Paper | Title | Other Keywords | Page |
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MOPWA048 | Transverse Emittance Measurement for Low Energy Ion Beams Using Quadrupole Scan Method | ion, emittance, plasma, ECR | 226 |
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Low energy ion beam facility (LEIBF) * at IUAC consists of all permanent magnet 10 Ghz electron cyclotron resonance (ECR) ion source (NANOGUN) ** along with 400 kV high voltage accelerating platform, a switching cum analysing magnet and electrostatic quadrupoles. Higher beam currents of heavy charge states and low energy of ion beams puts tremendous challenge to transport the ion beam from source to target. The normalized emittance of analysed ion beam is measured for specific charge to mass ratio using electrostatic quadrupole scan method *** for various source parameters like RF power and injection pressure of gas etc. For various m/q ratios, the normalized transverse emittance ranges from 0.1 to 0.6 mm-mrad. It is attributed to beam rotation induced by ECR axial magnetic field, effect of ion temperature in plasma, non linear electric fields and space charge etc which play a significant role in emittance growth.
* A. Mandal et. al. Proceedings of IPAC2011, WEPC011, San Sebastián, Spain ** D Kanjilal et. al. Indian J. Pure Appl. Phys. 39 (2001) 25 *** I. G. Brown:The physics and technology of ion sources |
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MOPJE022 | Physical Model of Partial RF Discharge in Isochronous Cyclotrons | electron, cyclotron, plasma, ion | 323 |
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The physical model for the partial RF discharge - based on the ionization of molecules of residual gas by electron detachment as a result of the electro-dissociation of negative hydrogen ions in isochronous cyclotrons - is proposed in this paper. The result of the simulation of the ionization of gas molecules by these electrons using RF voltage inside the Eclipse cyclotron (kinetic energy of 11 MeV) is presented. The analysis of the conductivity of the RF plasma (partial RF discharge) is given. The influence of the magnetic field on the properties of the partial RF discharge is discussed. The application of this model is for isochronous cyclotrons with low kinetic energy (10-15 MeV). | |||
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MOPHA013 | Superconducting Radio Frequency Cavity Degradation Due to Errant Beam | cavity, ion, linac, vacuum | 805 |
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Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05- 00OR22725 for the U.S. Department of Energy. In 2009, the Superconducting Radio Frequency (SRF) cavities at the Spallation Neutron Source (SNS) began to experience significant operational degradation [1]. The source of the degradation was found to be repeated striking of cavity surfaces with errant beam pulses. The Machine Protection System (MPS) was designed to turn the beam off during a fault condition in less than 20 μseconds [2] as these errant beam pulses were not unexpected. Unfortunately an improperly operating MPS was not turning off the beam within the designed 20 μseconds, and the SRF cavities were being damaged. The MPS issues were corrected, and the SRF performance was restored with cavity thermal cycling and RF processing. However, the SRF cavity performance has continued to degrade, though at a reduced rate compared to 2009. This paper will detail further study of errant beam frequency, amount lost per event, causes, and the corrective actions imposed since the initial event. |
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MOPHA025 | Control System for FRANZ Facility | controls, ion, proton, neutron | 830 |
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The Frankfurt Neutron Source at the Stern- Gerlach Zentrum (FRANZ) will use the reaction of 7Li(p, n)7Be to produce an intense neutron beam. The neutron energy will be between 10 and 500 keV depending on the primary proton beam, which is variable between 1.8 and 2.2 MeV. A volume type ion source will be used to deliver a 120 keV proton beam with currents up to 200 mA. Like any other facility, FRANZ will need a powerful and reliable control system that also allows monitoring the whole accelerator target areas and experiments. Also interlock and safety systems have to be included to protect personnel from radiation hazards associated with accelerator operations and accompanying experiments. The FRANZ control system is still under development. The ion source will be the first element to be controlled, and to gain experience. A test ion source will be used for testing and examining the performance of this control system. In this paper, the plasma properties, filament ageing and an internal control loop for stable beam production with respect to controlling issues will be discussed. | |||
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MOPTY082 | Beam Instrumentation of the PXIE LEBT Beam Line | emittance, ion, solenoid, diagnostics | 1129 |
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The PXIE accelerator is the front-end test stand of the proposed Proton Improvement Plan (PIP-II) initiative: a CW-compatible pulsed H− superconducting RF linac upgrade to Fermilab’s injection system. The PXIE Ion Source and Low-Energy Beam Transport (LEBT) section are designed to create and transfer a 1–10 mA H− beam, in either pulsed (0.001–16 ms) or DC mode, from the ion source through to the injection point of the RFQ. This paper discusses the range of diagnostic tools Allison-type Emittance Scanner, Faraday Cup, Toroid, DCCT, electrically isolated diaphragms – involved in the commissioning of the beamline and preparation of the beam for injection into the RFQ. | |||
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WEPWA012 | Design of a Microwave Frequency Sweep Interferometer for Plasma Density Measurements in ECR Ion Sources | plasma, ion, simulation, diagnostics | 2512 |
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Electron Cyclotron Resonance Ion Sources (ECRIS) are among the candidates to support the growing request of intense beams of multicharged ions. Their further development is related to the availability of new diagnostic tools, nowadays consisting of few types only of devices designed on purpose for such compact machines. Microwave Interferometry is a non-invasive method for plasma diagnostics and represents the best candidate for the whole plasma density measurements. Interferometry in ECR Ion Sources is a challenging task due to their compact size. The typical density range of ECR plasmas (1011-1012 cm-3) causes the probing beam wavelength to be in the order of few centimetres, which is comparable to the chamber radius. The paper describes the design of a new microwave interferometer based on the so-called "frequency sweep" method: the density is here derived by the frequency shift of a beating signal obtained during the fast sweep of both probing and reference microwave signals; inner cavity multipaths contributions can thereby be suppressed by cleaning the spurious frequencies from the beating signal spectrum. | |||
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WEPWA027 | Gas Flow Influence on Negative Hydrogen Ion Generation within the Microwave-Driven Negative Ion Source | ion, electron, operation, experiment | 2555 |
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H− ion was generated through two processes within a volume Cs- free source. The density of molecule hydrogen gas will impact the electron temperature within the primary discharge chamber that will influence the population of vibrationally excited H2*. Within the extraction region, the interaction between molecule hydrogen and H− ion will is cause the dissociation of negative ion. To better understand the gas flow influence on H− ion generation within a volume negative ion source, a new Cs-free volume microwave-driven H− source body with two gas inlets was developed at Peking University (PKU). Experiment on gas flow and gas pressure distribution within the plasma chamber was carried out with this source body. In the meantime a two dimensional (2D) model for gas flow was developed. Details will be presented in this paper.
[1] S.X. Peng, H.T. Ren, Y. Xu, T. Zhang, etc., CW/Pulsed H− Ion Beam Generation with PKU Cs-free 2.45 GHz Microwave Driven Ion Source. O5-06, NIBS 2014, Accepted for publication in AIP, 2014/11/04. |
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WEPWA031 | A Compact Multiply Charged Ion Source for Hadrontherapy Facility | ion, plasma, injection, solenoid | 2563 |
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The ion sources, required by medical applications, must provide intense ion beams, with high reproducibility, stability and brightness. AISHa (Advanced Ion Source for Hadrontherapy) is a compact ECRIS whose hybrid magnetic system consists of a permanent Halbach-type hexapole magnet and a set of independently energized superconducting coils. These will be enclosed in a compact cryostat with two cryocoolers to operate without LHe. The microwave injection system has been designed for maximizing the beam quality through a fine frequency tuning within the 17.3-18.4 GHz band which is possible by using an innovative variable frequency klystron. The introduction of an integrated oven will allow the production of metal ions beams with relatively high intensity. “Accel-decel” extraction system will be used. The LEBT line will consist of a solenoid and a 90° dipole for ions selection. Two diagnostic boxes, made of Faraday cups, beam wires and slits, will allow the investigation of the beam composition and its properties. Moreover, a system of scintillating screens and CCD cameras, placed after the solenoid will allow the investigation of the Frequency Tuning Effect on the source performances. | |||
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WEPWA059 | RF Plasma-Based Ion Source Modeling on Unstructured Meshes | ion, simulation, plasma, electron | 2637 |
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Funding: This work was performed under the auspices of the Department of Energy, Office of Basic Energy Sciences Award #DE-SC0009585. Ion source performance for accelerators and industrial applications can be improved through detailed numerical modeling and simulation. There are a number of technical complexities with developing robust models, including a natural separation of important time scales (rf, electron and ion motion), inclusion of plasma chemistry, and surface effects such as secondary electron emission and sputtering. Due to these computational requirements, it is typically difficult to simulate ion sources with Particle-In-Cell codes. An alternative is to use fluid-based codes coupled with electromagnetics in order to model ion sources. These types of models can simulate plasma evolution and rf-driven flows while maintaining good performance. We show here recent results on modeling the H− ion source for the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) using the fluid plasma modeling code USim. We present new meshing capabilities for generating and parallelizing unstructured computational meshes that have increased our parallel code performance and enabled us to model inductively coupled plasmas for long periods of operation. |
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WEPJE011 | High Reliability, Long Lifetime, Continuous Wave H− Ion Source | ion, electron, plasma, extraction | 2695 |
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Funding: Small Business Innovation Research (SBIR) Phase II Phoenix Nuclear Labs (PNL) is developing a high-current, long-lifetime negative hydrogen (H−) ion source in partnership with Fermilab as part of an ion beam injector for future Intensity Frontier particle accelerators. In this application, continuous output with long lifetime and high reliability and efficiency are critical. Existing ion sources at Fermilab rely on plasma-facing electrodes and are limited to lifetimes of a few hundred hours, while requiring relatively high gas loads on downstream components. PNL's H− ion source uses an electrodeless microwave plasma generator which has been extensively developed in PNL's positive ion source systems, demonstrating 1000+ hours of operation and >99% continuous uptime. A magnetic filter preferentially blocks energetic electrons produced in the plasma, while allowing cold electrons and fast neutrals through toward a cesiated surface converter to produce the desired H− ions, which are extracted into a low energy beam using electrostatic lenses. The design specifications are 5-10 mA of continuous H− current at 30 keV with <0.2 pi-mm-mrad beam emittance. Construction and testing of the H− ion source is underway at PNL. |
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WEPTY048 | An RFQ Direct Injection Scheme for the IsoDAR High Intensity H2+ Cyclotron | rfq, ion, cyclotron, injection | 3384 |
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IsoDAR is a novel experiment designed to measure neutrino oscillations through electron-antineutrino disappearance, thus providing a definitive search for sterile neutrinos. In order to generate the necessary anti-neutrino flux, a high intensity primary proton beam is needed. In IsoDAR, H2+ is accelerated, and is stripped into protons just before the target, to overcome space charge issues at injection. As part of the design, we have refined an old proposal to use an RFQ to axially inject bunched H2+ ions into the driver cyclotron. This method has several advantages over a classical low energy beam transport (LEBT) design: (1) The bunching efficiency is higher than for the previously considered two-gap buncher and thus the overall injection efficiency is higher. This relaxes the constraints on the H2+ current required from the ion source. (2) The overall length of the LEBT can be reduced. (3) The RFQ can also accelerate the ions. This enables the ion source platform high voltage to be reduced from 70 kV to 30 kV, making underground installation easier. We will present preliminary RFQ design parameters and first beam dynamics simulations from the ion source to the spiral inflector. | |||
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THPF003 | BEST 70P Cyclotron Factory Test | ion, cyclotron, injection, emittance | 3680 |
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Best Cyclotron Systems Inc (BCSI) designed and manufactured a 70MeV compact cyclotron for radioisotope production and research applications. The cyclotron undergone exhaustive factory testing that has been successfully completed at Best Theratronics facility in Ottawa, Canada. The first 70MeV cyclotron has been build for the INFN-LNL laboratory in Legnaro, Italy. The cyclotron has external negative hydrogen ion source, four radial sectors with two dees in opposite valleys, cryogenic vacuum system and simultaneous beam extraction on opposite lines. The beam intensity is 700μA with variable extraction energy between 35 and 70MeV. We are reporting the factory acceptance testing results confirming the individual cyclotron systems performance and beam acceleration to 1MeV probe. Detail measurements of each system stability and performance have been taken as well as full characterisation of beam acceleration through the injection line and on to the 1MeV probe. The BEST70p cyclotron may also be used as injector to a post-accelerator or for the production of the radioactive beams. | |||
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THPF028 | Conceptual Design of a Novel RFQ for Medical Accelerators | rfq, ion, simulation, alignment | 3751 |
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At the Heidelberg Ion Beam Therapy Centre HIT we operate a 4-rod RFQ as first stage of a 7 MeV/u injector linac followed by an IH-DTL. During the first years of patient treatment the injector performance was perfectly adequate, even though the transmission of the linac remained below the theoretical expectations. New developments in dose delivery technology already realised or to come in the future increase the demand on higher beam intensities which will finally result in shorter irradiation times. As measurements performed at our test bench have confirmed that there is a margin for higher transmissions especially for the RFQ we are currently preparing for a new RFQ design. While keeping the original design parameters, the new RFQ should be optimised with respect to the transmission of beams from different ion sources such as electron cyclotron resonance or electron beam ion sources. All parts of the RFQ will be put up for discussion including electrodes, stems, tank and the integrated rebuncher. The design work will profit from new concepts that have evolved at our own and other medical heavy ion facilities in operation and from the progress modern simulation tools have run through. | |||
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THPF029 | Preparation of an Ion Source for an Extra Low Energy Synchrotron | ion, extraction, antiproton, electron | 3755 |
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Funding: The work is supported within the framework of the Helmholtz Association’s Accelerator Research and Development (ARD) program. ELENA* is a compact ring for cooling and further deceleration of 5.3 MeV antiprotons delivered by the CERN Antiproton Decelerator (AD) down to 100 keV. Because of the long AD cycle of 100 s, it is foreseen to use a source for protons and H− with a kinetic energy of 100 keV for commissioning and start-ups. The source, designed to provide 0.2 to 2.0μsec pulses with 3x107 ions, is based on a proven multicusp volume source used at the COSY/Jülich** injector cyclotron. The source and its auxiliaries were refurbished, upgraded to ±100 keV operation at the Forschungszentrum Jülich and have been set in operation at CERN in April 2015 for first tests of new equipments. * V. Chohan [ed.], ELENA ring and its Transfer Lines – Design Report Geneva 2014, DOI 10.5170/CERN-2014-002 ** R. Maier Nucl. Instr. Meth. A 390 (1997) P.1. |
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THPF073 | Progress of the RAON Heavy Ion Accelerator Project | ion, cryomodule, ECR, rfq | 3848 |
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Construction of the RAON heavy ion accelerator facility is under way in Korea that includes both the In-flight Fragment (IF) and Isotope Separation On-Line (ISOL) facilities to support cutting-edge researches in various science fields. Prototyping and testing of major components are proceeding including 28 GHz ECR ion source, RFQ, superconducting cavities, cryomodules, superconducting magnets. Superconducting magnets of 28 GHz ECR ion source are fabricated and tested. First article of prototype superconducting cavities are delivered that were fabricated through domestic vendors and tested at TRIUMF. Prototype HTS(High Tc Superconducting) magnets is in progress. Progress report of the RAON accelerator systems is presented. | |||
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THPF110 | Offline Testing of the CARIBU EBIS Charge Breeder | ion, electron, operation, rfq | 3973 |
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Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357. In 2015 an electron beam ion source (EBIS) will be installed at the ATLAS facility to charge breed radioactive beams from the Californium Rare Isotope Breeder Upgrade (CARIBU). Currently an ECR ion source is used to charge breed CARIBU beams. The EBIS will provide beams with much less contamination and higher breeding efficiencies. In preparation for its installation at ATLAS the EBIS has been successfully commissioned offline. The EBIS was configured in the offline facility to closely mimic the conditions expected in the ATLAS installation, so commissioning results should be representative of its performance with CARIBU. The EBIS breeding efficiency was tested with pulses of 133Cs1+ from a surface ionization source, and for multiple operational modes maximum breeding efficiencies greater than 25% could be achieved. After transmission losses the total efficiency of the system was 15-20%. The contaminants were expectedly very low for a UHV system with nominal pressures of ~1 – 3 x 10-10 Torr. |
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THPF126 | PXIE Low Energy Beam Transport Commissioning | solenoid, ion, emittance, simulation | 4013 |
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Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the United States Department of Energy The Proton Improvement Plan II at Fermilab is a program of upgrades to the injection complex [1]. At its core is the design and construction of a CW-compatible, pulsed H− superconducting RF linac. To validate the concept of the front-end of such machine, a test accelerator (a.k.a. PXIE) is under construction [2]. It includes a 10 mA DC, 30 keV H− ion source, a 2m-long LEBT, a 2.1 MeV CW RFQ, followed by a MEBT that feeds the first of 2 cryomodules taking the beam energy to ~25 MeV, and a High Energy Beam Transport section (HEBT) that takes the beam to a dump. The ion source and LEBT, which includes 3 solenoids, several clearing electrodes/collimators and a chopping system, have been built, installed, and commissioned to full specification parameters. This report presents the outcome of our commissioning activities, including phase-space measurements at the end of the beam line under various neutralization schemes obtained by changing the electrodes’ biases and chopper parameters. |
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THPF127 | Scheme for a Low Energy Beam Transport with a Non-neutralized Section | ion, space-charge, emittance, rfq | 4016 |
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Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the United States Department of Energy A Low Energy Beam Transport (LEBT) line is the part of a modern ion accelerator between an ion source (IS) and a Radio-Frequency Quadrupole (RFQ). Typically, it includes 1-3 solenoidal lenses for focusing and relies on transport dynamics with nearly complete beam space charge neutralization over the entire length of the LEBT. In this paper, we discuss the possibility and rationality of imposing un-neutralized transport in the portion of the LEBT adjacent to the RFQ. For estimations, we will use the parameters from PXIE, a test accelerator presently being constructed at Fermilab. |
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THPF141 | Design of a Compact All-Permanent Magnet ECR Ion Source Injector for ReA at MSU NSCL | ion, ECR, injection, extraction | 4054 |
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Funding: Work supported by Michigan State University and the National Science Foundation Grant PHYS-1102511. The design of a compact all-permanent magnet electron cyclotron resonance (ECR) ion source injector for the ReAccelerator Facility (ReA) at the Michigan State University (MSU) National Superconducting Cyclotron Laboratory (NSCL) is currently being carried out. The ECR ion source injector will augment the electron beam ion trap (EBIT) charge breeder as an off-line stable ion beam injector for the ReA linac. The objective of the ECR ion source injector will be to provide CW beams of heavy ions from hydrogen to masses up to 136Xe within the ReA charge-to-mass ratio (Q/A) operational range from 0.2 to 0.5. The ECR ion source will be mounted on a high-voltage platform that can be adjusted to provide the required 12 keV/u injection energy into a room temperature radio-frequency quadrupole (RFQ) for further acceleration. The beam line consists of a 30 kV tetrode extraction system, mass analyzing section, and optical matching section for injection into the existing ReA Low Energy Beam Transport (LEBT) line. The design of the ECR ion source and the associated beam line are discussed. |
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THPF142 | High Intensity Source of He Negative Ions | ion, target, polarization, electron | 4057 |
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He- ion can be formed by an attachment of additional electron to the excited metastable 23S1 He atom. Electron affinity in this metastable He- ion is A=0.08 eV with excitation energy 19.8 eV. Production of He- ions is difficult because the formation probability is very small but destruction probability is very high. Efficiency of He- ions generation was improved by using of an alkali vapor targets for charge exchange He- sources. Low current He- beams were used in tandem accelerators for research and technological diagnostics (Rutherford scattering). The development of high-intensity high-brightness arc-discharge ion sources at the Budker Institute of Nuclear Physics (BINP) has opened up an opportunity for efficient production of more intense and more brighter He- beam which can be used for alpha particles diagnostics in a fusion plasma and for realization of a new type of a polarized 3He− ion source. This report discusses the high intense He- beams production and a polarized 3He− ion source based on the large difference of extra-electron auto-detachment lifetimes of the different 3He− ion hyperfine states. | |||
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THPF147 | Increasing the Beam Brightness of a Duoplasmatron Proton Ion Source | emittance, extraction, brightness, ion | 4070 |
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Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396 The LANSCE accelerator facility operates with two independent ion injectors for H+ and H− particle beams. The H+ ion beam is formed using a duoplasmatron source followed by a 750 keV Cockroft-Walton accelerating column. Formation of an optimal plasma meniscus is an important feature for minimizing beam emittance and maximizing beam brightness. An experimental study was performed to determine optimal conditions of extracted H+ beam for maximizing beam brightness. Study was based on measurements of beam emittance versus variable beam current and extraction voltage. Measurements yielded 0.52 as the best ratio of beam perveance to Child - Langmuir perveance for maximizing beam brightness. As a result of optimization, beam brightness was increased by a factor of 2. |
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THPF148 | LANSCE H+ RFQ Status | rfq, beam-transport, ion, linac | 4073 |
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Funding: This work is supported by the U. S. Department of Energy Contract DE-AC52-06NA25396. The LANSCE linear accelerator at Los Alamos National Laboratory provides H− and H+ beams to several user facilities that support Isotope Production, NNSA Stockpile Stewardship, and Basic Energy Science programs. These beams are initially accelerated to 750 keV using Cockcroft-Walton (CW) based injectors that have been in operation for over 37 years. To reduce long-term operational risks and to realize future beam performance goals for LANSCE we are completing fabrication of a 4-rod Radio-Frequency Quadrupole (RFQ) and design of an associated beam transport line that together will eventually become the modern injector replacement for the existing obsolete H+ injector system. A similar H− system is also planned for future implementation. An update on the status and progress of the project will be presented. |
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