevertheless, tens of Prefectures and organizations are eagerly considering the possibility of having a carbon ion therapy facility in Japan. Germany, Austria, Italy, China, Taiwan and Korea also desire to have one.A carbon beam accelerator of moderate cost is about 100 Million USD. With the "CBS" design philosophy, which will be described in this paper, the cost could be factor of 2 or 3 less, while improving its performance more than standard designs. Novel extraction techniques, a new approach to a high intensity beam, a new scanning method of a superμbeam and an extremely light weight carbon rotating gantry will be presented.This new CBS will have an impact on the medical accelerator community.
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| RPAP020 | Fixed Field Alternating Gradient Accelerators (FFAG) for Fast Hadron Cancer Therapy | proton, resonance, acceleration, cyclotron | 1667 | ||
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Funding: * AMS supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF0009 |
Cancer accelerator therapy continues to be ever more prevalent with new facilities being constructed at a rapid rate. Some of these facilities are synchrotrons, but many are cyclotrons and, of these, a number are FFAG cyclotrons. The therapy method of "spot scanning” requires many pulses per second (typically 200 Hz), which can be accomplished with a cyclotron (in contrast with a synchrotron). We briefly review commercial scaling FFAG machines and then discuss recent work on non-scaling FFAGs, which may offer the possibility of reduced physical aperture and a large dynamic aperture. However, a variation of tune with energy implies the crossing of resonances during the acceleration process. A design can be developed such as to avoid intrinsic resonances, although imperfection resonances must still be crossed. Parameters of two machines are presented; a 250 MeV proton therapy accelerator and a 400 MeV carbon therapy machine. |
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| RPAP023 | RF-Based Accelerators for HEDP Research | linac, extraction, focusing, target | 1829 | ||
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Funding: This work sponsored by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. |
Accelerator-driven High-Energy Density Physics experiments require typically 1 nanosecond, 1 microcoulomb pulses of mass 20 ions accelerated to several MeV to produce eV-level excitations in thin targets, the "warm dense matter" regime. Traditionally the province of induction linacs, RF-based acceleration may be a viable alternative with recent breakthroughs in accelerating structures and high-field superconducting solenoids. A reference design for an RF-based accelerator for HEDP research is presented using 15 T solenoids and multiple-gap RF structures configured with either multiple parallel beams (combined at the target) or a single beam and a small stacking ring that accumulates 1 microcoulomb of charge. In either case, the beam is ballistically compressed with an induction linac core providing the necessary energy sweep and injected into a plasma-neutralized drift compression channel resulting in a 1 mm radius beam spot 1 nanosecond long at a thin foil or low-density target. |
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| RPAP024 | The ORNL Multicharged Ion Research Facility (MIRF) High Voltage Platform Project | ion-source, permanent-magnet, electron, beam-transport | 1853 | ||
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Funding: This research was sponsored by the Office of Basic Energy Sciences, and the Office of Fusion Energy Sciences of the U.S. DOE under contract No. DE-AC05-00OR22725 with UT-Battelle, LLC. |
We report on initial testing and implementation of a new high voltage platform recently installed at the ORNL MIRF. The platform is powered by a 250 kV, 30 kVA isolation transformer and features an all permanent magnet Electron Cyclotron Resonance (ECR) ion source, designed and fabricated at CEA/Grenoble, that utilizes microwave power levels of up to 750W in the frequency range 12.75 – 14.5 GHz to provide intense dc beams of singly and multiply charged ions for acceleration to energies up to 270 x q keV. The primary application of these ion beams is to study fundamental collisional interactions* of multicharged ions with electrons, atoms, and surfaces. More applied investigations in the area of ion implantation,** and ion beam development for use in semiconductor doping operations are carried out as well. Design details of the HV platform and the associated beamline-switchyard will be presented at the conference, together with performance characteristics of the all permanent magnet ECR source, of the beam transport from ion source to end-station, and of a novel electrostatic spherical sector beam switcher for directing beam to the various on-line experiments. *F.W . Meyer, Trapping Highly Charged Ions: Fundamentals and Applications, J. Gillaspy, ed., Nova Science Pub., New York, 2000, pp. 117-164. **F. W. Meyer et al., AIP Conf. Proc. 635, p. 125 (2002). |
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| RPAP039 | Accelerator and Ion Beam Tradeoffs for Studies of Warm Dense Matter | target, emittance, plasma, chromatic-effects | 2568 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy under University of California contract W-7405-ENG-48 at LLNL, University of California contract DE-AC03-76SF00098 at LBNL, and contract DEFG0295ER40919 at PPPL. |
One approach to heat a target to "Warm Dense Matter" conditions (similar, for example, to the interiors of giant planets or certain stages in Inertial Confinement Fusion targets), is to use intense ion beams as the heating source. By consideration of ion beam phase space constraints, both at the injector, and at the final focus, and consideration of simple equations of state, approximate conditions at a target foil may be calculated. Thus target temperature and pressure may be calculated as a function of ion mass, ion energy, pulse duration, velocity tilt, and other accelerator parameters. We examine the variation in target performance as a function of various beam and accelerator parameters, in the context of several different accelerator concepts, recently proposed for WDM studies. |
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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-source, diagnostics, 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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| RPAP043 | Beam-Based Alignment in the RHIC eCooling Solenoids | alignment, quadrupole, electron, proton | 2771 | ||
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Funding: U.S. DOE. |
Accurate alignment of the electron and ion beams in the RHIC electron cooling solenoids is crucial for well-optimized cooling. Because of the greatly differing rigidities of the electron and ion beams, to achieve the specified alignment accuracy it is required that transverse magnetic fields resulting from imperfections in solenoid fabrication be down by five orders of magnitude relative to the pure solenoid fields. Shimming the solenoid field to this accuracy might be accomplished by survey techniques prior to operation with beam, or by methods of beam-based alignment. We report on the details of a method of beam-based alignment, as well as the results of preliminary measurements with the ion beam at RHIC |
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| RPAP045 | Development of Laser-Induced Fluorescence Diagnostic for the Paul Trap Simulator Experiment | ion-source, laser, diagnostics, 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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| RPAT001 | Experimental Results of a Non-Destructive Emittance Measurement Device for H- Beams | emittance, laser, simulation, dipole | 782 | ||
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For the diagnostic of high power ion beams, non-destructive measurement devices should not only provide minimum influence on the beam itself, but also avoid various problems that occur when the high power density of the beam penetrates surfaces like slit- or pinhole plates. On the other hand, measurements of resolution should be comperable with destructive methods. Beams of negative ions offer the use of a non-destructive Emittance Measurement Instrument (EMI) based on the principle of photo detachment. Interaction of laser photons with the negative ions causes electron detachment. Due to moving the postion of the well collimated laser beam acros the ion beam the produced neutral atoms are well suited to detect the transverse beam emittance like a classical slit-grid device. After separation in a magnetic dipole, the neutrals can be viewed on a scintillator screen with a CCD camera. To investigate the use of such a photo detachment EMI and to study the transport of negative ions an experiment consisting of H minus ion source, electrostatic LEBT and EMI was constructed. The paper will present the setup of the experimental hardware and first results of measurements.
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| RPAT002 | Production of Inorganic Thin Scintillating Films for Ion Beam Monitoring Devices | proton, monitoring, diagnostics, 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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| RPAT022 | Optical Faraday Cup for Heavy Ion Beams | heavy-ion, diagnostics, 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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| RPAT027 | Tomographic Measurement of Longitudinal Emittance Growth Due to Stripping Foils | emittance, booster, heavy-ion, electron | 2000 | ||
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Funding: Work performed under the auspices of the US Department of Energy. |
During beam acceleration at the Brookhaven accelerator complex, heavy ions are stripped off their electrons in several steps. Depending on the properties of the stripping foils, this process results in an increased energy spread and therefore longitudinal emittance growth. A tomographic phase space reconstruction technique has been applied to quantify the associated emittance growth for different stripping foil materials. |
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| RPAT032 | An Ionization Profile Monitor for the Tevatron | vacuum, electron, injection, collider | 2227 | ||
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Funding: Work supported by the U.S. Department of Energy. |
Primarily to study emittance blowup during injection and ramping, an ionization profile monitor has been developed for the Tevatron. It is based on a prototype installed in the Main Injector, although with extensive modifications. In particular, the electromagnetic shielding has been improved, the signal path has been cleaned up, and provisions have been made for an internal electron source. Due to the good Tevatron vacuum, a local pressure bump is introduced to increase the primary signal, which is then amplified by a microchannel plate and detected on anode strips. For the DAQ, a custom ASIC developed for the CMS experiment is used. It is a combined charge integrator and digitizer, with a sensitivity of a few fC, and a time-resolution that allows single bunch measurement. Digitization is done in the tunnel to reduce noise. Preparations for detector installation were made during the long 2004 shutdown, with the installation of magnets, vacuum chambers, vacuum pumps and cabling. The actual detector will be installed sometime during the spring fo 2005. This paper describes the design of the detector and associated electronics and presents various bench test results. |
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| RPAT042 | Emittance Scanner Optimization for Low Energy Ion Beams | emittance, scattering, SNS, proton | 2705 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. |
Ion beam emittances are normally measured as two-dimensional distributions of the beam current fraction within a window dx centered at position coordinate x and a window dx’ centered at trajectory angle x’. Unthresholded rms emittances evaluated from experimental data are very sensitive to noise, bias, and other undesired signals. Undesired signals occur when particles from outside the measured window dx*dx’ contribute to the signal from the particles within the measured window. Increasing the window size increases the desired signal while most undesired contributions remain unchanged. However, the decreasing resolution causes an error in the emittance results, especially in the rms emittance. Using theoretical distributions we will present the tradeoff between resolution and accuracy. |
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| ROAB001 | DARHT-II Long-Pulse Beam-Dynamics Experiments | induction, electron, vacuum, background | 19 | ||
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Funding: This work was supported by the U.S. National Nuclear Security Agency and the U.S. Department of Energy under contract W-7405-ENG-36. |
When completed, the DARHT-II linear induction accelerator (LIA) will produce a 2-kA, 18-MeV electron beam with more than 1500-ns current/energy "flat-top." In initial tests DARHT-II has already accelerated beams with current pulse lengths from 500-ns to 1200-ns full-width at half maximum (FWHM) with more than1.2-kA, 12.5-MeV peak current and energy. Experiments are now underway with a ~2000-ns pulse length, but reduced current and energy. These pulse lengths are all significantly longer than any other multi-MeV LIA, and they define a novel regime for high-current beam dynamics, especially with regard to beam stability. Although the initial tests demonstrated absence of BBU, the pulse lengths were too short to test the predicted protection against ion-hose instability. The present experiments are designed to resolve these and other beam-dynamics issues with a ~2000-ns pulse length beam. |
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| ROAB003 | Highly Compressed Ion Beams for High Energy Density Science | target, plasma, heavy-ion, acceleration | 339 | ||
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Funding: Work performed under auspices of USDOE by U. of CA LLNL & LBNL, PPPL, and SNL, under Contract Nos. W-7405-Eng-48, DE-AC03-76SF00098, DE-AC02-76CH03073, and DE-AC04-94AL85000, and by MRC and SAIC. |
The Heavy Ion Fusion Virtual National Laboratory (HIF-VNL) is developing the intense ion beams needed to drive matter to the High Energy Density (HED) regimes required for Inertial Fusion Energy (IFE) and other applications. An interim goal is a facility for Warm Dense Matter (WDM) studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target "foils," which may in fact be foams or "steel wool" with mean densities 1% to 100% of solid. This approach complements that being pursued at GSI, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the requirements for warm dense matter experiments, and describe suitable accelerator concepts, including novel broadband traveling wave pulse-line, drift-tube linac, RF, and single-gap approaches. We show how neutralized drift compression and final focus optics tolerant of large velocity spread can generate the necessarily compact focal spots in space and time. |
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| ROAB004 | Ion Effects in the DARHT-II Downstream Transport | septum, simulation, target, ion-effects | 375 | ||
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Funding: Work supported by US NNSA/DOE. |
The DARHT-II accelerator produces an 18-MeV, 2-kA, 2-μs electron beam pulse. After the accelerator, the pulse is delivered to the final focus on an x-ray producing target via a beam transport section called the Downstream Transport. Ions produced due to beam ionization of residual gases in the Downstream Transport can affect the beam dynamics. Ions generated by the head of the pulse will cause modification of space-charge forces at the tail of the pulse so that the beam head and tail will have different beam envelopes. They may also induce ion-hose instability at the tail of the pulse. If these effects are significant, the focusing requirements of beam head and tail at the final focus will become very different. The focusing of the complete beam pulse will be time dependent and difficult to achieve, leading to less efficient x-ray production. In this paper, we will describe the results of our calculations of these ion effects at different residual-gas pressure levels. Our goal is to determine the maximum residual-gas pressure allowable in DARHT-II Downstream Transport such that the required final beam focus is achievable over the entire beam pulse under these deleterious ion effects. |
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| ROAB005 | Helical Pulseline Structures for Ion Acceleration | acceleration, vacuum, coupling, induction | 440 | ||
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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 Berkeley National Laboratory, Contract DE-AC03-76SF00098. |
The basic concept of the "Pulseline Ion Accelerator" involves launching a ramped high voltage pulse on a broad band traveling wave (slow-wave) structure. An applied voltage pulse at the input end with a segment rising linearly in time becomes a linear voltage ramp in space that propagates down the line, corresponding to a (moving) region of constant axial accelerating electric field. The ions can "surf" on this traveling wave, experiencing a total energy gain that can greatly exceed the peak of the applied voltage. The applied voltage waveform can also be shaped to longitudinally confine the beam against its own space charge forces, and (in the final stage) to impart an inward compression to the beam for neutralized drift compression in heavy ion HEDP applications. In the first stages of a heavy ion accelerator, the pulseline velocity needs to be the order of 1% of the speed of light and the line must be sufficiently non-dispersive for the broad band voltage pulse propagating down the line to have minimal distortion. Experimental characterization of the dispersion and pulse propagation at low voltage on several helix models will be presented, and compared with theoretical predictions.* *Caporaso, et al, "Dispersion Analysis of the Pulseline Accelerator," this conference. |
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| ROPB002 | Experiments Studying Desorbed Gas and Electron Clouds in Ion Accelerators | electron, quadrupole, diagnostics, 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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| ROPB005 | Recent Experiment Results on Fast Ion Instability at 2.5 GeV PLS | vacuum, simulation, storage-ring, damping | 466 | ||
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We present recent experiment results on the fast ion instability that were performed at the PLS storage ring. With higher vacuum pressures of three orders of magnitude than nominal one by He gas injection into the ring, increases of a factor of around three in the vertical beam size were observed by interferometer system. From the various measurement results, we estimated growth times for the instability as a funcion of vacuum pressure and beam current. We also compared the results with those of the computer simulations and analytical calculations.
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| ROPB006 | Filling in the Roadmap for Self-Consistent Electron Cloud and Gas Modeling | electron, simulation, quadrupole, heavy-ion | 525 | ||
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Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California, LLNL and LBNL under contracts W-7405-Eng-48, and DE-AC03-76F00098. |
Electron clouds and gas pressure rise limit the performance of many major accelerators. A multi-laboratory effort to understand the underlying physics via the combined application of experiment,* theory, and simulation is underway. We present here the status of the simulation capability development, based on a merge of the three-dimensional parallel Particle-In-Cell accelerator code WARP and the electron cloud code POSINST, with additional functionalities.** The development of the new capability follows a "roadmap" describing the different functional modules, and their inter-relationships, that are ultimately needed to reach self-consistency. Newly developed functionalities include a novel particle mover bridging the time scales between electrons and ions motion.*** Samples of applications of the new capability to the modeling of intense charge dominated beams**** and LHC beams***** will be shown as available. *A.W. Molvik, these proceedings. **J.-L. Vay, Proc. "ECLOUD04," Napa (California), 2004. ***R.H. Cohen, these proceedings. ****P.A. Seidl, these proceedings. *****M.A. Furman, these proceedings. |
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| RPPE005 | Ions for LHC: Beam Physics and Engineering Challenges | electron, injection, luminosity, linac | 946 | ||
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The first phase of the heavy ion physics program at the LHC aims to provide lead-lead collisions at energies of 5.5 TeV per colliding nucleon pair and ion-ion luminosity of 1027 cm-2s-1. The transformation of CERN’s ion injector complex (Linac3-LEIR-PS-SPS) presents a number of beam physics and engineering challenges. Conversion of the Low Energy Antiproton Ring (LEAR) to a Low Energy Ion Ring (LEIR) is under way: the high-current electron cooling system, novel broad-band RF cavities and vacuum equipment to achieve 10-12 mbar are the major challenges. Commissioning of LEIR with beam will start in the middle of 2005. Major hardware changes in Linac3 include the installation of the new ECR ion source and of the energy ramping cavity. The PS will have a new injection system and RF gymnastics. A stripping insertion between PS and SPS must not disturb the proton operation. In the LHC itself, there are fundamental performance limitations due to various beam loss mechanisms. To study these without risk of damage there will be an initial period of operation with a reduced number of nominal intensity bunches. While reducing the work required to commission the LHC with ions in 2008, this will still enable early physics discoveries.
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| RPPE030 | Corrugated Thin Diamond Foils for SNS H- Injection Stripping | SNS, lattice, Spallation-Neutron-Source, injection | 2152 | ||
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Funding: MEP acknowledges a SURE fellowship, supported by Science Alliance, a UT Center of Excellence. RNP acknowledges an appointment to the U.S. DOE SULI Program at the Oak Ridge National Laboratory. SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a collaboration of six US National Laboratories: ANL, BNL, TJNAF, LANL, LBNL, and ORNL. |
We have prepared and tested corrugated, thin diamond foils for use in stripping the SNS H- Linac beam. Diamond has shown promise for providing ca. 10X increased lifetime over traditional carbon foils. The preferred foil geometry is 10.5 by 20 mm at 350 microgram/cm2, mechanically supported on preferably one, but no more than two, edges. The foils are prepared by chemical vapor deposition (CVD) on a patterned silicon substrate, followed by chemical removal of the silicon. This yields a foil with trapezoidal corrugations to enhance mechanical strength and foil flatness. Both micro- and nano-crystalline diamond foils have been grown. Microwave plasma CVD methods that incorporate high argon gas content were used to produce the latter. Sixteen foils of a variety of characteristics have been tested using the BNL 750 keV RFQ H- beam to simulate the energy deposition in the SNS foil. Long foil lifetimes, up to more than 130 hours, have been demonstrated. Characterization of the foils after beam testing indicates creation of sp2 defects within the ion beam spot. Current efforts are centered on development of corrugation patterns that will enhance flatness of single-edge supported foils. |
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| RPPE034 | Measurements of the Energy Deposition Profile for 238U Ions with Energy 500 and 950 MEV/U in Stainless Steel and Copper Targets | target, heavy-ion, energy-calibration, vacuum | 2318 | ||
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Funding: Supported by the grant of the GSI-INTAS #03-54-3588. |
Sub-millimeter wall thickness is foreseen for the vacuum tubes in the magnets of the superconducting dipoles of the SIS100 and SIS300 of the FAIR Project. The Bragg peak of the energy deposition by the U ions in these walls may lie dangerously close to the superconducting cables. Thus the precise knowledge of the dE/dx profile is essential for estimating the heat load by the lost ions in the vicinity of the superconducting wires. Here we present the results of the measurement of the U ion beam energy deposition profile in Cu and stainless steel targets and compare the measured data with the Monte-Carlo simulation using the SHIELD code. |
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| RPPE041 | Design and Construction of the CERN LEIR Injection Septa | septum, vacuum, injection, cathode | 2690 | ||
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The Low Energy Ion Ring (LEIR) transforms long pulses from Linac 3 into high brilliance ion bunches for LHC by means of multi-turn injection, electron cooling and accumulation. The LEIR injection comprises a magnetic DC septum followed by an inclined electrostatic septum. The electrostatic septum has been newly designed and built. The magnetic septum is mainly recovered from the former LEAR machine, but required a new vacuum chamber. Dynamic vacua in the 10-12 mbar range are required, which are hard to achieve due to the high desorption rate of ions lost on the surface. A new interlock and displacement control system has also been developed. The major technical challenges to meet the magnetic, electrical and vacuum requirements will be discussed.
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| RPPE047 | Upgrade of RHIC Vacuum Systems for High Luminosity Operation | vacuum, electron, injection, luminosity | 2977 | ||
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Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the U.S. Department of Energy. |
With increasing ion beam intensity during recent RHIC operations, pressure rises of several decades were observed at most room temperature sections and at a few cold sections. The pressure rises are associated with electron multi-pacting, electron stimulated desorption and beam ion induced desorption and have been one of the major intensity and luminosity limiting factors for RHIC. Improvement of the warm sections has been carried out in the last few years. Extensive in-situ bakes, additional UHV pumping, anti-grazing ridges and beam tube solenoids have been implemented. Several hundred meters of NEG coated beam pipes have been installed and activated. Vacuum monitoring and interlock were enhanced to reduce premature beam aborts. Preliminary measures, such as pumping before cool down to reduce monolayer condensates, were also taken to suppress the pressure rises in the cold sections. The effectiveness of these measures in reducing the pressure rises during machine studies and during physics runs are discussed and summarized. |
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| RPPE050 | Development of NEG Coating for RHIC Experimental Beamtubes | cathode, vacuum, electron, luminosity | 3120 | ||
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Funding: Work performed under Contract No. DE-AC02-98CH10886 under the auspices of the U.S. Department of Energy. |
As RHIC beam intensity increases beyond original scope, pressure rises in some regions have been observed. The luminosity limiting pressure rises are associated with electron multi-pacting, electron stimulated desorption and beam induced desorption. Non-Evaporable Getter (NEG) coated beampipes have been proven effective to suppress pressure rise in synchrotron radiation facilities. Standard beampipes have been NEG coated by a vendor and added to many RHIC UHV regions. BNL is developing a cylindrical magnetron sputtering system to NEG coat special beryllium beampipes installed in RHIC experimental regions. It features a hollow, liquid cooled cathode producing power density of 500W/m and deposition rate of 5000 Angstrom/hr on 7.5cm OD beampipe. The cathode, a titanium tube partially covered with zirconium and vanadium ribbons, is oriented for horizontal coating of 4m long chambers. Ribbons and magnets are arranged to provide uniform sputtering distribution and deposited NEG composition. Vacuum performance of NEG coated pipes was measured. Coating analysis includes energy dispersive spectroscopy, auger electron spectroscopy and scanning electron microscopy. System design, development, and analysis results are presented. |
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| RPPE051 | NEG Pumping Strip Inside Tevatron B2 Magnets | vacuum, power-supply, storage-ring | 3144 | ||
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Funding: DOE |
NEG pumping strips were installed inside four Tevatron B2 Magnets in order to improve the vacuum environment in B2 magnets that have embedded unbakable vacuum chamber. The prelimary results shown the total presure in that region was significant reduced. Complelte testing and opertation results will be available soon. |
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| RPPE065 | Beam Loss Ion Chamber System Upgrade for Experimental Halls | radiation, target, beam-losses, monitoring | 3650 | ||
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Funding: Work supported by: U.S. DOE Contract No DE-AC05-84ER4015. |
The Beam loss Ion Chamber System (BLICS) was developed to protect Jefferson Labs transport lines, targets and beam dumps from a catastrophic "burn through." Range changes and testing was accomplished manually requiring the experiment to be shut down. The new upgraded system is based around an "off the shelf" Programmable Logic Controller located in a single controll box supporting up to ten individual detectors. All functions that formerly required an entry into the experimental hall and manual adjustment can be accomplished from the Machine Control Center (MCC). A further innovation was the addition of a High Voltage "Brick" at the detector location. A single cable supplies the required voltage for the Brick and a return line for the ion chamber signal. The read back screens display range, trip point, and accumulated dose for each location. The new system is very cost effective and significantly reduces the amount of lost experimental time. |
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| RPPE074 | The Multichannel Deflection Plates Control System for the ALF Facility at the APS | octupole, power-supply, controls, free-electron-laser | 3937 | ||
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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. |
A deflection plate control system was developed as part of SPIRIT (Single Photon Ionization / Resonant Ionization to Threshold), a new secondary neutral mass spectrometry (SNMS) instrument that uses tunable vacuum ultraviolet light from the ALF (Argonne Linear Free-electron laser) facility at the APS for postionization. The system comprises a crate controller with PC104 embedded computer, 32 amplifiers, and two 1-kV power supplies. Thirty-two D/A converters are used to control voltages at the deflection plates within ± 400 V with 100-mV resolution. An algorithm of simultaneous sweeping of up to 16 XY areas with 10-μs time resolution also has been implemented in the embedded computer. The purpose of the system is to supply potentials to various ion optical elements for electrostatic control of keV primary and secondary ion beams in this SNMS instrument. The control system is of particular value in supplying (1) bipolar potentials for steering ions, (2) multiple potentials for octupole lenses that shape the ion beams, and (3) ramped deflection potentials for rastering the primary ion beam. The system has been in use as part of the SPIRIT instrument at the ALF facility since 2002. |
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| RPPP012 | Collective Effects in the CLIC Damping Rings | wiggler, damping, emittance, radiation | 1312 | ||
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The small emittance, short bunch length, and high current in the CLIC damping ring could give rise to collective effects which degrade the quality of the extracted beam. In this paper, we survey a number of possible instabilities and estimate their impact on the ring performance. The effects considered include fast beam-ion instability, coherent synchrotron radiation, and electron cloud, in addition to conventional single and multi-bunch instabilities.
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| RPPT053 | Studies of the Injection System in the Decay Ring of Beta-Beam Neutrino Souce Project | injection, septum, emittance, factory | 3221 | ||
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After being accelerated the beta radioactive ions are accumulated in a decay ring. The losses due to their decay are compensated with regular injections in presence of filled bucket. Without a damping mechanism, the new particles are injected at a different energy from the stored beam energy, then the old and the new buckets are merged with RF manipulation. This type of injection has to be done, in a dispersive region, in presence of closed orbit bump and a septum magnet. The sizes of the injected beam and of the stored beam have to be adjusted in order to minimize the losses on the septum and to maximize the stored intensity keeping small beam sizes. The dispersion has to be large enough in order to decrease the energy difference. The injection system may be located either in the arc or in a straight section, both possibilities have been studied.
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| RPPT062 | Radiation Simulations for the Proposed ISOL Stations for RIA | target, shielding, radiation, simulation | 3561 | ||
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Funding: This work is supported in part by Michigan State University, the U.S. Department of Energy, and the National Research Council of Canada. |
The Department of Energy's Office of Nuclear Physics, within the Office of Science (SC), has given high priority to consider and analyze design concepts for the target areas for the production of rare isotopes via the ISOL technique at the Rare-Isotope Accelerator (RIA) Facility. Key criteria are the maximum primary beam power of 400 kW, minimizing target change-out time, good radiological protection, flexibility with respect to implementing new target concepts, and the analysis and minimization of hazards associated with the operation of the facility. We will present examples of on-going work on simulations of radiation heating of targets, surrounding components and shielding, component activation, and levels of radiation dose, using the simulation codes MARS, MCNPX, and PHITS. These results are important to make decisions that may have a major impact on the layout, operational efficiency and cost of the facility, hazard analysis, shielding design, civil construction, component design, and material selection, overall layout, and remote handling concepts. |
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| RPPT063 | Radiation Simulations and Development of Concepts for High Power Beam Dumps, Catchers and Pre-separator Area Layouts for the Fragment Separators for RIA | simulation, radiation, target, quadrupole | 3594 | ||
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Funding: This work is supported in part by Michigan State University, the US DOE, and the Gesellschaft für Schwerionenforschung, Germany. |
The development of high-power beam dumps and catchers, and pre-separator layouts for proposed fragment separators of the Rare-Isotope Accelerator (RIA) facility are important in realizing how to handle the 400 kW in the primary beam. We will present examples of pre-conceptual designs of beam dumps, fragment catchers, and the pre-separator layout. We will also present examples of ongoing work on radiation simulations using the heavy-ion-transport code PHITS, characterizing the secondary radiation produced by the high-power ion beams interacting with these devices. Results on radiation heating of targets, magnet coils, associated hardware and shielding, component activation, and levels of radiation dose will be presented. These initial studies will yield insight into the impact of the high-power dissipation on fragment separator design, remote handling concepts, nuclear safety and potential facility hazard classification, shielding design, civil construction design, component design, and material choices. Furthermore, they will provide guidance on detailed radiation analyses as designs mature. |
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| RPPT064 | Holifield Radioactive Ion Beam Facility Development and Status | target, ion-source, extraction, light-ion | 3641 | ||
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Funding: Managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. |
The Holifield Radioactive Ion Beam Facility (HRIBF) is a national user facility dedicated to nuclear structure, reactions, and nuclear astrophysics research with radioactive ion beams (RIBs) using the isotope separator on-line (ISOL) technique. An integrated strategic plan for physics, experimental systems, and RIB production facilities have been developed and implementation of the plan is under way. Specific research objectives are defined for studying the nature of nucleonic matter, the origin of elements, solar physics, and synthesis of heavy elements. Experimental systems upgrade plans include new detector arrays and beam lines, and expansion and upgrade of existing devices. A multifaceted facility expansion plan includes a $4.75M High Power Target Laboratory (HPTL), presently under construction, to provide a facility for testing new target materials, target geometries, ion sources, and beam preparation techniques. Additional planned upgrades include a second RIB production system (IRIS2), an external axial injection system for the present driver cyclotron, ORIC, and an additional driver accelerator for producing high-intensity neutron-rich beams. |
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| RPPT072 | Ion Chamber Arrays for the NuMI Beam at Fermilab | target, hadron, proton, focusing | 3892 | ||
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The NuMI beamline and the MINOS experiment will study at a long baseline the possible oscillation of muon neutrinos and provide a precision measurement of the oscillation parameters. Neutrinos are produced from charged pion decays, where the pions are produced from interaction of the 120 GeV FNAL Main Injector proton beam with a graphite target. Ion chamber arrays have been built to monitor the resulting muons from pion decays, as well as remnant hadrons at the end of the NuMI decay pipe. The arrays of ion chambers measure both the intensity and lateral profile of the muon and hadron beams, allowing studies of sytematics of the neutrino beam. We will describe the design, construction, and precise calibration of the ion chamber arrays. Initial data from commissioning of the beam line and experience from long-term operations will be presented.
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| ROPC003 | RIKEN RI Beam Factory Project | cyclotron, heavy-ion, extraction, acceleration | 320 | ||
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The world-top-class radioactive-isotope-beam (RIB) facility, which is called ?RI beam factory (RIBF)?, is under construction at RIKEN. This facility is based on the so-called ?in-flight RI beam separation? scheme. Late in 2006, a new high-power heavy-ion accelerator system consisting of a cascade of three ring cyclotrons with K=570 MeV (fixed frequency, fRC), 980 MeV (Intermediate stage, IRC) and 2500 MeV (superconducting, SRC), respectively, will be commissioned. This new accelerator system will boost energies of the output beams from the existing K540-MeV ring cyclotron up to 440 MeV/nucleon for light ions and 350 MeV/nucleon for very heavy ions. These energetic heavy-ion beams are converted into intense RI beams via the projectile fragmentation or in-flight fission of uranium ions by the superconducting isotope separator, BigRIPS, under construction. The combination of the SRC and BigRIPS will expand our nuclear world into presently unreachable region. Major experimental installations are under priority discussion as the second phase program. Construction of the second phase is expected to start in 2006.
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| ROPC005 | RIA Post Accelerator Design | linac, rfq, emittance, acceleration | 425 | ||
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Overall design of the post accelerator for the RIA project is described with emphasis on performance for different ion beams. Characteristics for beams from A=10 to A=240 will be provided with an estimate of output intensities. The rational for selection of different accelerating structures, both for the normal conducting and for the superconducting types, will be provided for a system design that accelerates beams to at least 10 MeV/u.
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| ROPC008 | Experimental Progress in Fast Cooling in the ESR | electron, emittance, injection, scattering | 615 | ||
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The ESR storage ring at GSI is operated with highly charged heavy ions. Due to the high electric charge the ions interact much stronger with electromagnetic fields. Therefore both cooling methods which are applied to stored ions in the ESR, stochastic cooling and electron cooling, are more powerful than for singly charged particles. The experimental results exhibit cooling times for stochastic cooling of a few seconds. For cold ion beams, electron cooling provides cooling times which are one to two orders of magnitude smaller. The beams are cooled to beam parameters which are limited by intrabeam scattering. At small ion numbers, however, intrabeam scattering is suppressed by electron cooling, clear evidence was found that the ion beam forms a one-dimensional ordered structure, a linear chain of ions. The strengths of stochastic cooling and electron cooling are complementary and can be combined favorably. Stochastic cooling is employed for pre-cooling of hot secondary beams followed by electron cooling to provide ultimate beam quality. In a similar manner, first experiments with carbon ions have been performed to use electron cooling as a pre-cooling method in combination with laser cooling.
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| ROPC009 | First Acceleration with Superconducting RF Cavities at ISAC-II | simulation, acceleration, diagnostics, 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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| FOAC003 | New Concepts in FFAG Design for Secondary Beam Facilities and Other Applications | proton, cyclotron, resonance, acceleration | 261 | ||
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Fixed Field Alternating Gradient accelerators offer much higher acceptances and repetition rates - and therefore higher beam intensities - than synchrotrons, at the cost of more complicated magnet and rf cavity designs. Perhaps because of the difficulty and expense anticipated, early studies never progressed beyond the stage of successful electron models, but in recent years, with improvements in magnet and rf design technology, FFAGs have become the focus of renewed attention. Two proton machines have now been built, and three more, plus a muon phase rotator, are under construction. In addition, more than 20 designs are under study for the acceleration of protons, heavy ions, electrons and muons, with applications as diverse as treating cancer, irradiating materials, driving subcritical reactors, boosting high-energy proton intensity, and producing neutrinos. Moreover, it has become apparent that FFAG designs need not be restricted to the traditional 'scaling' approach, in which the orbit shape, optics and tunes are kept fixed. Dropping this restriction has revealed a range of interesting new design possibilities. This paper will review the various approaches being taken.
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| FPAE027 | Status of the ISAC-II Accelerator at TRIUMF | linac, acceleration, vacuum, heavy-ion | 2003 | ||
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A heavy ion superconducting linac is being installed at TRIUMF to increase the final energy of radioactive beams at ISAC. A first stage of 20MV consisting of five medium beta cryomodules each with four quarter wave bulk niobium cavities and a superconducting solenoid is being installed with initial beam commissioning scheduled for Dec. 2005. The initial cryomodule has met cryogenic and rf performance specifications. In addition we have demonstrated acceleration of alpha particles in an off-line test. A 500W refrigerator system has been installed and commissioned in Jan. 2005 with cold distribution due for commissioning in Sept. 2005. A transfer beamline from the ISAC accelerator and beam transport to a first experimental station are being installed. The status of the project will be presented.
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| FPAE028 | Design of the High Intensity Exotic Beams SPIRAL 2 Project | linac, rfq, quadrupole, beam-losses | 2044 | ||
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The SPIRAL 2 facility will be able to deliver stable heavy ion beams and deuteron beams at very high intensity, allowing to produce and accelerate light and heavy rare ion beams. The driver will accelerate a 5 mA deuteron beam up to 20 MeV/u and also q/A=1/3 heavy ions up to 14.5 MeV/u. The injector consist of the ion sources, a 4-vane RFQ and the low and medium beam transfer lines. It is followed by an independently phased superconducting linac with compact cryostats separated with warm focusing sections. The overall design and results of simulations with combined errors, the results of tests of prototypes for the most critical components are presented.
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| FPAE029 | Setup and Performance of the RHIC Injector Accelerators for the 2005 Run with Copper Ions | booster, injection, emittance, extraction | 2068 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy. |
Copper ions for the 2005 run of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory are accelerated in the Tandem, Booster and AGS prior to injection into RHIC. The setup and performance of this chain of accelerators will be reviewed. |
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| FPAE032 | ORIC Beam Energy Increase | extraction, cyclotron, septum, proton | 2257 | ||
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Funding: Managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05=00OR 22725. |
The detection of and solution to a beam interference problem in the Oak Ridge Isochronous Cyclotron (ORIC) extraction system has yielded a 20% increase in the proton beam energy. The beam from ORIC was designed to be extracted before the nu r equal one resonance. Most cyclotrons extract after the nu r equal one resonance, thus getting more usage of the magnetic field for energy acceleration. We have now determined that the electrostatic deflector septum interferes with the last accelerated orbit in ORIC, with the highest extraction efficiency obtained near the maximum nu r value. This nu r provides a rotation in the betatron oscillation amplitude that is about the same length as the electrostatic septum thus allowing the beam to jump over the interference problem with the septum. With a thinned septum we were able to tune the beam through the nu r equal one resonance and achieve a 20% increase in beam energy. This nu r greater than one extraction method may be desirable for very high field cyclotrons since it provides ten times the clearance at extraction compared to dee voltage gain, thus allowing the possibility of utilizing a magnetic extractor. |
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| FPAE033 | Operational Availability of the SNS During Commissioning | linac, SNS, ion-source, diagnostics | 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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| FPAE037 | SPIRAL 2 RFQ Prototype First Tests | rfq, vacuum, pick-up, acceleration | 2488 | ||
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The SPIRAL2 RFQ is designed to accelerate at 88MHz two kinds of charge-over-mass ratio, Q/A, particles. The proposed injector can accelerate a 5 mA deuteron beam (Q/A=1/2) or a 1 mA particles beam with q/A=1/3 up to 0.75 MeV/A. It is a CW machine which has to show stable operation, provide the request availability, have the minimum losses in order to minimize the activation constraints and show the best quality/cost ratio. The prototype of this 4-vane RFQ has been built and tested. It allowed to verify the mechanical assembly concept (RFQ without any brazing step). The full power was easily injected in the cavity, with no concerns for the RF joints. The paper describes the different achievements.
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| FPAE040 | First Operation of PIAVE, the Heavy Ion Injector Based on Superconducting RFQ's | vacuum, linac, ion-source, acceleration | 2621 | ||
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The Positive Ion Accelerator for low-Velocity Ions (PIAVE), based on superconducting RFQ's (SRFQ's), has been completed in fall 2004 with the first acceleration of beams from the ECR ion source. Superconducting RFQ's were used, for the first time, for beam acceleration on a user-oriented accelerator complex. A general status of the injector performances is given: it includes, besides the SRFQ's, eight superconducting (SC) QWR's and three bunchers; the beam is received from an ECR source on a HV platform and is delivered, through the SC accelerator ALPI, to nuclear physics experimental apparatuses. The paper emphasizes, in particular, the technological challenges related to the operation of the SC cavities, the cryogenics, control, diagnostics and vacuum systems.
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| FPAE042 | Beam Commissioning of the Superconducting RFQs of the New LNL Injector PIAVE | rfq, linac, emittance, simulation | 2696 | ||
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PIAVE is the new injector of the LNL superconducting heavy ion linac ALPI; the injector is able to accelerate ions up to U (Q/q=8.5) with a final energy of more than 1 MeV/u. During the last two months of 2004 the superconducting RFQ, composed by two Nb structures operating at 80 MHz, has been commissioned using the O+3 and Xe+18 beams produced by the ECRIS ALICE. The beam has been accelerated up to 587 keV/u reaching the main design parameters (energy, longitudinal and transverse emittance, transmission) and demonstrating a stable and reproducible operation. This is the first operational beam accelerated by a superconducting RFQ.
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| FPAE051 | Performance of a CW RFQ Injector for the IUCF Cyclotron | cyclotron, proton, rfq, ion-source | 3179 | ||
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Funding: The State of Indiana, Indiana University, and the DOE (Grant No DE-FG-02000ER62966) supported this work. |
A 750 keV RFQ proton pre-injector was installed in place of a 600 keV Cockroft-Walton high voltage terminal for the IUCF k220 Cyclotron.* The pre-injector consists of a 20 keV microwave ion source and LEBT, a unique design 750 keV CW RFQ, and a short transfer beam line to the k15 injector cyclotron center region.** This pre-injector system was installed and commissioned in June of 2003 and is now in routine service as the sole injection system to the cyclotrons. This contribution will discuss the performance of the CW RFQ pre-injector and the transmission properties of the beam through the cyclotrons. *D.L.Friesel, et al., App. of Acc. in Res. and Ind., eds. J.L. Duggan and I.L. Morgan, Denton, 651(2000). **V.P. Derenchuk, et al., 2003 Particle Accelerator Conference, Portland, OR, (2003), edited by A. Jackson and E. Lee. |
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| FPAE052 | The LENS 7 MeV, 10 mA Proton Linac | proton, rfq, target, linac | 3200 | ||
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Funding: This work has been supported by the National Science Foundation under grants DMR-0220560, and DMR-0320627, by the Indiana 21st Century Science and Technology Fund, and by the Department of Defense. |
The Indiana University Cyclotron Facility (IUCF) has constructed and placed in operation a Low Energy Neutron Source (LENS) using a 10 mA, 7 MeV proton beam incident on a beryllium target. The proton delivery system (PDS) consists of a 25 keV proton injector, an AccSys Technology, Inc. PL7 Linac* and a beam transport line with non-linear beam spreading.** The accelerator and beamline equipment used in this construction are refurbished and upgraded components from the IUCF CIS/Cooler synchrotron*** facility. After commissioning the beam current at 7 MeV will be 10 mA with a pulse width of up to 300 μs and > 1% duty factor. The PDS was constructed and commissioning started in 2004. First operating results will be described. *D.L. Friesel and W. Hunt, Linac98, pp61-63. **W.P. Jones, et. al., "Non-Linear Beam Transport System for the LENS 7 MeV Proton Beam," this proceedings. ***D.L. Friesel, et. al., EPAC2000, pp. 539-541. |
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| FPAE053 | Isobar Suppression by Photodetachment in a Gas-Filled RF Quadrupole Ion Guide | rfq, laser, quadrupole, photon | 3250 | ||
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Funding: Managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC05-00OR22725. Co-author Aaron Havener was under a U.S. DOE Science Undergraduate Laboratory Internship. |
A novel method is described for selective suppression of isobar contaminants in negative radioactive ion beams. Negative ion beams extracted from an ion source were decelerated to low energies and injected into a gas-filled radio-frequency quadrupole (RFQ) ion guide where the ions were cooled and unwanted ions were selectively removed by non-resonant photodetachment with photons of sufficient energy. Simulation studies show that the laser-ion interaction time in a 40 cm long RFQ ion guide can be on the order of milliseconds, thus, high efficiency photodetachment is possible with commercially available CW lasers. There are a number of adjacent-Z species whose negative ions are such that photodetachment can be used to suppress the unwanted negative ion species while leaving the species of interest intact. Examples of particular interest include suppressing the 56Co- component in a mixed 56Ni- + 56Co- beam and the 17O- component in a mixed 17O- + 17F- beam. In a proof–of-principle experiment a CW Nd:YAG laser at 1064 nm wavelength was used to selectively remove Co- ions in the (Ni, Co) pair. With laser power on the order of 3 W, 95% of Co- beams were suppressed while only 10% of Ni- beams were neutralized in a He-filled RFQ guide. |
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| FPAE055 | Heavy-Ion Beam Dynamics in the RIA Post-Accelerator | linac, rfq, focusing, emittance | 3301 | ||
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Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. W-31-109-ENG-38. |
The RIB linac includes two strippers for the heaviest ions and three main sections: a room temperature injector up to an energy of ~100 keV/u, a superconducting (SC) linac for ions with charge-to-mass ratio 1/66 or more up to an energy of ~1 MeV and a higher energy SC linac to produce 10 MeV/u beams up to the mass of uranium. The RIA post-accelerator is a complex system designed for acceleration singly-charged ions before the stripper and includes many different accelerating and focusing structures operating both at room and cryogenic temperatures. Extensive accelerator design studies and end-to-end beam dynamics simulations have been performed to minimize the cost of the linac while providing high-quality and high-intensity radioactive beams. Specifically, we have found that cost-effective acceleration can be provided by several hybrid RFQs in the front end. The hybrid RFQs have been proposed and developed for acceleration of low-velocity heavy ions.* For the beam focusing in the second section it is appropriate to use electrostatic lenses and SC quadrupoles inside common cryostats with the resonators. The electrostatic lenses are most effective in the first cryostat of the SC linac. *P.N. Ostroumov and A.A. Kolomiets. Proc. of the PAC-2001, Chicago, IL, June 18-22, 2001, p. 4077. |
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| FPAE057 | Beam Dynamics Studies and Beam Quality in the SNS Normal-Conducting Linac | emittance, linac, ion-source, simulation | 3381 | ||
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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 accelerator systems will provide a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron production. The accelerator complex consists of an H- injector capable of producing 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The linear accelerator consists of a Drift Tube Linac, a Coupled-Cavity Linac and a Superconducting Linac which provide 1.5 mA average current to the accumulator ring. The staged beam commissioning of the accelerator complex is proceeding as component installation progresses. Recently, the normal-conducting linear accelerator was beam commissioned. A number of beam dynamics and beam quality measurements will be reported, including the measurement of transverse emittances in the H- injector, and the evolution of halo and emittance along the linac. |
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| FPAE068 | Charge Strippers in the RIKEN RI-Beam Factory | cyclotron, injection, heavy-ion, factory | 3751 | ||
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In the RIKEN RI-Beam Factory, ions from hydrogen to uranium are planned to be accelerated by four cyclotrons and linacs using four stripper sections. The charge stripping schemes for typical ions and the selection of the charge strippers are described. The results of the measurements on charge state fractions are presented.
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| FPAE070 | A Collimation Scheme for Ions Changing Charge State in the LEIR Ring | vacuum, electron, lattice, accumulation | 3816 | ||
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Avalanche-like pressure rise and an associated decrease of the beam lifetime, caused by (i) beam loss due to charge exchange interactions with rest gas molecules and (ii) ion impact induced outgassing, is a potential limitation for heavy ion accelerators operating at low energy. Capture of electrons from the electron cooler is another source of ion losses and thus, of pressure rise. The vacuum system of the LEIR ring has to be upgraded to reach the dynamical vacuum pressure in the low 10-12 Torr range necessary to reach design performance. A collimation system to intercept lost ions by absorber blocksmade of low beam induced outgassing material will be installed. This paper reviews the collimation scheme and simulations of beam loss patterns around the ring.
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| FPAE071 | Initial Results on Neutralized Drift Compression Experiments (NDCX-IA) for High Intensity Ion Beam | plasma, diagnostics, 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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| FPAE072 | RF-Kicker System for Secondary Beams at NSCL/MSU | kicker, secondary-beams, quadrupole, cyclotron | 3880 | ||
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The design and construction of a radio frequency (RF) kicker system at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU) has been proposed. This RF kicker system will be used to purify secondary beams of rare isotopes after the existing A1900 Fragment Separator and will open a wide range of possibilities for new experiments at the forefront of nuclear science. The proposed system is studied as an efficient alternative to the traditional approach using Wien Filter. Rare neutron deficient secondary beams are challenging to purify because of the presence of intense contaminants that cannot be removed by the traditional energy loss method. However, velocity differences resulting in time-of-flight differences can be used for the effective separation of the beams transversely using the time-varying electromagnetic fields of the RF kicker. Its technical design will be presented together with the beam dynamics analysis of a secondary beam in realistic 3D electromagnetic fields. The expected purification improvement of the exotic beams for the foreseen nuclear physics experiments will be shown in details.
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| FPAE075 | Radiation Damage to the Elements of the SIS300 Dipoles | dipole, extraction, radiation, simulation | 3943 | ||
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Funding: Supported by the grant of the GSI-INTAS Project #03-54-3588. |
Radiation damage to various elements of the cosine-theta type dipoles of the SIS300 synchrotron of the FAIR Project was calculated. Among the elements under consideration were the superconducting cable, insulating materials, and high-current by-pass protection diodes. The Monte-Carlo particle transport codes MARS and SHIELD were used to simulate propagation of the lost ions and protons, together with the products of nuclear interactions in the material of the elements. It was found that the lifetime of the protection diodes under irradiation is a more restrictive limit for the tolerable level of beam losses than the occurrence of magnet quenches. |
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| FPAE076 | The System of Nanosecond 280-keV-He+ Pulsed Beam | ion-source, quadrupole, target, focusing | 3982 | ||
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Funding: We would like to acknowledge the support of the Thailand Research Fund, the National Research Council of Thailand, the Thai Royal Golden Jubilee Scholarship Program, the Faculty of Science, and the Graduate School of Chiang Mai University. |
At Fast Neutron Research Facility,the 150 kV-pulseds neutron generator is being upgraded to produce a 280-keV-pulsed-He beam for time-of-flight Rutherford backscattering spectrometry. It involves replacing the existing beam line elements by a multicusp ion source, a 400-kV accelerating tube, 45o-double focusing dipole magnet and quadrupole lens. The Multicusp ion source is a compact filament-driven of 2.6 cm in diameter and 8 cm in length. The current extracted is 20.4 μA with 13 kV of extraction voltage and 8.8 kV of Einzel lens voltage. The beam emittance has been found to vary between 6-12 mm mrad. The beam transport system has to be redesigned based on the new elements. The important part of a good pulsed beam depends on the pulsing system. The two main parts are the chopper and buncher. An optimized geometry for the 280 keV pulsed helium ion beam will be presented and discussed. The PARMELA code has been used to optimize the space charge effect, resulting in pulse width of less than 2 ns at a target. The calculated distance from a buncher to the target is 4.6 m. Effects of energy spread and phase angle between chopper and buncher have been included in the optimization of the bunch length. |
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| FPAE077 | LSP Simulations of the Neutralized Drift Compression Experiment | simulation, focusing, plasma, emittance | 4006 | ||
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Funding: Work supported by the VNL for HIF through PPPL and LBNL. |
The Neutralized Drift Compression Experiment (NDCX) at Lawrence Berkeley National Laboratory involves the longitudinal compression of a singly-stripped K ion beam with a mean energy of 250 keV in a meter long plasma. We present simulation results of compression of the NDCX beam using the PIC code LSP. The NDCX beam encounters an acceleration gap with a time-dependent voltage that decelerates the front and accelerates the tail of a 500 ns pulse which is to be compressed 110 cm downstream. The simulations model both ideal and experimental voltage waveforms. Results show good longitudinal compression without significant emittance growth. |
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| FPAP012 | The Effect of Inhomogeneous Magnetic Field on Budker-Chirikov Instability | electron, resonance, simulation, betatron | |||
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The two-beams electron - ion system consists of a nonrelativistic ion beam propagating co-axially with a high-current relativistic electron beam in a longitudinal inhomogeneous magnetic field. The effect of the longitudinal inhomogeneous magnetic field on instability Budker-Chirikov (BCI) in the system is investigated by the method of a numerical simulation in terms of the kinetic description of both beams. The investigations are development of investigations in*,**. Is shown, when the inhomogeneity magnetic field results in the decreasing of an increment of instability Budker-Chirikov and the increasing of length of propagation of a electron beam. Also is shown, when take place the opposite result.
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*Yu.Ya. Golub, N.E.Rozanov, Nuclear Instruments and Methods in Physics Research, A358 (1995) 479. **Yu.Ya. Golub, Proceedings of EPAC 2002, Paris, France, p. 1497. |
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| FPAP016 | Initial Self-Consistent 3-D Electron-Cloud Simulations of LHC Beam with the Code WARP+POSINST | electron, simulation, proton, heavy-ion | 1479 | ||
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Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California, LLNL and LBNL under contracts W-7405-Eng-48, and DE-AC03-76F00098. |
We present initial results from the self-consistent beam-cloud dynamics simulations of a sample LHC beam, using a newly developed set of modeling capability based on a merger of the three-dimensional parallel Particle-In-Cell accelerator code WARP and the electron cloud code POSINST.*,** Although the storage ring model we use as a test bed to contain the beam is much simpler and shorter than the LHC, its lattice elements are realistically modeled, as is the beam and the electron cloud dynamics. The simulated mechanisms for generation and absorption of the electrons at the walls are based on previously validated models available in POSINST.*** *J.-L. Vay, these proceedings. **J.-L. Vay, Proc. "ECLOUD04," Napa (California), 2004. ***M.T.F. Pivi and M.A. Furman, Phys. Rev. STAB, PRSTAB/v6/i3/e034201. |
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| FPAP021 | A Cross-Platform Numerical Model of Ion-Wall Collisions | simulation, electron, heavy-ion, vacuum | 1707 | ||
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Ion collisions with beam-pipe walls is a significant source of secondary electron clouds and desorbed neutral gasses in particle accelerators. Ions may reflect from beam-pipe walls and undergo further collisions downstream. These effects can cause beam degradation and are expected to be problematic in the design of heavy ion accelerators. The well-known SRIM code provides physically-based monte carlo simulations of ion-wall collisions. However, it is difficult to interface SRIM with high-performance simulation codes. We present details on the development of a package of Python modules which integrate the simulation of ion-wall interactions at grazing incidences with the high-performance particle-in-cell and electron cloud codes WARP and POSINST. This software package, called GriPY, calculates reflected angles and energies of ions which strike beam-pipe walls at grazing incidences, based upon interpolation of monte carlo statistics generated by benchmark simulations run in SRIM for a variety of relevant incident angles and energies. We present here solutions for 1.8 MeV K+ ions and 1 Gev protons incident on stainless steel.
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| FPAP026 | Multispecies Weibel Instability for Intense Ion Beam Propagation Through Background Plasma | plasma, background, electron, heavy-ion | 1952 | ||
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Funding: Research supported by the U.S. Department of Energy. |
In application of heavy ion beams to high energy density physics and fusion, background plasma is utilized to neutralize the beam space charge during drift compression and/or final focus of the ion beam. It is important to minimize the deleterious effects of collective instabilities on beam quality associated with beam-plasma interactions. Plasma electrons tend to neutralize both the space charge and current of the beam ions. It is shown that the presence of the return current greatly modifies the electromagnetic Weibel instability (also called the filamentation instability), i.e., the growth rate of the filamentation instability greatly increases if the background ions are much lighter than the beam ions and the plasma density is comparable to the ion beam density. This may preclude using underdense plasma of light gases in heavy ion beam applications. It is also shown that the return current may be subject to the fast electrostatic two-stream instability. |
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| FPAP027 | Hybrid Quantum Mechanical–Quasi-Classical Model for Evaluating Ionization and Stripping Cross Sections in Atom-Ion Collisions | target, electron, heavy-ion, plasma | 1988 | ||
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Funding: Research supported by the U.S. Department of Energy. |
Ion-atom ionization cross sections are needed in many applications employing the propagation of fast ions through matter. When experimental data or full-scale theoretical calculations are non-existent, approximate methods must be used. The most robust and easy-to-use approximations include the Born approximation of quantum mechanics and the quasi-classical approach utilizing classical mechanics together with the Bohr-Sommerfeld quantization rule.* The simplest method to extend the validity of both approaches is to combine them, i.e., use the two different approaches but only for the regions of impact parameters in which they are valid, and sum the results to obtain the total cross section. We have recently investigated theoretically and experimentally the stripping of more than 18 different pairs of projectile and target atoms in the range of 3-38 MeV/amu to study the range of validity of various approximations. The results of the modified approach agree better with the experimental data than either the Born approximation or the quasi-classical approach, applied separately. *I. D. Kaganovich et al., "Formulary and scaling cross sections for ion-atom impact ionization," http://arxiv.org/abs/physics/0407140. |
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| FPAP028 | Ion Beam Pulse Interaction with Background Plasma in a Solenoidal Magnetic Field | plasma, electron, background, target | 2062 | ||
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Funding: Research supported by the U.S. Department of Energy. |
Background plasma can be used as an effective neutralization scheme to transport and compress intense ion beam pulses, and the application of a solenoidal magnetic field allows additional control and focusing of the beam pulse. Ion beam pulse propagation in a background plasma immersed in an applied solenoidal magnetic field has been studied both analytically and numerically with three different particle-in-cell codes (LSP, OOPIC-Pro and EDPIC) to cross-check the validity of the results. Very good charge and current neutralization is observed for high values of the solenoidal magnetic field.* However, for intermediate values of the solenoidal magnetic field, current neutralization is a complex process, and a sizable self-magnetic field is generated at the head of the beam. Collective wave excitations are also generated ahead of the beam pulse. *I. D. Kaganovich, E. A. Startsev and R. C. Davidson, Nuclear Instruments and Methods in Physics Research A, in press (2004). |
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| FPAP031 | Model of Electron Cloud Build Up with Secondary Ion-Electron Emission as a Source of Delayed Electrons | electron, vacuum, proton, space-charge | 2197 | ||
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For explanation of anomaly long electron cloud surviving after the gap between bunches it was proposed beam particle leaking to the gap and anomaly high reflectivity of low energy electrons in collision with pipe wall. We will attract an attention to some other possibilities of efficient electron generation in the high vacuum environment and delay electron generation after gap between bunches. Model of electron cloud build up with secondary ion-electron emission as a source of delay electrons is presented and discussed. This model is used for explanation of bunched beam instability in Los Alamos PSR, prediction of e-cloud generation in SNS, and can be important for pressure rise in cold sections of RHIC. A fast desorbtion by ion of physically adsorbed molecules can explain a "first pulse Instability" observed in LA PSR
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| FPAP033 | Beam Energy Scaling of Ion-Induced Electron Yield from K+ Ions Impact on Stainless Steel Surfaces | electron, target, heavy-ion, diagnostics | 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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| FPAT020 | A Fast Chopper for Intensity Adjustment of Heavy-Ion Beams | impedance, linac, heavy-ion, vacuum | 1692 | ||
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Funding: CRDF Grant. |
There are several heavy-ion linac projects being developed worldwide. For example, the Rare Isotope Accelerator Facility [J.A. Nolen, Nucl. Phys. A. 734 (2004) 661] currently being designed in the U.S. will use both heavy-ion and light ion beams to produce radionuclides via the fragmentation and spallation reactions, respectively. With simultaneous beam delivery to more than one target independent adjustment of relative beam intensities is essential. A fast traveling wave chopper can be used to modulate cw beam intensity at low energy ~200 keV/u. Such a device should have high frequency characteristics at high power level. By increasing the wave impedance of the traveling wave structure up to 200 Ohm one can reduce power requirements to the fast voltage pulser. Several design options of the high-impedance structure are discussed. |
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| FPAT025 | Electron Dynamics of the Rod-Pinch Diode in the Cygnus Experiment at Los Alamos | electron, cathode, simulation, plasma | 1901 | ||
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In this work, two-dimensional particle-in-cell simulations are used to examine the electron physics in the rod-pinch diode, a device that can be used to produce a relatively low-energy (a few MeV) radiographic electron source. It is found that with diode parameters for which the electrons' dominant dynamics are approximated well as a magnetized fluid, the diode produces an electron source with a desired small spot size as the electrons drift to and impinge on the anode tip. However, for a large cathode-to-anode radius ratio, a population of electrons that consists predominantly of electrons emitted from the downstream surface of the cathode is found to propagate in the upstream direction and the diode may perform anomalously as a consequence. A method is proposed for improving the quality of the electron source by suppressing electron emission from the downstream cathode surface to reduce the presence of unmagnetized electrons.
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| FPAT028 | Extraction Compression and Acceleration of High Line Charge Density Ion Beams | acceleration, space-charge, simulation, heavy-ion | 2032 | ||
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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. |
HEDP applications require high line charge density ion beams. An efficient method to obtain this type of beams is to extract a long pulse, high current beam from a gun at high energy, and let the beam pass through a decelerating field to compress it. The low energy beam bunch is loaded into a solenoid and matched to a Brillouin flow. The Brillouin equilibrium is independent of the energy if the relationship between the beam size (a), solenoid magnetic field strength (B) and line charge density is such that (Ba)2 is proportional to the line charge density. Thus it is possible to accelerate a matched beam at constant line charge density. An experiment, NDCX-1c is being designed to test the feasibility of this type of injectors, where we will extract a 1 microsecond, 100 mA, potassium beam at 160 keV, decelerate it to 55 keV (density ~0.2 microC/m), and load it into a 2.5 T solenoid where it will be accelerated to 100–150 keV (head to tail) at constant line charge density. The head-to-tail velocity tilt can be used to increase bunch compression and to control longitudinal beam expansion. We will present the physics design and numerical simulations of the proposed experiment |
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| FPAT029 | High Voltage Operation of Helical Pulseline Structures for Ion Acceleration | coupling, impedance, acceleration, vacuum | 2092 | ||
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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 Berkeley National Laboratory, Contract # DE-AC03-76SF00098. |
The basic concept for the acceleration of heavy ions using a helical pulseline requires the launching of a high voltage traveling wave with a waveform determined by the beam transport physics in order to maintain stability and acceleration.* This waveform is applied to the front of the helix, creating over the region of the ion bunch a constant axial acceleration electric field that travels down the line in synchronism with the ions. Several methods of driving the helix have been considered. Presently, the best method of generating the waveform and also maintaining the high voltage integrity appears to be a transformer primary loosely coupled to the front of the helix, generating the desired waveform and achieving a voltage step-up from primary to secondary (the helix). This can reduce the drive voltage that must be brought into the helix enclosure through the feedthroughs by factors of 5 or more. The accelerating gradient is limited by the voltage holding of the vacuum insulator, and the material and helix geometry must be chosen appropriately. The helix must also be terminated into its characteristic impedance, and designs of terminations incorporated into the helix internal enclosure are presented in the paper. *Briggs, et al, "Helical Pulseline Structures for Ion Acceleration," this conference. |
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| FPAT034 | Dispersion Analysis of the Pulseline Accelerator | beam-loading, impedance, acceleration, vacuum | 2330 | ||
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Funding: This work was perfomed 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. |
We analyze the sheath helix model of the pulseline accelerator.* We find the dispersion relation for a shielded helix with a dielectric material between the shield and the helix and compare it against the results from 3-D electromagnetic simulations. Expressions for the fields near the beam axis are obtained. A scheme to taper the properties of the helix to maintain synchronism with the accelerated ions is described. An approximate circuit model of the system that includes beam loading is derived. *"Helical Pulseline Structures for Ion Acceleration," Briggs, Reginato, Waldron, this conference. |
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| FPAT037 | Electromagnetic Simulations of Helical-Based Ion Acceleration Structures | simulation, coupling, injection, pulsed-power | 2485 | ||
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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. |
Helix structures have been proposed* for accelerating low energy ion beams using MV/m fields in order to increase the coupling effeciency of the pulsed power system and to tailor the electromagnetic wave propagation speed with the particle beam speed as the beam gains energy. Calculations presented here show the electromagnetic field as it propagates along the helix structure, field stresses around the helix structure (for voltage breakdown determination), optimizations to the helix and driving pulsed power waveform, and simulations showing test particles interacting with the simulated time varying fields. *"Helical Pulseline Structures for Ion Acceleration," Briggs, Reginato, Waldron, this conference. |
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| FPAT043 | Application of Selected Momentum Correction Method Using Induction Voltage Modulator | induction, storage-ring, injection, emittance | 2762 | ||
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A method for momentum correction of a selected beam particle using a controllable induction voltage modulator is proposed for a low flux ion beam. The corrected ion beam has a small momentum error restricted by a detection error at a kinetic energy analyzer and a voltage fluctuation at the induction voltage modulator. The application of this selected momentum correction scheme is discussed by using numerical simulations.
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| FPAT049 | Upgrade of the PF Ring Vacuum Control System | vacuum, controls, cathode, storage-ring | 3061 | ||
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Having been operated for more than two decades, the PF ring vacuum control system had become superannuated. The system reliability had been degraded and the maintenance work had been difficult. In addition, the device operability had not been high because the operating software, written in BASIC, had been running in a stand-alone computer. In the summer of 2004, the vacuum control system was upgraded to solve these problems. In this upgrade, the operating system was constructed in the EPICS environment. And numerous NIM modules composing hardware interfaces between vacuum device controllers and the operating computers were replaced by reliable PLCs.
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| FPAT059 | Event Driven Automatic State Modification of BNL's Booster for NASA Space Radiation Laboratory Solor Particle Simulator | booster, optics, radiation, extraction | 3447 | ||
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Funding: Work performed under Contract #DE-AC02-98CH10886 with the auspices of the U.S. Department of Energy. |
The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The NSRL makes use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. NASA is interested in reproducing the energy spectrum from a solar flare in the space environment for a single ion species. To do this we have built and tested a set of software tools which allow the state of the Booster and the NSRL beam line to be changed automatically. In this report we will desribe the system and present results of beam tests. |
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| FPAT063 | Control System for the ORNL Multicharged Ion Research Facility High-Voltage Platform | ion-source, vacuum, controls, power-supply | 3591 | ||
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Funding: Work supported by U. S. DOE Office of Fusion Energy Sciences and Office of Basic Energy Sciences under contract No. DE-AC05-00OR22725 with UT-Battelle, LLC. |
A control system for the 250-kV platform and beamlines for accelerating and transporting multiply-charged ion beams produced by an all-permanent-magnet ECR ion source has been developed at the ORNL Multicharged Ion Research Facility. The system employs Experimental Physics and Industrial Control System (EPICS) software controlling an Allen-Bradley ControlLogix Programmable Logic Controller (PLC). In addition to the I/O control points of the PLC, other devices are controlled directly by the EPICS computer through RS-232 and GPIB interfaces. PLC chassis are located at each major electrical potential of the facility, that is, at the ECR source potential, at the platform potential, and at ground potential used in the beamlines transporting ions to the various experimental end-stations. Connection of the control system components to the EPICS host is accomplished via EtherNet, including fiber optic links to the HV platform. The user interface is designed with the Extensible Display Manager (EDM) software and custom applets perform such tasks as mass-to-charge ratio scans of the platform analyzing magnet and archival of source and beamline operating parameters. |
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| FPAT080 | Simulations of Beam Injection and Extraction into Ion Sources | injection, plasma, simulation, background | 4069 | ||
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Funding: INFN-LNL |
Charge breeding, consistiting of injecting singly charged ion into ECRIS(Electron Cyclotron Resonance Ion Sources) to extract an highly charged ion beam, is a promising technique for rare or radioactive ion beam. Efficiency and extracted beam temperature are dominated by the strong collisional diffusion of charged ion inside source. A computer code, named BEAM2ECR, written to simulate details of the injection, ionization, collision and extraction processes is described.* A model of injection plasma sheath and of source fringe field were recently added. Neutral injection is also supported, for comparison with other techniques, like gas feeding or metal vapor injection. Results, clearly favouring near axis injection for most cases are described. Code is written in C-language and possibility of concurrent execution over a Linux cluster was recently added. *M. Cavenago, O. Kester, T. Lamy and P. Sortais, Rev. Sci. Instrum. 73, 537 (2002). |
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| FOAA008 | Superconducting RF Development at Nuclear Science Centre | linac, vacuum, electron, coupling | 625 | ||
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Funding: Nuclear Science Centre, New Delhi, India. |
A Superconducting Linac is being installed as a booster for the 15 UD Pelletron accelerator at Nuclear Science Centre (NSC). The accelerating structure for this linac is a Nb QWR cavity, designed and fabricated as a joint collaboration between NSC and ANL, USA. Initial cavities required for the first linac module were fabricated at ANL. For fabrication of cavities required for future modules a Superconducting Resonator Fabrication Facility has been set up at NSC. Three quarter wave resonator (QWR) cavities have been fabricated using the in-house facility. This facility has been used for repairs on the resonators which sprung leaks. Fabrication of fifteen resonators for the second and third linac modules is under progress. Eight resonators along with a superconducting solenoid has been installed in the first linac cryostat and tested for energy gain with a pulsed beam of 90 MeV Si from the Pelletron. Acceleration of the ions to 96 MeV was measured downstream and beam transmission through the linac was measured to be ~ 100%. |
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| FOAB001 | Compact Neutron Generators for Medical, Home Land Security, and Planetary Exploration | ion-source, plasma, target, electron | 49 | ||
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Funding: This work is being support by U.S. Department of Energy under contract No. DE-AC03-76SF00098. |
The Plasma and Ion Source Technology Group at Lawrence Berkeley National Laboratory has developed various types of advanced D-D (neutron energy 2.5 MeV), D-T (14 MeV) and T-T (0 – 9 MeV) neutron generators for wide range of applications. These applications include medical (Boron Neutron Capture Therapy), homeland security (Prompt Gamma Activation Analysis, Fast Neutron Activation Analysis and Pulsed Fast Neutron Transmission Spectroscopy) and planetary exploration in form of neutron based, sub-surface hydrogen detection systems. These neutron generators utilize RF induction discharge to ionize the deuterium/tritium gas. This discharge method provides high plasma density for high output current, high atomic species from molecular gases, long life operation and versatility for various discharge chamber geometries. Three main neutron generator developments are discussed here: high neutron output co-axial neutron generator for BNCT applications, point neutron generator for security applications, compact and sub-compact axial neutron generator for elemental analysis applications. Current status of the neutron generator development with experimental data will be presented. |
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| FOAB004 | Construction of FFAG Accelerators in KURRI for ADS Study | ion-source, acceleration, proton, booster | 350 | ||
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KART (Kumatori Accelerator driven Reactor Test) project is in progress at Kyoto University Research Reactor Institute (KURRI) from the fiscal year of 2002. The purposes of this project is the feasibility study of ADS, such as studying the effect of incident neutron energy on the effective multiplication factor of the subcritical nuclear fuel system. We are now constructing a proton FFAG accelerator complex as a neutron production driver for this project. Our accelerator complex consists of a 2.5 MeV FFAG with induction acceleration as an injector, 20 MeV and 150 MeV FFAGs with RF acceleration as a booster and a main ring, respectively. Our FFAG injector is a spiral sector type with 32 trim coils to produce a magnetic field of variable field index. Both booster and main rings are the radial sector type in which the field index is determined by the shape of pole-face. The test operations of the injector and the whole FFAG complex are expected around the spring and summer in 2005, respectively. Then this FFAG complex will be combined with our Kyoto University Critical Assembly (KUCA) in KURRI by the end of March 2006 for the feasibility study.
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| FOAB009 | The Frankfurt Funneling Experiment | rfq, emittance, linac, ion-source | 677 | ||
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Funding: BMBF |
Funneling is a technique to multiply beam currents of rf-accelerators in several stages at low energies to prevent problems with space charge. The Frankfurt Funneling Experiment is a prototype of such a stage. Two beams accelerated in a Two-Beam RFQ are combined to one beam axis with a funneling deflector. The last part of the RFQ electrodes of our Two-Beam RFQ has been replaced to achieve a 3d focus of both beams at the beam crossing point behind the RFQ in the center of the deflector. A newly designed multi cell funneling deflector and first results of the new experimental set-up will be presented. |
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| FOAD001 | Frozen Beams | storage-ring, lattice, resonance, laser | 4 | ||
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In general, the temperature of a charged particle beam traveling in an accelerator is very high. Seen from the rest frame of the beam, individual particles randomly oscillate about the reference orbit at high speed. This internal kinetic energy can, however, be removed by introducing dissipative interactions into the system. As a dissipative process advances, the beam becomes denser in phase space or, in other words, the emittance is more diminished. Ideally, it is possible to reach a "zero-emittance" state where the beam is Coulomb crystallized. The space-charge repulsion of a crystalline beam just balances the external restoring force provided by artificial electromagnetic elements. In this talk, general discussion is made of coasting and bunched crystalline beams circulating in a storage ring. Results of molecular dynamics simulations are presented to demonstrate the dynamic nature of various crystalline states. A possible method to approach such an ultimate state of matter is also discussed.
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| FOAD004 | Laser Cooling of Relativistic Heavy Ion Beams | laser, synchrotron, electron, heavy-ion | 401 | ||
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Funding: Partially funded by the german BMBF (06ML183). |
We report on the first laser cooling of a bunched beam of multiply charged C3+ ions performed at the ESR (GSI) at a beam energy of E=1.47GeV. Moderate bunching provided a force counteracting the decelerating laser force of one counterpropagating UV laser beam. This versatile type of laser cooling lead to longitudinally space-charge dominated beams with an unprecedented relative momentum spread of 10-7. Concerning the beam energy and charge state of the ion, the experiment depicts an important intermediate step from the established field of laser cooling of ion beams at low energies toward the laser cooling scheme proposed for relativistic beams of highly charged heavy ions at the future GSI facility FAIR. |
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| FOPA003 | Challenges and Progress in the FAIR Accelerator Project | dipole, antiproton, synchrotron, proton | 294 | ||
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An international "Facility for Antiproton and Ion Research (FAIR)" was proposed to be built at GSI, providing unique conditions for experiments involving heavy ion and antiprotons beams. The new accelerator complex consists of the fast ramped s.c. heavy ion synchrotrons, SIS100/300 and a storage ring system for experiments with radioactive ions and antiprotons. The two stage concept for SIS100/300 provides optimum conditions for the generation of beams with high intensities per cycle and in average, over a wide energy range and with various time structures. Bunch compression enables a matching to the production targets and storage rings. The storage ring complex was optimized for fast cooling and accumulation of the generated secondary beams. Unique conditions for internal target experiments with radioactive beams will be provided in NESR and for antiproton beams in the high energy storage ring HESR. The new accelerators require R&D work in various fields of technologies and beam physics, as e.g. operation with low charge state, high intensity, heavy ion beams in dynamic vacuum conditions, development of fast ramped s.c. magnets, powerful, low frequency rf systems, stochastic cooling systems and medium energy electron coolers.
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