Paper | Title | Page |
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THPMF001 | Beam Dynamics Studies for Beam Focusing and Solenoid Alignment at SINBAD | 4026 |
SUSPF020 | use link to see paper's listing under its alternate paper code | |
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SINBAD (Short INnovative Bunches and Accelerators at DESY) facility under construction at DESY plans to host several experiments for the production of ultra-short bunches and will be a test facility for high-gradient compact novel acceleration techniques. The ARES (Accelerator Research Experiment at SINBAD) linac is foreseen to produce ultra-short bunches to be injected e.g. into Novel Dielectric Laser Acceleration structures or Laser Wake-Field Acceleration experiments. The work presented in this paper is based on optimization of the focusing system consisting of solenoids for the ARES, which have been studied earlier in detail but is revisited for updated beamline. Moreover tolerances for the possible misalignment of solenoids are presented investigating the effect on the beam properties during the gun commissioning.
* J. Zhu, R. Assmann, U. Dorda, B. Marchetti, "Matching sub-fs electron bunches for laser-driven plasma acceleration at SINBAD", Nucl. Instrum. Methods Phys. Res., Sect. A 829, 229 (2016) |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF001 | |
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THPMF002 | Studies for Injection with a Pulsed Multipole Kicker at ALBA | 4030 |
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Injection into the ALBA storage ring presently uses a conventional local injection bump with four dipole kickers. However, following the promising results of the first tests with single multipole kicker injection at other light sources, studies to implement this new injection scheme have been started for ALBA. Two possible designs for the kicker have been considered: a pure octupole and a non-linear magnet similar to the BESSY type. A comparison between the expected performances of the two kicker designs has been carried out in terms of injection efficiency and transparency for the users. This paper summarises the beam dynamics results from multi-particle tracking simulations and the proposed kicker magnet design. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF002 | |
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THPMF005 | Evaluating the Impact of Diamond-II Possible Lattices on Beamlines | 4033 |
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At Diamond Light Source we are considering an upgrade of the machine aimed at significantly reduced emittance (la factor 20), that follows a worldwide trend in similar synchrotron radiation sources. An important aspect in the design of the upgrade is the optimization of the photon beam properties, such as flux, brilliance, spot size, divergence or coherence of the new sources and how these are translated into requirements on the electron beam and on the machine design. We present a study based on a combination of accelerator physics tracking codes (AT, elegant) and of radiation codes (SPECTRA, SRW, SHADOW), with the aim at bridging the gap between machine and beamlines. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF005 | |
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THPMF006 | Control of the Nonlinear Dynamics for Medium Energy Synchrotron Light Sources | 4037 |
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MAX-IV has introduced a paradigm shift in the design philosophy for the "Engineering-Science" in the quest for a diffraction limited Synchrotron Light Source. Similarly, SLS-2 has introduced a systematic method for controlling the Linear Optics beyond some 20 years of TME inspired paper designs; by introducing Reverse Bends to disentangle dispersion and focusing, which enables Longitudinal Gradient Bends to efficiently reduce the emittance. Similarly, we outline a systematic approach for how to control the Nonlinear Dynamics for these systems, by a method that was pioneered for the conceptual design of the Swiss Light Source in the mid-1990s; subsequently benchmarked and validated by the commissioning. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF006 | |
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THPMF007 | Commissioning of the Hybrid Superconducting/Normal Conducting RF System in the Diamond Storage Ring | 4042 |
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Two 500 MHz HOM damped normal conducting cavities have been installed in the Diamond storage ring to ensure continuity of operation of Diamond in the event of a failure of one of the two existing superconducting cavities. Following receipt from the manufacturer, the cavities were incorporated into an assembly including vacuum pumping, cooling and interlocked diagnostics and then tested for vacuum integrity and RF performance. Both cavities were then conditioned up to high power in Diamond's RF test facility before being installed in the storage ring in August and November 2017. Conditioning and operation has been carried out using a new digital LLRF system. Results of acceptance tests and commissioning with power and beam are presented, together with the current status of the hybrid RF system and options for further improvement of the system in the near future. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF007 | |
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THPMF008 | Conceptual Design of an Accumulator Ring for the Diamond II Upgrade | 4046 |
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Diamond Light Source is in the process of reviewing several lattice options for a potential storage ring upgrade. As part of these studies, it has become clear that a substantial reduction in emittance can be achieved by adopting an on-axis injection scheme, thereby relaxing the constraints on the dynamic aperture. In order to achieve the necessary injected bunch properties for this to be viable, a new accumulator ring would be needed. In this paper we review the requirements placed on the accumulator ring design, describe the lattice development process and analyse the performance of the initial, conceptual design. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF008 | |
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THPMF009 | Lattice Options for DIAMOND-II | 4050 |
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Funding: Diamond Light Source Ltd Generalized MBA (Multi-Bend-Achromat) Chasman-Green type lattices, with a low-dispersion mid-straight, have been studied and refined by pursuing a generalized Higher Order Achromat to control the non-linear dynamics to obtain a robust design. New candidate lattice have been produced aiming for a horizontal emittance of 150 pm×rad for off-axis injection and 75 pm×rad for on-axis, the latter making use of reverse bends. The results of these studies and evaluations have been summarized in this paper. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF009 | |
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THPMF010 | Status of Elettra and Future Upgrades | 4054 |
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The operational status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with the possible future upgrades especially concerning the next ultra low emittance light source Elettra 2.0 | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF010 | |
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THPMF011 | Femtosecond Laser Ablation for Manufacturing of X-ray Lenses and Phase Corrector Plates | 4057 |
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Funding: DOE SBIR The next generation light sources such as diffraction limited storage rings and high repetition rate free electron lasers (FELs) will generate X-ray beams with significantly increased peak and average brilliance. These future facilities will require X-ray optical components capable of handling large instantaneous and average power densities while tailoring the properties of the X-ray beams for a variety of scientific experiments. In this paper we report on research and development of a single crystal diamond compound refractive lens. Diamond lenses presented here are fabricated by fs-laser cutting and subsequent polishing. Grating interferometry measurement data of these lenses had been performed at the Advanced Photon Source (Argonne). Besides the lenses, we fabricated and tested several phase correction plates, a refractive elements designed to correct for cumulative X-ray beam aberrations. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF011 | |
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THPMF012 | Tapered Flying Radiofrequency Undulator | 4059 |
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Funding: DOE SBIR DE-SC0017145 The x-ray free electron laser (x-FEL) efficiency, measured as a fraction of the electron beam power converted into light, is typically below 0.1% for most of the x-FEL facilities presently in operation. Undulator tapering techniques can be used to improve the conversion efficiency by 1-2 orders of magnitude. However at present there are no robust tapered undulator x-FEL schemes operating at 10% efficiency. In this paper we report on the development of tapered radiofrequency (RF) undulator. An RF undulator is a microwave waveguide in which strong RF field is excited that interacts with a charged particle beam forcing it to radiate coherent x-rays while undergoing a wiggling motion. RF undulators are attractive for use in x-FELs due to their large beam aperture and a short undulator period. Strongly tapered RF undulators (with tapering of a wavelength) due to non-resonant trapping regime allow keeping high overall XFEL efficiency being driven by laser plasma accelerated beams usually having high enough current but large energy spread (1-10%). |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF012 | |
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THPMF013 | The Stripline Kicker Prototype for the CLIC Damping Rings at ALBA: Installation, Commissioning and Beam Characterisation | 4062 |
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The extraction system for the CLIC Damping Rings has very tight specifications. Therefore a full characterisation of the behaviour of the stripline kicker under conditions as close as possible to the expected working conditions will be very valuable. To that end the CLIC stripline has been installed in the ALBA Synchrotron Light Source and has been characterised with beam. Prior to its installation, the effect of the stripline kicker on the machine impedance has been assessed. The installation has required the design of an absorber to screen the stripline from synchrotron radiation and additional BPMs have been installed for a better kick angle determination. The commissioning of the stripline with beam has been performed following closely beam parameters, pressure and temperature. The studies with beam include the determination of the longitudinal and transverse impedance of the kicker*, the field homogeneity when excited with a dc field and the field ripple when pulsed. This contribution reports on the first experience with the stripline kicker for the CLIC DR in the ALBA storage ring and presents the results of the initial beam characterisation.
* M. Carla et al., "Beam based impedance measurements of the CLIC stripline at ALBA", Proc. of IPAC'2017. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF013 | |
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THPMF014 | First Experiments at the CLEAR User Facility | 4066 |
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The new "CERN Linear Electron Accelerator for Research" (CLEAR) facility at CERN started its operation in fall 2017. CLEAR results from the conversion of the CALIFES beam line of the former CLIC Test Facility (CTF3) into a new testbed for general accelerator R&D and component studies for existing and possible future accelerator applications. CLEAR can provide a stable and reliable electron beam from 60 to 220 MeV in single or multi bunch configuration at 1.5 GHz. The experimental program includes studies for high gradient acceleration methods, e.g. for CLIC X-band and plasma technology, prototyping and validation of accelerator components, e.g. for the HL-LHC upgrade, and irradiation test capabilities for characterization of electronic components and for medical applications. An overview of the facility capabilities and a summary of the latest results will be presented. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF014 | |
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THPMF015 | Lifetime and Beam Losses Studies of Partially Strip Ions in the SPS (129Xe39+) | 4070 |
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The CERN multipurpose Gamma Factory proposal relies on using Partially Stripped Ion (PSI) beams, instead of electron beams, as the drivers of its light source. If such beams could be successfully stored in the LHC ring, fluxes of the order of 1017 photons/s, in the gamma-ray energy domain between 1 MeV and 400 MeV could be achieved. This energy domain is out of reach for the FEL-based light sources as long as the multi TeV electron beams are not available. The CERN Gamma Factory proposal has the potential of increasing by 7 orders of magnitude the intensity limits of the present Inverse Compton Scattering sources. In 2017 the CERN accelerator complex demonstrated its flexibility by producing a new, xenon, ion beam. The Gamma Factory study group, based on this achievement, requested special studies. Its aim was to inject and to accelerate, in the SPS, partially stripped xenon ions Xe39+ measure their life time, and determine the relative strength of the processes responsible for the PSI beam losses. This study, the results of which are presented in this contribution, was an initial step in view of the the future studies programmed for 2018 with lead PSI beams. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF015 | |
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THPMF016 | Design of a Terahertz Radiation Source for Pump-Probe Experiments | 4073 |
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Narrow-band, tuneable, high-power terahertz radiation is highly demanded for pump-probe experiments at light source facilities. Since the requested radiation properties are not well covered by current terahertz radiation sources, an accelerator-based terahertz source employing the slotted-foil technique in combination with transverse deflecting cavities is proposed in this work. A detailed design has been worked out, and the behaviour of the electron beam and the created terahertz radiation is studied via numerical simulations. The results show that the proposed source produces tuneable terahertz radiation that can meet most of the demanded specifications. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF016 | |
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THPMF017 | Operation Improvements and Emittance Reduction of the ESRF Booster | 4077 |
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The ESRF storage ring will be replaced by the Extremely Brilliant Source (EBS) in 2020 and the equilibrium emittance will decrease from the present 4 nmrad to 134 pmrad. The current injector system, composed by a linac and a synchrotron booster, will be used to inject into the new storage ring. To increase the injection efficiency in the new storage ring, three methods to reduce the horizontal emittance of the booster have been considered and tested. This paper presents the studies and achievements in terms of operation improvements and emittance reduction. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF017 | |
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THPMF019 | ESRF-EBS Lattice Model with Canted Beamlines | 4081 |
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The ESRF Extremely Brilliant Source (ESRF-EBS) lattice model is updated to include three canted beamlines. The cells are modified where necessary to include 3-Pole Wiggler (3PW), 2-Pole Wiggler (2PW) and Short Bending Magnet (SBM) sources. Several lattices are obtained for the different stages that will bring from commissioning to operation with users. A scheme for tune modification keeping key optics knobs unchanged is proposed. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF019 | |
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THPMF020 | A 4th Generation Light Source for South-East Europe | 4084 |
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In Europe, most of the Synchrotron Light Sources are located in the middle, west and northern regions while the south-east is still lacking any major project. Hence a new initiative has been set up to propose the construction of a 4th Generation Light Source in that region. Design requirements limit the beam energy between 2.5 GeV to 3 GeV, the circumference is limited to 350 m, the emittance should be smaller than 250 pm rad and at least 14 to 16 straights have to be available for the users. Several mag-net configurations have been investigated and the results revealed that the HMBA lattice can fully meets the requirements and is therefore proposed for the Light Source in the SEE-region of Europe. These studies show that for a 4th Generation Light Source with energies up to 3 GeV a circumferences of 350 m will be adequate. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF020 | |
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THPMF021 | ESRF Operation Status | 4088 |
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The European Synchrotron Radiation Facility (ESRF) is undergoing the second phase (2015-2022) of an Up-grade which concerns its infrastructure, beamlines and X-ray source. This paper reports on the present operational source performance, highlighting the most recent developments, and the preparation of the Extremely Brilliant Source project. The renovation of the injector and the recent operation in top-up mode are also detailed. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF021 | |
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THPMF022 | Study of Possible Beam Losses After Post-Linac Collimation at European XFEL | 4092 |
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The European XFEL has been operating with the undulator beam line SASE1 and SASE3 since April 2017 and February 2018, respectively. Despite of the fact that the post-linac collimation has collimated the beam halo to ~20 σ level*, relative high radiation doses have been measured especially in the diagnostic undulator (DU) section**. In order to find the sources of beam losses after post-linac collimation, BDSIM simulations have been performed. In this paper, we will first present the possible losses generated by the wire scanners upstream of the undulators during a scan. The simulation results will be compared with the measured doses along SASE1 and SASE3 undulators. Based on the simulation results, we will estimate the frequency for wire scanner opera-tions. Besides, the simulations with large extension of beam halo hitting the vacuum chamber aperture transition will also be presented. Finally, other possible radiation dose sources will be discussed.
* S. Liu et al., in Proc. of FEL 2017, Santa-Fe, USA, Aug. 2017, paper TUP003. ** F. Wolff-Fabris et al.,IPAC-2018 contribution. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF022 | |
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THPMF024 | Commissioning and Operation of FAST Electron Linac at Fermilab | 4096 |
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We report results of the beam commissioning and first operation of the 1.3 GHz superconducting RF electron linear accelerator at Fermilab Accelerator Science and Technology (FAST) facility. Construction of the linac was completed and the machine was commissioned with beam in 2017. The maximum total beam energy of about 300 MeV was achieved with the record energy gain of 250 MeV in the ILC-type SRF cryomodule. The pho-toinjector was tuned to produce trains of 200 pC bunches with a frequency of 3 MHz at a repetition rate of 1 Hz. This report describes the aspects of machine commission-ing such as tuning of the SRF cryomodule and beam optics optimization. We also present highlights of an experimental program carried out parasitically during the two-month run, including studies of wake-fields, and advanced beam phase space manipulation. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF024 | |
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THPMF025 | Emittance Measurements at FAST Facility | 4100 |
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Funding: *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The FAST facility at Fermilab recently been commissioned has demonstrated the generation of electron beam within a wide range of parameter (energy, charge) suitable for accelerator-science and beam-physics experiments. This accelerator consists of a photo-electron gun, injector, ILC-type cryomodules, and multiple downstream beam-lines. It will mainly serve as injector for the upcoming Integrable Optical Test Accelerator (IOTA). At the same time we will also carry out a LINAC based intense gamma ray experiment based on the Inverse Compton scattering. It is essential to understand the beam emittance for both experiments. A number of techniques are used to characaterizing the beam emittance including slit based method and quad scan method. An on-line emittance measurement based on multi-slit method is developed so the emittance measured will be immediately available to support further beam optimization. In this report we will present the results from the emittance studies using this tool. We will also present the emittance measurement based on quads scan technique for the high energy beam line. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF025 | |
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THPMF028 | Coherent Stacking Scheme for Inverse-Compton Scattering at MHz Repetition Rates | 4103 |
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Funding: Work sponsored by the DNDO award 2015-DN-077-ARI094 to Northern Illinois University and US DOE contract DE-AC02-07CH11359 to Fermilab. An experiment to produce 1-MeV gamma rays via Compton back-scattering of infrared photons on 250-MeV electron bunches is currently in preparation at the Fermilab Accelerator Science & Technology (FAST) facility. To increase the gamma-ray flux the energy of the infrared laser pulses are planned to be amplified within the interaction region using a resonant cavity. This passive amplifier composed of a Fabry-Perot cavity will allow the laser pulse bunches to coherently and constructively stack. Our estimates, based on theoretical models, show that the laser pulse energy can be increased from approximately 1-2 mJ at the exit of the last active amplifier to 5 -10 mJ at the interaction point when the laser repetition rate is set at the nominal value of 3 MHz. This paper details the cavity design option(s) and associated wave-optic simulations. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF028 | |
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THPMF029 | Novel MCP-Based Electron Source Studies | 4107 |
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Microchannel plates were recently proposed as cathodes for electron guns, as part of a novel electron lens design to be tested in the IOTA facility at FNAL. We experimentally assessed the suitability of microchannel plate technology in this design and studied the microchannel plate based photomultiplier (MCP-PMT) system using different sources of light pulses. Here we present the results of the nanosecond time response tests and the maximum current density tests as well as the dependency on the magnetic field strength. Several ideas how to proceed beyond O(100 mA/cm2) density observed in the first tests. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF029 | |
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THPMF030 | VSR Injector Upgrade at BESSY II | 4110 |
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BESSY VSR is a fully funded project at the Helmholtz-Zentrum in Berlin (HZB). The objective is to produce simultaneously both long and short pulses in the storage ring. The implications for the existing injector systems and the upgrade strategy are presented. Envisaged is a global upgrade which includes additional accelerating structures to reduce the bunch length in the booster, orbit measurements and implementing longitudinal feedback. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF030 | |
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THPMF031 | In-Vacuum APPLE II Undulator | 4114 |
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APPLE II undulators are widely used in many synchrotron radiation facilities for the generation of arbitrarily polarized light, because they provide the highest magnet fields among all planar variably polarizing permanent magnet undulators (PMUs). So far, in-vacuum permanent magnet undulators (IVUs) have a fixed polarization, either planar or elliptical / helical. A variably polarizing in-vacuum undulator was never built due to the engineering challenges. We present the design of a new in-vacuum APPLE II, which will extend the photon energy range to tender X-rays in the 1.7 GeV storage ring BESSY II. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF031 | |
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THPMF032 | Preparation and Testing of the BERLinPro Gun 1.1 Cavity | 4117 |
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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) is foreseen. Here the status of the Gun 1.1 cavity is described, including results of the recent vertical testing. Lessons learned from the production and preparation process are summarized, also in order to identify issues critical for the production of Gun 2.0. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF032 | |
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THPMF033 | Design of the Beamline Elements in the BESSY VSR Cold String | 4123 |
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Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association The four SRF cavities in the BESSY VSR module will be linked by bellows, which will be equipped with inner coaxial shielding pipes to prevent both parasitic fundamental mode losses and beam-induced heating. The central bellow will also act as a collimator for synchrotron radiation generated in the closest upstream dipole magnet. Additional bellows at the module's ends are needed to connect with the warm BESSY beam pipe. Outside the module the beam pipe cross section transitions will be located, which will be equipped with toroidal HOM absorbing elements. In the paper the recent design considerations and specifications for all those components will be described. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF033 | |
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THPMF034 | Status Report of the Berlin Energy Recovery Linac Project BERLinPro | 4127 |
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Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a demonstration facility for the science and technology of ERLs for future light source applications. BERLinPro is designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the last year's progress, including the comissioning of the gun module as the first SRF component to be installed in BERLinPro. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF034 | |
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THPMF035 | Numerical Analysis of Excitation Property of Pulse Picking by Resonant Excitation at BESSY II | 4131 |
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The pulse picking by resonant excitation (PPRE) method is applied at BESSY II to provide pseudo single bunch operation by separating the radiation from one horizontally enlarged bunch from the light of the multi-bunch filling. The bunch is enlarged by an excitation with an external signal close to the tune resonance. The variation of the beam size depends strongly on the frequency and amplitude of the excitation signal. In this paper we show the properties of the PPRE bunch studied by analytical modeling and numerical calculations using Elegant. The simulation results are compared with beam size measurements using a new interferometry beam size monitor at BESSY II. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF035 | |
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THPMF036 | Status of the Conceptual Design of ALS-U | 4134 |
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Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The ALS-U conceptual design promises to deliver diffraction limited performance in the soft x-ray range by lowering the horizontal emittance to about 70 pm rad resulting in two orders of brightness increase for soft x-rays compared to the current ALS. The design utilizes a nine bend achromat lattice, with reverse bending magnets and on-axis swap-out injection utilizing an accumulator ring. This paper shows some aspects of the completed conceptual design of the accelerator, as well as some results of the R&D program that has been ongoing for the last years. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF036 | |
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THPMF038 | Status of the BESSY VSR Project | 4138 |
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BESSY VSR is set out to provide a variable pulse pattern to the BESSY II users. This project is now fully funded and heading into its implementation phase. The pulse pattern, consisting of long and short pulses, require inserting cavities providing a 3rd and a 3.5th harmonic of the fundamental harmonic of the ring. Therefore 1.5 and 1.75 GHz cavities are developed with appropriate higher order mode damping spectrum. Similarly the BESSY II ring and injector chain has to be upgraded to provide appropriate diagnostics and increase the injection efficiency. In this paper we give the current status of the project and give an overview of scientific challenges currently being tackled. | ||
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THPMF039 | Study of Magnesium Photocathodes for Superconducting RF Photoinjectors | 4142 |
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Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1. The superconducting RF photoinjector (SRF Gun II) has successfully served for the ELBE user facility at HZDR. Nevertheless, the quality of photocathodes is one of the most critical issues in improving the stability and reliability for its application. Magnesium has a comparably low work function (3.6 eV) and shows a quantum efficiency up to 0.3% after laser cleaning. However, the present cleaning process with a high intensity laser beam is time consuming and produces unwanted surface roughness, which leads to a higher thermal emittance. Thermal treatment and Excimer laser cleaning for Mg cathodes are investigated as alternative methods. In this work, the new cleaning procedures are tested and optimized, and the quantum efficiency of Mg samples with different microstructure, composition and suppliers are compared. |
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THPMF040 | Experiences with the SRF Gun II for User Operation at the ELBE Radiation Source | 4145 |
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Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1. The second version of the superconducting RF pho-toinjector (SRF Gun II) was successfully commissioned at the ELBE radiation source in 2014. The gun features an improved 3.5-cell niobium cavity combined with a super-conducting solenoid integrated in the cryostat. With a Mg photocathode the SRF Gun II is able to generate bunches with up to 200 pC and with sub-ps length in CW mode with 100 kHz pulse frequency for the THz radiation fa-cility at ELBE. In the ELBE linac, the beam is accelerat-ed, gets a proper correlated energy spread, and is com-pressed in a magnetic chicane. Sub-ps pulses are obtained producing coherent diffraction radiation and superradiant undulator radiation. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF040 | |
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THPMF041 | Low Emittance Lattice for PF-AR | 4148 |
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PF-AR is a synchrotron-type 6.5 GeV light source in KEK. The user-run was started in 1987, and the lattice is almost the same as the original one. Now we consider the emittance improvement to enlarge the horizontal tune advance in the normal cell. Thanks to this manipulation, the emittance will be improved to about a half of the current value. | ||
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THPMF042 | Beam Based Measurement of Injection Parameters at KEK-PF | 4152 |
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KEK-PF is a 2.5 GeV synchrotron radiation facility. In recent years, the injection efficiency using conventional pulsed septum and kicker magnets has decreased. The main cause of this problem seems to be the change of the injection parameters due to the accumulation of the errors including the effect of the earthquake on March 11, 2011. For the improvement of the injection efficiency, the precise and detailed parameters of the beam injection under present configuration are essential. In order to fix these parameters, we measure the response of the pulsed magnets by using injected and stored beams. In this presentation, we show the beam based measurement and the simulation results for the PF ring injection system. | ||
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THPMF043 | Development and Present Status of Photon Factory Light Sources | 4155 |
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Photon Factory of KEK manages two light sources, Photon Factory storage ring (PF-ring) and Photon Factory Advanced Ring (PF-AR) with an energy of 2.5 GeV and 6.5 GeV, respectively. Although it is unfortunate that the operation time of the accelerators is decreasing recent years due to a budget shortage and some unavoidable reconstructions, we are continuing the operation with a low failure rate and constructing a new beamline based on a novel undulator. Preparing for the start of the physics run of Super KEKB Factory, a new full energy beam transport line from the injector LINAC to PF-AR was constructed. With an installation of pulsed quadrupole magnets for the LINAC, continuous top-up injection has been established simultaneously for the four storage rings of PF and Super KEKB, and the operation of them has become compatible. As a result of increasing the injection energy of PF-AR form 3 GeV to 6.5 GeV, the beam instability during the injection disappeared, and the stability and efficiency of the injection improved significantly. | ||
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THPMF045 | Synchronized Beam Position Measurement for SuperKEKB Injector Linac | 4159 |
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Toward SuperKEKB project, the injector linac upgrade is ongoing for aiming at the stable beam operation with low emittance and high intensity bunch charge. One of the key challenges is a low emittance preservation of electron beam because the vertical emittance of 20 mm.mrad or less should be transported to the main ring without a damping ring. For this purpose, the fine alignment of accelerator components is a crucial issue since the linac alignment was badly damaged by the big earthquake in 2011. From the simulation results of emittance growth, the alignment of the quadrupole magnets and accelerating structures should be conducted at the level of 300 um in rms along the 600-m-long linac. In addition, we are aiming at the level of 100 um alignment in rms within the short range distance of 100 m long. Even after the fine component alignment can be achieved, the fine beam orbit manipulation is necessary for low emittance preservation. For these reasons, we have developed the new BPM readout system based on VME64x. The new system has improved the precision of beam position measurement up to 3 um from 25 um. We will describe the software development of the new BPM readout system. | ||
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THPMF046 | Precision Charge Measurement of 40~MeV Electron-Beam to Calibrate Air Fluorescence Telescope for Cosmic Ray Observation | 4163 |
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The Telescope Array (TA) is ultra-high energy cosmic ray observation (UHECR). TA is using the fluorescence detectors (FD) for observation the air fluorescence(AFY) which are emitted in the cascade generated by an UHECR in atmosphere. One of the important observables is primary energy of UHECR, however it has 21% systematic uncertainty. For reduction of the uncertainty, we have been operated an 40-MeV electron linear accelerator from 2010 which we have constructed for absolute energy calibration. The accelerator is located at 100 m from FD station, and can shot electron beam which the direction is vertical into the air, the energy is 40-MeV, the pulse width is 1 micro-second, and the beam charge is 160 pC. The AFY efficiency and FD calibration parameters can be calibrated, which means energy scale of UHECR, by observation of the AFY which are generated by the electron beam in the air. The most important beam parameter is beam charge. The requirement of the accuracy of charge measurement is a few %, then we have developed the double faraday cups and one current transfer system. We calibrated the current transfer by the double faraday cups, and we could achieve about 1% accuracy. | ||
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THPMF048 | Bunch Length Measurements Using CTR at the AWA with Comparison to Simulation | 4166 |
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Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357. In this paper we present electron bunch length measurements at the Argonne Wakefield Accelerator (AWA) photoinjector facility. The AWA accelerator has a large dynamic charge density range, with electron beam charge varying between 0.1 nC - 100 nC, and laser spot size diameter at the cathode between 0.1 mm - 18 mm. The bunch length measurements were taken at different charge densities using a metallic screen and a Martin-Puplett interferometer to perform autocorrelation scans of the corresponding coherent transition radiation (CTR). A liquid helium-cooled 4K bolometer was used to register the interferometer signal. The experimental results are compared with Impact-T and OPAL-T numerical simulations. |
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THPMF049 | Photoinjector Optimization Studies at the AWA | 4169 |
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Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357. With a variable charge range of 0.1 nC - 100 nC, the Argonne Wakefield Accelerator facility (AWA) has a unique and dynamic set of operating parameters. Adjustment of the optics and occasionally the rf phases is required each time the bunch charge is changed. Presently, these adjustments are done by the operator during each experiment. This is time consuming and inefficient, more so at high charge and for complex experimental set ups. In an attempt to reduce the amount of time spent adjusting parameters by hand, several optimization methods in simulation are being explored. This includes using the well-known Genetic Algorithm (NSGA-II), incorporated into OPAL-T. We have also investigated a model-based method and novel structure based algorithms developed at ANL. Ongoing efforts include using these optimization methods to improve operations at the AWA. Simulation results will be compared to measured beam parameters at the AWA, and one optimization method will be selected for use in guiding operations going forward. |
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THPMF050 | High-Efficient XFELO Based on Optical Resonator with Self-Modulated Q-Factor | 4172 |
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In this paper we describe an efficient XFELO having a new non-stationary out-coupling scheme. It consists of two undulator sections placed inside optical cavity. The first section is a conventional uniform undulator and the second one is a tapered undulator. At start time point X-ray radiation is mostly produced by the uniform section. Mirrors of XFELO's optical resonator are designed so that diffraction Q-factor reaches the highest value, i.e losses are near zero. As X-ray power increases the tapered undulator begins to contribute more to radiation power. However a portion of that power misses mirrors of the optical cavity, because those are tuned to confine radiation produced by the first undulator. This process establishes a steady state operation of the XFELO. | ||
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THPMF051 | Research of a Locally-round Beam in HEPS Storage Ring Using Solenoids | 4175 |
SUSPF023 | use link to see paper's listing under its alternate paper code | |
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"Round beam", that is, a beam with equivalent transverse emittance, is expected for a significant fraction of the beamline users in light sources. We investigate the possibility of reaching round beam in a storage ring, by means of a local exchange of the apparent horizontal and vertical emittance, performed with solenoids in a dedicated insertion line in the storage ring. In this paper, we show that a locally-round beam can be achieved by using solenoid in High Energy Photon Source (HEPS) storage ring, particularly to one of the design having natural emittance of 34.2 pm·rad. | ||
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THPMF052 | The Swap-Out Injection Scheme for the High Energy Photon Source | 4178 |
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Funding: Work supported by Natural Science Foundation of China (No.11605212). The on-axis swap-out scheme is a promising injection scheme for di raction-limited storage rings, since it only re- quires a rather small dynamic aperture and thus potentially allows a higher brightness compared to traditional o -axis injection schemes. However, a full charge injector is neces- sary for this scheme and its design can be nontrivial, in par- ticular to satisfy the large single bunch charge requirements in special lling patterns for timing experiments. In the High Energy Photon Source, we propose using the booster also as a high energy accumulator ring to recapture the spent bunches extracted from the storage ring, so as to relax the challenges in generation and acceleration of bunches with a high charge, and as a cost-e ective solution compared to building a dedicated full energy accumulator ring. In this paper, the beam dynamics issues of this scheme will be presented, trade-o s between the storage ring and booster beam parameters and hardware specifications will also be discussed. |
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THPMF053 | Study of the Dynamic Aperture Reduction Due to Error Effects for the High Energy Photon Source | 4182 |
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Funding: Work supported by Natural Science Foundation of China(No.11605212). The 6 GeV High Energy Photon Source (HEPS) employs a lattice of 48 hybrid 7BA cells, aims to achieve a natural emittance between 30 to 60 pm, within a circumference of about 1.3 km. In the performance evaluation of optimized lattices, we found that the dynamic aperture of the bare lat- tice were su cient for on-axis swap-out injection, but a large reduction in the dynamic aperture was observed in the simu- lation when including lattice imperfections and even after dedicated lattice corrections. In this paper, we identi ed the feed-down e ects of sextupoles as the major source of DA reduction, and proposed to use dedicated sextupole movers to e ciently reduce the orbit o sets in sextupoles, to par- tially recover the dynamic aperture, sextupole mover-based optics correction schemes were also discussed. |
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THPMF054 | Beam Performance Simulation with Error Effects and Correction on HEPS Design | 4186 |
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The High Energy Photon Source (HEPS) is a 6-GeV, ul-tralow-emittance kilometre-scale storage ring light source to be built in China. In this paper, the progress of the error and correction effect study on HEPS over the past one year will be presented, including error requirement and correction progress update. And beam performance eval-uation with static error and correction on orbit, optics, emittance and dynamic aperture will be presented. | ||
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THPMF055 | Ion Instability Simulation in the HEPS Storage Ring | 4189 |
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The High Energy Photon Source (HEPS), a kilometre scale storage ring light source, with a beam energy of 6 GeV and transverse emittances of a few tens of pm.rad, is to be built in Beijing and now is under design. We investigate the ion instability in the storage ring with high beam intensity and low-emittance. We performe a weak-strong simulation to show characteristic phenomena of the instability in the storage ring. | ||
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THPMF056 | Optimisation Study of the Fabry-Pérot Optical Cavity for the MARIX/BRIXS Compton X-Ray Source | 4192 |
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We present the study of the optimization of the optical cavity parameters, in order to maximise the flux of scattered photons in the Compton scattering process. In the optimisation, we compensate the losses of the photon number due to the elliptical shape of the laser pulse in optical cavity with a high focusing electron beam. | ||
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THPMF057 | Multi Colour X-Gamma Ray Inverse Compton Back-Scattering Source | 4196 |
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We present a simple and new scheme for producing multi colour Thomson/Compton radiation with the possibility of controlling separately their polarization, based on the interaction of one single electron beam with two and more laser pulses that can come from the same laser setup or from two different lasers system and that collide with the electrons at different angle inside one optical cavity. One of the most interesting cases for medical applications is to provide two X-ray pulses across the iodine K-edge at 33.2 keV. The iodine is used as contrast medium in various imaging techniques and the availability of two spectral lines accross the K-edge allows one to produce subtraction images with a great increase in accuracy. | ||
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THPMF058 | The MariX source (Multidisciplinary Advanced Research Infrastructure with X-rays) | 4199 |
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MariX (Multidisciplinary advanced research infra-structure with X-rays) is a joint project of INFN and University of Milan, aiming at developing a twin X-ray Source of advanced characteristics for the future Sci-entific Campus of the University of Milan. Presently in its design study phase, it will be built in the post Expo area located in north-west Milan district. The first component of the X-source MariX is BriXS (Bright and compact X-ray Source), a Compton X-ray source based on superconducting cavities technology for the electron beam with energy recirculation and on a laser system in Fabry-Pérot cavity at a repetition rate of 100 MHz, producing 20-180 keV radiation for medical applications. The BriXS accelerator is also serving as injector of a 3.8 GeV superconductive linac, driving a X-ray FEL at 1 MHz, for providing coherent, moderate flux radiation at 0.3-10 KeV at 1 MHz. Scientific case, layout and typical parameters of MariX will be discussed. | ||
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THPMF059 | Simulation Studies of Beam Commissioning and Expected Performance of the SPring-8-II Storage Ring | 4203 |
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In the SPring-8 upgrade project, the 5-bend achromat lattice is adopted for achieving a very low emittance of 157 pm.rad at 6 GeV. Since the dynamic aperture (DA) and the beam performance become sensitive against errors due to the strong quadrupoles and sextupoles, we carried out tracking simulations to evaluate the tolerance of machine imperfections such as the misalignment, magnetic field errors, the BPM offset, etc. It is found that the first-turn-steering (FTS) with the use of single-pass BPM's is indispensable because even under strict (but attainable) tolerances the beam cannot be stored without steering kicks. We then confirmed that after the FTS a sufficiently large DA can be obtained for accumulating the beam by the off-axis injection. By performing the orbit and optics corrections for the stored beam, we can finally achieve an emittance value of 160 ~ 180 pm.rad, being close to the design value. We also found that a naive application of the SVD algorithm to orbit corrections yields unwanted local bumps between BPM's and this deteriorates the vertical emittance. A possible scheme to avoid such local bumps by effectively interpolating the measured orbit will be discussed. | ||
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THPMF060 | Touschek Beam Loss Simulation for Light Source Storage Rings | 4206 |
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In light source storage rings, it is important to know the distribution of lost electrons due to the Touschek scattering for protecting insertion devices (IDs) from radiation damage. This will become crucial especially in future light sources where narrow gap in-vacuum IDs are normally used. While the Touschek scattered electron begins to oscillate in the horizontal direction with the amplitude proportional to the dispersion at the scattering point and to the momentum deviation after scattering, the motion is converted into the vertical direction due to the betatron coupling and some of the scattered electrons are lost at the narrow gaps of in-vacuum IDs. The momentum deviation by the Touschek scattering reaches 5% more, and according to which the vertical oscillation is more excited. Hence electrons even scattered at small horizontal dispersion are also lost at narrow gap IDs. We carried out computer simulations by taking the present SPring-8 storage ring and a planned 3GeV low-emittance ring as examples. The results and possible measures for ID protection will be presented. | ||
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THPMF061 | Updates on Hardware Developments for SPring-8-II | 4209 |
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We will report the updates on hardware developments for SPring-8-II including a status on a test half-cell construction. A major upgrade of SPring-8, SPring-8-II, targeting substantial improvements in the light source performance is based on a five-bend achromat lattice at an electron energy of 6 GeV*, and hardware accommodating with the new lattice have been extensively developed**. Some of key features are permanent dipole magnets, SUS vacuum chambers, highly accurate and reliable electron and photon beam position monitors, and an extremely small emittance beam injection from the SACLA linac to the storage ring. In the process of the optimization, we cannot rely merely on independent developments; the high packing factor lattice naturally imposes an integration of the individual efforts into a whole design. Thus, a test-half cell has been constructed as one of important milestones, where we need to carefully look through specification balances between different components, physical and magnetic interferences, etc. The presentation will give overall status on the developments as well as the test half-cell construction.
* H. Tanaka et al., Proc. of IPAC2016, Busan, Korea (2016), p.2867. K. Soutome and H. Tanaka, PRAB 20, 064001 (2017). ** e,g, T. Watanabe et al., PRAB 20, 072401 (2017). |
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THPMF062 | Smith-Purcell Radiation for Bunch Length Measurements at the Injection of MESA | 4213 |
SUSPF021 | use link to see paper's listing under its alternate paper code | |
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Funding: Federal Ministry of Education and Research MELBA is a test apparatus for the injector of the energy recovering, superconducting accelerator MESA in Mainz. A chopper-buncher system containing two circularly deflecting cavities and a first and second harmonic buncher cavity have been built. They serve to produce short bunches with a longitudinal extension < 600 μm (one degree of RF-phase) in the longitudinal focus for beam currents of up to 10mA. We intend to use Smith-Purcell Radiation (SPR) to test this arrangement. SPR is generated if a charged particle passes close to a periodic metallic structure, e.g. a grating. The signal has a coherent part which increases its intensity quadratically with the bunch charge if the bunch length is smaller than or comparable to the grating period. Different gratings can be placed below the electron beam to determine the length of the electron bunches. This measurement is non-destructive. The generated THz radiation will be observed with a bolometer cooled down to 4.2K which offers sufficient sensitivity in our regime of operation. |
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THPMF063 | The MESA 15 kW cw 1.3 GHz Solid State Power Amplifier Prototype | 4216 |
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The Mainz Energy recovering Superconducting Accelerator MESA is a multi-turn energy recovery linac with beam energies in the 100 MeV regime currently designed and build at Institut für Kernphysik (KPH) of Johannes Gutenberg-Universität Mainz. The main accelerator consists of two superconducting Rossendorf type modules, while the injector MAMBO (MilliAMpere BOoster) relies on normal conducting technolgy. The high power RF system is planned completely in solid state technology. With the high power demands of the normal conducting RF cavities up-to-date transistor technology with increased power density has to be used. A 15 kW CW power ampifier prototype with the new technology has been developed by Sigma Phi Electronics and deliverd to KPH. In this paper we will present the results of the performance measurements of the amplifier. | ||
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THPMF064 | Beam Based Alignment of SRF Cavities in an Electron Injector Linac | 4219 |
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Funding: Funded by DFG through Cluster of Excellence EXC 1098/2014 "PRISMA" and RTG 2128 "AccelencE" and by the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871 Proper alignment of accelerating cavities is an important issue concerning beam quality of accelerators. In particular SRF cavities of injector linacs using high accelerating gradients on low beta electron beams can affect the beam quality significantly when not aligned perfectly. On the other hand knowing the exact position of every cavity after several cool-down cycles of a cryomodule can be difficult depending on the cryomodule design. We will report on operational experience on the SC injector of the Darmstadt superconducting linac and ERL (S-DALINAC) showing unexpected effects on beam dynamics and beam quality. Operators could observe transverse beam deflections by changing accelerating phases of the injector SRF-cavities while a growth of tranverse emittance occurred at the same time. As beam currents in the S-DALINAC injector do never exceed 100 μA and the effects could even be observed at nA beam currents space-charge effects could be eliminated to be the reason for these observations. In this work we will report on the possibility to align SRF cavities after cooldown by measuring the transverse deflection of the beam and compare results with beam dynamics simulations. |
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THPMF066 | Performance of a Full Scale Superconducting Undulator with 20 mm Period Length at the KIT Synchrotron | 4223 |
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Within the collaborative effort between KIT and Bilfinger Noell GmbH the development of a full scale superconducting undulator with 20 mm period length (SCU20) has been completed. This device addresses the reliability and reproducibility aspects of the manufacturing process, allowing for the status of a commercial product. The conduction cooled 1.5 m long coils were characterized in the KIT horizontal test facility CASPER II and later assembled in the final cryostat. The system was extensively tested in the final configuration before installation in the KIT storage ring KARA (Karlsruhe Research Accelerator) to be the source of the NANO beamline in December 2017. Here we present the performance of the device. | ||
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THPMF067 | Design and Tests of Switchable Period Length Superconducting Undulator Coils | 4226 |
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Several photon beamlines in different synchrotron make use of undulators with switchable period length, which offer a larger tunability of the emitted photons energy. Superconducting technology allows switching the period length by changing the sign of the current in separately powered subset of windings. We present here the design and tests performed in liquid helium of switchable period length superconducting undulator coils performing period doubling from 17 mm to 34 mm. | ||
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THPMF068 | Commissioning Status of FLUTE | 4229 |
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FLUTE (Ferninfrarot Linac- Und Test-Experiment) will be a new compact versatile linear accelerator at the KIT. Its primary goal is to serve as a platform for a variety of accelerator studies as well as to generate strong ultra-short THz pulses for photon science. The phase I of the project, which includes the RF photo injector providing electrons at beam energy of 7 MeV and a corresponding diagnostics section, is currently being commissioned. In this contribution, we report on the latest progress of the commissioning phase. The status of the gun conditioning will be given, followed by an overview of the RF system and the laser system. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF068 | |
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THPMF069 | Perturbation to Stored Beam by Pulse Sextupole Magnet and Disturbance of the Sextupole Magnetic Field in Aichi Synchrotron Radiation Center | 4232 |
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In the Aichi synchrotron radiation center (Aichi-SR), a pulse sextupole magnet (PSM) has been installed as a pulse magnet for beam injection. This leads to the injection scheme without using a bump orbit and stable supply of the synchrotron radiation. In Aichi-SR we have performed usual injection scheme with 4 kicker magnets and making the bump. Because the circumference of the Aichi-SR is only 72 m, 3 beam lines are inside the bump. The Aichi-SR has performed top-up operation since its public open, so it is a crucial subject to eliminate the disturbance of the synchrotron radiation during the injection. We have installed the PSM in 2015 and developed the beam study continuously. At present, however, a perturbation to the stored beam by the PSM still has been observed and is not acceptable. We have performed beam diagnostic experiment and concluded that an additional dipole kick affects the beam. From the magnetic field measurement data, we have discussed the source of the additional kick; most likely is an eddy current on the Ti coating inside the ceramics duct of the PSM. The beam diagnostics experiment and the magnetic field measurement will be discussed in the presentation.
Present affiliation of the first auther : Karlsruhe Institute of Technology |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF069 | |
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THPMF070 | Non-Linear Optics and Low Alpha Operation at the Storage Ring KARA at KIT | 4235 |
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The storage ring Karlsruhe Research Accelerator (KARA) at KIT operate in a wide energy range from 0.5 to 2.5 GeV. Different non-linear effects, in particular, residual octupole components of the magnetic field of the CATACT wiggler at high field level (2.5 T), proximity of the working point to a vertical sextupole resonance Qy=8/3 and weak coupling octupole resonance 2Qx+2Qy=19, high chromaticity, etc. decrease the beam life time. This is because of the reduced dynamic aperture and momentum acceptance for off-momentum particles. A new operation point at high vertical tune Qy=2.81 was tested. For this, injection and ramping tables have been modified. First the values were optimized by simulations, then during beam tests, to minimize betatron tune shaking during beam-energy ramps. It stabilized high-current beams by the fast-feedback system the whole process: injection at 0.5 GeV, ramping, and operation at 1.3 GeV cycles. It essentially improved life time and beam current. In addition, new low-alpha tables have been created and tested, resulting in the reduction of the momentum compaction factor to 10-4. Short bunch operation at 0.5GeV injection energy was also tested successfully. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF070 | |
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THPMF071 | Design of a Very Large Acceptance Compact Storage Ring | 4239 |
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Design of a very large acceptance compact storage ring is underway at the Institute for Beam Physics and Technology of the Karlsruhe Institute of Technology (Germany). Combination of a compact storage ring and a laser wake-field accelerator (LWFA) might be the basis for future compact light sources and advancing user facilities. Meanwhile the post-LWFA beam is not fitted for storage and accumulation in conventional storage rings. New generation rings with adapted features are required. Different geometries and lattices of a ring operating between 50 to 500 MeV energy range were investigated. The model suitable to store the post-LWFA beam with a wide momentum spread (1% to 2%) and ultra-short electron bunches of fs range was chosen as basis for further detailed studies. The DBA-FDF lattice with relaxed settings, split elements and high order optics of tolerable strength allows improving the dynamic aperture up to 20 mm. The momentum acceptance of the compact lattice exceeds 8% while dispersion is limited. The physical program includes turn-by-turn phase compression of a beam, crab cavities, dedicated alpha optics mode of operation, non-linear insertion devices etc. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF071 | |
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THPMF072 | Implementation of Ultra-Low Frequency Non-Linear Raman Spectroscopy with the Gun Laser at FLUTE | 4242 |
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At the Karlsruhe Institute of Technology (KIT) the new compact versatile linear accelerator FLUTE is currently under commissioning. This accelerator will provide intense broadband THz pulses for spectroscopic experiments. Here, we demonstrate the implementation of a coherent Raman spectrometer using the RF gun laser of FLUTE. With our experiment, we can measure the Raman spectrum at ultra-low frequencies. The measurement principle, which was recently published, is based on coherent nonlinear excitation of the observed sample. The spectrometer consists of a stretcher and an interferometer, which can be simply built from standard optics. We will show that the accessible spectral range overlaps well with that from the THz pulses of the planned FLUTE experiment. Thus, the coherent Raman experiment can provide spectral information complementary to absorption spectral measurements using the THz radiation of FLUTE. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF072 | |
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THPMF074 | Study of the Saturation of Radiation Energy Caused by the Space Charge Effect in a Compact THz Coherent Radiation Source | 4245 |
SUSPF018 | use link to see paper's listing under its alternate paper code | |
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Funding: Institute of Advanced Energy, Kyoto University To generate an intense quasi-monochromatic Terahertz Coherent Undulator Radiation (THz-CUR), a compact linac system, which employs a magnetic electron bunch compressor with a beam energy of 4.6 MeV, has been constructed at Kyoto University. The THz-CUR has suc-cessfully been generated in a frequency range from 0.16 to 0.65 THz with a bunch charge of 60 pC. The maximum micro-pulse energy of THz radiation was observed higher than 1 μJ at 0.16 THz with 160 pC. However, when a bunch charge was higher than 80 pC, the micro-pulse energy of THz radiation gradually went to the saturation and obviously at the bunch charge higher than 110 pC because of the bunch lengthening and degradation of electron beam quality due to the space charge effect. The dependence of a bunch length on a bunch charge has been studied by GPT simulation and compared with CTR and CUR experiments. The trends of the measured results from CUR and CTR are in good agreement with the GPT simulation. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF074 | |
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THPMF076 | New Simulation Programs for Partially Stripped Ions - Laser Light Collisions | 4249 |
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We present for the first time two new indipendent Monte Carlo codes for simulating the collisions of Partially Stripped Ions with Laser light. Such collisions if realised at LHC could drive a high intensity gamma source and are the back-bone of the recent Gamma Factory proposal. The implementation aspects will be discussed and the simulation results will be compared. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF076 | |
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THPMF077 | A Novel 7BA Lattice for a 196-m Circumference Diffraction-Limited Soft X-Ray Storage Ring | 4252 |
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Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract No. DEAC02-05CH11231 The current baseline for the ALS Upgrade to a diffraction-limited soft x-ray storage ring is a 9BA lattice with two dispersion bumps for localized chromatic corrections. Although this lattice meets the very aggressive emittance goal, it offers limited margins in terms of dynamic aperture and momentum acceptance. In this paper we explore a different approach based on a 7BA lattice with distributed chromatic correction. This lattice relies heavily on longitudinal gradient bends and reverse bending in order to suppress the emittance so that despite fewer bends an emittance comparable to the baseline lattice can be reached albeit with larger dynamic aperture and momentum acceptance. We present linear optics design, trade-offs between achievable emittance and longitudinal stability, as well as the employed nonlinear tuning approach and the resulting performance of this alternate lattice. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF077 | |
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THPMF078 | Simulation of Trajectory Correction in Early Commissioning of the Advanced Light Source Upgrade | 4256 |
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Funding: *Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231. The ALS upgrade into a diffraction-limited soft x-rays light source requires a small emittance, which is achieved by much stronger focusing than in the present ALS. Very strong focusing elements and a relatively small vacuum chamber make the required rapid commissioning a significant challenge. This paper will describe the progress towards a start-to-end simulation of the machine commissioning and present first simulation results. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF078 | |
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THPMF080 | Physical and Chemical Roughness of Alkali-Animonide Cathodes | 4259 |
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Over the last decade, alkali-antimonides have been investigated as high QE cathodes in green light and more recently as ultra-low intrinsic emittance cathodes in near-threshold red wavelengths at cryogenic temperatures*. Nano-meter scale surface non-uniformities (physical roughness and chemical roughness or work function variations) are thought to limit the smallest possible emittance from these materials at the photoemission threshold under cryogenic conditions**. Despite this, the surfaces of alkali-antimonides have not been well characterized in terms of the surface non-uniformities. Here, we present measurements of both the physical and chemical roughness of alkali-antimonide surfaces using several surface characterization techniques like atomic force microscopy, kelvin probe force microscopy, low energy electron microscopy and near-threshold photoemission electron microscopy and show how such non-uniformities limit the intrinsic emittance.
*L. Cultrera et al Phys. Rev. ST Accel. Beams 18, 113401 (2015) **J. Feng et al, J. of Appl. Phys. 121, 044904 (2017) |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF080 | |
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THPMF081 | Intrinsic Emittance of Single Crystal Cathodes | 4263 |
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The transverse momentum of electrons is conserved during photoemission from atomically ordered surfaces of single crystal materials. Photocathodes used in all photoinjectors today have disordered surfaces and do not exploit this phenomenon. Recently, using this conservation of transverse momentum, significant reduction in intrinsic emittance was demonstrated from the (111) surface of silver*. Here, we present measurements of transverse momentum distributions of electrons photoemitted from the ordered surfaces of Ag and Cu single crystals at several photon energies. These measurements will help in understanding the photoemission process and show how band-structure and the conservation of transverse momentum can be used to obtain further reduction in intrinsic emittance from photocathodes.
*Karkare et al., Phys. Rev. Lett. 118, 164802 (2017) |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF081 | |
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THPMF082 | Suppression of Microbunching Instability Using a Quadrupole Inserted Chicane in Free-Electron-Laser Linacs | 4267 |
SUSPF011 | use link to see paper's listing under its alternate paper code | |
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The microbunching instability (MBI) driven by beam collective effects in a linear accelerator of a free-electron laser (FEL) facility can significantly degrade the electron beam quality and FEL performance. A method exploited longitudinal mixing derived from the natural transverse spread of the beam was proposed several years ago using two dipoles to suppress the instability. In this paper, instead of using bending magnets to introduce the transverse-to-longitudinal coupling, which will lead to an inconvenient deflection of the downstream beam line, we propose a scheme using a quadrupole inserted chicane to introduce the longitudinal mixing inside the accelerator transport system to suppress this instability. And we finally eliminate the transverse-to-longitudinal coupling after the dogleg section. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF082 | |
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THPMF083 | Dynamic Simulation for Low Energy Compton Scattering Gamma-Ray Storage Ring | 4271 |
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We have designed a dedicated low-energy electron storage ring to generate gamma-rays based on Compton scattering technique. The natural emittance of the ring is 3.4 nm at 500 MeV beam energy and the ring circumference is about 59 m. The resulting maximum gamma-ray photon energy is about 4 MeV by interacting with ~1 um laser. Due to the large energy loss associated with the gamma-ray photon emission, the electron beam dynamics are greatly affected. We have simulated the whole physics process including Compton scattering, radiation damping and quantum excitation and find that the equilibrium energy spread may be increased by one orders of magnitude depending on the laser parameters. We have studied the dependence of the equilibrium state on the laser intensity and wavelength, and the electron parameters based on our candidate ring lattice. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF083 | |
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THPMF084 | Numerical Shot Noise Modeling and Particle Migration Scheme | 4274 |
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Funding: US Department of Energy under Contract no. DEAC02-05CH11231 In order to model correct statistical properties of shot noise, special particle loading algorithms were developed and used in FEL community. However, the compatibility of such loading algorithms with particle migration scheme across numerical mesh is not well studied. Here, we address the necessity of special particle migration scheme for different loading algorithms and present a possible solution pair. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF084 | |
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THPMF085 | Beam Dynamics Simulation of the Solenoid Sextupole Error in the LCLS-II Injector | 4277 |
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The LCLS-II injector is a high brightness, high-repetition rate RF injector that consists of a 186 MHz VHF photo-electron gun, a focusing solenoid, a buncher cavity, another focusing solenoid, and a superconducting accelerating cryomodule to boost the electron beam energy to about final 100MeV. The solenoids provide transverse focusing and emittance compensation for the electron beam. However, in reality, the solenoid is not perfect due to manufacturing errors. Especially, the sextupole error in the solenoid field, which can cause significant beam emittance growth. In this paper, we report on the beam dynamics study of the effects of sextupole errors in the current LCLS-II injector. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF085 | |
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THPMF086 | Reliability Improvement on Wiggler Period Averaging Approximation | 4281 |
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Funding: US Department of Energy under Contract no. DEAC02-05CH11231 As the wiggler period averaging is subject to reliability issue, many efforts on FEL codes without such approximations are made at the cost of heavier computation loads. However, efforts toward increasing the reliability of such approximation are few. In this report, we present a new capability of IMPACT code suite based on such approximation with the addition of perturbative corrections to wiggler period averaging error. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF086 | |
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THPMF088 | R&D Activity on Alkali-Antimonied Photocathodes at INFN-Lasa | 4284 |
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Based on the long-term experience on R&D and production of cesium telluride photocathodes for the high brightness photo-injectors and the past experience on green photocathodes developed in ‘90s , we have started a new R&D activity aiming to reach a reproducible and robust recipe for green photocathodes usable in RF gun. In this paper we present and discuss the first results so far obtained on K2CsSb photoemissive films deposited on polished Mo plugs and the plan for future studies. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF088 | |
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THPMF089 | Design of a Radial RF Electron Gun | 4287 |
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Funding: DOE Accelerator Stewardship Program Most electron beam sources generate beams that propagate away from the source in a single primary direction, with the overall envelope being either pencil-like or sheet-like. We present the design of a radial RF electron gun, intended to produce a radially propagating electron beam (either towards or away from an axis) with the overall envelope being that of an expanding or contracting annulus. Such a source has several potential advantages for materials processing, and may also be useful as the basis for unique optical elements for hadron machines. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF089 | |
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THPMF090 | Linac Design Elements for Spaceborne Accelerators | 4291 |
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Funding: Los Alamos National Laboratory LDRD and Program Development Los Alamos National Laboratory, in collaboration with SLAC and Goddard Space Flight Center, have begun developing a high-duty-factor, MeV-range linear accelerator intended for use on satellites, specifically to probe the magnetosphere-ionosphere linkage. The design makes use of low-beta C-band cavities operating at moderate gradients, individually powered by 500-W RF amplifier chips. We present the current state of the design, and technology maturation efforts including RF amplifier performance studies, cavity tuner design and an initial acceleration test using a DC beam source and single RF cavity. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF090 | |
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