| Paper | Title | Page |
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| MOPVA019 | 60 pC Bunch Charge Operation of the Compact ERL at KEK | 890 |
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| The compact ERL (cERL) at KEK was operated in March 2017 to demonstrate generation, acceleration and transportation of the target bunch charge of 60 pC without energy recovery. However, the maximum bunch charge was limited to 40 pC due to the limitation of the excitation laser power. For the bunch charge of 40 pC, the bunch length and the normalized emittance were measured in the injector diagnostic line. The results of the bunch length measurement gave good agreement with the values that had been obtained by model simulation. The measured normalized rms emittances for 40 pC were 0.9 to 2.4 mm mrad, and they were lager than the design value of 0.6 mm mrad. To achieve the design emittance, we have studied the source of the emittance growth for the bunch charge of 40 pC. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA019 | |
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| MOPVA020 | S2E Simulation of an ERL-Based High-Power EUV-FEL Source for Lithography | 894 |
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An energy recovery linac(ERL)-based free electron laser(FEL) is a possible candidate of a high-power EUV source for lithography. The ERL can provide a high-current and high-quality electron beam for the high-power FEL and also greatly reduce the dumped beam power and activation compared to ordinary linacs. An ERL-based EUV-FEL source has been designed using available technologies and resources*. For this design, we perform Start-to-End(S2E) simulation from the electron gun to the exit of the decelerating main linac to track the electron beam parameters and to evaluate the FEL performance. The electron bunches from the injector are off-crest accelerated to 800 MeV and compressed in the 1st arc and/or chicane to obtain a high-peak current for high FEL output. After the undulator section for SASE FEL, they are decompressed in the 2nd arc and then decelerated in the main linac to optimize the energy spread or the energy recovery efficiency. This paper will present the S2E simulation for the designed EUV-FEL source.
* N. Nakamura et al., Proc. of ERL2015, Stony Brook, NY, USA, pp.4-9. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA020 | |
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| MOPVA021 | Optics Design of the Compact ERL Injector for 60 pC Bunch Charge Operation | 898 |
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| EUV-FEL light source based on ERL has been designed at KEK for EUV lithography light source. The advantage of ERL is to accelerate high average current beam due to CW operation, and it is possible to drive high average power FEL. To generate the target EUV-FEL power, which is 10 kW, the bunch charge of 60 pC, the beam energy of 10.5 MeV and the bunch length of 1 ps are required at the end of the EUV-FEL injector. In order to demonstrate the target beam performance for the EUV-FEL accelerator, a high charge beam test was carried out at the cERL in KEK. We designed a new optics of the cERL injector prior to the high charge beam operation. To calculate beam dynamics more accurately, accelerator models corrected according to the condition of the actual cERL injector is used for the optics design. From results of the optics design that minimized the emittance and bunch length using the corrected accelerator models, the emittance and bunch length at the end of injector are 0.8 mm-mrad and 3.4 ps. Furthermore, based on the design optics, we carried out high bunch charge beam operation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA021 | |
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| WEPAB043 | DQBA Lattice Option for the KEK-LS Project | 2675 |
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| KEK-LS is a fourth generation 3GeV light source and will be constructed in KEK Tsukuba campus. The lattice is 20 cells of ESRF type HMBA (Hybrid Multi Bend Achromat) with short straight section that enables to double the numbers of insertion device beam lines. The circumference is about 570m, and the horizontal natural emittance about 133pmrad. The conceptual design report (CDR) was published in October 2016. Adding two quadrupole magnets to the short straight section of the original lattice in CDR, the lattice design flexibility, emittance and dynamic apertures are improved. In this presentation, we show this new DQBA (Double Quadrupole Bend Achromat) lattice option for KEK-LS project. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB043 | |
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| WEPAB044 | Construction and Commissioning of Direct Beam Transport Line for PF-AR | 2678 |
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| PF-AR was constructed as an accumulator ring for TRISTAN, and in the KEKB era it has been revitalized as a 6.5 GeV synchrotron radiation source. The injection energy was 3 GeV and the beam was accelerated to 6.5 GeV prior to the user run. The original beam transport line (BT) from the LINAC to the PF-AR shared its upstream part with the the BT line of KEKB High Energy Ring (HER). The injection-mode change from PF-AR to HER or vice versa needs about 10 minutes for the magnet cycling procedure of the shared part. In SuperKEKB, the upgrade of KEKB, the lifetime of HER is about 10 minutes. The mode-switch operation of the BT is, therefore, not allowed for maintaining the highest luminosity of the SuperKEKB. In order to avoid this problem, a new 6.5 GeV BT line dedicated to PF-AR has been constructed. This also enables the top-up injection for the user run. The commissioning of the new BT line has been completed in this March, and now the first user run has been operated successfully. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB044 | |
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| WEPAB045 | Development of Dedicated Linac and Booster for KEK PF | 2681 |
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| KEK Photon Factory (PF) is a major light source facility in Japan. The injector of PF is KEK LINAC and it is shared with other three rings; PF-AR, SuperKEKB HER (High Energy Ring) and LER (Low Energy Ring). Due to the large electricity consumption, all accelerators in KEK are shut down during every summer for about 3 months. In 2017, because of the LINAC upgrade for SuperKEKB Phase 2 operation, the summer shutdown will be extended to about 5 months. On the other hand, the PF users always strongly wish the shorter shutdown and longer operation. Especially the structural biology users require the ability for the measurement within about 2 weeks after the irregular sample manufacture throughout the year. In order to satisfy these requests, the independent injector system is required for the realization of such longer operation. The examined system consists of an about 100 MeV small linac and a booster ring in the present PF ring tunnel. We show the results of the feasibility study for the independent injector system for the PF ring. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB045 | |
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| WEPAB046 | New HMBA Lattice for PF-AR | 2684 |
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| Photon Factory Advanced Ring (PF-AR) has been operated for users about 30 years from 1987. The lattice and optics are not almost changed from the original one as the TRISTAN booster ring constructed in 1984. The lattice employs FODO structure and the horizontal emittance for the 6.5 GeV user run is about 300 nmrad. In order to improve the performance of PF-AR dramatically, the full replacement of the accelerator to the ESRF type HMBA (Hybrid multi bend achromat) lattice is examined. In order to geometrically fit the new lattice to the present PF-AR tunnel, the new ring consists of 12 cells with four long straight sections. The emittance is improved to about 500 pmrad at 3 GeV. With the present user experimental hall at the north half of the ring, at least eight undulator beam lines can be constructed. The simulated dynamic aperture is about 1.5 cm at the long straight section with reasonable magnetic errors and COD correction. The Touschek lifetime is about 6 hours. The beam injection with conventional injection system causes no problem and the beam lifetime is long enough. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB046 | |
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| WEPIK071 | Resistive-Wall Impedance Effects for the New KEK Light Source | 3095 |
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KEK Light Source (KEK-LS) is a 3-GeV storage ring of 20-cell HMBA (Hybrid Multi-Bend Achromat) lattice*, which is planned to be constructed as a successor of the two existing Photon Factory storage rings (PF ring and PF-AR) in the KEK Tsukuba Campus. In this ring, a lot of in-vacuum undulators with a small magnetic gap (4 mm at minimum) will be installed and the vacuum pipe of a small aperture (25 mm in diameter) will be used. In addition, NEG coating, having a low electric conductivity, will be utilized for the vacuum pipe to ensure a sufficient beam lifetime early in the machine commissioning. In this paper, the heating power due to the longitudinal RW impedance and the growth rate of coupled-bunch instability caused by the transverse RW impedance are calculated and the effects of the RW impedance on KEK-LS are presented.
* K. Harada et al., Proc. of IPAC2016, Busan, Korea, pp.3251-3253; K. Harada et al., these proceedings. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK071 | |
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| WEPVA059 | Construction of the New Septum Magnet Systems for PF-Advanced Ring | 3398 |
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| From July 2016 we are constructing a new beam transport (BT) line for the Photon Factory Advanced Ring (PF-AR). The new BT line was designed to transport the full energy 6.5-GeV beam directly from the LINAC, and the top up injection will be possible for the PF-AR. We designed and produced new pulsed septum magnet systems for this project. Two pulsed septum magnets are used for the injection of the 6.5-GeV beam. The septum magnets were constructed with a passive type magnet, a copper eddy current shield and a silicon steel magnetic shield. The magnetic fields of these magnets have been measured by the search coil method. We paid attention to evaluating eddy current losses of the SUS beam duct in the magnetic field measurement. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA059 | |
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| WEPVA060 | Construction of the New Kicker Magnet Systems for PF-Advanced Ring | 3401 |
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| From July 2016 we are constructing a new beam transport (BT) line for the Photon Factory Advanced Ring (PF-AR). The new BT line was designed to transport the full energy 6.5-GeV beam directly from the LINAC, and the top up injection will be possible for the PF-AR. We designed and produced new kicker systems for this project. Three kicker magnets are used for the injection of the 6.5-GeV beam. The kicker magnets were designed as a window frame type ferrite core magnet. The magnetic fields of these magnets have been measured by the search coil method. We paid attention to evaluating eddy current losses of the metal coated ceramic duct in the magnetic field measurement. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA060 | |
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