| Paper | Title | Page |
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| MOPGW038 | Collimator’s Impact Into the Transverse Emittance Growth at KEK Compact ERL | 174 |
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| In high-intensity particle accelerators, unwanted trans-verse and longitudinal wakefields arise when the high-charge particle beam passes through the narrow chambers or locations with small transverse apertures, such as collimator jaws. Transverse wakefields impose a transverse kicks to the beam, changing its shape, and leading to the growth of the transverse emittance. Longitudinal wakes cause the beam energy losses, heating of the narrow chambers etc. In the present study we investigated the collimator’s impact to the beam. Thus, we evaluated the collimator’s wakefields through the CST simulations. We estimated the corresponding transverse kicks and longitudinal wakes. In the summary simulation results were cross-checked with correspondent analytical expressions. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW038 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPGW036 | 1 mA Stable Energy Recovery Beam Operation with Small Beam Emittance | 1482 |
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A compact energy-recovery linac (cERL) have been operating since 2013 at KEK to develop critical components for ERL facility. Details of design, construction and the result of initial commissioning are already reported*. This paper will describe the details of further improvements and researches to achieve higher averaged beam current of 1 mA with continuous-wave (CW) beam pattern. At first, to keep the small beam emittance produced by 500 kV DC-photocathode gun, tuning of low-energy beam transport is essential. Also, we found some components degrades the beam quality, i.e., a non-metallic mirror which disturbed the beam orbit. Other important aspects are the measurement and mitigation of the beam losses. Combination of beam collimator and tuning of the beam optics can improve the beam halo enough to operate with 1 mA stably. The cERL has been operated with beam energy at 20 MeV or 17.5 MeV and with beam rep-rate of 1300 MHz or 162.5 MHz depending on the purpose of experiments. In each operation, the efficiency of the energy recovery was confirmed to be better than 99.9 %.
* S. Sakanaka, et.al., Nucl. Instr. and Meth. A 877 (2017)197, https://doi.org/10.1016/j.nima.2017.08.051 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW036 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPGW037 | Systematic Measurements of the Coherent THz Spectra by Magnetic Bunch Compression at the Compact ERL | 1486 |
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| Short electron bunch beam is one of the key elements of a Free Electron Laser (FEL) or intense THz coherent light source. The Energy Recovery Linac (ERL) has the strong advantage of operation of such an electron bunch at high repetition rate and is expected to increase the photon flux. At the Compact ERL in KEK site, we have demonstrated the magnetic bunch compression at the 180-degree return arc and measured the THz spectra of the Coherent Transition Radiation (CTR). This paper reports the revamped THz beamline and the improvement of the beam tuning as well as the systematic measurements of the THz spectra by magnetic bunch compression. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW037 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPRB035 | Stimulated Emission of THz Coherent Diffraction Radiation in an Optical Cavity by a Multibunch Electron Beam | 1763 |
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Funding: JSPS KAKENHI Accelerator-based terahertz (THz) radiation has been expected to realize a high-power broad-band source. Employing a low-emittance and short-bunch electron beam at a high repetition rate, a scheme to resonantly excite optical cavity modes of THz spectrum range via coherent diffraction radiation has been proposed. The confocal cavity design is the special case that resonance conditions of all the eigen modes coincide, resulting in realizing broad-band excitation. But in general cases of non-confocal cavities, the resonance condition depends on the mode, and the resonance peak becomes wide and weak. We performed an experiment with a non-confocal cavity as a follow-up experiment of that we have done with a confocal cavity. The result confirmed that the confocal design is the key for a broad-band source. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB035 | |
| About • | paper received ※ 26 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| WEPGW036 | Archive System of Beam Injection Information at SuperKEKB | 2550 |
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The archive system is one of the most important tools for the modern accelerators. It records the machine parameters during the operation so that we can retrieve and review the status of machine anytime later. SuperKEKB develops the injection archiver system. This system records the injection related parameters, pulse-by-pulse*. The information related with beam injections is fully recorded and it can be utilize to understand the condition of injection operation. Besides, the recorded data can be utilized also for the understanding of beam background related with injections.
* "Archive System for Injection Current at SuperKEKB", in Proc. of 15th Annual Meeting of PASJ, Nagaoka, Japan. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW036 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| THPMP012 | New Industrial Application Beamline for the cERL in KEK | 3475 |
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| The new beam line for the industrial applications is constructed at the cERL (compact Energy Recovery LINAC) in KEK. In these applications, only north straight sections of cERL consisting of injector and main LINAC will be used. The test for the radio isotope production and electron beam irradiation for the materials are firstly planned with very small beam current without energy recovery. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP012 | |
| About • | paper received ※ 11 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| THPTS027 | Accelerator Implementing Development of Ceramics Chamber with Integrated Pulsed Magnet for Beam Test | 4164 |
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We advance the development of Ceramics Chamber Integrated Pulsed Magnet (CCIPM) of air-core type as the application to low emittance ring with a narrow bore of light source accelerator in the future. The CCIPM is composed of ceramics cylinder of 60 mm diameter and four copper coils, which are implanted in the groove penetrated on the ceramic thickness along 30 cm length by silver brazing*. In addition to this structure, we succeeded in the implementations of cable connecting base that mechanically connect the coils and power supply with feeder lines and the pattern shape coating inside the ceramic cylinder. Improved brazing technique made it possible to braze the coil and the base on the coil at the same time that the coils are implanted in the ceramic thickness. Newly developed functional coating can reduce the eddy current caused by main magnetic field and pass the alternate component of beam wall current by capacitance structure. We report the details about the performance from the viewpoint of vacuum, magnetic field, insulation on the accelerator implementation with the approach to new technical development, and the preparation progress of beam test in beam-transport line.
* C. Mitsuda, et al., in Proc. IPAC2015, Richmond, VA, USA, p. 2879 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS027 | |
| About • | paper received ※ 12 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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