| Paper | Title | Page |
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| MOP027 | Study on Nitrogen Infusion using KEK New Furnace | 95 |
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| KEK has been carried out high-Q/high-G R&D, to realize high performance of SRF cavities toward ILC. KEK constructed a new furnace, which is dedicated for N-infusion studies. We performed more than 10 times of N-infusion trials using 1.3 GHz single-cell cavities. Some results showed better Q-values up to high field, however, some results showed degraded Q-E slopes probably due to contamination. Improvement of accelerating gradient is not observed at moment. We have tried to clean the furnace and Nitrogen injection line to reduce the effect of contamination. Details of procedures of N-infusion, results of vertical tests, condition of the furnace including RGA spectrum and Nb sample analysis results are shown. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP027 | |
| About • | paper received ※ 04 July 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019 | |
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| MOP077 | Ceramic Study on RF Windows for Power Coupler, Waveguide, and Klystron in Particle Accelerator | 255 |
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| R&Ds on different types of ceramic used in power coupler, waveguide, and klystron for particle accelerators are under progress in Center of Innovation (COI) at KEK, and at some outside companies. There are five important parameters on the properties of ceramics; that is, relative permittivity, dielectric loss tangent, surface and volume resistivity, and secondary electron emission coefficient. For measurements of these parameters, eight kinds of ceramic samples supplied from five vendors have been measured using three different measurement systems since 2017. In this report, the recent results for these studies will be presented in detail. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP077 | |
| About • | paper received ※ 22 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019 | |
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| MOP083 | R&D of Copper Electroplating Process for Power Couplers: Effect of Microstructures on RRR | 278 |
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| Power couplers for superconducting cavities are required to have both low-thermal conductivity and high-electrical conductivity, because high-thermal conductivity and low-electrical conductivity could generate unexpected increase for heat load. In order to combine these contrary properties, power couplers are made of stainless steel and plated with copper plating. As electrical conductivity of copper layer affects dynamic heat load, it is crucial to optimize plating processes. In this study, we investigated influences of plating parameters (i.e., thickness of copper layer, plating bath composition, bath temperature, heat-treatment conditions) on RRR by collaborative work among Nomura plating, CETD, and KEK. As a result, we obtained high-RRR samples with conditions noted below; (1) electroformed copper plate, (2) copper layer thickness of over 50 µm, and (3) heat-treatment at 200deg-1h, (4) other plating bath composition. In addition, we observed microstructures of several samples, then found that microstructures of copper layer are strongly related to RRR. In this paper, we will present the recent results for this investigation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP083 | |
| About • | paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019 | |
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WETEA6 |
Successful Beam Commissioning in STF-2 Cryomodules for ILC | |
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| Beam commissioning of the STF-2 accelerator was successfully done at the Superconducting RF Test Facility (STF) in KEK from February to March 2019. As a result of various cavity tuning, LLRF control tuning, and beam tuning, the beam energy finally reached 271 MeV, and the accelerating gradient of each cavity estimated from beam energy was 32.0 MV/m. This result satisfies 31.5 MV/m, which is the operating specification of the International Linear Collider (ILC) project, and is an important milestone in the ILC technology demonstration. In this talk, we will report on the detailed results of beam commissioning. | ||
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Slides WETEA6 [13.702 MB] | |
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| FRCAB4 | Development of High Intensity, High Brightness, CW SRF Gun with Bi-Alkali Photocathode | 1219 |
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| Superconducting conduction electron guns can realize high acceleration voltage and high beam repetition. KEK has been developing the 1.3 GHz elliptical type 1.5 cell superconducting RF gun to investigate fundamental performance. The surface cleaning methods and tools were developed by using KEK SRF gun cavity #1 and surface peak electric field reached to 75 MV/m without field emission. We will apply this technique to the SRF gun cavity #2 for beam operation. The gun cavity #2 equips the helium jacket, frequency tuner cathode position adjuster to operate the electron beam. The RF structure was designed based on the gun cavity #1. The cathode rod is made of Nb. The photocathode deposited on the cathode rod will be cool down to 2K to minimize thermal emittance. The fabrication of the gun cavity #2 and helium jacket were completed. 4 times vertical tests were carried out. We will report the vertical test results and preparation of the horizontal test. | ||
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Slides FRCAB4 [10.826 MB] | |
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAB4 | |
| About • | paper received ※ 23 June 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019 | |
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