| Paper | Title | Page |
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| THPOY027 | Commissioning Status of SuperKEKB Injector Linac | 4152 |
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| The SuperKEKB main ring is currently being constructed for aiming at the peak luminosity of 8 x 1035 cm-2s−1. The electron/positron injector linac upgrade is also going on for increasing the intensity of bunch charge with keeping the small emittance. The key upgrade issues are the construction of positron damping ring, a new positron capture system, and a low emittance photo-cathode rf electron source. The injector linac beam commissioning started in the October of 2013. In this paper, we report the present status and future plan of SuperKEKB injector commissioning. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY027 | |
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| WEPMY037 | Cold Model Cavity for 20-K Cryocooled C-band Photocathode RF Gun | 2635 |
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Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT). A cryocooled 2.6-cell C-band photocathode RF gun is under development at Nihon University in collaboration with KEK. The RF characteristics of a pillbox-type 2.6-cell C-band RF cavity at 20 K were in agreement with the theoretical predictions. The result of the cold test for a cavity with the input coupler confirmed the same characteristics. Based on these results a refined cold model of the 20-K cryocooled photocathode RF gun has been designed using SUPERFISH and CST-STUDIO. The separation between the TM01 pi and the TM01 half-pi modes has been increased from 20 MHz to 52 MHz by extending the diameter of the cavity iris and reducing the disk thickness. The 2.6-cell structure has been modified from pillbox to ellipsoid-like type. The end-plate of the 0.6-cell cavity has a center hole for bead-pull measurements of the on-axis electric filed through the entire structure. Mounting of a photocathode assembly in the end-plate has not been considered, since the purpose is solely to measure the low-power and low-temperature RF characteristics. A new design for the input coupler has been employed. The cavity will be completed early in 2016. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY037 | |
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| WEPMY038 | Optimization of C-band RF Input Coupler as a Mode Converter for 20-K Cryocooled Photocathode RF Gun | 2638 |
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Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT). Development of a cryocooled 2.6-cell C-band photocathode RF gun has been conducted at Nihon University in collaboration with KEK. An RF mode converter from square TE10 to circular TM01 mode has been employed as an RF input coupler that has a coupling coefficient of approximately 20 at 20 K to the 2.6-cell accelerating structure. In the previous design, the circular waveguide in the mode converter formed part of the accelerating cavity. After the cold test of the cavity completed in 2014, the coupler design was modified to work as a pure mode converter with a VSWR of 1 at 5712 MHz. From the design simulation using CST-STUDIO, the insertion loss in the converter is 0.2 %. The TM010 and TM011 modes excited in the circular waveguide were separated by several ten MHz from the accelerating frequency. The simulation has suggested that the amplitude of the transverse electric filed on the axis in the circular waveguide is reduced to approximately 2 % of that in the longitudinal direction. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY038 | |
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| THPOW056 | Fiber Laser Development for Dielectric Laser-driven Accelerator and Electron Beam Source | 4070 |
| SUPSS024 | use link to see paper's listing under its alternate paper code | |
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Our group is aiming for developing a table-top electronμbeam source, whose beam size is micro-meter order so that we can irradiate just the nuclei of cells (1μm) and observe the behavior in real time. This beam source will be realized by dielectric laser-driven accelerators(DLAs), which is expected to produce acceleration gradients of ~GV/m. To drive these accelerators, ultra-short pulse laser has to be incident to the structure*. We chose Ytterbium (Yb) fiber laser for generating and amplifying ultra-short laser pulse, which has high quantum efficiency and can easily pumped by LD, and is proper to produce ultra-short pulses because of its wide-band oscillation. We succeeded in getting ultra-short pulse (central wavelength: {1030} nm, average output: 10 W, pulse duration: ~10 ps, reputation rate: 84 MHz) from Yb fiber laser system. Also in order to make electron bunch by photo cathode, we then converted the obtained IR laser to UV of 258 nm (4ω) using BBO and LBO crystals. We are planning to amplify the pulses by Yb:YAG in future, which has its amplification band in {1030} nm.
* K. Koyama el al., "Design Of Photonic Crystal Accelerator For Radiation Biology," IPAC'12 Proceedings (2014) |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW056 | |
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