| Paper | Title | Page |
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| TUPAB001 | Proof of Concept of CLIC Final Focus Quadrupoles Stabilization | 1290 |
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| The Compact LInear Collider (CLIC) [1] luminosity requires extremely low beam emittances. Therefore, high beam position stability is needed to provide cen-tral collisions of the opposing bunches. Since ground motion (GM) amplitudes are likely to be larger than the required tolerances, an Active Vibration Control (AVC) system is required to damp quadrupole motion to the desired value of 0.2 nm RMS at 4 Hz. This paper focuses on the vertical final focus quadrupoles (QD0, QF1) stabilization and demonstrates its feasibility. An AVC system to be installed under QD0 and QF1 has been developed and successfully tested at LAPP. Based on a dedicated homemade sensor with an ex-tremely low internal noise level of 0.05 nm at 4 Hz, it damps GM in the frequency range [3;70] Hz by up to 30 dB, leading to RMS values of approximately 0.25 nm at 4 Hz. Simulations based on GM measured in the Compact Muon Solenoid (CMS) experimental hall [2] show that with such a GM level, the specifications would only be achieved with a Passive Insulation (PI) system, which would filter ground motion starting at ~ 25 Hz | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB001 | |
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| TUPAB002 | Material Tests for the ILC Positron Source | 1293 |
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| The positron source is a vital system of the ILC. The conversion target that yields 1014 positrons per second will undergo high peak and cyclic load during ILC operation. In order to ensure stable long term operation of the positron source the candidate material for the conversion target has to be tested. The intense electron beam at the Mainz Microtron (MAMI) provides a good opportunity for such tests. The first results for Ti6Al4V are presented which is the candidate material for the positron conversion target as well as for the exit window to the photon beam absorber. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB002 | |
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| TUPAB003 | High Energy Density Irradiation With MAMI LINAC | 1296 |
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| In order to build a positron source for the ILC, a high energy density irradiation is needed to test the used materials. At the MAMI linear accelerator such a radiation can be provided at different electron energies. With a macro pulsed source it is possible to imitate a yearlong radiation at the ILC within several hours. Small transversal beam sizes need to be provided with the focusing system and be measured at high beam currents using transition radiation and current measurements. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB003 | |
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| TUPAB004 | Progress of 7-GeV SuperKEKB Injector Linac Upgrade and Commissioning | 1300 |
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| KEK injector linac has delivered electrons and positrons for particle physics and photon science experiments for more than 30 years. It is being upgraded for the SuperKEKB project, which aims at a 40-fold increase in luminosity over the previous project KEKB, in order to increase our understanding of new physics beyond the standard model of elementary particle physics. SuperKEKB asymmetric electron and positron collider with its extremely high luminosity requires a high current, low emittance and low energy spread injection beam from the injector. Electron beams will be generated by a new type of RF gun, that will provide a much higher beam current to correspond to a large stored beam current and a short lifetime in the ring. The positron source is another major challenge that enhances the positron bunch intensity from 1 to 4 nC by increasing the positron capture efficiency, and the positron beam emittance is reduced from 2000 micron to 20 micron in the vertical plane by introducing a damping ring, followed by the bunch compressor and energy compressor. The recent status of the upgrade and beam commissioning is reported. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB004 | |
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| TUPAB005 | Investigation of Beam Variation and Emittance Growth Simulation With Both Misalignments and the Beam Jitter for SuperKEKB Injector Linac | 1304 |
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Funding: This work was supported by JSPS KAKENHI Grant Number 16K17545. The SuperKEKB is e+/e− circular collider for high luminosity, 8Â¥times1035 as a target value. For the high luminosity, the injector linac is required to transport low emittance high-charged electron beam and positron beam to the ring. A charged beam with an offset from a center of cavity is affected by the wakefield depending on both the offset size in the cavity and longitudinal particle position in the beam. The wakefield causes emittance growth. This growth can be suppressed by appropriate orbit control so as to cancel the wakefield effect of the cavities in total. On the other hands, the beam variation in 6-dimensional phase space also induces the emittance growth. Emittance growth by both misalignments and 6-dimensional beam jitter was evaluated by particle tracking simulation. Investigation of beam jitter and drift was also performed by correlation analysis between beam position and measured parameter, charge or temperature. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB005 | |
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| TUPAB006 | Achievement of Stable Pulsed Operation at 31 MV/m in the STF-2 Cryomodule for the ILC | 1308 |
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| In the Superconducting RF Test Facility (STF) in KEK, the cooldown test for the STF-2 cryomodule with 12 cavities has been done totally three times since 2014. In 2016, the 3rd cooldown test for the STF-2 cryomodule including the capture cryomodule with 2 cavities, which was used for Quantum Beam Project in 2012, was successfully done. The main purpose is the vector-sum operation with 8 cavities at average accelerating gradient of 31 MV/m as the ILC specification, and the others are the measurement for Lorenz Force Detuning (LFD) and unloaded Q value, and Low Level RF (LLRF) study, etc. During 8 cavities operation, piezo actuators were used for the compensation of LFD, and the feed-forward and vector-sum control system by LLRF worked perfectly for keeping the lowest forward power and the stable flat-top of accelerating gradient. In this paper, the result for the STF-2 cryomodule in the 3rd cooldown test will be presented in detail. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB006 | |
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| TUPAB007 | Analysis of the Dependability of the LHC Quench Detection System During LHC Run 2 and Further System Evolution | 1311 |
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| The quench detection system (QDS) of the LHC superconducting circuits is an essential part of the LHC machine protection and ensures the integrity of key elements of the accelerator. The large amount of hardwired and software interlock channels of the QDS requires a very high system dependability in order to reduce the risk of affecting the successful operation of the LHC. This contribution will present methods and tools for systematic fault tracking and analysis, and will discuss recent results obtained during the LHC production run in 2016. Measures for maintaining and further improving of the system performance will be explained. An overview of the further evolution of the LHC QDS also in view of the upcoming High Luminosity Upgrade of the LHC will be given. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB007 | |
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| TUPAB008 | CEPC Linac Design and Beam Dynamics | 1315 |
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| Circular Electron-Positron Collider (CEPC) is a 100 km ring e+ e− collider for a Higgs factory, which is organized and led by the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences (CAS) in collaboration with a number of institutions from various countries. The linac of CEPC is a normal con-ducting S-band linac with frequency in 2856.75 MHz and provide electron and positron beam at an energy up to 10 GeV with bunch charge in 1.0 nC and repetition frequency in 100 Hz. The linac scheme will be detailed discussed in this paper, including electron bunching system, positron source design, and main linac. Positrons are generated using a 4 GeV electron beam with bunch charge 10 nC hit tungsten target and the positron source design are presented. The beam dynamic results with longitudinal short Wakefield, transverse Wakefield and errors are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB008 | |
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| TUPAB009 | Design Study on CEPC Positron Damping Ring and Bunch Compressor | 1318 |
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| The primary purpose of CEPC damping ring is to reduce the transverse phase spaces of positron beam to suitably small value at the beginning of Linac and also adjust the time structure of positron beam for reinjection into the Linac. Longitudinal bunch length control was provided to minimize wake field effects in the Linac by a bunch compressor system after the damping ring. Both designs for damping ring and bunch compressor were discussed in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB009 | |
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| TUPAB010 | High-Gradient Breakdown Studies of X-Band Choke-Mode Structures | 1322 |
| SUSPSIK005 | use link to see paper's listing under its alternate paper code | |
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| As an alternative design for Compact Linear Collider (CLIC) main accelerating structures, X-band choke-mode damped structures had been studied for several years. However, the performance of choke-mode cavity under high power is still in lack of research. Two standing-wave single-cell choke-mode damped accelerating structures working at 11.424 GHz and one reference structure without choke were designed, manufactured, low-power measured, and tuned by accelerator group at Tsinghua University. High-power test had been done on them to study the breakdown phenomenon in high gradient and how the choke affects high-gradient properties. A max gradient of 75 MV/m were achieved by the choke-mode structure and the choke breakdown limited further increasing of the gradient. Inner surface inspection of the choke-mode structures indicates that the axial part of the choke limits the performance of the structure. Based on this observation, three new choke-mode structures were designed and being manufactured. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB010 | |
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| TUPAB011 | Beam Dynamics Simulation in Two Versions of New Photogun for FCC-ee Electron Injector Linac | 1326 |
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| New high-energy frontier project FCC is now under development at CERN. The project includes three modes: ee, hh and eh interactions for FCC. New injection system for FCC-ee is planned to consist of new ~ 2-14 GeV electron linac and electron-positron converter. Injector linac should provide two regimes: ~250 pC bunches for injection and ~6 nC bunches for e−/e+ conversion. Two possible schemes of photogun are comprised and results of beam dynamics simulation in both FCC-ee injection linac photoguns are discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB011 | |
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| TUPAB012 | Comparison of Prismatic and Circular Biperiodical Accelerating Structures of 27 GHz Operating Frequency | 1330 |
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| As known a biperiodical accelerating structure (BAS) represents as a system based on disk loaded waveguide (DLW) operating on Pi/2 mode and is widely used for the compact electron linacs. Earlier such structure with operating frequency of 27 GHz was proposed for medical application and beam dynamics simulations and electrodynamics modeling were done [1-2]. It was shown that such structure manufacturing should have very high accuracy and can be manufactured using electro erosive technology only. It is very complex for axi-symmetrical geometry to use such technology. Interesting option will to use a prismatic geometry BAS. In this report the design of a prismatic and disk-loaded BAS will discus, simulation results and analysis will presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB012 | |
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| TUPAB013 | Beam Dynamics Study and Electrodynamics Simulations for the CW RFQ | 1333 |
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A compact university scale CW research proton accelerator, as well as driver linac with three branches of experimental beam lines, delivering beam energy of 3, 30 and 100 MeV for experiments, are recently under development in Russia. First results of the beam dynamics simulations for such a linac were already shown in *. The recently developed advanced RFQ cavity design is presented. The low energy beam transport line (LEBT), dedicated to transport proton beam from an ECR ion source, as well as to match beam emittance to the RFQ acceptance, was investigated. The results of beam dynamics simulations for LEBT are discussed.
* W.Barth, T.Kulevoy, S.Polozov, S.Yaramyshev, Proc. of HB-2016, 188-190. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB013 | |
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| TUPAB014 | Preliminary Design of FCC-ee Pre-Injector Complex | 1337 |
| SUSPSIK006 | use link to see paper's listing under its alternate paper code | |
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| The design of a 100 km circular e+e− collider with extremely high luminosity is an important component of the global Future Circular Collider (FCC) study hosted by CERN. FCC-ee is being designed to serve as Z, W, H and top factory, covering beam energies from 45.6 to 175 GeV. For the injectors, the Z-operation is the most challenging mode, due to the high total charge and low equilibrium emittance in the collider at this energy. Thus, fulfilling the Z-mode will also meet the demands for all other modes of FCC-ee. This goal can be achieved by using a 6 GeV NC linac with an S-band RF frequency of 2.856 GHz and a repetition rate of 100 Hz. This linac will accelerate two bunches per RF pulse, each with a charge of 6.5 nC. Positrons will be generated by sending 4.46 GeV e- onto a hybrid target so that the e+ created can still be accelerated to 1.54 GeV in the remaining part of the same linac. The emittance of the e+ beam will then shrink to the nm level in a 1.54 GeV damping ring. After damping, the e+ will be reinjected into the linac and accelerated to 6 GeV. The e- and e+ will then be accelerated alternately to 45.6 GeV in the booster, before they are injected into the collider. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB014 | |
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| TUPAB015 | Pulsed Beam Tests at the SANAEM RFQ Beamline | 1341 |
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Funding: Turkish Atomic Energy Authority A proton beamline consisting of an inductively coupled plasma (ICP) source, two solenoid magnets, two steerer magnets and a radio frequency quadrupole (RFQ) is developed at the Turkish Atomic Energy Authority's (TAEA) Saraykoy Nuclear Research and Training Center (SNRTC-SANAEM) in Ankara. In Q4 of the 2016 the RFQ was installed in the beamline. The high power tests of the RF power supply and the RF transmission line were done successfully. The high power RF conditioning of the RFQ was performed recently. The 13.56 MHz ICP source was tested in two different conditions, CW and pulsed. The characterization of the proton beam was done with ACCTs, Faraday cups and a pepper-pot emittance meter. Beam transverse emittance was measured in between the two solenoids of the LEBT. The measured beam is then reconstructed at the entrance of the RFQ by using computer simulations to determine the optimum solenoid currents for acceptance matching of the beam. This paper will introduce the pulsed beam test results at the SANAEM RFQ beamline. In addition, the high power RF conditioning of the RFQ will be discussed. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB015 | |
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| TUPAB016 | The CLIC Main Linac Module Updated Design | 1345 |
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| In 2016, CLIC implementation working groups have started their reflection on how to finalize the CLIC design work in the different areas of the project, aiming for a technical design and an overall implementation plan for CLIC being available for the next European Strategy Update around 2019. One of the working groups has focused its attention on the Main Linac hardware, which has brought together the different competences of the study with the aim of producing an advanced set of specifications for the design, installation and operation of the CLIC module. As the fundamental unit for the construction of the Main Beam linac, the CLIC module needs to move from the existing prototypes exploring its performance into an advanced and functional unit where the full life cycle of the module is considered. The progress of the working group activity is summarized in this paper, with considerations on the requirements for the design of the next-phase CLIC module. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB016 | |
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| TUPAB017 | Results of the Beam-Loading Breakdown Rate Experiment at the CLIC Test Facility CTF3 | 1348 |
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| The RF breakdown rate is crucial for the luminosity performance of the CLIC linear collider. The required breakdown rate at the design gradient of 100 MV/m has been demonstrated, without beam presence, in a number of 12 GHz CLIC prototype structures. Nevertheless, the beam-loading at CLIC significantly changes the field profile inside the structures, and the behaviour with beam needs to be understood. A dedicated experiment in the CLIC Test Facility CTF3 to determine the effect of beam on the breakdown rate has been collecting breakdown data throughout the year 2016. The complete results of the experiment and the effect of the beam-loading on the breakdown rate are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB017 | |
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| TUPAB018 | Initial Data From an Electron Cloud Detector in a Quadrupole Magnet at CesrTA | 1352 |
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Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505 In September 2016, we installed a detector in a quadrupole magnet that measures the electron cloud density using two independent techniques. Stripline electrodes collect cloud electrons which pass through holes in the beam-pipe wall. The array of small holes shields the striplines from the beam-induced electromagnetic pulse. The beam-pipe chamber has also been designed so that microwave measurements of the electron cloud density can be performed. The resonant microwaves are confined to be within the 56 cm length of the quadrupole. The detector is placed in a newly installed quadrupole that is adjacent to an existing lattice quadrupole of the same polarity. Since they are powered independently, their relative strengths can be varied with stored beam – allowing electron cloud measurements to be made as a function of gradient. This paper presents the first data obtained with this detector with trains of positron bunches at 5.3 GeV. The detector is installed in the Cornell Electron Storage Ring and is part of the test accelerator program for the study of electron cloud build-up using electron and positron beams from 2 to 5 GeV. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB018 | |
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| TUPAB020 | AREAL 50 MeV Electron Accelerator Project for THz and Middle IR FEL | 1355 |
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| Advanced Research Electron Accelerator Laboratory (AREAL) is an electron accelerator project based on photo cathode RF gun. First phase of the facility is a 5 MeV energy RF photogun, which is currently under operation. The facility development implies energy upgrade to 50 MeV with further delivery of the electron beam to the undulator sections for Free Electron Laser and coherent undulator radiation generation in MIR and THz frequency ranges respectively. In this report the design study of AREAL 50 MeV facility main systems along with the beam dynamics and characteristics of expected radiation are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB020 | |
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| TUPAB021 | The Study of Focus-Dependent Dark Current for AREAL RF Photogun | 1358 |
| SUSPSIK021 | use link to see paper's listing under its alternate paper code | |
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| AREAL (Advanced Research Electron Accelerator Laboratory) is a project of linear accelerator based facility aimed to produce ultra-short electron bunches with small emittance. In the first phase of AREAL project an electron beam with energy up to 5 MeV is produced by the electron RF photogun and used for irradiation experiments in biology, microelectronics and accelerator technology development. For such experiments the exact calculation of absorbed dose and electron bunch peak current is one of important conditions. The presence of a dark current in electron gun affects the electron emission from photocathode, the exact absorbed dose calculation, and in general harms the machine performance. In this paper the estimation of dark current amount, produced in the electron gun, the ways to avoid its influence on experiments are discussed. The dark current measurements are compared with the simulation results. The electron beam separation from a dark current is discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB021 | |
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| TUPAB022 | TRIUMF ARIEL e-Linac Ready for 30 MeV | 1361 |
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Funding: TRIUMF is funded under a contribution agreement with the National Research Council of Canada. The ARIEL electron linac (e-linac) in its present configuration has a 10 mA electron gun and a single-cavity 10 MeV injector cryomodule followed by the accelerator cryomodule intended to house two 10-MeV-capable SRF cavities. There are momentum analysis stations at 10 MeV and 30 MeV. In October 2014, using a total of two cavities, the e-linac demonstrated 22.9 MeV acceleration. In 2017 an additional SRF cavity was installed in the accelerator cryomodule, thereby completing its design specification; and leading to 30 MeV acceleration capability. The 9-cell 1.3 GHz cavities are a variant of the TESLA type, modified for c.w. operation and recirculation. An unusual feature of the module is the power feed of two cavities by one klystron through a wave-guide type power divider, and closed loop control of the combined voltage from the cavities. Initial operation of the two-cavity control, including power and phase balancing, is reported. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB022 | |
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| TUPAB023 | Commissioning of the 10MeV Electron Injector Cryomodule for VECC at TRIUMF | 1365 |
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| TRIUMF (Vancouver) and VECC (Kolkata) have been engaged in a collaboration on superconducting electron linacs since 2008. The motivation for the collaboration was to support initiatives at both labs, ARIEL at TRIUMF and ANURIB at VECC, to augment the respective radioactive ion beam (RIB) programs with the addition of a high intensity electron linac driver to produce RIBs through photo-fission. The common linac architecture is based on five 1.3GHz nine-cell SRF cavities housed in three cryomodules; a single cavity injector (ICM) and a pair of two cavity accelerating modules (ACM). Final design goals are 50MeV and 10mA/3mA at TRIUMF/VECC respectively. A ARIEL e-linac demonstrator with two cold cavities in two modules successfully accelerated beam to 20MeV. Recently the VECC 10MeV injector cryomodule was commissioned with beam. A summary of the ICM design and results of the commissioning will be presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB023 | |
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| TUPAB025 | Experimental Results for Multiphoton Nonlinear Photoemission Processes on Phil Test Line | 1369 |
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One of the prerequisites for the next generation high luminosity light sources is the availability of the short electron bunches. It also has several applications in other domains, including medical diagnostics and high-resolution imaging. In principle, using photoelectric effect a short electron bunch can initially be generated by illuminating a photocathode with an ultra-short light pulse of appropriate wavelength. Strong EM fields from a RF gun or similar accelerating structures, synchronized with the incoming laser pulses, are then used to accelerate these electron bunches initially up to an energy of tens of MeV. We present our preliminary results on the experimental investigation of two-photon nonlinear photoemission processes for the generation of picosecond, low-charge electron bunches conducted at PHIL photoinjector facility. A comparison of the emission efficiency and bunch characteristics with the single photon emission process is also made.
*PHIL is an acronym for Photo-injector at Linear Accelerator Laboratory (LAL). |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB025 | |
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| TUPAB026 | Status of the Cryogenic Undulator CPMU-17 for EMIL at BESSY II / HZB | 1372 |
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| The CPMU-17 is the hard X-ray radiation source of a canted double undulator system for the Energy Materials In-situ Laboratory EMIL at BESSY II [1]. Various ambitious concepts are realized in this undulator such as Dy-hardened PrFeB-magnets, direct liquid Nitrogen cooling, dual loop feedback gap drive based on an optical micrometer and a low permeability stainless steel In-Vacuum(IV)-girder without keepers. The magnets are sorted according to Helmholtz coil and stretched wire data. Reproducibility and accuracy measurements of two IV-measurement tools needed for the CPMU-17 are presented: an IV-Hall probe bench and an IV-Moving Wire. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB026 | |
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| TUPAB027 | Production, Tuning and Processing Challenges of the BERLinPro Gun1.1 Cavity | 1375 |
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Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association For the BERLinPro energy recovery LINAC, HZB is developing a superconducting 1.4-cell electron gun, which, in its final version, is planned to be capable of CW 1.3 GHz operation with 77 pC/bunch. For this purpose a series of three superconducting cavities, denoted as Gun 1.0, Gun 1.1 (both designed for 6 mA) and Gun 2.0 (100 mA) are foreseen. Gun 1.0 now reached operational status and the Gun 1.1 cavity is completely manufactured. In the paper the chronology of manufacturing, tuning and processing of the Gun 1.1-cavity is described, also giving details about combined mechanical/electrodynamic simulations, which were performed in order to gain deeper understanding of the cavity's unexpected tuning behavior. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB027 | |
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| TUPAB028 | Measuring the Spectral Response of Cs-K-Sb Photocathodes for BERLinPro | 1378 |
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| A spectral response setup was commissioned at the Cs-K-Sb photocathode preparation and analysis system developed for the BERLinPro project. The setup is designed to measure the spectral quantum efficiency from 370 to 700 nm and to monitor the photocurrent during the photocathode growth process and the photocathode lifetime at 515 nm. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB028 | |
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| TUPAB029 | UHV Photocathode Plug Transfer Chain for the BERLinPro SRF-Photoinjector | 1381 |
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| A dedicated particle free UHV photocathode plug transfer chain from the preparation system to the SRF-Photoinjector was set up and commissioned at HZB for the BERLinPro project. The plug handling system was designed in collaboration with the ELBE team at HZDR, where the same transfer chain is in commissioning phase. In the future the exchange of photocathodes between the laboratories offers the possibility to test different types of photocathodes in different SRF-photoinjectors. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB029 | |
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| TUPAB030 | Construction and Status of the Thrice Recirculating S-DALINAC | 1384 |
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Funding: Work supported by DFG through RTG 2128 and CRC 634. From 1991 until 2015 the S-DALINAC (Superconducting-DArmstadt-LINear-ACcelerator) was operated as a twice recirculating electron accelerator. Its design energy of 130 MeV in cw-operation was not reached so far due to a lower quality factor of the SRF cavities and thus a higher dissipated power to the helium bath. In 2015/2016 a third recirculation has been built. Enabling a fourth passage through the main linac, the accelerating gradients can be reduced to fit the resulting dissipated power to the available cooling power for running at design energy. The upgrade to a thrice recirculating accelerator required the reconstruction of main parts of the existing lattice as well as an installation of a new beam line. All magnets had to be aligned carefully in position and orientation using high-precision metrology sensors. This contribution will present an overview of the construction and the alignment process. A latest status of the commissioning will be given. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB030 | |
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| TUPAB031 | Status and Perspectives of the S-DALINAC Polarized-Electron Injector | 1388 |
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Funding: Work supported by the Deutsche Forschungsgemeinschaft through grants GRK 2128 and SFB 1245 The S-DALINAC Polarized Injector (SPIn) uses GaAs photocathodes to provide pulsed and/or polarized electron beams for nuclear-structure investigations. Recently, a test facility for Photo-Cathode Activation, Test and Cleaning using atomic-Hydrogen \mbox{(Photo-CATCH)} has been developed. This setup uses an inverted-insulator geometry for the photo-electron gun. Currently, tests and optimizations are conducted at \mbox{Photo-CATCH} in order to implement this new gun design at SPIn. We will present the current status of \mbox{Photo-CATCH}, the planned upgrade of SPIn (aimed at an operational voltage of 200 kV) and future measurements. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB031 | |
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| TUPAB032 | Development of a Cryogenic GaAs DC Photo-Gun for High-Current Applications | 1391 |
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Funding: Work supported by DFG (GRK 2128) and BMBF (05H15RDRB1) For high-current applications of GaAs photocathodes it is necessary to maximize the charge lifetime of the cathode material to ensure reliable operation. By means of cryogenic cooling of the electrode, the local vacuum conditions around the source can be improved due to cryogenic adsorption of reactive rest-gas molecules at the surrounding walls. Furthermore, the cooling also allows a higher laser power deposited in the material, resulting in higher currents that can be extracted from the cathode. Ion-backbombardment is expected to be reduced using electrostatic bending of the electrons behind the cathode. To measure the characteristics of such an electron source, a dedicated set-up is being developed at the Photo-CATCH test facility in Darmstadt. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB032 | |
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| TUPAB033 | Design of a Stripline Kicker for the ELBE Accelerator | 1393 |
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| ELBE is a linac based cw electron accelerator serving different secondary beams one at a time. Depending on the user demand the bunch repetition rate may vary from single pulse up to 13 MHz. For the future different end stations should be served simultaneously, hence specific bunch patterns have to be kicked to other beam-lines. To use e.g. one bunch out of the bunch train very short kicking durations have to be realized. The variability of the bunch pattern and the frequency resp. switching time are one of the main arguments for a stripline-kicker combined with HV-switches as basic concept. A nearly homogenous field in the kicker has to be realized for uniform deflection of the electron bunch and emittance grow of the bunch has to be kept as low as possible. Furthermore the fast switching ability of the kicker demands for a fast decay of the HV-pulse resp. its reflections in the structure implying a specific design of the kicker elements. For this reason a design with two tapered active electrodes and two ground fenders was optimized in time and frequency domain with the software package CST. Additionally a first prototype was manufactured for laboratory and first beam-line tests. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB033 | |
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| TUPAB035 | Field Quality of 1.5 m Long Conduction Cooled Superconducting Undulator Coils with 20 mm Period Length | 1395 |
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The Institute for Beam Physics and Technology (IBPT) at the Karlsruhe Institute of Technology (KIT) and the industrial partner Babcock Noell GmbH (BNG) are col-laborating since 2007 on the development of superconducting undulators both for ANKA and low emittance light sources. The first full length device with 15 mm period length has been successfully tested in the ANKA storage ring for one year*. The next superconducting undulator has 20 mm period length (SCU20) and is also planned to be installed in the accelerator test facility and synchrotron light source ANKA. The SCU20 1.5 m long coils have been characterized in a conduction cooled horizontal test facility developed at KIT IBPT. Here we present the local magnetic field and field integral measurements, as well as their analysis including the expected photon spectrum.
*S. Casalbuoni et al., Characterization and long term operation of a novel superconducting undulator with 15 mm period length in a synchrotron light source, Phys. Rev. ST Accel. Beams, vol. 19, p.110702, Nov. 2016. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB035 | |
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| TUPAB036 | Training and Characterization of 1.5m Long Conduction Cooled Superconducting Undulator Coils with 20 mm Period Length | 1399 |
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| The Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology (KIT), and the company Babcock Noell GmbH (BNG) are running an R&D program on superconducting undulators (SCUs). The collaboration is working on a SCU with 20 mm period length (SCU20) for ANKA, the test facility and synchrotron radiation source, run by the IBPT. The 1.5 m long undulator coils have been tested in a conduction-cooled environment. This contribution describes the training, the stability and the thermal behavior of the coils. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB036 | |
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| TUPAB037 | An Optimized Lattice for a Very Large Acceptance Compact Storage Ring | 1402 |
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| Combining a circular storage ring and a laser wakefield accelerator (LWFA) might be the basis for future compact light sources and advancing user facilities to different commercial applications. Meanwhile the post-LWFA beam is not directly suitable for storage and accumulation in conventional storage rings. New generation rings with adapted features are required. Different geometries and ring lattices of very large-acceptance compact storage ring operating between 50 to 500 MeV energy range were studied. The main objective was to create a model suitable to store the post-LWFA beam with a wide momentum spread (2% to3%) and ultra-short electron bunches of fs range. The DBA-FDF lattice with relaxed settings, split elements and optimized parameters allows to open the dynamic aperture up to 20 mm while dispersion is limited and sextupole strength is high. The proposed machine model could be a basis for further, more detailed design studies. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB037 | |
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| TUPAB038 | Electron Acceleration With a Ultrafast Gun Driven by Single-Cycle Terahertz Pulses | 1406 |
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Funding: This work was supported by the European Research Council under the European Union Seventh Framework Program (FP/2007-2013)/ERC Grant Agreement no. 609920. We present results on an improved THz-driven electron gun using transversely-incident single-cycle THz pulses using a horn-coupler. Intrinsic synchronization between the electrons and the driving field was achieved by using a single laser system to create electrons by UV photoemission and to create THz radiation by difference frequency generation in a tilted-pulse front geometry. Details of the optical setups for the UV and THz pulses will be described as well as preliminary results showing evidence of electron acceleration. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB038 | |
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| TUPAB039 | Installation Management for the European XFEL Main Accelerator | 1409 |
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| By end of 2016, the main accelerator of the European XFEL was completed. To build this complex machine in a minimum of time, certain management methods were introduced in mid 2015, which accelerated the installation process substantially. In the following 64 weeks additional 84 % of the main accelerator were set up. This was possible due to an improved planning, the reinforcement of two teams as well as a permanent controlling and optimizing of the installation process. In this paper, the installation process from July 2015 to end 2016 and the measures which speeded up the workflow are described. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB039 | |
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| TUPAB040 | Status Update of the SINBAD-ARES Linac Under Construction at DESY | 1412 |
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| ARES (Accelerator Research Experiment at Sinbad) is a linear accelerator for the production of low charge (from few pC to sub-pC) electron bunches with 100 MeV energy, fs and sub-fs duration and excellent arrival time stability. This experiment is currently under construction at DESY Hamburg and it is foreseen to start operation by the beginning of 2018 with the commissioning of the RF-gun. After an initial beam characterization phase, ARES will provide high temporal resolution probes for testing novel acceleration techniques, such as Laser driven plasma Wake-Field Acceleration (LWFA), Dielectric Laser Acceleration (DLA) and THz driven acceleration. In this work we present an overview of the present design of the linac with a special focus on 3D integration and planned installation phases of the beamline. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB040 | |
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| TUPAB041 | Improvements in Production of Magnets and Pole Pieces for Undulators | 1415 |
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| Permanent magnets and highly saturable pole pieces are widely used in the setup of undulators as well as dipoles, quadrupoles and sextupoles. We will present actual improvements of precision, homogeneity and basic material properties in the range of NdFeB-based permanent magnets and CoFe-based soft magnetic alloys. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB041 | |
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| TUPAB042 | Current Status of IPM Linac Control System | 1418 |
| SUSPSIK084 | use link to see paper's listing under its alternate paper code | |
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| This paper reports the progress of the control system for IPM 10 MeV accelerator. As an electron linac, it consists of beam injection acceleration tube, radio frequency production and transmission, target, diagnostics and control and safety. In support of this source, an EPICS-based integrated control system has been designed and being implemented from scratch to provide access to the critical control points and continues to grow to simplify operation of the system. In addition to a PLC-based machine protection component and IO interface, a CSS-based suite of control GUI monitors systems including Modulator and RF, Vacuum, Magnets, and electron gun. An overview of this system is presented in this article. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB042 | |
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| TUPAB043 | Design and Simulation of Voltage Multiplier Column of a 300keV, 10mAParallel Fed Cockcroft Walton Electron Accelerator for Industrial Applications | 1421 |
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| In this article a 300keV, 10mA multiplier column has been designed for a parallel fed Cockcroft Walton electron accelerator for industrial applications. The parallel fed Cockcroft Walton multiplier is a capacitive coupling multiplier with diode rectification which can convert an input RF voltage to a low ripple output DC voltage. In this research tried to get a low ripple (300keV output) dc voltage. At first, the voltage multiplier column has been simulated with pspice simulation software. After doing the pspice simulations, optimum value of different parameters has been get. At the end we try to get the optimum values of pspice simulations with a mechanical design with CST STODIO. The mechanical design of voltage multiplier and its equivalent circuit hah a good accordance with each other. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB043 | |
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| TUPAB044 | SIMULATION, MEASUREMENT AND TUNING OF A PROTOTYPE DISK LOADED RF CAVITY | 1424 |
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| Constant impedance accelerator RF cavities are constructed from similar resonator cells that stacked to each other. Best operation condition is achieved when all of cells resonate in one resonance frequency with similar quality factors. So, measurement and tuning of RF cavities is the critical step for final best operation of linear accelerators. In this paper, the electromagnetic computer simulations, RF measurement and final tuning of a nine cell periodic accelerator structure was represented. All of cavities tuned in one resonant frequency and according to theoretical concepts we obtain nine resonant modes from RF measurements by vector network analyzer. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB044 | |
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| TUPAB045 | Design and Construction of a Pre-Buncher for Iranian Low Energy Linear Accelerator | 1428 |
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| Iranian IPM low energy linear accelerator project (e-Linac) is in its final steps for commissioning. Beam dynamic simulations with and without Pre-buncher prior to buncher was done. The results represent improvement in capturing efficiency better than 25% by application of Pre-buncher cavity. In this paper, we present the simulation, construction, RF measurements and vacuum test results. After construction, we measured RF reflection coefficient better than -33 dB in the nominal frequency of 2997.9 MHz with quality factor of 4500. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB045 | |
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| TUPAB047 | Design of a Low Emittance High Current Photocathode RF Gun for the IPM Linear Accelerator | 1431 |
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| The IPM accelerator project is developing a 50 MeV linear accelerator as an injector for a terahertz source or an IR FEL. The design specifications require a laser driven photocathode located in one end of a high gradient RF cavity operated at 3 GHz frequency and a solenoid channel for the beam transport. In this work, we report on the RF design of an special photocathode RF gun and its associated focusing channel for the emittance compensation process along the whole injector. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB047 | |
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| TUPAB048 | Long Beam Pulses With SLED Compression in DAΦNE LINAC | 1434 |
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| The DAΦNE LINAC is a ~60 m long, S-band (2856 MHz) linear accelerator, made up by four 45 MW klystrons with SLED compression, and by 15 travelling-wave, 2/3p, SLAC-type, 3 m long accelerating sections. It serves as injector of the DAΦNE e+ e− collider, with 510 MeV, 10 ns long, electron and positron pulses, and the Beam-Test Facility extraction line, with variable beam energy and intensity and with pulses from 1.5 to 40 ns. A new pulsing system for the gun allows longer beam pulses, but the shape of the accelerating field in the sections due to the SLED compression has to be taken into account. We describe the tuning of the RF power, phase and delays in the pre-buncher, buncher and following accelerating sections, and the results of the tests performed in order to reach >200 ns 500 MeV electron pulses and the characterization of the quality of the beam in terms of energy spread, time distribution, etc. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB048 | |
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| TUPAB049 | Development of the High Power Terahertz Light Sources at LEBRA Linac in Nihon University | 1437 |
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Funding: This work was supported by JSPS KAKENHI (Grant-in-Aid for Young Scientists (B)) Grant Number JP16K17539. Development of a THz light source has been underway at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University in collaboration with National Institute of Advanced Industrial Science and Technology (AIST) since 2011. Basic research on coherent transition radiation (CTR) in the THz region has been carried out using the Parametric X-ray Radiation (PXR)-beam line of LEBRA. Since fiscal year 2016, the THz transport line has been constructed on the same axis as the PXR beam line taking the construction cost and simultaneous use of the two beams into account. Basic measurement and intensity upgrading test have been carried out for the THz lights generated on the PXR-generating electron beam line. The average intensity of the THz lights obtained at the output port in the accelerator room has been 5 mW. Construction of the THz transport beam line and the property of the THz lights is discussed in the report. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB049 | |
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| TUPAB050 | A Lifetime Study of CsK2Sb Multi-Alkali Cathode | 1440 |
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Funding: Quantum beam project by the Ministry of Education, Culture, Sports, Science, and Technology, entitled High Brightness Photon Beam by Laser Compton Scattering and Cooperative supporting Program for Research Education in University by KEK(High Energy Accelerator Research Organization) \rm CsK2Sb is a high performance photo-cathode for accelerators requiring the high brightness electron beam. It can be driven by a green laser generated as SHG of a solid state laser. The quantum efficiency is as high as 10\%. In this article, the robustness of the cathode was studied experimentally. We found that 1/e lifetime of the cathode was inversely proportional to the vacuum pressure. The normalized temporal life was \rm (4.72± 0.08)× 10-5~Pa.hour for 532 nm laser. The lifetime regarding to the extracted charge density was also inversely proportional to the vacuum pressure. The normalized charge life was \rm (1.19± 0.03± 0.04)× 10-4 Pa.C/mm2. The cathode is robust enough for a high brightness electron accelerator. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB050 | |
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| TUPAB051 | Substrate Dependence of CsK2Sb Cathode Performance | 1443 |
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Funding: Quantum beam project by the Ministry of Education, Culture, Sports, Science, and Technology, entitled High Brightness Photon Beam by Laser Compton Scattering and Cooperative supporting Program for Research and education in University by KEK(High Energy Accelerator Research Organization). \rm CsK2Sb is a high performance cathode which can be driven with a green laser. The cathode is generated by evaporation on a substrate in a high vacuum environment. The cathode was evaporated on various material and surface condition to evaluate the dependence of the cathode performance. GaAs (100), Si(100), and Si(111) were examined as samples of the substrate. For each materials, the cathode on the cleaned and as-received substrates were examined and those on the cleaned showed better performance than the as-received for all materials. The detail of the experimental results are presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB051 | |
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| TUPAB053 | Proof-of-Principle Experiment of Phase-Combined Undulator | 1446 |
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A huge attractive force is the largest concern in designing a mechanical structure of undulators, in which an accurate control and high uniformity of the gap between the upper and lower magnetic girders are required. This problem is especially serious for in-vacuum undulators, in which the girders are located inside the vacuum chamber. We have proposed a new concept called a phase-combined undulator, which has intrinsically no magnetic force*. In this undulator, the magnetic forces acting on the girders locally head to the longitudinal axis instead of the attractive direction, and are actually canceled out in total. Numerical calculations have shown that the attractive force will be reduced down to a negligible level. Recently, we performed a proof-of-principle experiment to examine the feasibility of this undulator concept in terms of the force between the girders and magnetic field distribution, which will be reported in the conference.
* R. Kinjo and T. Tanaka, Phys. Rev. ST Accel. Beams 17, 122401 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB053 | |
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| TUPAB055 | Development of compact magnetic field measurement system available for in-vacuum undulators | 1449 |
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A low-emittance 3-GeV KEK-LS* ring has been designed at KEK. KEK-LS's undulators can produce extremely high brightness light ranging from VUV to X-ray. Brightness of undulator light strongly depends on the phase error of its periodic magnetic field. Then a precise magnetic field adjustment is required in order to prevent the reduction of the brightness performance. Generally, the adjustment is performed by the conventional field measurement system equipped with hole-probes on a huge stone table. But, for the in-vacuum undulator, the measurement must be performed without the vacuum chamber. The additional phase error caused by reattaching the chamber is not negligible for the low emittance rings. Therefore, some groups have developed measurement systems available for the direct field measurement inside the chamber**,***. We have started to develop a compact measurement system. Our system is compacted and stabilized by utilizing the rigid metal beam of the undulator frame instead of the stone table. In the conference, we will report the detail of the system and the present status of the development.
* KEK-LS HP, http://kekls.kek.jp/ ** T. Tanaka, et al., Physical Review ST-AB, vol.12, p.120702 (2009). *** M. Musardo, et al., Proceedings of IPAC2015, Richmond, VA, USA, p.1693 (2015). |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB055 | |
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| TUPAB056 | New Achievements of the Laser System for RF-Gun at SuperKEKB Injector | 1452 |
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| For realizing high charge and low emittance electron and positron beams in SuperKEKB, we have been making improvements in current laser system for RF-gun. In order to realize more excellent thermal management in current laser system at high repetition rate operation, novel soldering Yb:YAG thin disk and copper tungsten heat sink laser head is manufactured via gold tin solder. Comparing with old design, less residual stress is introduced and more efficient thermal removal can be obtained. These new soldering laser heads are placed into a compact vacuum chamber and cooled by Peltier plates directly. This design can realize higher gain and amplification factor in regenerative amplifier and multi-pass amplifier. In addition, the compact and simple cooling method can achieve excellent thermal management for the purpose of realize laser operation at high repetition rate for following phases of SuperKEKB project. A perspective towards the next step experiment is also presented in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB056 | |
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| TUPAB059 | Study on CsKSb Photocathode for the RF Electron Gun | 1456 |
| SUSPSIK022 | use link to see paper's listing under its alternate paper code | |
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At Waseda University, we have been developing a Cs-Te photocathode S-band RF electron gun and application experiments of the electron beam. On the experiments, charge amount is important factor, which strongly depends on laser power and photocathode quality. At present, we are studying CsKSb photocathode to increase the charge amount of an electron beam generated from the RF-Gun. As a result of using CsKSb photocathode in the RF-cavity, we obtained as much charge as using Cs-Te photocathode but the lifetime was shorter than that of Cs-Te. In order to lengthen the photocathode lifetime, we tried to coat a protective film on CsKSb photocathode surface and investigated its robustness for poor vacuum condition that simulates cathode transportation and usage in the RF-Gun. In this conference, we report current status of fabricating coated photocathode and future prospects.
A. Buzulutskov et al. The protection of K-Cs-Sb photocathodes with CsBr films Nuclear Instruments and Methods in Physics Research A 400 (1997) 173-176 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB059 | |
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| TUPAB060 | Development of the Laser System for the Proof-of-Principle Experiment of Crab Crossing Laser-Compton Scattering | 1460 |
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An X-ray source via laser-Compton scattering has the advantage of small source, energy tunability and quasi-monochromaticity and is expected to be applied in a wide range of fields such as the industry and medical care. In laser-Compton scattering, the luminosity, which represents the collision frequency between the electrons and the photons, is very important. Increasing the luminosity is strongly required for increasing the scattered photon flux. One way to increase the luminosity is tilting electron bunches at the collision point, which is called crab crossing. It is the way to create the head-on collision artificially. The purpose of this study is the proof-of-principle of the crab crossing laser-Compton scattering. In this conference, we will report the design optimization and construction of the laser system for the collision and future prospects.
Variola Alessandro, et al. Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators. Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB060 | |
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| TUPAB062 | Single Dipole Kicker Injection Into the Sesame Storage Ring | 1463 |
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| SESAME (Synchrotron Radiation Light Source in Allan, Jordan) consists of an 800 MeV injector (original from BESSY I, Berlin, Germany) and a 2.5 GeV storage ring. Extraction out of the Booster is done by means of a bumper, a delay-line kicker, and a direct driven in-vacuum septum. This paper will present the injection procedure into the storage ring. Simulations of the injection process are compared to the results obtained during commissioning | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB062 | |
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| TUPAB063 | High Energy Transport Line Design for the HEPS Project | 1466 |
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| The High Energy Photon Source (HEPS), a kilometer-scale storage ring light source with the energy of 6GeV is to be built in China. For the injection scheme of the stor-age ring, on-axis injection is the baseline scheme. To simultaneously accommodate on-axis accumulation and swap-out injection schemes, we designed two high energy transport lines. In this paper we will report the detailed design of these two transport lines, including the layout and lattice design. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB063 | |
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| TUPAB064 | Development of a PrFeB Cryogenic Permanent Magnet Undulator (CPMU) Prototype at IHEP | 1469 |
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| A PrFeB cryogenic permanent magnet undulator (CPMU) prototype is under construction for High Energy Photon Source Test Facility (HEPS-TF) at IHEP. The device is a full scale in-vacuum undulator with a magnetic length of 2 meters and a period of 13.5 mm, and it will work at less than 85K. The whole design scheme of prototype is presented and the specifications are given, where the consideration of in-vacuum magnetic measurement bench is also included. The development progress is introduced. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB064 | |
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| TUPAB065 | The Progress of HEPS Booster Design | 1472 |
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| The High Energy Photon Source (HEPS), a kilometre-scale, ultralow-emittance storage ring light source, is to be built in Beijing, China. For HEPS, a full energy booster synchrotron operating at a frequency of 2Hz is considered. In this paper, we will report the progress of the lattice design and physics studies on HEPS booster, containing the injection consideration, ramping process, error studies, and so on. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB065 | |
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| TUPAB066 | Mechanical Design of a Cryogenic Permanent Magnet Undulator at IHEP | 1475 |
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High Energy Photon Source (HEPS) at Institute of High energy Physics (IHEP) is a new 6 GeV third generation electron storage ring. Insertion devices play a significant role in achieving the high performance of the photon source. A 13.5mm period-length Cryogenic Permanent Magnet Undulator (CPMU) prototype is designed and under construction. The mechanical structure designed based on physical requirements will be presented.
Work supported by Project of High Energy Photon Source Test Facility, email address: sunsc@ihep.ac.cn |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB066 | |
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| TUPAB067 | Studies of Beam Lifetime at HEPS | 1478 |
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| The electron storage ring's beam lifetime is determined by scattering of the electrons at the nucleus and the shell of the atoms of the residual gas (gas lifetime) and the scattering of electrons within a bunch (Touschek lifetime).Beam lifetime studies have been performed at the 6 GeV electron storage ring HEPS. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB067 | |
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| TUPAB068 | Design of the CPMU Vacuum System at the HEPS | 1482 |
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| The High Energy Photon Source (HEPS) is a 3rd generation synchrotron radiation light source. Its beam energy is 6 GeV and its emittance is less than 60 pm'rad, which can provide high brilliance hard X-rays to several tens of experimental stations. The Cryogenic Permanent Magnet Undulator (CPMU) is one of the key components to achieve the high brilliance. And its vacuum system is necessary to provide an ultra-high vacuum environment for CPMU operation. To design the CPMU vacuum system, we do experiments to test the outgassing rate, estimate the total gas load, calculate the effective pumping speed, design the baking program and select all pumps and other vacuum equipments. This paper presents the design specifications and the assemblage status of the CPMU vacuum system. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB068 | |
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| TUPAB070 | S-Band Accelerating Structure for High-Gradient Upgrade of TTX | 1485 |
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| Thomson scattering x-ray source is an indispensable scientific X-ray imaging tool in various research fields. The 3-meter S-band linac in Tsinghua Thomson scatter-ing X-ray source (TTX) has been running at an accelerat-ing gradient of 15 MV/m so far. The gradient will be upgraded to 30MV/m by replacing the old structure with a shorter linac. Detailed optimization of the RF design of the new S-band linac structure is presented in this paper. Finally, further research on energy upgrade with X-band structures are also discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB070 | |
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| TUPAB071 | Experimental Results on THz Superradiation From the Undulator in Tsinghua University Beamline | 1488 |
| SUSPSIK024 | use link to see paper's listing under its alternate paper code | |
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| In this paper, the first operation of a widely tunable 8-period undulator at terahertz (THz) frequency in Tsinghua University beamline was reported. Superradiate undulator radiation from sub-picosecond electron bunches compressed by chicane was observed. The measured radiation curve shows clearly that the radiation energy is proportional to the charge square, and the THz frequency can be changed from 0.4 THz to 10 THz with narrow-band spectrums. Our results demonstrate a high power and tunable coherent THz source, which could be useful for many applications in the future. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB071 | |
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| TUPAB074 | Measurements of Thermal Emittance for Cesium Telluride Photocathodes in an L-Band RF Gun | 1491 |
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| The thermal emittance is a major contributor to the final emittance of an electron beam in a photocathode RF gun. In this paper we present measurement results of thermal emittance for the cesium telluride photocathode at the Argonne Wakefield Accelerator (AWA) facility using the quadrupole scan method. Measurements of the thermal emittance vs. the laser spot size are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB074 | |
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| TUPAB075 | Compact High Energy Electron Radiography System Based on Permanent Magnet Quadrupole | 1494 |
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| High energy electron radiography(HEER) is a promising diagnostic method for High Energy Density Physics (HEDP) or Inertial Confinement Fusion (ICF) owing to its capability of picosecond-nanometer spatio-temporal resolution, and is cost-effective in the meantime. A Compact HEER (CHEER) system based on Permanent Magnet Quadrupoles (PMQ) instead of conventional electromagnetic quadrupole is proposed. Its lattice design and beam optics optimization is finished, and experiment is to be carried out on Tsinghua Thomson X-ray source (TTX) beamline after PMQs fabrication and installation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB075 | |
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| TUPAB076 | Design of an X-Band Photocathode for Tsinghua Thomson Scattering X-Ray Source | 1497 |
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| Compared with S-band and C-band accelerating structures, X-band structures can run at a higher accelerating gradient and are more compact in size. In order to obtain higher electron energy in a limited space, a new X-band photo-injector operating at 11.424GHz has been designed at the Accelerator Laboratory of Tsinghua University. The structural design of the X-band photo-cathode RF gun and the accelerating structures as well as the beam dynamics simulation are presented in this paper, followed by the optimization of the structure based on the dispersed optimization experiment method(DOE). The results show that the design satisfies the working requirements with a small space occupied and a high beam quality. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB076 | |
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| TUPAB077 | A Combined THz/X-ray Source Based on Brake-applied Velocity Bunching and Magnetic Compression | 1500 |
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Funding: Work supported by Chinese Universities Scientific Fund under Contracts WK2310000063 and WK2310000047 Ultrashort electron beam can be realized by the process of velocity bunching and magnetic compression. Velocity bunching technique is able to compress the bunch at relatively low energy, which presents peculiar challenges when approaching a very high current and a low transverse emittance in photoinjectors. A brake-applied velocity bunching scheme was proposed, so that the transverse emittance of the beam could be almost compensated even if the compression factor was extremely high. By adding a magnetic compressor, one could obtain a shorter beam and achieve the coherent synchrotron radiation in THz range. Meanwhile, when making the final compressed beam collide with the laser, one could acquire high energy X-ray pulses. This opens the possibility for some interesting combinations of pump-and-probe experiments. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB077 | |
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| TUPAB080 | Considerations of the HALS Injection System and a New Non-linear Kicker Design | 1503 |
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Funding: Work supported by The National Key Research and Development Program of China No. 2016YFA0402000(2016YFA0402002) Hefei Advanced Light Source (HALS) is a newly designed diffraction-limited synchrotron radiation source with an energy of 2GeV and a natural emittance of 18.4 pm. A project to build test facility of this new light source has been approved and funded in 2017. Among many key subsystems, the injection system of HALS is a very important one. Both on-axis swap out, on-axis longitudinal accumulation and off-axis single multipole kicker injection are considered. For on-axis fast kicker injection, basic parameters of the system are given. Layout of kickers and septums are presented. For off-axis multipole injection, non-linear kickers (NLK) draw much attention in recent years, various studies have been carried out in many laboratories. But it suffered from low injection efficiency and has not been used in routine operation. In this paper, we propose a new ferrite-loaded non-linear kicker (FNLK) and a prototype FNLK has been developed and tested. Compared to the air bus design of NLK, the FNLK not only improves the flat region of magnetic field but also reduce the error sensitivity of bars' position. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB080 | |
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| TUPAB082 | Research of L-Band Disk-Loaded Waveguides Travelling Wave Accelerating Structures for a High Power Linac | 1506 |
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| L-band Electron Accelerator is widely used for industrial irradiation. This paper describes a constant-impedance, disk-loaded structure operating on the 2Pi/3 mode. The design details of L-band travelling wave accelerating structures are presented. All RF parameters in metal disk-loaded waveguides and fields were calculated. The SUPERFISH code was used to design the bunching and accelerating cavities. At the same time, we also calculated the beam dynamics. Some model cavities have been fabricated and experimental studies were carried on. In this study, some valuable results were obtained, which can provide a beneficial datum for the design and manufacture of L-band travelling-wave accelerating structures of 50MeV LINAC. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB082 | |
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| TUPAB083 | Commissioning Experience and Beam Optimization for DCLS Linac | 1509 |
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| Dalian Coherent Light Source (DCLS), which will focus on the Physical Chemistry with time-resolved pump-probe experiments and EUV absorption spectroscopy techniques, is the first high gain FEL user facility in China. The 300MeV linac consists of a laser-driven rf-gun followed by 7 Sband accelerating tubes. A magnetic chicane is adopted to get the desired 300A peak current. After 5 months component installation, first photoelectrons were generated on 17 August 2016. In this paper, we give a summary of the commissioning experience and the beam parameters measurements. In addition, beam jitter sources are studied based on real machine performances. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB083 | |
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| TUPAB084 | Beam Stability Modeling and Jitter Control for SXFEL Linac | 1513 |
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| FEL operations foresee stringent requirements for the stability of the global linac output parameters and this requirement is particularly stringent for the successful operation of an externally seeded FEL. In order to understand the sensitivity of these parameters to jitters of various error sources along the SXFEL linac, studies have been performed based on analytical methods and tracking code simulations. Using the tolerance budget as guidance, beam jitter control techniques are discussed on the view of the beam dynamics. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB084 | |
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| TUPAB086 | Design Study of a High-Intensity, Low-Energy Electron Gun | 1517 |
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| An independently-tunable-cells thermionic RF gun (ITC-RF gun) is adopted in a compact FEL-THz facility due to its compactness, low-cost and high intensity. An electron gun is required to generate maximum beam current of 3.2 A at low energy of 15keV for the ITC-RF gun, which creates difficulties for the design of electron gun because of the strong space charge effect. A double-anode gridded gun structure is adopted that controls the beam current easily while maintains the energy dispersion less than 0.5%, with high perveance and high compression ratio. CST code has been used extensively for design optimization, which includes electrode shape, influences of grid, installation errors. A measurement scheme is also proposed for key parameters verification. Beam current, emittance and energy dispersion can be measured. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB086 | |
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| TUPAB087 | Undulator Commissioning Experience at PAL-XFEL | 1520 |
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| Pohang Accelerator Laboratory (PAL) is developing a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator while soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. In this report, the final measurement results of all the undulators, phase matching scheme, and the commissioning experiences will be summarized. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB087 | |
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| TUPAB088 | Wire Position System to Consistently Measure and Record the Location Change of Girders Following Ground Changes | 1523 |
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| Several parts that comprise the large scientific device should be installed and operated at the accurate three-dimensional location coordinates where they should be subjected to survey and alignment. The location of the aligned parts should not be changed in order to ensure that the electron beam parameters of PAL-XFEL remain stable and can be operated without any problems. As time goes by, however, the ground goes through uplift and subsidence, which consequently deforms building floors. The deformation of the ground and buildings changes the location of several devices including magnets and RF accelerator tubes, which eventually leads to the alignment errors. Once alignment errors occur with regard to these parts, the electron beam deviates from its course and beam parameters change accordingly. PAL-XFEL has installed the Hydrostatic Leveling System to measure and record the vertical change of buildings and ground consistently and systematically and the Wire Position System to measure the two dimensional changes of girders. This paper is designed to introduce the operating principle and design concept of WPS and discuss the current situation regarding installation and operation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB088 | |
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| TUPAB092 | MYRRHA Control System Development | 1527 |
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| The approach to the MYRRHA Control System (CS) development will be described. The effort, time and resources needed to develop the control systems are often underestimated by a significant factor. This brings unnecessary setbacks to the projects. Understanding CS requirements at an early machine conception stage is paramount for adequate CS design. Awareness of sheer project size and interdisciplinary complexity is imperative for successful project execution. In the first part of the paper the MYRRHA roadmap, milestones, status and its future needs will be presented with an emphasis on the phased approach leading to the 100 MeV program. The second part of the paper will give the status of the MYRRHA CS development within this phased approach. Best practices for coherent integration will be discussed. The CS should provide a flexible framework for the integration of devices. Interfaces and services need to be defined early in the integration process, and the number of different interfaces and platforms should be kept to a minimum. The implications of the choice of technologies and of SW development processes on the overall reliability and availability have to be established. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB092 | |
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| TUPAB093 | Race-Track Microtron with Pulse-to-Pulse Beam Energy Switch | 1530 |
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| A race-track microtron with a few beam orbits can be an alternative to a standard electron linear accelerator in a number of applications in which high beam power is not needed, like radiation therapy, industrial radiography or cargo inspection. In these cases the advantages of race-track microtrons are low RF power consumption, and consequently low cost of the RF system, and a possibility of beam energy switch in a wide range by extracting the beam from different orbits. In the present work we describe the concept of a race-track microtron with pulse-to-pulse beam energy switch in the range from 3 MeV to 9 MeV. Special attention is given to the optimization of the end magnets of a new type which provide both the accelerating structure bypass and vertical beam focusing. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB093 | |
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| TUPAB094 | Emittance Improvements in the MAX IV Photocathode Injector | 1533 |
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| The MAX IV injector design predicts a beam with 100 pC of charge and an emittance lower than 1 mm mrad. The photocathode pre-injector is based on the now close to standard 1.6-cell gun adapted to 2.9985 GHz, in combination with a Ti:Sapphire laser system. This system reaches the requirements of the injector operation for the SPF, but can be tuned beyond specifications to open up new operation modes. During 2016 and 2017 several aspects where investigated to improve the emittance from the current gun, the goal was to meet the SPF specifications. In this paper we report on the progress, discuss the steps taken leading to a final emittance of ~ 1 mm mrad and beyond. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB094 | |
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| TUPAB095 | The New MAX IV Gun Test Stand | 1537 |
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| The gun test stand from MAX-Lab has been upgraded and moved to a new facility at the MAX IV Laboratory. The new test stand will reuse parts of the equipment from the old test stand but a number of improvements to the setup are be made. In this paper we report on the design of the new gun test stand, research plans in the near future as well as planned and possible future research topics. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB095 | |
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| TUPAB096 | Pulse Shaping at the MAX IV Photoelectron Gun Laser | 1541 |
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| A motivation for the development of a versatile, programmable source of shaped picosecond pulses for use in photocathode electron gun preinjectors is presented. We present the experimental setup for arbitrary longitudinal pusle shaping of the MAX IV photocathode gun laser. The setup consists of a grating-based Fourier-domain shaper capable of stretching the pulses directly in the UV domain. Preliminary results are presented and discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB096 | |
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| TUPAB097 | MAXIV Photocathode Gun Laser System Specification and Diagnostics | 1544 |
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| The MAXIV injector has two guns - a thermionic used for ring injections, and a photocathode used for short pulse facility operation. A commercial Ti:sapphire laser from KMLabs drives the copper based photocathode gun. It has been running without major issues for more than 3 years. The laser delivers up to §I{500}{\textmu J} on the cathode at the third harmonic, §I{263}{nm}, via a vacuum laser transport system. To achieve the desired pulse duration of 2–§I10{ps} the laser pulses, originally ~§I{100}{fs} long, are stretched with a prism pair and the resulting §I{1.5}{ps} pulses stacked by a series of birefringent \textalpha -BBO crystals. Diagnostics consist of photodiodes, spectrometers, and cameras. Longitudinal pulse characterization is done with a cross correlator and a UV FROG. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB097 | |
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| TUPAB099 | Status of MAX IV Linac Beam Commissioning and Performance | 1547 |
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| The MAX IV linac is used both for full energy injection into two storage rings at 3 GeV and 1.5 GeV, and as a high brightness driver for a Short Pulse Facility (SPF). The linac has also been designed to handle the high demands of an FEL injector. The linac is now routinely injecting into the two storage rings, and commissioning work is focused towards delivering high brightness pulses to the SPF. In this paper we present results from characterisation of the linac in ring injection mode, as well as results from measurements of key parameters for the SPF such as bunch length and emittance. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB099 | |
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| TUPAB102 | Compact Electron RF Travelling Wave Gun Photo Injector | 1550 |
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| This paper reports on studies of a travelling wave photo gun as multipurpose device. The gun would be a cheap and compact alternative to thermionic guns with a bunching system or a standing wave photo injector gun. It allows one to reach much larger beam energies at the gun output. It can provide a beam with energy of up to 50 MeV and several hundred pC charge with low emittance and short bunch length. The laser system is a compact, industrial grade system with high MTBF and low maintenance cost. The gun design is based on the two-meter accelerating structures installed in SwissFEL, only the input coupler has been modified to accommodate the cathode. The gun is powered by a C-band (5.712 GHz) modulator-klystron system, identical to those of SwissFEL. The input coupler is a simple double feed coupler and it has been designed to increase the electric field enhancement at the cathode surface to improve the emittance. The first three accelerating cells have been readjusted in length in order to get the proper phase advance and synchronism with the beam. The remaining 110 accelerating cells and the output coupler follows the original design of the accelerating cavities for SwissFEL. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB102 | |
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| TUPAB103 | Orbit Correction With Path Length Compensation Based on Rf Frequency Adjusments in TPS | 1553 |
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| The 3 GeV Taiwan Photon Source has been routinely operated for public users since September 2016. Orbit reproducibility and stability are critical for the quality of user experiments. Ambient temperature variations and earth tides can cause a change in circumference, changing in turn the beam energy, and orbit drift. Therefore both, orbit correction and rf frequency adjustments are necessary to keep the ring circumference constant. A Fast Orbit Feedback (FOFB) system combined with rf frequency correction deduced from the fast corrector strengths is applied to the FOFB routine. The correlation between the measured frequency variation with ambient temperature and earth tides is also reported in this article. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB103 | |
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| TUPAB104 | Optimized Undulator to Generate Low Energy Photons From Medium to High Energy Accelerators | 1556 |
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| While emitting low energy photons from a medium or high energy storage ring, the on-axis heat load on the beam line optics can become a critical issue. In addition, the heat load in the bending magnet chamber, especially in the vertical and circular polarization mode of operation may cause some concern. In this work, we compare the heat loads for the APPLE-II and the Knot-APPLE, both optimized to emit 10 eV photons from the 3 GeV TPS. Under this constraint the heat load analysis, synchrotron radiation performance and features in various polarization modes are presented. Additional consideration is given to beam dynamics effect. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB104 | |
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| TUPAB105 | Field Measurement System for a Cryogenic Permanent Magnet Undulator in TPS | 1559 |
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| Short period in-vacuum, permanent magnet undulators operating at cryogenic temperatures are being developed worldwide to serve as brilliant and coherent light sources for medium energy storage rings. A hybrid cryogenic permanent magnet undulator (CU) with PrFeB magnets has now been designed and constructed at NSRRC [1]. To characterize the performance and to determine magnetic field errors after cool down poses some technical chal-lenges compared to room temperature undulators. A new system combining a Hall probe and a stretched wire has been designed to measure the field integrals, trajectory, phase errors, and K value under low temperature and vacuum conditions. Field measurements in this cryogenic undulator will be performed around 77 K as well as at room temperature, making temperature dependent calibra-tion of the Hall probes necessary. The main features and improvement of the measurement and calibration system are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB105 | |
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| TUPAB106 | Development of a Cryogenic Permanent Magnet Undulator for the TPS | 1562 |
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| Development of a cryogenic permanent magnet undu-lator (CPMU) at the Taiwan Photon Source (TPS) is the most recent activity toward a new light source for the Phase-II beamlines. A hybrid-type CPMU with a period length of 15 mm is under construction with PrFeB permanent-magnet materials. A maximum effective magnetic field of 1.77 T at a gap of 3 mm is expected when the magnets (PMs) are cooled down around 77 K. The features desired for the TPS CPMU are low-intrinsic-phase-error characteristics and high thermal budget for various kinds of heat loads. The design of the TPS CPMU is discussed in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB106 | |
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| TUPAB107 | Study of 60 Hz Beam Orbit Fluctuations in the Taiwan Photon Source | 1566 |
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| The Taiwan Photon Source is a 3 GeV synchrotron light source at NSRRC. To achieve high quality experimental results, it is important to minimize beam motion. During the installation of insertion devices and front-ends, the beam motion around 60 Hz became significant. The response matrix together with singular value decomposition was used to identify the transmitter of the superconducting radio frequency system as the source for the 60 Hz perturbations. This was subsequently corrected by rerouting the grounding of the mains in the transmitters. Yet, the 60Hz orbit fluctuation became even more serious after the next shutdown. A serious of experiments are performed to dig out that the beam was disturbed by the magnetic field from newly installed fan motors. Shielding the fans with mu-metal and increasing the distance between fan and beam pipe drastically reduced the leakage field and greatly increased beam stability. These errors could be prevented at the design stage in the ideal case. However, these errors happened finally and need to be dug out and eliminated. The method and experiences are summarized in this report. These will benefit others who facing the similar problems. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB107 | |
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| TUPAB108 | Upgrade of BTS Control System for the Taiwan Light Source | 1570 |
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| The Taiwan Light Source (TLS) is a third generation of synchrotron light source, and it has been operated since 1993. The TLS control system is a proprietary design. It was performed minor upgrade several times to avoid obsolete of some system components and keep up-to-date during last two decades. The control system of BTS (Booster-to-Storage ring) transport line includes control interfaces of power supplies, screen monitors, vacuum and temperature. The cPCI (CompactPCI) based EPICS IOC (Input Output Controller) has been adopted for renewing TLS BTS control system to replace the existed VME based ILC (Intelligent Local Controller) to be as an easy-to-maintain control environment. Moreover, each TLS control console supports not only the existing control software interfaces, but also the newly developed EPICS graphical user interfaces. Upgraded TLS BTS control system had been successfully commissioning in February 2017. Compare new system with old system, new system provides more functionality, fast response, and highly reliability. The efforts are summarized at this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB108 | |
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| TUPAB109 | Study on Injection with Pulsed Multipole Magnet for SPS Storage Ring | 1573 |
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| Pulsed multipole magnet (PM) has zero magnetic field at the centre, therefore it introduces no perturbation to the stored beam. It has been demonstrated that this injection scheme is able to minimise the oscillation of the stored beam, and thus make it suitable for top-up operation. To investigate the suitability of employing this injection method at Siam Photon Source, PM was modelled and optimised for best performance using particle tracking based method. This work presents injection optimisation process with PM considering various constraints such as position of injected beam, injection conditions, and effects of installed IDs. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB109 | |
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| TUPAB110 | Possible Limits of Plasma Linear Colliders | 1576 |
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| Plasma linear colliders have been proposed as next or next-next generation energy-frontier machines for high-energy physics. I investigate possible fundamental limits on energy and luminosity of such type of colliders, considering acceleration, multiple scattering off plasma ions, intrabeam scattering, bremsstrahlung, and betatron radiation. The question of energy efficiency will also be addressed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB110 | |
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| TUPAB111 | Energy Distribution and Work Function Measurements for Metal Photocathodes with Measured Levels of Surface Roughness | 1580 |
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Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453. The minimum achievable emittance in an electron accelerator depends strongly on the intrinsic emittance of the photocathode electron source which is measureable as the mean longitudinal and transverse energy spreads in the photoemitted electrons. Reducing emittance in an accelerator driving a Free Electron Laser (FEL) delivers significant reduction in the saturation length for an x-ray FEL, reducing machine cost and increasing x-ray beam brightness. There are many parameters which affect the intrinsic emittance of a photocathode. Surface roughness is a significant factor*, and consequently the development of techniques to manufacture low roughness photocathodes with optimum emission properties is a priority for the electron source community. In this work, we present transverse energy distribution and work function measurements made using our TESS facility** for electrons emitted from copper and molybdenum photocathodes with differing levels of measured surface roughness. * Proc. FEL '06, THPPH013, 583-586 ** Proc. FEL '13, TUPPS033, 290-293 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB111 | |
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| TUPAB114 | Design Study for a Plasma Undulator Experiment Using Capillary Based Discharge Plasma Source | 1584 |
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| A plasma undulator is formed when a short laser pulse is injected into plasma off-axis or at an angle that causes the centroid of this laser pulse to oscillate. Ponderomotively driven plasma wake will follow this centroid given that the product of the plasma wave number and the characteristic Rayleigh length of the laser is much larger than one. This oscillating transverse wakefield may work as an undulator forcing particles to follow sinusoidal trajectories and emit synchrotron radiation. In this paper, plans for an experiment are introduced and resulting radiation and injected beam characteristics are discussed. The aforementioned laser centroid oscillations are demonstrated using, EPOCH, a PIC code for laser-plasma interactions. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB114 | |
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| TUPAB115 | Impact of Electron Beam Heating on Insertion Devices at Diamond Light Source | 1588 |
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| Electron beam heating is a widely observed phenomenon at synchrotron facilities around the world, and has a large impact particularly on cryogenic insertion devices, but also on room temperature devices. This paper seeks to outline electron beam heating measurements taken at Diamond Light Source (DLS) and produces an empirical heat load relationship that matches the form of heating through the anomalous skin effect, although gives an order of magnitude higher than that predicted by theory. Resistive wall heating should vary inversely with the gap of installed cryogenic and permanent magnet insertion devices. This is also examined in this paper and the results presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB115 | |
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| TUPAB116 | Insertion Devices at Diamond Light Source: A Retrospective Plus Future Developments | 1592 |
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| 2017 marks the tenth year of Diamond operation, during which time all insertion device straights have been filled. Diamond Light Source is a third generation, 3 GeV facility that boasts 29 installed insertion devices. Most room temperature devices have been designed, manufactured and measured in-house, and progress has been made in structure design and control systems to ensure new devices continue to meet stringent requirements placed upon them. The ‘completion' of the storage ring is not, however, the end of activity for the ID group at Diamond, as beamlines map out potential upgrade paths to Cryogenic Permanent Magnet Undulators (CPMUs) and SuperConducting Undulators (SCUs). This paper traces the progress of ID design at Diamond, and maps out future projects such as the upgrade to CPMUs and the challenges of designing a fixed-gap mini-wiggler to replace a sextupole in the main storage ring lattice. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB116 | |
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| TUPAB117 | Conceptual Design of a Novel SCAPE Undulator | 1596 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. A concept of a novel SuperConducting Arbitrarily Polarizing Emitter, or SCAPE, has recently been suggested at the Advanced Photon Source. It consists of two pairs - both vertical and horizontal - of superconducting planar magnets assembled around a beam vacuum chamber. Such a device will be capable of generating either planar or circularly polarized photons, depending on which pair of magnets is energized. The magnetic simulation suggests that due to the employment of superconducting technology, the expected magnetic field is higher than that of the APPLE undulators. The SCAPE undulators could be useful for the fourth generation of storage rings with a multi-bend achromat lattice, as well as for the FELs where utilization of round beam vacuum chambers becomes possible. The results of magnetic modelling, as well as the design concept of the SCAPE, are presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB117 | |
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| TUPAB121 | Bench Measurements and Beam Tests of a Prototype Stripline Kicker for Swap-Out Injection in the ALS-U | 1599 |
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Funding: Work supported by the the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The ALS upgrade to a diffraction-limited light source (ALS-U Project) relies on a swap-out injection scheme, where the circulating current is maintained constant by injecting on-axis fresh bunch trains, replacing old trains, which are simultaneously extracted. The realization of a stripline kicker to perform such an operation presents several challenges in terms of optimal matching to the pulser, contributions to the beam coupling impedance, and dissipation of the power deposited by the stored beam. To test our design choices for the ALS-U kicker, we have built and installed on the ALS a kicker with characteristics similar to the design for the ALS-U, as the more challenging aspects of the project are concerned. In particular, while the small distance between stripline electrodes reduces the required pulser voltage, the extreme proximity of the circulating beam requires a careful evaluation of the interaction between beam and kicker. In this paper we present the first measurements with beam, after the test kicker installation, together with the results of bench measurements performed on a cold model and computer simulations. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB121 | |
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| TUPAB122 | Engineering Optimization of The Support Structure and Drive System for the LCLS-II Soft X-Ray Undulator Segments | 1602 |
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Funding: Work supported by the Director, O'ce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Linear Coherent Light Source II (LCLS-II) project, an upgrade to the free-electron laser facility at SLAC, is replacing the undulator system from a fixed gap to a variable gap system to enable tuning of the photon energy range. The LCLS-II project will include a soft x-ray (SXR) beam line and a hard x-ray (HXR) beam line. The SXR undulators are conventional vertical-gap horizontally-polarizing devices while the HXR undulators are novel horizontal-gap vertically-polarizing devices. This paper describes in detail the development of the SXR mechanical support structure and drive system. The effort has included extensive analysis of the various components to ensure that the undulators will perform within the design specifications. Engineering simulations undertaken and experiments performed to validate the computer modeling are presented together with measurement results from prototype and pre-production undulators. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB122 | |
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| TUPAB123 | Hard X-Ray and Soft X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project | 1605 |
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Funding: Work supported by the Director Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Stanford Linear Accelerator Laboratory is currently constructing the Linear Coherent Light Source II (LCLS-II), a free-electron laser (FEL) which will deliver x-rays at an energy range between 0.2 keV and 5 keV at high repetition rate of up to ~1 MHz using a new 4 GeV superconducting RF linac, and at and an energy range between 1 keV and 25 keV when driven by an existing copper linac at up to 120 Hz repetition rate. To cover the full photon energy range, LCLS-II includes two variable-gap, hybrid-permanent-magnet undulator lines: A soft x-ray undulator (SXR) line with 21 undulator segments optimized for a photon energy range from 0.2 keV to 1.3 keV plus a hard x-ray undulator (HXR) line with 32 undulator segments designed for a photon energy range from 1.0 keV to 25.0 keV. Lawrence Berkeley National Laboratory is responsible for fabricating the 53 undulator segments. This paper summarizes the main parameters and design attributes for both LCLS-II undulator segment types. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB123 | |
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| TUPAB124 | Development of the Manufacturing and QA Processes for the Magnetic Modules of the LCLS-II Soft X-Ray Undulators | 1609 |
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Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. A new free electron laser being built at SLAC National Accelerator Laboratory, the Linear Coherent Light Source II (LCLS-II), will use 21 soft x-ray undulators (SXR) and 32 hard x-ray undulators (HGVPU). Lawrence Berkeley National Laboratory (LBNL) is responsible for the design and manufacturing of all variable-gap, hybrid permanent-magnet undulators. The physics requirements for the undulators specify a longitudinal pole misalignment maximum rms error of 25 μm and a vertical pole misalignment maximum error of 50 μm. In addition, magnet positioning critically influences the gap-dependent field properties due to saturation effects at the smallest operational gaps. This paper discusses the manufacturing and QA methods developed to carefully control the longitudinal and vertical pole and magnet positions during undulator production. Inspection results are discussed based on data gathered during construction of a prototype as well as pre-production soft x-ray undulator. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB124 | |
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| TUPAB125 | Magnetic Field Measurements at LBNL on Soft X-Ray and Hard X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project | 1612 |
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Funding: Work supported by the Director, O'ce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Stanford Linear Accelerator Laboratory is currently constructing the Linear Coherent Light Source II (LCLS-II), a FEL which will deliver x-rays at an energy range 0.2-5 keV at high repetition rate of up to 1 MHz using a new 4 GeV superconducting linac, and at an energy range 1-25 keV when using the existing copper linac at up to 120 Hz. To cover the full photon energy range, LCLS-II includes two variable-gap, hybrid-type permanent magnet undulator lines: A soft x-ray undulator (SXR) line with 21 undulator segments for the photon energy range 0.2-1.3 keV plus a hard x-ray undulator (HXR) line with 32 undulator segments designed for a photon energy range from 1-5 keV when using the superconducting linac. The HXR line is also designed to support 25 keV and higher photon energies when using the existing copper linac. Lawrence Berkeley National Laboratory (LBNL) is responsible for fabricating the undulators and tuning 23 of the HXR undulators. This paper summarizes the magnetic field measurements carried out on the pre-production undulators and describes the plans at LBNL for the magnetic measurements on the HXR undulators in series production. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB125 | |
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| TUPAB126 | Multi-objective Genetic Optimization of Single Shot Ultrafast Electron Diffraction Beamlines | 1615 |
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| We present the results of multi-objective genetic algorithm optimizations of two single-shot ultrafast electron diffraction (UED) beam lines. The first is based on a 225 kV dc gun featuring a novel cryocooled photocathode system and buncher cavity. The second uses a 100 MV/m 1.6 cell normal conducting rf (NCRF) gun, as well as a 9 cell 2 Pi/3 bunching cavity placed between two solenoids. Optimizations of the transverse projected emittance as a function of bunch charge are presented and discussed in terms of the scaling laws derived in the charge saturation limit. Additionally, optimization of the transverse coherence length as a function of final rms bunch length at the sample location have been performed. These results demonstrate the viability of the approaches taken for both beamlines studied as well as the use of using genetic algorithms in the design and operation of UED beamlines. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB126 | |
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| TUPAB127 | A Cryogenically Cooled High Voltage DC Photogun | 1618 |
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| A DC high voltage photogun with cryogenically cooling of the electrode has been newly built at Cornell University. This gun is designed to provide a DC high voltage and a photocathode in this gun can be cooled down to a cryogenic temperature. A photocathode puck design from INFN/DESY/LBNL is used, so we will be able to run a photocathode from other institutions as well. This paper describes the mechanical, thermal, and high voltage design of this gun. We also present data of high voltage conditioning and the thermal profile along the electrode structure. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB127 | |
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| TUPAB128 | Single Photoemitter Tips in a DC Gun: Limiting Aberration-induced Emittance | 1622 |
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| Ultrafast electron diffraction (UED) offers unique advantages over x-ray diffraction, like stronger scattering cross-section, versatility in sample types and ability to offer smaller apparatus foot print. There is a growing need to increase brightness of electron beams especially for single-shot UED applications. We explore the utilization of field enhancement from a micron-scale single tip inside a DC gun to obtain brighter sub-pC electron beams using a nominal cathode electric field of several MV/m. The additional field enhancement can place moderate voltage sources on par with the highest gradient devices and allow improved performance presently not possible in the existing photoemission guns. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB128 | |
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| TUPAB129 | Optimization of Beam Dynamics for an S-Band Ultra-High Gradient Photoinjector | 1626 |
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Funding: Work Supported by DOE/SU Contract DE-AC02-76-SF00515, US NSF Award PHY-1549132, the Center for Bright Beams, and DOE SCGSR Fellowship. Travel to IPAC'17 supported by the Div. of Phys. of the US NSF (Accel. Sci. Prog.) and the Div. of Beam Phys. of the APS New electron sources with improved brightness are desired to enhance the capabilities of FELs, making them more compact and fully coherent. Improvements in electron source brightness can be achieved by increasing electric fields on the cathode of photo-emitted electron guns. Recent developments in pulsed RF accelerator structures show that very high gradient fields can be sustained with low breakdown rates by operating at cryo-temperatures, which when applied to photoguns will lead to a large increase in the electron beam brightness. In particular, our simulations show that when operating with a peak gradient field of 240 MV/m on the cathode of an S-band, electron beam brightness of 80~nC/(mm· mrad)2/mm can be achieved with 100~pC bunches. In this paper, we present the design and optimization of an 1.x cell S-Band RF photoinjector, where the x varies from 4-6. The optimization in brightness has been obtained by using a multi-objective genetic algorithm on the solutions calculated with the ASTRA code. We calculate the optimum length of the rf gun, position of accelerating structure, and laser pulse dimensions for a variety of charges. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB129 | |
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| TUPAB130 | Status of the LCLS-II Superconducting RF Linac | 1630 |
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| The LCLS-II project requires the assembly and installation of 37 cryomodules in order to deliver a 4 GeV electron beam to the undulators to produce both soft and hard x-ray pulses at a repetition rate up to 1 MHz. All of the cryomodules will operate in continuous wave mode, with 35 operating at 1.3 GHz for acceleration and 2 operating at 3.9 GHz to linearize the longitudinal beam profile. The assembly and testing of the 1.3 GHz cryomodules is well underway and the 3.9 GHz cryomodule work is entering into the pre-cryomodule testing and component validation phase. Both of these efforts will be reported on in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB130 | |
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| TUPAB132 | A Novel Dual-Mode Dual-Frequency Linac Design | 1634 |
| SUSPSIK123 | use link to see paper's listing under its alternate paper code | |
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| In this paper we will present a new type of accelerator structure that operates simultaneously at two accelerating modes with two frequencies. The frequencies are not harmonically related, but rather have a common sub-harmonic. This design will use a recently developed parallel-feeding network that feeds every cavity cell independently using a distributed feeding network. This will overcome many of the practical complications of coupled cell structure. We will provide the theoretical background for our dual-mode design as well as present our optimized design that operates at C and X bands simultaneously and provides enhanced gradient and efficiency compared to single-mode designs. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB132 | |
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| TUPAB133 | Perturbation Analysis for Beam Trajectories. Determining Local Shielding Containment for LCLS-II | 1637 |
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Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515 Containment of beam losses by halo and momentum/energy collimators is a well-established practice for normal operation of particle accelerators where tracking codes are applied. However, for exceptional events, such as magnet power failures, severe lattice mis-match, etc., ad-hoc analytical approaches are typically applied. Oftentimes those simplified methods are not automatic; they don't define the full phase-space of mis-steered trajectories and cannot keep up with beam-line upgrades. Moreover, there may exist a disconnect between the teams analyzing consequences of errant beams and those involved in beam-line design. With electron beams exceeding 100 kW, design of LCLS-II at SLAC National Accelerator Laboratory required exhaustive beam-containment studies to avoid potential destruction of components and excessive dose rates. The geometry of the different beam-lines and the nominal optics was built with MadFLUKA [1], and FLUKA [2] Monte Carlo code along with perturbations to magnetic fields was used to inspect failures compatible with beam operations and hardware settings. Consequences of mis-steered rays and the respective mitigations were directly analyzed with FLUKA. [1] M. Santana-Leitner et al., MadFLUKA Beam Line 3D Builder. Simulation of Beam Loss Propagation in Accelerators, IPAC14 proceedings, MOPME040 [2] A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014) |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB133 | |
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| TUPAB134 | Life Expectancy Studies for LCLS-II Permanent Magnet Undulators | 1640 |
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Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515 LCLSII at SLAC National Accelerator Laboratory will add a 4 GeV superconducting Linac to the existing 20 GeV Cu structure. Electron beams from the two sources going through two new variable gap undulators [*] will produce FEL ranging 200-5000 keV at up to 929 kHz, also reaching 20 keV at low frequency. Such performance will be achieved by hybrid design undulators with NdFeB magnet blocks until radiation-induced demagnetization exceeds 0.01%. This is a sizable challenge, as LCLS-II will carry 120 kW beams in both its soft (SXR) and hard (HXR) beam-lines. Even small fractional losses could result excessive if too frequent or not detected and aborted fast enough. A model of SXR undulator was set for FLUKA [**] radiation transport, including segments, phase-shifters, quadrupoles, RFBPM, stands/pillars and interconnecting parts. Components were installed according to MAD files, which were also used to code the optics. Beam-loss/shower propagation was simulated for beam mis-steering, interception at wire scanners and gas-bremsstrahlung interactions. Results help set limits on shut-off times, uniform loss levels and wire scanner use, and to define placement for beam loss monitors. * M. Leitner et al, Hard X-Ray and Soft X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project, these proceedings ** A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014) |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB134 | |
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| TUPAB135 | A 1.75 mm Period RF-Driven Undulator | 1643 |
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Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437. To reduce the linac energy, and hence the size required for a Free Electron Laser radiating at a given wavelength, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling* the electromagnetic fields while maintaining over-moded features for power handling capability and electron beam wakefield mitigation. In this work, we present a novel end section of an RF undulator at 91.392 GHz. To confine the fields inside the undulator, a corrugated waveguide is connected through a matching section to a linear taper and a mirror. After the mirror, a Bragg reflector and a matching section are used to reflect back all the fields leaking out of the mirror opening. * F. Toufexis, J. Neilson, and S.G. Tantawi, Coupling and Polarization Control in a mm-wave Undulator, these proceedings. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB135 | |
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| TUPAB136 | Coupling and Polarization Control in a mm-wave Undulator | 1647 |
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Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437. To reduce the linac energy required for an FEL radiating at a given wavelength, and hence its size, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling the electromagnetic fields while maintaining overmoded features for power handling capability and electron beam wakefield mitigation. We have designed a mm-wave undulator cavity at 91.392 GHz*. This undulator requires approximately 1.4 MW for sub-microsecond pulses to generate an equivalent K value of 0.1. Transferring such amounts of power in mm-wave frequencies requires overmoded corrugated waveguides, and coupling through irises creates excessive pulsed heating. We have designed a novel mode launcher that allows coupling power from a highly overmoded corrugated waveguide to the undulator through the beam pipe. Additionally, this mode launcher can be used along with grating polarizers to control the polarization of the produced light. * F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB136 | |
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| TUPAB137 | Evaluation of FEL Performance with a Longer Injector Drive Laser Pulse at the LCLS | 1651 |
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Funding: US DOE under grant No. DE-AC02-76SF00515. It is known that the X-ray Free Electron Laser (FEL) performance strongly depends on the beam emittance and peak current. Lengthening injector laser pulse can improve the injector emittance but the injector peak current is notably compromised, in comparison to nominal laser pulse. With this longer laser pulse, a stronger bunch compression through downstream bunch compressors is thus required to keep same final peak current as the nominal laser pulse mode. This process may cause stronger micro-bunching effect. At the LCLS, we perform preliminary experiments with doubling injector laser pulse. In this paper, we present the experimental results of the injector emittance, microbunching effects and FEL performance with the longer drive laser pulse. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB137 | |
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| TUPAB138 | LCLS-II Injector Physics Design and Beam Tuning | 1655 |
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Funding: US DOE under grant No. DE-AC02-76SF00515. LCLS-II is a proposed high-repetition rate (up to 1 MHz) Free Electron Laser X-ray light source, based on a CW normal conducting (NC) RF gun injector and a CW 4-GeV superconducting (SC) linac, under construction at SLAC. LCLS-II CW injector consists of a 186 MHz NC RF gun, two solenoids, two BPMs, 1.3 GHz NC RF buncher, and 1.3 GHz SC standard 8-cavity cryomodule to boost the beam energy >95 MeV, and 5 pairs of steering correctors. In this paper, we describe the injector physics design including the beam optimization and low level RF requirement, and also present the studies of beam performance with any one SC cavity failure. The beam tuning procedure is developed with the correctors and two BPMs. The simulations of the phase/amplitude calibration for the gun and buncher and beam based alignment for cathode, two solenoids, and RF buncher with the limited diagnostics, will be presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB138 | |
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| TUPAB139 | Design of an X-Band Photoinjector Operating at 1 kHz | 1659 |
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| A kHz repetition rate RF photoinjector with novel features has been designed for the ASU CXLS project. The photoinjector consists of a 9.3 GHz 4.5 cell standing-wave RF cavity that is constructed from 2 halves. The halves are brazed together, with the braze joint bisecting the irises and cells, greatly simplifying its construction. The cathode is brazed onto this assembly. RF power is coupled into the cavity through inline circular waveguide using a demountable TM01 mode launcher. The mode launcher feeds the power through 4 ports distributed azimuthally to eliminate both dipole and quadrupole field distortions. The brazed-in cathode and absence of complex power coupler result in a very inexpensive yet high performance device. The clean design allows the RF cavity to sit entirely within the solenoid assembly. The cathode gradient is 120 MV/m at 3 MW of input power. The cathode cell is just 0.17 RF wavelength so that laser arrival phase for peak acceleration is 70 degrees from zero crossing resulting in exit energy of 4 MeV. The photoinjector will operate with 1μs pulses at 1 kHz, dissipating 3 kW of heat. Details of the design are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB139 | |
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| TUPAB140 | Analysis and Correction of in-Vacuum Undulator Misalignment Effects in a Storage Ring Synchrotron Radiation Source | 1663 |
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Funding: Work was partially supported by US DOE SBIR grants DE-SC0006284 and DE-SC0011237. In-vacuum undulators (IVU) are currently very extensively used at different light source facilities, and in particular in medium-energy storage rings, for the production of high-brightness and high-flux hard X-rays. The relatively small (~5 mm or less) vertical magnetic gaps used in these planar undulators make them, however, rather sensitive to the accuracy of alignment of magnet arrays with respect to electron orbit in the vertical plane. Based on results of commissioning of a number of IVUs at hard X-ray beamlines of NSLS-II, their eventual misalignment with respect to the electron orbit was found to be among frequent reasons of spectral underperformance of the beamlines. We will present results of simulations of different IVU misalignment effects on magnetic fields seen by electron beam and on the emitted undulator radiation spectra. The simulations show e.g. that an impact of angular misalignment of an IVU on the radiation spectrum can be minimized if the IVU elevation is selected to make the electron orbit to pass through the IVU magnetic center. Experimental results of spectrum-based alignment of IVUs at hard X-ray beamlines will be presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB140 | |
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| TUPAB142 | Tracking of Electrons Created at Wrong RF Phases in the RHIC Low Energy Cooler | 1666 |
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Funding: Work supported by the US Department of Energy under contract No. DE-SC0012704. The RHIC Low Energy Cooler will be based on a 400 keV DC electron gun with a photo-cathode and a 2.2 MeV SRF booster cavity. Electron that leave the cathode at the wrong time may be decelerated and turned around in the booster and return to the cathode with energies up to 1 MeV. On the way back these electron will encounter the defocussing EM fields up to nine following electron bunches. Such electrons may be created for various reasons: Cosmic rays, stray laser light including a catastrophic failure of the laser timing system or as secondaries of returning electrons. We present tracking results from the GPT program* and discuss the consequences for the machine protection system. * www.pulsar.nl |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB142 | |
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| TUPAB143 | Dependence of LEReC Beam Energy Spread on Photocathode Laser Modulation | 1669 |
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| Present requirements to the photocathode DC gun of the low energy RHIC electron cooling (LEReC) project is to produce 100 ps long bunch of electrons with 130 pC charge. The laser pulse of required length will be produced with the stacking of multiple few picosecond long sub-pulses. Depending on the choice of the laser sub-pulse length and on the relative delay between these sub-pulses one can obtain laser pulse with various longitudinal intensity modulations. The longitudinal modulation of laser intensity creates longitudinal modulation of electron bunch charge. Such modulation is known to cause the growth of e-beam uncorrelated energy spread in photoinjectors - the effect we would like to avoid. In this paper we estimate growth of e-beam energy spread due to its initial density modulation and set requirements to the maximum allowable depth of longitudinal modulation of photocathode laser intensity. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB143 | |
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| TUPAB145 | Alignment of Electron and Ion Beam Trajectories in Non-Magnetized Electron Cooler | 1672 |
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| The cooling section (CS) of the low energy RHIC electron cooler (LEReC) consists of two 20 m long parts each containing six solenoids with trajectory correctors placed inside the solenoids and the BPMs located downstream of each solenoid. The solenoids are used to minimize the scalloping of the electron beam envelope. To obtain the cooling it is required to keep the overall RMS electron angles in the cooling section below 100 urad. Possible mechanical misalignment, such as shift and inclination of the CS solenoids can cause an unacceptable misalignment of the e-beam trajectory with respect to the ideal trajectory set by ions. Therefore, it is critical to perform a beam based alignment of the CS solenoids. In this paper we suggest a procedure for such an alignment. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB145 | |
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| TUPAB146 | Vibration Measurements of Super-Conducting Undulator at SSRF | 1675 |
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Funding: Work supported by the National Natural Science Foundation of China (Grant No. 11405255) A Super-Conducting Undulator (SCU) is being built at SSRF. Mechanical stability of SCU is critical to beam stability since the central load is supported by special strings in SCU and the vibration of load will cause directly the vibration of beam. In this paper, vibration results of several key components including central load, cold head, frame support, etc, are studied under different working mode of compressors. The ground vibrations at different distances are compared to get the influence of compressors to SCU. Useful suggestions and possible measures are described to mitigate the vibration and improve SCU stability. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB146 | |
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| TUPAB147 | The Final RF-Design of the 36 MHz-HSI-RFQ-Upgrade at GSI | 1678 |
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| In Darmstadt/Germany the existing accelerator cite GSI is expanding to one of the biggest joint research projects worldwide: FAIR, a new antiproton and ion research facility with so far unmatched intensities and quality. The existing accelerators will be used as pre-accelerators and therefor need to be upgraded to fulfill the requirements with respect for intensity and beam quality. In a first step the 9.2 m long 36 MHz-HSI-RFQ for high current beams will obtain new electrodes to reach the specific frequency and to allow a higher electric strength. Therefor several simulations with CST MWS have been done. The final RF-design will be presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB147 | |
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| TUPAB148 | Investigation of a Splitring-RFQ for High Current Ion Beams at Low Frequencies | 1680 |
| SUSPSIK042 | use link to see paper's listing under its alternate paper code | |
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| For hadron linacs RFQs are the first stage of acceleration. To reach high intensities a new Splitring-RFQ is investigated. Not only a high current and high beam quality/brilliance should be achieved, also a good tuning flexibility and comfort for maintenance are part of the study. It will consist of two stages with 27 MHz and 54 MHz to accelerate ions with an A/q of 60 up to energies of 200 keV/u. Therefor RF simulations with CST MWS were done to study the quality factor and the shunt impedance as well as tuning possibilities. First results and the status of the project will be presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB148 | |
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