| Paper | Title | Page |
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| TUPTS001 | Improvements in Rf Multi Cusp Negative Ion Source | 1928 |
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| D-Pace’s 13.56 MHz Radio Frequency (RF) multi cusp negative ion source uses an Aluminium Nitride (AlN) dielectric window for coupling RF power from an external antenna to the plasma chamber. Ion source operation was limited to low RF power (< 3500 W) due to failures (cracks) occurring on the window during experiments. Such events can cause damages to the vacuum system and plasma chamber. The current work deals with simulations performed on the ion source to study the factors leading to the failure of the window. Based on results from the simulations, a new design was introduced. The improved design yielded positive results in terms of source performance and stability of the AlN window. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS001 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS004 | Development of a Penning Ion Source Test Stand for Production of Alpha Particles | 1932 |
| TUPTS002 | use link to see paper's listing under its alternate paper code | |
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Medical cyclotron manufacturers are seeking less-costly and more compact ion sources than Electron Cyclotron Resonance Ion Sources (ECRIS) for alpha particle production, which are currently capable of generating beam currents up to 2 mA at energies of 30 keV for axial injection into these cyclotrons. Penning Ion Sources by comparison are relatively old technologies mostly used for cheap singly-charged ion production. However, these ion sources have been used in the past for high-current multiply-charged state ion production of heavy ions up to a few mA of current, and are much smaller, cheaper, and less complex than ECRISs. Therefore, we are developing a Penning Ion source test stand to produce high-current alpha-particles for medical cyclotrons. This requires designs and simulations of all the primary components of the ion source. This system will be used to fully characterize the output beam current and internal plasma properties as a function of varying gas pressure, ion source geometries, magnetic field strength, arc voltage/current, and material properties. The result will be a source optimized for maximum alpha particle beam currents, to be used as a prototype for a commercial Penning Ion Source.
* J. Bennet. A Review of PIG Sources for Multiply Charged Heavy Ions. IEEE Transactions on Nuclear Science, 1972. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS004 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS005 | Advanced Beam Transport Solutions for ELIMAIA: A User Oriented Laser-Driven Ion Beamlines | 1936 |
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| Laser-target acceleration represents a promising alternative to standard accelerators for several potential applications, especially medical ones, but some extreme features make laser-driven ion beams not directly usable. Therefore, a large effort has been recently devoted to development of beam-transport solutions to obtain controlled and reproducible beams. In this framework, a collaboration has been established between INFN-LNS (IT) and Eli-Beamlines-IoP (CZ) to realize a complete transport beam-line, named ELIMED, dedicated to the transport, diagnostics and dosimetry of laser-driven ion beams. The transport beamline is made by three sections: a set of high field gradient permanent magnet quadrupoles with large acceptance is used to collect and inject ions in the selection section; a magnetic chicane made of C-shaped resistive dipoles is able to select beams with high resolution and to work as an active energy modulator. The final beam shaping is done by two resistive quadrupoles. In this contribution the status of the beamline is described together with the tests performed with conventional accelerators at INFN-LNS. Feasibility study of possible upgrades are also reported. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS005 | |
| About • | paper received ※ 15 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS006 | Tests at High RF Power of the ESS Medium Beta Cryomodule Demonstrator | 1940 |
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| CEA is in charge of the 30 elliptical medium and high-beta cryomodules to be installed in the ESS tunnel in Lund, Sweden. Before launching the assembly of the series cryomodules, CEA developed a medium-beta cryomodule technology demonstrator in a collaboration with IPNO, LASA and ESS. This paper briefly presents the cryomodule assembly and summarizes the main results of the high RF power tests performed in 2018 in a dedicated test stand in CEA Saclay. The main ESS requirements were reached: Eacc = 16.7 MV/m in cavities, Pforward = 1.1 MW in power couplers, RF pulses length = 3.6 ms at 14 Hz. The piezo tuners efficiently compensated the Lorentz forces detuning and could stabilize the accelerating field better than 1% over the full length of the expected ESS 2.86 ms beam pulse without any LLRF regulation system. Following this successful validation CEA started the assembly of the first ESS medium-beta series cryomodule | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS006 | |
| About • | paper received ※ 06 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS007 | SPIRAL2 RFQ Bunch Length and Longitudinal Emittance Measurements. | 1944 |
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| The SPIRAL2 RFQ is designed to accelerate light and heavy ions up to A/Q=3 in CW mode to 0.75MeV/u. During its commissioning, the bunch lengths measured using a Beam Extension Monitor were compared with simulations for different ion species (Proton, Helium, Oxygen, Argon). The longitudinal emittances measured using the 3 gradients method and a multiparticule optimization method were also compared successfully to the expected ones. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS007 | |
| About • | paper received ※ 19 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS008 | The Pulsing Chopper-Based System of the Arronax C70XP Cyclotron | 1948 |
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Funding: This work is, in part, supported by a grant from the French National Agency for Research called "Investissements d’Avenir", Equipex Arronax-Plus noANR-11-EQPX-0004 and LabexIRON noANR-11-LABX-18-01. The Arronax Public Interest Group (GIP) uses a multi-particle cyclotron to perform irradiation from a few pA up to hundreds of uA on various experiments and targets *. To support further low intensity usage and extend the beam time structure required for experiments such as pulsed experiments studies (radiolysis, proton therapeutic irradiation) and high intensity impact studies, it has been devised a pulsing system in the injection of the cyclotron. This system combines the use of a chopper, low frequency switch, and a control system based on the new extended EPICS network. This paper details the pulsing system adopted at Arronax, the last results in terms of time structure, various low intensity experimental studies performed with alpha and proton beams and the dedicated photon diagnostics. * F.Poirier et al., "Studies and Upgrades on the C70 Cyclotron Arronax", CYC16, September 2016, TUD02. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS008 | |
| About • | paper received ※ 12 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS009 | Operating the SNS RF H− Ion Source with a 10% Duty Factor | 1951 |
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Funding: This work was performed at Oak Ridge National Laboratory under contract DE-AC05-00OR22725 and at Los Alamos National Laboratory under contract DE-AC52-06NA25396 for the U.S. Department of Energy. The SNS (Spallation Neutron Source) (radio-frequency) RF-driven, H− ion source injects ~50 mA of H− beam into the SNS accelerator at 60 Hz with a 6% duty factor. It injects up to 7 A·hrs of H− ions during its ~14-week service cycles, which is an unprecedented lifetime for small-emittance, high-current pulsed H− ion sources. The SNS source also features unprecedented low cesium consumption and can be installed and started up in <10 h. Presently, the LANSCE (Los Alamos Neutron Science CEnter) accelerator complex in Los Alamos is fed by a filament-driven, biased converter-type H− source that operates with a high plasma duty factor of 10%. It needs to be replaced every 4 weeks with a ~4 day startup phase. The measured negative beam current of 16-18 mA falls below the desired 21 mA acceptance of LANSCE’s accelerator especially since the beam contains several mA of electrons. LANSCE and SNS are exploring the possibility of using the SNS RF H− source at LANSCE to increase the H− beam current and the ion source lifetime while decreasing the startup time. For this purpose, the SNS H− source has been tested at a 10% duty factor by operating it at 120 Hz with 840 µs plasma pulses generated with ~30 kW of 2 MHz RF power, and extracting ~25 mA around-the-clock for 28 days. This, and additional tests and other considerations are discussed in this paper. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS009 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS011 | Vacuum Lifetime and Surface Charge Limit Investigations Concerning High Intensity Spin-polarized Photoinjectors | 1954 |
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Funding: DFG excellence initiative PRISMA+, Bundesministerium für Bildung und Forschung "Verbundforschung FKZ 05K16UMA" The Small Thermalized Electron Source at Mainz (STEAM) is a dc photoemission source. It is designed to operate at up to 200kV bias voltage with an accelerating field of up to 5 MV/m at the cathode surface. In several experiments, the properties of GaAs operating under the conditions of spin-polarized photoemission were investigated. Its performance, quantum efficiency lifetime and surface charge limit observations for bulk-GaAs will be discussed. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS011 | |
| About • | paper received ※ 29 April 2019 paper accepted ※ 28 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS012 | Emittance Reduction of RF Photoinjector Generated Electron Beams By Transverse Laser Beam Shaping | 1958 |
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| Laser pulse shaping is one of the key elements to generate low emittance electron beams with RF photoinjectors. Ultimately high performance can be achieved with ellipsoidal laser pulses, but 3-dimensional shaping is challenging. High beam quality can also be reached by simple transverse pulse shaping, which has demonstrated improved beam emittance compared to a transversely uniform laser in the ‘pancake’ photoemission regime. In this contribution we present the truncation of a Gaussian laser at a radius of approximately one σ in the intermediate (electron bunch length directly after emission about the same as radius) photoemission regime with high acceleration gradients (up to 60 MV/m). This type of electron bunch is used e.g. at the European XFEL and FLASH free electron lasers at DESY, Hamburg site and is being investigated in detail at the Photoinjector Test facility at DESY in Zeuthen (PITZ). Here we present ray-tracing simulations and experimental data of a laser beamline upgrade enabling variable transverse truncation. Initial projected emittance measurements taken with help of this setup are shown, as well as supporting beam dynamics simulations. Additional simulations show the potential for substantial reduction of slice emittance at PITZ. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS012 | |
| About • | paper received ※ 24 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS013 | Characterization of an Electron Gun Test Setup Based on Multipacting | 1961 |
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| A multipacting electron gun (MEG) is a micro-pulse electron source, based on secondary electron emission in a resonant microwave cavity structure, for the generation of low emittance electron bunches in continuous wave operation. Based on numerical simulations, an experimental test setup for low-energy electron beams at 3 GHz has been established. In this contribution we show a detailed description and characterization of the RF test stand, supported by first results on charge collection measurements of the output current with respect to important operational parameters like power transmission and modifiable mechanical dimensions in the assembly of the experiment. This is a milestone in the development of a MEG setup for higher energetic electron beams and subsequent investigation of essential beam characteristics like emittance and energy distribution for the optimization with regard to best possible beam quality and future fields of application. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS013 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS014 | SINGLE SHOT CATHODE TRANSVERSE MOMENTUM IMAGING IN PHOTOINJECTORS | 1964 |
| SUSPFO016 | use link to see paper's listing under its alternate paper code | |
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| In state of the art photoinjector electron sources, cathode performance determines the lower limit of achievable beam emittance. Measuring the thermal emittance at the photocathodes in electron guns is of vital importance for improving the injectors. Traditional methods, like solenoid scan, pepper-pot, need multi-shots and are time-consuming, therefore suffer from machine stability. Here we propose a new method, named cathode transverse momentum imaging. By tuning the gun solenoid focusing, the electrons’ transverse momentum at the cathode is imaged to a downstream screen, which enables a single shot measurement. Several experiments have been done at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) with a Cs2Te cathode. Measurements of cathode transverse momentum, the corresponding spectra, cathode transverse momentum map and its correlation with surface electric field are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS014 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS015 | Design Steps Towards an Electron Source for Ultrafast Electron Diffraction at DELTA | 1968 |
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Funding: MERCUR Pr-2017-0002 Ultrafast electron diffraction (UED) is a pump-probe technique to explore the structural dynamics of matter, combining sub-angstrom De-Broglie wavelength of electrons with femtosecond time resolution. UED experiments require ultrashort laser pulses to pump a sample, electron bunches with small emittance and ultrashort length to analyze the state of the sample and excellent control of the delay between them. Electrons accelerated to a few MeV in a photocathode gun offer significant advantages compared to keV electrons from electrostatic electron sources regarding emittance, bunch length and, due to the reduction of space charge effects, bunch charge. Furthermore, thicker samples and hence a wider range of possible materials are enabled by the longer mean free path of MeV electrons. In this paper, design steps towards a university-based UED facility with ultrashort and low-emittance MeV electron bunches are presented, including the transverse and longitudinal focusing schemes, which minimize space charge effects and nonlinearities. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS015 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS021 | Basic Design of the RF Power System for IRANCYC-10 Accelerator | 1972 |
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| In this paper the basic design of an RF system to produce the required power of IRANCYC-10 cyclotron accelerator is reported. The designed system can generate 15 kW power at the operating frequency of 71 MHz CW. The authors provide a step-by-step ex-planation of the process of the design. It is carried out in three sections; (1) RF design features of the acceler-ator is investigated and power value is calculated in accordance with the requirements of the cyclotron, (2) the choice of solid state amplifiers as the RF power source is presented with its available power and struc-ture, (3) design of insertion instruments is reported to transfer and combine the RF power. The purpose of the paper is to achieve the best performance of the RF system, as well as decreasing overall size by using modular devices. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS021 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS023 | A CENTRAL REGION UPGRADE OF THE k800 SUPERCONDUCTING CYCLOTRON AT INFN-LNS | 1975 |
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| The Superconducting Cyclotron (CS) at INFN-LNS in Catania is currently under an upgrade process. The plan is to deliver beams of ions with mass number 𝐴 ≤ 40 with power up to 10 kW. This ambitious goal can be achieved increasing the efficiency of the injection and extraction processes. An extraction efficiency close to 100% is expected by extracting the specific ion beams from the CS by stripping and no longer by electrostatic deflectors. The beams are injected axially and bent onto the median plane with a spiral inflector. Currently, the injection efficiency stays around 15%, also including the effect of a drift buncher placed in the axial injection line. In order to increase the injection efficiency, the study of an upgraded CS central region is ongoing at INFN-LNS. In this paper, the results of simulations of beam tracking through the cyclotron axial bore, the spiral inflector, the central region and further up to the extraction system are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS023 | |
| About • | paper received ※ 29 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS024 | Design of a Full C-Band Injector for Ultra-High Brightness Electron Beam | 1979 |
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| High gradient rf photo-injectors have been a key development to enable several applications of high quality electron beams. They allow the generation of beams with very high peak current and low transverse emittance, satisfying the tight demands for free-electron lasers, energy recovery linacs, Compton/Thomson sources and high-energy linear colliders. In the paper we present the design of a new full C-band RF photo-injector recently developed in the framework of the XLS-Compact Light design study and of the EuPRAXIA@SPARC_LAB proposal. It allows to reach extremely good beam performances in terms of beam emittance (at the level of few hundreds nm), energy spread and peak current. The photo-injector is based on a very high gradient (>200 MV/m) ultra-fast (RF pulses <200 ns) C-band RF gun, followed by two C band TW structures. Different types of couplers for the 1.6 cell RF gun have been considered and also a new compact low pulsed heating coupler working on the TM020 mode on the full cell has been proposed. In the paper we report the design criteria of the gun, the powering system, and the results of the beam dynamics simulations. We also discuss the case of 1 kHz repetition rate. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS024 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS025 | Arc and Convertor Current Transient Studies for Multi-cusp Cesiated Surface Conversion H− Source at Lansce | 1983 |
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| The Multi-cusp Cesiated Surface Conversion H− Ion Source at the Los Alamos Neutron Science Center (LANSCE) has provided beam at ~14 mA, 120 Hz, and 10% D.F. for many years of neutron science research. Recently, random high current transients were discovered in the arc current used to ionize hydrogen in the LANSCE H− ion source, and in the convertor current used to convert protons to H− ions. Most have no effect, but more severe transients can cripple beam output. Hypothesized causes are related to cesiation effects, plasma potential changes, tungsten filament vaporation/sputtering, or from the pulsed power system. A dedicated study was recently done on the LANSCE H− Ion source test stand to determine the cause of these transients. Current understanding indicates that the more severe transients come from a combination of cesiation effects and plasma potential changes. The status of these current transient studies on the LANSCE H− ion source will be discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS025 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS026 | Negative Electron Affinity GaAs Cathode Activation With CsKTe Thin Film | 1986 |
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Funding: This work is partly supported by Japan-US Cooperative grant for scientific studies, Grant aid for scientific study by MEXT Japan (KAKENHI). Negative Electron Affinity (NEA) GaAs cathode is an unique device which can generate a highly polarized electron beam with circularly polarized light. The NEA surface is conventionally made by Cs and \rm O/NF3 adsorption on the cleaned p-doped GaAs crystal, but the robustness of the cathode is very limited, so that the electron emission is easily lost by residual gas adsorption, ion back-bombardment, etc. To improve the cathode robustness, NEA activation with a stable thin-film on GaAs surface according to Hetero junction hypothesis has been proposed by the author. An experiment of the NEA activation with CsKTe thin film was carried out at Hiroshima University and a significant electron emission with 1.43 eV photon was observed which strongly suggested NEA activation. The cathode showed 16 to 20 times improvement of lifetime comparing to GaAs activated with Cs and O. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS026 | |
| About • | paper received ※ 26 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS027 | Progress of J-PARC LINAC Commissioning | 1990 |
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| After energy and intensity upgrade to 400MeV and 50mA respectively, J-PARC linac were ready for 1 MW beam power from RCS. J-PARC is now successfully operated at 50mA/400MeV for 500kW at neutron target, and on the way to 1MW. The next milestones 1.2 and 1.5MW from RCS are relying on feasibility and property of increase of peak current to 60 mA and the pulse width to 600us in linac. Beam studies were carried out at linac to study the initial beam parameters from ion source/RFQ, to find the optimized lattice and matching, to clarify beam loss source and to mitigate the loss/residue dose for the power upgrade. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS027 | |
| About • | paper received ※ 17 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS028 | Extraction System of Upgraded AVF Cyclotron of RCNP | 1993 |
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The AVF cyclotron of RCNP have been utilized for the purposes of basic research in physics, RI production for medicine and industrial applications as well as injector of ring cyclotron. Increasing beam intensity without decreasing beam quality can make improvements in all purposes. The improvement and repair of the AVF cyclotron are being carried out currently. We designed the new LEBT, injection, acceleration and extraction systems and we report on the extraction system here. High extraction efficiency is indispensable when increasing the beam intensity since beam loss causes activation of apparatus. New extraction system consists of deflector electrodes and two gradient correctors and probes. One gradient corrector causes a horizontally focus effect on the beam and the other causes horizontally defocus effect to avoid spreading of the beam with strong defocus effect caused by the main cyclotron magnetic field. Simulation study confirmed that 10 MeV proton, 65 MeV proton and 140 MeV alpha particles with 2 mm × 3 mrad could pass through the newly designed extraction system and the existing beam transport line. Beam simulation has been performed by utilizing SNOP* and OPAL** codes.
* SNOP V.L. Smirnov, S.B. Vorozhtsov, Proc. of RUPAC2012 TUPPB008 325 (2012) ** The OPAL (Object Oriented Parallel Accelerator Library) Framework, Andreas Adelmann et al., PSI-PR-08-02, (2008-2018) |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS028 | |
| About • | paper received ※ 01 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS029 | The New Eddy Current type Septum Magnets for Upgrading of Fast Extraction in Main Ring of J-PARC | 1997 |
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| The J-PARC Main Ring (MR) is working on imporved beam to 750 kW by shorting the repetition period from 2.48 s to 1.3 s which we call 1Hz operation. The septum magnets for fast extraction in MR will be improved to the new septum magnets which can operate 1Hz. The new magnets will be installed to MR in 2021. In this poster we will report about the new low field septum magnet for the fast extraction. The present septum magnets are conventional type. Therefore, we have problem in durability of thin septum coil by its magnetic vibration, and large leakage field at the exit of the circulating beam duct. The new septum magnets are eddy current type. The eddy current type does not have septum coil, but has a thin septum plate. We can expect that there is no problem in durability of septum coil, and leakage field can be reduced. The output of the present power supply are pattern current which of flat top is 10 ms width, the new one is short pulse which of one is 10 us. The short pulse consists of fundamental and 3rd harmonic sin-wave pulse. We can expect that the flatness and reproducibility of flat top current can be improved. We confirmed that 1Hz operation and high accuracy of its output current and magnetic field with the new septum magnet system. We had some problem in unexpected instability of output current. In this report we also summarize the measure against the instabillity. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS029 | |
| About • | paper received ※ 26 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS030 | The New High Field Septum Magnets for Upgrading of Fast Extraction in Main Ring of J-PARC | 2001 |
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| The J-PARC Main Ring (MR) is working on imporved beam to 750 kW by shorting the repetition period from 2.48 s to 1.3 s which we call 1Hz operation. There are fout high field septum magnet along the fast extraction line in the MR, and these will be improved to the new magnets which can operate 1Hz frequency. The new high field septa will be installed in 2021. In this poster we will report about the performance of these new septum magnets. These high field septum magnets are called Septum 30(SM30), 31(SM31), 32(SM32), 33(SM33). We will replace SM30, SM31, and SM32. One reasons of cethe replacement is installation of a large-size quadrupole magnet to upsteam postion of the septa. We need to change the longitudinal length of the septa. Second is large aperture of the beam duct for reduction of beam loss by the collision of the halo of the proton beam to the duct. The new high field SM30, SM31 and SM32 have large aperture. and the material of the beam ducts for extraction line are ceramics for reduction of amount of heat generation by eddy current on the surface of the duct. The maetial of the circulating duct are titanium for reduction of radioactivation. On the other hand, the power supply will not be replaced, then the current power supplies will be used for these new septa. The new SM30, SM31, and SM32 were produced in 2015. The first test operation of SM31 were conduced with 2.48 s repein 2015, and we have meaured the magnetic field without problem. In 2018, we conduced the first 1Hz operation with SM30. The minimum repetition period of the operation was 1.16 s without any problem. We measuered magnetic fields in the gap of the pole and in the circulating beam duct. In this report we will report the detail of the results of the operation and field measurement. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS030 | |
| About • | paper received ※ 26 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS032 | Radiation Design of New 30 kW Beam Dump of J-PARC Main Ring | 2005 |
| TUPTS031 | use link to see paper's listing under its alternate paper code | |
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| The J-PARC Main Ring (MR) has a beam dump for the beam study and beam abort. Its present capacity is 7.5 kW in one hour average which is limited by radiation condition for the environments. The number of protons in one MR cycle is 2.6·10+14 in recent days, which corresponds to the beam power of 500 kW. As the top energy of J-PARC MR is 30 GeV, the number of available beam shots is restricted to less than twenty in one hour with such an intense beam. It imposes a big limitation on high power beam tuning and study. The number of protons is expected to become 3.3·10+14 for MW operation. Hence, an upgrade of the beam dump from 7.5 kW to 30 kW is planned. The radiation dose rate should be less than 0.25μSv/h on the ground. The backscattered neutron flux should be examined in the accelerator tunnel. The new dump design on radiation matters is described in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS032 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS033 | J-PARC RCS: High-Order Field Components Inherent in the Injection Bump Magnets and Their Effects on the Circulating Beam During Multi-Turn Injection | 2009 |
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| The J-PARC RCS utilizes four sets of pulsed dipole magnets for the formation of injection orbit bump. The injection bump magnets have a large aspect ratio (gap length/core length), so there are other high-order field components inherent in their magnetic fields in addition to the main dipole component. The high-order field components, which locally exist in the injection section not following the lattice super-periodicity, have a significant influence on the circulating beam during multi-turn injection via the excitation of high-order random betatron resonances. This paper discusses the detailed mechanism of emittance growth and beam loss caused by the high-order field components of the injection bump magnets including its correction scenario on the basis of numerical simulation and experimental results. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS033 | |
| About • | paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS034 | Development of Low Inductance Circuit for Radially Symmetric Circuit | 2013 |
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| Radiation symmetric type circuits using semiconductors of SIC-MOSFETs, one of next generation semiconductors, are composed of circuits in which many semiconductor switches are multiplexed in series and in parallel. Since the lengths of all parallel circuits are equal, the output waveform will not be distorted due to timing jitter or level change. This circuit is useful for outputting the waveform of ultrafast short pulse. Therefore, we have developed a circuit that achieves further low inductance by making the power transmission circuit into a double circular ring structure equal to the coaxial shape. Compare the inductance value obtained from the structure and the output waveform. In addition, we compare the calculation and the actual measurement in the actual test and present the verification result of the developed circular ring structure. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS034 | |
| About • | paper received ※ 01 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS035 | Vacuum Tube Operation Analysis for 1.2 MW Beam Acceleration in J-PARC RCS | 2017 |
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| The J-PARC RCS has successfully accelerated 1 MW proton beam, matching the designed beam power. Therefore, we have considered acceleration beyond the designed beam power, with the next target being 1.2 MW. An issue for 1.2 MW beam acceleration is the rf system. The present anode power supply is limited by its output current, and the vacuum tube amplifier suffers from an unbalance of the anode voltage swing, arising from the combination of multi-harmonic rf driving and push-pull operation. We have investigated the mitigation of the maximum anode currents and unbalanced tubes by choosing appropriate circuit parameters of the rf cavity with the tube amplifier. We describe the analysis results of the vacuum tube operation for 1.2 MW beam acceleration in the RCS. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS035 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS036 | Operation Status of J-PARC Rapid Cycling Synchrotron | 2020 |
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| The 3 GeV rapid cycling synchrotron (RCS) at the Japan Proton Accelerator Research Complex (J-PARC) provides more than 500 kW beams to the Material and Life Science Facility (MLF) and Main Ring (MR). In such a high-intensity hadron accelerator, even losing less than 0.1% of the beam can cause many problems. Such lost protons can cause serious radio-activation and accelerator component malfunctions. Therefore, we have conducted a beam study to achieve high-power operation. In addition, we have also maintained the accelerator components to enable stable operation. This paper reports the status of the J-PARC RCS over the last year. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS036 | |
| About • | paper received ※ 10 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS038 | The Operation Status of CSNS Front End | 2024 |
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Funding: Work supported by National Natural Science Foundation of China(11875271) China spallation neutron source (CSNS), as the China’s first 100kW beam power pulsed neutron source, its operation target beam power is now larger than 50kW. During the beam power upgrading process of CSNS to 50kW from 2018 to 2019, many improvements have been made for the front end of CSNS. In this paper, the commissioning and improvement of front end as well as the laboratory construction are introduced. The improvements mainly focus on solving the stability of ion source and the spark of Radio Frequncy quadrupole (RFQ) caused by the pre-chopped beam into RFQ. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS038 | |
| About • | paper received ※ 08 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS045 | Simulation Analysis of LLRF Feedforward Compensation to Beam Loading for CiADS LINAC | 2027 |
| TUPTS042 | use link to see paper's listing under its alternate paper code | |
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| A simulation is coded to calculate the beam loading in the cavity of CiADS and the response of the LLRF system. In the pulse operating mode, the fluctuation of amplitude and phase of the cavity field contributed by the transient beam loading is traced. During the simulation the effect of beam current fluctuation, and timing jitter were determined. The deviation margin of relational parameters is lined out to meet the requirement for cavity stability with amplitude 0.1% and phase 0.1°. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS045 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS046 | Commissioning of a Compact THz Source Based on FEL | 2030 |
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| The layout of the THz source based on FEL was de-scribed in this paper. The THz source was based on a FEL which was composed of a compact 8-14MeV LINAC, undulator, optical resonance, THz wave measurement system and so on. The facility was designed in 2013 and the typical running parameter got in 2017 were as the following: energy is of 12.7MeV, energy spread is of 0.3%, macro-pulse is of 4 μs, pulse length of micro-pulse is of 6ps, emittance is of 24 mm.mrad. After that the ma-chine was commissioning for production THz radiation. In November 2018, the THz wave was test and got THz wave signal, the spectrum was also got. This year, we plan to measure the output power of the THz source. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS046 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS047 | Improvement of 6D Brightness by a 1.4-cell Photocathode RF Gun for MeV Ultrafast Electron Diffraction | 2033 |
| SUSPFO069 | use link to see paper's listing under its alternate paper code | |
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| Recent research indicates that ultrafast electron diffraction and microscopy (UED/M) have unprecedented potential in probing ultrafast dynamic processes, especially in organic and biological materials. However, reaching the required brightness while maintaining high spatiotemporal resolution requires new design of electron source. In order to produce ultrashort electron beam with extreme high brightness, a 1.4-cell RF gun is being developed to reach higher acceleration gradient near the photocathode and thus suppress the space charge effect in the low energy region. Simulation of the 1.4-cell RF photocathode gun shows considerable improvement in bunch length, emittance and energy spread, which all lead to better temporal and spatial resolution comparing to traditional 1.6-cell RF photocathode gun. The results demonstrate the feasibility of sub-ps temporal resolution with normalized emittance less than 0.1 πmm·mrad while maintaining 1 pC electron pulse. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS047 | |
| About • | paper received ※ 24 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS048 | Preliminary Study on the Injection System Upgrade for CSNS-II | 2037 |
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Funding: Work supported by National Natural Science Foundation of China (Project No. U1832210) The first phase of the China Spallation Neutron Source (CSNS-I) had completed the national acceptance in August, 2018. The physics design of the second phase (CSNS-II) has already begun. The CSNS-II accelerator upgrade contains three main components, including the Linac energy upgrade from 80 MeV to 300 MeV, injection system upgrade, and new Magnetic Alloy dual-harmonic cavity. In this paper, a preliminary study on the injection system upgrade had been done. A preliminary upgrade scheme for the injection system would be given. Furthermore, some preliminary simulation and calculation for the upgrade injection system had been carried out. The analysis results showed that most injection parameters can preliminarily meet the requirements of accelerator power upgrade. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS048 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS050 | Design and Analysis of the Cold Cathode Ion Source for 200 MeV Superconducting Cyclotron | 2040 |
| SUSPFO077 | use link to see paper's listing under its alternate paper code | |
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| SC200 is a superconducting isochronous cyclotron which generates 200 MeV, 400 nA proton beam for particle therapy. The cold-cathode-type Penning ion gauge (PIG) ion source for the internal ion source of SC200 has been selected as an alternative and preliminary designed. In this paper, design of ion source and test bench are demonstrated. Currently, the properties of ion source have been simulated for a variety of electric field distributions and magnetic field strengths. The secondary electron emission in electromagnetic field has been simulated. It provides reference for the optimization design of arc chamber. In addition, the sample of cold-cathode-type ion source has been tested on the test bench and extracted beam intensity has been measured over 200 μA. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS050 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS051 | Recent Beam Commissioning of LEAF at IMP | 2043 |
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| LEAF (Low Energy intense-highly-charged ion Accelerator Facility) has been successfully commissioned with several beams in CW regime, covering the M/Q from 2 to 7, such as H2+, He2+, C4+, O4+, He+, Kr13+, N2+ et al. This paper presents recent beam commissioning results. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS051 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS052 | Conceptual Design of a High-Performance Injector Based on Rf-Gated Gridded Thermionic Gun for Thz Fel | 2046 |
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| Free-Electron Laser (FEL) has higher requirements on electron beam properties, for example, low transverse emittance, small energy spread, short bunch length and high peak current. Taking compactness and economy into account, we aim to design a high-performance linear accelerator based on a RF-gated gridded thermionic electron gun, which will be used as the injector of the oscillator-type THz FEL facility at Huazhong University of Science and Technology of China. The RF-gated grid will be modulated with the fundamental and 3rd harmonic microwave of the LINAC frequency, which will be very helpful to get high electron capture efficiency and short bunch length. Concerning velocity bunching effect in the LINAC, electron bunch with good symmetry of current profile and bunch length less than 10 ps can be obtained at the exit of the injector. In this paper, design and beam dynamics simulation for the high-performance injector are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS052 | |
| About • | paper received ※ 26 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS053 | Design of a 217 MHz VHF Gun at Tsinghua University | 2050 |
| SUSPFO084 | use link to see paper's listing under its alternate paper code | |
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| A 217 MHz VHF gun operating in CW mode is designing at Tsinghua University. The cathode gradient is designed to be 30 MV/m to accelerate the electron bunches up to 878 keV. The cavity profile is optimized in CST to minimize the input power, peak surface electric field, and peak wall power density. The multipacting analysis and the thermal analysis are also presented in this paper. Further gun shape optimization and mechanical design are ongoing. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS053 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS054 | 1st+2nd Harmonic Photocathode Bimodal Gun R&D | 2054 |
| SUSPFO086 | use link to see paper's listing under its alternate paper code | |
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Funding: U.S. Dept. of Energy A novel Bimodal Electron Gun is designed to apply microwaves at two harmonically-related frequency in a 0.6 cell RF gun to increase the RF breakdown threshold and enhance the beam quality. This stratagem is intended to allow the RF gun structure to support a high accelera-tion gradient as well as to manipulate the emittance evolution in the half cell. By selecting a proper ampli-tude ratio and phase relationship between the first and second harmonic RF field components in the gun cavity, the superposition of the harmonic field components can provide a flat-top like RF profile to omitting the RF emittance component in the gun, while increase the RF breakdown threshold. The recent status of the Bimodal Electron Gun R&D is presented, including the designs of the novel two frequency RF structure and the simulation of the beam dynamic. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS054 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS059 | Conceptual Design of the SC230 Superconducting Cyclotron for Proton Therapy | 2058 |
| TUPTS055 | use link to see paper's listing under its alternate paper code | |
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| Physical design of the compact superconducting cyclotron SC230 (91.5MHz) has been performed. The cyclotron will deliver up to 230 MeV beam for proton therapy and medico-biological research. We have performed simulations of magnetic and accelerating systems of the SC230 cyclotron and specified the main parameters of the accelerator. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS059 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS060 | Beam Dynamics Simulations in the Dubna SC230 Superconducting Cyclotron for Proton Therapy | 2061 |
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| We present results of the beam dynamics simulation for the compact isochronous superconducting cyclotron SC230. We have performed beam tracking starting from the ion source. The extraction system scheme and results of beam extraction simulations are presented. The codes and methods used for beam tracking are briefly described. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS060 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS061 | The Pre-Injector and Photocathode Gun Design for the MAX IV SXL | 2064 |
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| The design of the pre-injector, including the new gun, for the SXL project is being finalised for the desired modes of operation, 100 pC and 10 pC with short bunches. The photocathode gun is currently being manufactured and experiments in the MAX IV guntest facility are under preparation to verify the design. In this paper we present the design of the gun and the pre-injector and show some results from simulations using MOGA indicating an emittance below 0.3 mm mrad. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS061 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS065 | RF Conditioning of the CLARA 400 Hz Photoinjector | 2067 |
| TUPTS063 | use link to see paper's listing under its alternate paper code | |
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| Automated conditioning of the 400 Hz photoinjector for CLARA was begun and the conditioning program refined. The conditioning was performed at 100 Hz. Masks were used to detect breakdowns in the reflected power and phase, and the breakdown rate was limited to 5x106 breakdowns per pulse. The cavity gradient and breakdown rate evolution over the conditioning time is presented. Post-pulse multipactor and other evidence of electron effects were detected. Possible mechanisms for this are discussed. The conditioning was interrupted by breakdown in the waveguide after reaching 2.5 MW, and will be resumed after the planned 6 month shutdown of CLARA. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS065 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS066 | Re-optimisation of the ALICE Gun Upgrade Design for the 500-pC Bunch Charge Requirements of PERLE | 2071 |
| SUSPFO116 | use link to see paper's listing under its alternate paper code | |
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| The injector for PERLE, a planned ERL test facility, must be capable of delivering 500 pC bunches at a repetition rate of 40.1 MHz to provide a beam with 20 mA average current with a projected rms emittance of less than 6 mm mrad. This must be achieved at two different operational voltages 350 kV and 220 kV for unpolarised and polarised operation respectively. The PERLE injector will be based on an upgrade of a DC photocathode electron gun operated previously at ALICE ERL at Daresbury. The upgrade will add a load lock system for photocathode interchange. This paper presents the results of a re-optimisation of the electrode system as ALICE operated with a bunch charge of around 80 pC while PERLE needs a bunch charge of 500 pC. This re-optimisation was done using the many-objective genetic algorithm NSGAIII to minimise both the slice emittance and transverse beam size for both required operational voltages. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS066 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS068 | Progress on Design Studies for the ISIS II Upgrade | 2075 |
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| ISIS, the spallation neutron source at the Rutherford Appleton Laboratory in the UK, uses a 50 Hz, 800 MeV proton RCS to provide a beam power of 0.2 MW, delivered in 0.4 us long pulses. Detailed studies are now under way for a major upgrade. Accelerator designs using FFAs, conventional accumulator and synchrotron rings are being considered for the required MW beam power. This paper summarises the scope of the different research incorporating results from recent target studies and user consultations. Preliminary results for Fixed Field Alternating gradient (FFA) rings and conventional rings located in the existing ISIS synchrotron hall are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS068 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS069 | A Plasmonic Niobium Photocathode for SRF Gun Applications | 2079 |
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| The typical quantum efficiency of niobium is of the order 10-4, whilst also requiring UV lasers for emission. This paper presents the results of a plasmonic niobium surface that operates with IR laser via multiphoton emission. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS069 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS070 | Systematic Benchmarking of a Planar (N)UNCD Field Emission Cathode | 2083 |
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| Planar nitrogen-incorporated ultrananocrystalline diamond, (N)UNCD, is a unique and attractive field emission source because of the capability to generate high charge beam, the simplicity of production without shaped emitters, and the ease of handling with moderate vacuum requirement. In the presented study using an L-band normal conducting single-cell rf gun, a (N)UNCD cathode has been conditioned to 42 MV/m with a well-controlled manner and reached a maximum charge of 15 nC and an average emission current of 6~mA during a 2.5 us emission period. The systematic study of emission properties during the rf conditioning process illustrates the tunability of (N)UNCD in a wide range of surface gradients. This research demonstrates the versatility of (N)UNCD cathode which could enable multiple designs of field emission rf injector for industrial and scientific applications. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS070 | |
| About • | paper received ※ 20 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS071 | H+ and H− Ion Beam Injectors at LANSCE: Beam Production Status and Planned Injector Upgrades | 2087 |
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| The Los Alamos Neutron Science Center operates with two 750 keV Cockcroft-Walton accelerators for simultaneous injection of H+ and H− ion beams into a 800 MeV linear accelerator. The proton ion beam is produced using a duoplasmatron source and the H− ion beam is formed with a cesiated, multi-cusp-field, surface converter ion source. An overview of ion injector status, recent low energy beam transport line optimizations and ion source performance improvements will be presented. To reduce long term operational risks and to improve existing LANSCE beam production for all facility users, new injector upgrades are underway: 1) replacing the H+ CW injector with a Radio-Frequency Quadruple accelerator and 2) increasing H− ion beam brightness and extending source lifetime using the novel SNS RF negative ion source. The status of upgrade projects will be discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS071 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS073 | Analysis of Electron Beam Divergence in Diamond Field Emitter Array Cathodes | 2090 |
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Funding: Los Alamos National Laboratory (LANL) Laboratory Directed Research and Development (LDRD) program (Contract DE-AC52-06NA25396) and Sandia National Laboratories (Contract DE-NA-0003525). At Los Alamos National Laboratory (LANL), we have recently established a capability to fabricate diamond array cathodes for electron beam sources. Our fabricated diamond field emitter arrays (DFEAs) are the arrays of micrometer-scale diamond pyramids with nanometer-scale sharp tips and produce high per-tip current (> 15 μA per-tip) in DC testing. For the beam divergence measurements, we designed and assembled a test stand consisting of a DFEA cathode, a mesh aperture of 0.375-inch for an anode, and AZO (ZnO:Al2O3) screen coated on a sapphire substrate for beam visualization. A negative voltage of about 40 kV is applied to the cathode, and the mesh and the screen are kept at ground. We measure a size of the electron beam on the AZO screen at different mesh to screen distances at a fixed cathode-mesh gap in order to calculate the beam divergence angles. We also perform the beam dynamics simulations with Computer Simulation Technology (CST) Studio and General Particle Tracer (GPT) using a single pyramidal shape with a nanowire tip model. In this presentation, the measured experimental results of the beam divergences will be compared to the beam dynamic simulations. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS073 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS076 | RF Design of APEX2 Cavities | 2094 |
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Funding: Director of Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 APEX2 is a proposed high repetition rate, high brightness electron source based on CW normal conducting RF cavities, aiming to further extend the brightness performance for FEL and UED/UEM beyond APEX. APEX2 consists of two cavities, one gun cavity for generating photo-electrons and one following cavity for beam energy boosting. In this paper, we present the RF design of the APEX2 cavities. The design has considered both beam dynamics requirements and engineering feasibility. A novel geometry optimization method with Genetic Algorithm has been implemented in the design procedure. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS076 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS077 | Design of a High Gradient THz-Driven Electron Gun | 2098 |
| SUSPFO127 | use link to see paper's listing under its alternate paper code | |
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Funding: This work was supported by Department of Energy contract DE-AC02-76SF00515. This work was also supported by NSF grants PHY-1734015. We present the design of a high-gradient electron gun. The goal of this gun is to generate relativistic electrons using GV/m accelerating fields. The initial design is a standing-wave field-emission gun operating in the pi-mode with a cavity frequency of 110.08 GHz. A pulsed 110 GHz gyrotron oscillator will be used to drive the structure with power coupled in through a TM01 circular waveguide mode. The gun is machined in two halves which are bonded. This prototype will be used to characterize the electron beam and study RF breakdown at 110 GHz. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS077 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS078 | Coherent Electron Cooling (CeC) Experiment at RHIC: Status and Plans | 2101 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and NSF Grant No. PHY-141525 We will present currents status of the CeC experiment at RHIC and discuss plans for future. Special focus will be given to unexpected experimental results obtained during RHIC Run 18 and discovery of a previously unknown type of microwave instability. We called this new phenomenon micro-bunching Plasma Cascade Instability (PCI). Our plan for future experiments includes suppressing this instability in the CeC accelerator and using it as a broad-band amplifier in the CeC system. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS078 | |
| About • | paper received ※ 19 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS079 | Overcoming Multipacting Barriers in SRF Photoinjectors | 2105 |
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| Superconducting RF (SRF) photoinjectors are considered to be a potential breakthrough in the area of high brightness electron sources. However, there is always the very important question of the compatibility of SRF cavities and high quantum efficiency (QE) photocathodes. A deposition of active elements from high QE photocathodes on the surface of a cavity makes it more vulnerable to multipacting (MP) and could affect the operation of an SRF gun. On the other side, MP can significantly reduce the lifetime of a photocathode. It is well known in the SRF community that a strong coupling, high forward power and sufficient cleanliness of cavity walls are the key components to overcome a low-level MP zone. In this paper we present a theoretical model of passing a MP barrier which could help estimate the desirable conditions for successful operation of an SRF gun. We demonstrate our results for the 113 MHz SRF photo-injector for Coherent electron Cooling (CeC) alongside with the experimental observations and 3D simulations of the MP discharge in the cavity. The results of the theoretical model and simulations show good agreement with the experimental results, and demonstrate that, if approached carefully, MP zones can be easily passed without any harm to the photocathode. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS079 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS080 | Beam Dynamics Studies of an APEX2-Based Photoinjector | 2109 |
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| APEX2 is a proposed normal conducting radio-frequency (RF) electron gun operating in the very high frequency (VHF) range in continuous wave (CW) mode, designed to drive applications that require both high beam brightness and high repetition rate, such as free electron lasers (such as LCLS-II-HE), ultra-fast electron diffraction, and microscopy. The gun consists of a two-cell RF cavity operating at 162.5 MHz with a cathode field of 34 MV/m, together with an embedded focusing solenoid. We study the beam dynamics in an APEX-II-based photoinjector (up to ~20 MeV), targeting a transverse 95% beam emittance of 0.1 um at 12.5 A peak current for the case of 100 pC charge for FEL applications. The high cathode field leads to enhanced beam brightness, while the increased gun exit energy of ~1.5 MeV reduces the effects of space charge, and possibly eliminates the need for an RF buncher. The embedded solenoid is designed to control the transverse beam size while minimizing emittance growth due to geometric aberrations. As a result, the transverse beam performance targets are achieved, and ongoing work will further optimize longitudinal beam quality for downstream FEL transport. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS080 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS083 | Simulations and Experimental Plans for a High-Repetition-Rate Field-Enhanced Conduction-Cooled Superconducting RF Electron Source | 2113 |
| SUSPFO047 | use link to see paper's listing under its alternate paper code | |
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Funding: Work supported by DOE awards DE-SC0018367 with NIU and DE-AC02-07CH11359 with Fermilab. We present a novel RF design for a field enhanced electron source driven by field emission cathodes. The proposed electron source relies on the enhanced high electric field gradients at the cathode to simultaneously extract and accelerate electrons. The system will be tested in a conduction-cooled superconducting radio-frequency cavity recently demonstrated at Fermilab. In this paper, we present electromagnetic and thermal simulations of the setup that support the feasibility of the design. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS083 | |
| About • | paper received ※ 18 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS084 | Performances of Silicon-Based Field-Emission Cathodes Coated with UltraNano Crystalline Diamond | 2117 |
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Funding: Work supported by NSF grant PHY-1535401 and DOE award DE-SC0018367 with NIU Field-emission electron sources have been considered as possible candidates for the production of bright or high-current electron bunches. In this paper, we report on the experimental characterization of silicon-based field-emitter arrays (FEA) in a DC high voltage gap. The silicon cathodes are produced via a simple self-assembling process. The measurement reported in this paper especially compares the field-emission properties of a nanostructured and planar diamond-coated Si-based cathode. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS084 | |
| About • | paper received ※ 17 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS085 | Design Study of 3.6-cell C-band Photocathode Electron Gun | 2121 |
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| A C-band photocathode injector composed of a 3.6-cell C-band photocathode RF gun and two 1.8-meter C-band accelerating structures is proposed. The injector is a low emittance electron source for Free Electron Lasers (FEL) and other compact light sources. The RF structure of the cavities is designed with 2D SUPERFISH simulation. The Beam dynamic study in ASTRA helps rectify the 2D RF simulation. To feed the cavities, a design of extra coaxial coupler with RF gun structure is presented. With compact focusing solenoids, for 0.25nC bunch charge, the final energy can reach 6.9 MeV energy and the 95% emittance can be as low as 0.23 mm mrad (95%). All the details of RF design and beam dynamics studies are presented in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS085 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS086 | SNS Proton Power Upgrade Status | 2124 |
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Funding: Work performed at (or work supported by) Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. The Proton Power Upgrade (PPU) project at the Oak Ridge Spallation Neutron Source aims to double the beam power capability of the accelerator, from 1.4 to 2.8 MW. This will be done by a 30% increase in beam energy (from 1.0 to 1.3 GeV), and a 50% increase in beam current (from 25 to 38 mA averaged over a macropulse). The project is now well underway, after receiving approval to start preliminary design in April 2018. In this paper we will discuss recent technical developments in the project, including the warm linac RF system upgrade, a new topology for the high voltage converter modulators, an engineering review of the power capability of the injection dump, and a 2-MW-capability for the existing target station. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS086 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS088 | A Normal Conducting RF Gun as an Electron Source for JLEIC Cooling | 2127 |
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| The baseline design for a magnetized injector for the bunched-beam electron cooler ring, as part of the Jeffer-son Lab Electron Ion Collider (JLEIC) uses a DC photo-cathode electron gun as the source. A challenging aspect of this concept is transporting a 3.2nC electron bunch at low energy and preserving the angular momentum. An RF gun source has been investigated to gauge the potential advantages of high gradient on the photocathode and higher exit energy. The design is presented and compared with the baseline results. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS088 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS089 | Observations of the Femtosecond Laser-Induced Emission From the Diamond Field Emitter Tips | 2130 |
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Funding: Los Alamos National Laboratory LDRD Program We present the results of experimental observation of emission from single diamond field emitter tips when triggered by an ultra-short laser pulse. Diamond field emitter array (DFEA) cathodes were originally proposed for applications that require large current densities. DFEAs represent periodic arrays of diamond pyramids with micron-size dimensions and tips with diameters of the order of tens of nanometers. DFEAs are known to produce significant currents in field emission regime under direct current (DC) fields and in radio-frequency (RF) guns. It has been proposed that single diamond tip emitters can be employed for production of small tightly focused electron beams for dielectric laser accelerators (DLAs) that accelerate particles using the energy of light produced by infrared lasers. To generate short electron bunches required by DLAs diamond pyramids may be triggered with a laser. We have recently observed emission produced by a single diamond pyramid when triggered by a laser at different wavelengths from 256 nm to 2020 nm. We have conducted studies with the goal to understand mechanism of the emission. We clearly observed the change in emission mechanism when the wavelength changed from 256 nm to 512 nm. We believe that while the emission at 256 nm is a clear photoemission, the emission at longer wavelengths is likely the field emission caused by intense electric fields of the laser. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS089 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS090 | Experimental Results of Dense Array Diamond Field Emitters in RF Gun | 2134 |
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| We present experimental emission results from arrays of diamond field emitter tips operating in an RF gun at the Argonne Cathode Test-stand. Results from various arrays will be presented with different spacing between array elements. Very high charge densities were produced at various field gradients. The maximum field gradient for a particular geometry was discovered and break-down effects will be presented. Cathode lifetime was preliminarily studied. Further experiments are being planned and work on the cathode design optimization to produce higher quality beams will be discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS090 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS091 | Physics of Electron Beam Generation and Dynamics From Diamond Field Emitter Arrays | 2137 |
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Funding: Work supported by the LDRD program at Los Alamos National Laboratory Many applications such as compact accelerators and electron microscopy demand high brightness electron beams with small beam size and low emittance. Electric-field-assisted diamond emitters manufactured from semiconductor processes are strong candidates for cathodes in such sources. The micro-scale pyramid structure of the emitter has the desirable attribute of significant field enhancement at the sharp interfaces (apex and edges) to facilitate electron emission. We use the LSP particle-in-cell code to simulate the diamond emitter in a diode setup and obtain the beam size and divergence. An empirical fit of the fields around the apex is extracted for detail study. The trend of the beam divergence observed in the simulation is further corroborated using electron’s trajectory in the empirical field model. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS091 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS093 | Magnetized Gridded Thermionic Electron Source | 2140 |
| SUSPFO122 | use link to see paper's listing under its alternate paper code | |
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Funding: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy. The study of magnetized electron beam has become a high priority for its use in ion beam cooling as part of Electron Ion Colliders and the potential of easily forming flat beams for various applications. The demand for high average current for effective ion beam cooling has caused consideration of using bunched magnetized electron beam produced by a gridded thermionic electron gun. This paper presents the design of a potential electron source for JCIEC first measurements characterizing the beam properties of a magnetized thermionic gun. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS093 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS095 | Global Model of Multi-Chamber Negative Hydrogen Ion Sources with Updated Hydrogen Plasma Chemistry | 2144 |
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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. Global models of plasma discharges are used to calculate volume averaged number densities and temperatures of plasma components. The wall fluxes are estimated based on heuristic expressions that "patch" together analytic and semi-analytic solutions covering from low-pressure to high-pressure regimes. Due to the nature of the wall fluxes estimation, the global models are limited to single chamber designs. We present the extension of the Global Enhanced Vibrational Kinetic Model (GEVKM) * for the multi-chamber design with the updated hydrogen plasma chemistry **. The extended GEVKM consists of separate global models for macroscopic parameters of all species in each chamber coupled through interface boundary conditions. We compare our model with fluid simulation results for a plasma composition and species temperatures in the negative hydrogen ion source developed at IPP Garching. * Averkin S.N. et al, IEEE Trans. Plasma Sci., Vol. 43, N. 6, pp. 1926-1943, 2015. ** Yang W. et al, Phys. Plasmas, 25, 113509, 2018. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS095 | |
| About • | paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS096 | Fluid Models of Inductively Coupled Plasma Sources for Negative Hydrogen Ion Sources | 2147 |
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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. Negative hydrogen ion sources are widely used to produce neutron beams via spallation both for neutron science in its own right, and as neutron sources for fusion devices. Numerical modeling is a useful tool for trying to optimize negative hydrogen ion sources. However there are significant numerical and computational challenges that have to be overcome, including code performance and resolution of separation of time scales between ion and electron motions. One method is to utilize fluid models to simulate inductively coupled ion sources (ICPs). We have been developing algorithms to simulate negative hydrogen production in high-power, external-antenna ICP sources. We present simulation results using the USim*,** framework to model plasma chemistry that produces negative hydrogen, and model the effects of electron temperature on overall production rates. The numerical plasma chemistry models include processes of ionization, dissociation, recombination, as well as reactive dissociation of vibrationally resolved states and de-excitation of atomic hydrogen. We benchmark our plasma chemistry model results using plasma parameters relevant to experiments being carried out at the D-Pace Ion Source Test Facility. We have also been developing fluid-based drift/diffusion models for multi-component plasmas, such as those in negative hydrogen sources. These simulation results demonstrate enhancement of the effective diffusion rates in plasmas that contain both electrons and negative ions. * J. Loverich and A. Hakim, J. Fusion Sci., 29(6), 2010. ** J. Loverich et al., AIAA, Vol. 4012, 2011. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS096 | |
| About • | paper received ※ 19 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS099 | Predicting the Performances of Coherent Electron Cooling with Plasma Cascade Amplifier | 2150 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Recently, we proposed a new type of instability, Plasma Cascade Instability (PCI), to be used as the amplification mechanism of a Coherent Electron Cooling (CeC) system, which we call Plasma Cascade Amplifier (PCA). In this work, we present our analytical estimate of the cooling force as expected from a PCA- based CeC system and compare it with the simulation results. As examples, we apply our analysis to a few possible CeC systems and investigate the evolution of the circulating ion beams in the presence of cooling. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS099 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS101 | Bi-Alkali Antimonide Photocathodes for LEReC DC Gun | 2154 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Low Energy RHIC electron cooling (LEReC) is a bunched electron cooler at RHIC. The Bi-alkali photocathodes are chosen as electron source due to its long lifetime and high QE at visible wavelength. Because the DC gun needs to produce 24/7 beams over several months, cathode production system and multiple cathodes transferring systems are designed, commissioned and in operation. In this report, we will describe our photocathodes production and discuss the cathode’s performance from cathode growth system to the DC gun. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS101 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS102 | New Activation Techniques for Higher Charge Lifetime from GaAs Photocathodes | 2157 |
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| GaAs is the choice of photocathode material for polarized electron sources. The well established method of activating GaAs for beam extraction is to use Cs and Oxygen to create a ’Negative Electron Affinity’(NEA) layer. However, this layer is highly sensitive to vacuum and gets damaged due to ion back bombardment in DC guns. In this work, we explore activation methods that used Tellurium in conjunction with the usual Cs and Oxygen. We report our method to activate GaAs and show charge lifetime results for our activation method. Our results show that the use of Te could potentially help with longer charge lifetimes from GaAs cathodes in DC guns. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS102 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS103 | The Progress of High Current High Bunch Charge Polarized Electron HVDC Gun | 2160 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The high current and high bunch charge polarized electron source is essential for cost reduction of eRHIC. It aims to deliver electron beam with 10 mA average current and 5.3 nC bunch charge. We analyzed the mechanism of cathode degradation and proposed using a large strain superlattice GaAs photocathode in a high voltage DC gun to increase the charge lifetime above kilo Coulomb. The gun has been designed and fabricated and expected to start commissioning by the mid of this year. In this paper, we will present the modeling of ion back bombardment and cathode degrading. We proposed an anode offset scheme to increase cathode lifetime. Also, we will describe the details of gun design and the strategies to demonstrate high current high charge polarized electron beam from this source. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS103 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS104 | Spatio-Temporal Shaping of the Photocathode Laser Pulse for Low-Emittance Shaped Electron Bunches | 2163 |
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Funding: This work is supported by the U.S. DOE contract No. DE- SC0017750 with Euclid Techlabs LLC., No. DE-SC0018656 with NIU, and No. DE-AC02-06CH11357 with ANL. Photocathode laser shaping techniques to generate temporally shaped electron bunches are appealing owing to their simplicity. Such technique is being considered to form shaped electron bunches to enhance the transformer ratio in beam-driven accelerators. At low energy (i.e. during the emission process) the transverse and longitudinal space charge effects are coupled so that attaining a low beam transverse emittance require the laser to be spatiotemporal shaped. In this paper, we explore the generation of a linearly-ramped bunch with optimized transverse emittance by temporally and radially shaping the laser pulse to provide an adequate initial distribution. We discuss a possible implementation of the optical shaping technique and describe a planned experiment. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS104 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS105 | High Current High Charge Magnetized and Bunched Electron Beam from a DC Photogun for JLEIC Cooler | 2167 |
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Funding: This project was supported by the U.S. DOE Basic Energy Sciences under contract No. DE-AC05-060R23177. Additional support comes from Laboratory Directed Research and Development program. A high current, high charge magnetized electron beamline that has been under development for fast and efficient cooling of ion beams for the proposed Jefferson Lab Electron Ion Collider (JLEIC). In this paper, we present the latest progress over the past year that include the generation of picosecond magnetized beam bunches at average currents up to 28 mA with exceptionally long photocathode lifetime, and the demonstrations of magnetized beam with high bunch charge up to 700 pC at 10s of kHz repetition rates. Detailed studies on a stable drive laser system, long lifetime photocathode, beam magnetization effect, beam diagnostics, and a comparison between experiment and simulations will also be reported. These accomplishes marked an important step towards the essential feasibility for the JLEIC cooler design using magnetized beams. (To be inserted) |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS105 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS106 | First Commissioning of LCLS-II CW Injector Source | 2171 |
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Funding: The work is supported by DOE under grant No. DE-AC02-76SF00515 The LCLS-II injector source includes a 186MHz CW rf-gun, a 1.3 GHz CW rf-buncher, a loadlock system for photocathode change, two main solenoids, and a few essential diagnostics. The electron beam is designed to operate at a high repetition rate, up to 1-MHz. Since summer of 2018 we started LCLS-II injector source commissioning immediately after the major installation was completed. Initial commissioning showed the rf-gun was severely contaminated with hydrocarbons and very limited power <600W could be fed into the gun cavity. After a few significant processes, we eventually removed the hydrocarbons and successfully delivered desired rf power of 80 kW to the gun. This paper reports first com-missioning results including gun bakeout and vacuum processing, CW RF-gun and buncher operation with nom-inal power, and measurements of rf stability and dark current. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS106 | |
| About • | paper received ※ 10 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS108 | Numerical Simulations of RHIC FY17 Spin Flipper Experiments | 2174 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Spin flipper experiments during RHIC Run 17 have demonstrated the 97% effectiveness of polarization sign reversal during stores. Zgoubi numerical simulations were setup to reproduce the experimental conditions. A very good agreement between the experimental measurements and simulation results was achieved at 23.8GeV, thus the simulations are being used to help optimize the various Spin Flipper parameters. The ultimate goal for these simulations is to serve as guidance towards a perfect flip at high energies to allow a routine Spin Flipper use during physics runs. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS108 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS109 | Status of AC Dipole Project at Rhic Injectors for Polarized 3He, Update | 2177 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. An ac dipole will be used for the efficient transport of polarized 3He in the AGS Booster as it is accelerated to |Gγ|=10.5. The ac dipole introduces a coherent vertical beam oscillation which allows preservation of polarization through the two intrinsic resonances Gγ=12-νy and Gγ=6+νy resonances, by full spin flipping. The AGS Booster ac dipole will be tested with protons crossing the Gγ=0+νy intrinsic resonance, which has ac dipole requirements similar to polarized 3He crossing the Gγ=12-νy resonance, providing a convenient proof of principle. This paper gives a status of the project. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS109 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS110 | Scanning the AC Dipole Resonance Proximity Parameter in the AGS Booster | 2179 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. An ac dipole system is installed in the AGS Booster in view of acceleration of polarized helion for RHIC and the eRHIC EIC. The amplitude of the vertical coherent oscillations induced by the ac dipole depends greatly on the resonance proximity parameter, δm, which is the distance between resonance tune and driving tune. Due to the non-zero momentum spread, particles with different momenta will have different value of δm. The rapid acceleration rate of the booster would cause δm to sweep, the amount of which would depend on the energy and the duration of the ac dipole cycle. These effects are simulated using zgoubi, which set a range of δm values suitable for both high spin flip efficiency and minimizing emittance growth, and the results of the simulations are discussed. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS110 | |
| About • | paper received ※ 12 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS111 | Study on Improving Durability of Cs-Te Photocathode for an RF-gun | 2182 |
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| At Waseda University, we have been studying for high quality electron beam generation using 1.6 cell Cs-Te photocathode rf-gun. We use photocathode as the electron source, which can generate high- quality electron beam such as low emittance, and short bunch. The performance of photocathode is evaluated mainly in terms of quantum efficiency (Q.E.) and lifetime. Cs-Te photocathode used in the rf-gun is known for high Q.E. about 10% with UV light and relatively longer lifetime among semiconductor photocathodes. Since it is a hard environment for photocathode inside the gun, it is necessary to replace the photocathode every several months. In other words, in order to achieve long-term operation of rf-gun, it is necessary to find highly durable photocathode recipe. It has been reported that the Cs-Te photocathode by co-evaporation can produce a photocathode having a longer lifetime as compared with the sequential evaporation. Moreover, we have done studies to improve lifetime and durability of Cs-Te photocathode by coating the cathode surface with CsBr thin film. In this conference, we report the evaluation results of Cs-Te photocathode by co-evaporation, CsBr coating and future prospects. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS111 | |
| About • | paper received ※ 12 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS112 | Stand-alone Accelerator System Based on SRF Quarter-wave Resonators | 2185 |
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Funding: This material is based upon work supported by the U.S. Department of Energy under contracts DE-SC0017101 and DE-AC02-06CH11357. This research used resources of DOE ANL’s ATLAS facility. Superconducting accelerators are large and complex systems requiring a central refrigerator and distributed transfer systems to supply 2-4 K liquid helium. Stand-alone, cryocooler-based systems are of interest both to scientific facilities and industrial applications, as they do not require large cryogenic infrastructure and trained specialists for operation. Here we present our approach to the challenge of using low-power commercially available cryocoolers to operate niobium superconducting resonators at 4.4 K with high accelerating voltages and several watts of heating. Engineering and design results from RadiaBeam Systems, collaborating with Argonne National Laboratory, for a stand-alone liquid-cooled cryomodule with 10 Watts of 4.4 K cooling capacity housing a 72.75 MHz quarter-wave resonator operating at 2 MV for synchronous ions travelling at 7.7% of speed of light will be discussed. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS112 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS113 | Microwave Thermionic Electron Gun for Synchrotron Light Sources | 2189 |
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Funding: This work was supported by the U.S. Department of Energy, Office of Basic Energy Science, under contracts DE-SC0015191 and DE- AC02-06CH11357. Thermionic RF guns are the source of electrons used in many practical applications, such as drivers for synchrotron light sources, preferred for their compactness and efficiency. RadiaBeam Technologies has developed a new thermionic RF gun for the Advanced Photon Source at Argonne National Laboratory, which would offer substantial improvements in reliable operations with a robust interface between the thermionic cathode and the cavity, as well as better RF performance, compared to existing models. This improvement became possible by incorporating new pi-mode electromagnetic design, robust cavity back plate design, and a cooling system that will allow stable operation for up to 1 A of beam current and 100 Hz rep rate at 1.5 μs RF pulse length, and 70 MV/m peak on-axis field in the cavity. In this paper, we discuss the electromagnetic and engineering design of the cavity and provide the test results of the new gun. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS113 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS114 | Electron Stimulated Desorption from Cryogenic NEG-Coated Surfaces | 2193 |
| SUSPFO135 | use link to see paper's listing under its alternate paper code | |
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| Non-Evaporable Getter (NEG) coating has been used for years in many particle accelerators due to its advantages like evenly distributed pumping speed, low thermal outgassing, and low photon, electron and ion stimulated desorption yields. Although NEG coating has been tested at room temperatures intensively, there is little data on its behaviour at cryogenic temperatures. Tests in this environment are important for the Future Circular Collider (FCC) study and other accelerator facilities where the operational conditions of the beam screen are restricted to cryogenic temperatures. This work will provide some preliminary results on NEG properties at low temperatures, e.g. pumping speed and capacity, as well as its behaviour under electron bombardment, where electron stimulated desorption (ESD) yields will be calculated. The ternary Ti-Zr-V coating, deposited with dense and columnar structure, will be the first material to be tested at cryogenic temperatures in ASTeC Daresbury laboratory. The results were compared with the ones obtained at room temperature, offering an insight into the behaviour of NEG-coated cryogenic chambers when beam-induced effects are present. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS114 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS115 | The Progress in Physical Start-Up of the NSC KIPT Subcritical Neutron Source Facility Driven by an Electron Linear Accelerator | 2197 |
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| National Science Center ’Kharkov Institute of Physics &Technology’ (NSC KIPT), Kharkov, Ukraine and Argonne National Laboratory (ANL), Chicago, USA are jointly constructing and commissioning the Ukraine Neutron Source facility. The facility consists of a subcritical assembly driven by a 100MeV/100kW electron linear accelerator. The electron beam will be used for generating the neutrons for operating the subcritical assembly using tungsten or natural uranium target. The facility is planned to support the Ukraine nuclear industry, and provide a capability for performing reactor physics, material research, and basic science experiments, to produce medical isotopes, train young nuclear professionals. The integrating facility tests were completed at the end of 2018, and physical start-up operation began in 2019. The facility commissioning and current start-up results are presented and discussed in the paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS115 | |
| About • | paper received ※ 10 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS116 | Adjustment and Improvement of 100 MeV/100 kW Electron Linear Accelerator Parameters for the NSC KIPT SCA Neutron Source | 2200 |
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| The NSC KIPT SCA Neutron Source uses 100 MeV/ 100 kW electron linear accelerator as a driver for the generation of the initial neutrons. The electron linear accelerator was designed and manufactured by the Institute of High Energy Physics (IHEP) of China. At present, the accelerator was assembled at NSC KIPT, all the components were tested, and the first beam commissioning results are obtained. The pilot operation of the accelerator was started in 2018. The progress in the accelerator system operations and electron beam performance improvement are described in the paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS116 | |
| About • | paper received ※ 10 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS117 | Photocathode Activities at INFN LASA | 2203 |
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| We present the activity on alkali antimonide photocathodes at INFN LASA. The long term goal is to transfer to these photocathodes the know-how acquired in the successful development of cesium telluride photocathodes, nowadays used in many leading FEL facilities and accelerator complex. In this paper we present and discuss the results so far obtained on alkali antimonide films grown in our R&D system and the status of the new preparation system specifically designed for these sensitive materials. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS117 | |
| About • | paper received ※ 16 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS118 | LASA Activities on Surface Treatment of Low-beta Elliptical Cavities | 2207 |
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| This paper describes the efforts made by LASA on the development of surface treatments for low-beta elliptical cavities, for the current series production of ESS and the foreseen series production of PIP-II. The traditional techniques of buffered chemical polishing and electropolishing are here discussed taking into account the industrial environment, the practical issues due to the size and geometry of such cavities and according to the required qualification values for quality factor and accelerating gradient. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS118 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS119 | Status of the ESS Medium Beta Cavities at INFN - LASA | 2211 |
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| INFN-LASA contributes in-kind to the European Spallation Source ERIC with 36 6-cell cavities for the Medium Beta section of the Superconducting Linac. After having developed the electromagnetic and mechanical models, few prototypes have been produced and tested. Based on this experience, we are now supervisioning the cavity production at the industry, the resonators test at DESY and the delivery to CEA at Saclay. In this paper, we report on the status of the overall INFN-LASA contribution including also document handling, interface data exchange and QA/QC. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS119 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPTS120 | Status of the PIP-II Activities at INFN-LASA | 2215 |
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| INFN-LASA joined the international effort for the PIP-II project in Fermilab and it is expected to build the 650 MHz superconducting cavities required by the low-beta section of the 800 MeV front-end proton linac, as recently signed by US DOE and Italian MIUR. After developing the electro-magnetic and mechanical design, INFN-Milano started the prototyping phase by producing five single-cells and two complete 5-cells cavities. In a joint effort with Fermilab the road for the optimal surface treatment for such low-beta resonators has started in order to approach the existing state-of-the-art performances of beta 1 cavities. This paper reports the status of PIP-II activities at INFN-LASA summarizing manufacturing experience and preliminary experimental results. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS120 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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