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Research aiming to increase the RF breakdown threshold in electron/positron accelerators is being conducted at the Yale University Beam Physics Laboratory. Our two-beam accelerator approach employs a beam driven bimodal cavity structure. This cavity includes (i) two modes excited by the drive beam, with the higher mode frequency three times that of the fundamental TM010 mode; (ii) a low-current accelerated beam and high-current drive beam traversing the same cavity structure. This approach has the potential advantages of (a) operating at higher acceleration gradient with lower breakdown and pulsed heating rates than that of a single-mode cavity structure at the same acceleration gradient, due to the spatiotemporal field distribution properties in the bimodal cavities; and (b) obtaining high accelerating gradient with a low energy drive beam. Recent progress in simulations and work towards an experimental test stand is presented., Proceedings of the North American Particle Accelerator Conference, NAPAC2019, Lansing, MI, USA

A future European light source CompactLight is being proposed to extend FEL operation further into the x-ray region than other light sources by using a linac operating at X-band (12 GHz) with a short Ka-band (36 GHz) section for linearizing bunch phase space. The Ka-band system requires a high-power RF amplifier, synchronized with the main X-band source. We report here on design of a third-harmonic klystron amplifier for this application. Our design employs a four-cavity system with a multi-cell extended interaction output cavity. Initial simulation results indicate that more than 10 MW of 36-GHz power can be obtained with an efficiency exceeding 20%, and with 12-GHz drive power of 30 W. A preliminary design for a proof-of-principal experimental test of this concept is described, Proceedings of the North American Particle Accelerator Conference, NAPAC2019, Lansing, MI, USA

P, 本論文では,ERP (Enterprise Resource Planning)システムの研究開発と実施の観点から香料企業の特徴を分析し,香料企業におけるERPシステムの基本モデルを示した。また,筆者らが開発したERPシステムの実例を通して,この基本モデルの具体的な応用と得られた効果について述べた。最後に,運用組織,管理,技術の三つの要素について,成功のための枠組みを分析し,成功のキーとなる要因の分析を行った。香料企業においては,原料および製品の種類の多さ,顧客ニーズの多様さ,生産プロセスの単純さ,在庫品が占める資金量の多さ,頻繁に新製品の研究開発が行われるという産業の特徴を持っている。香料企業のERPシステム基本モデルの特徴は,新製品研究開発,注文書処理,原料購入の3つのプロセスが交差する点にある。顕著な効果を上げた実例の成功要因の分析により,3種類12個の主な成功要因が導き出された。実例とする企業の背景と情報化の段階の特徴により,これらの要因で最も重要なことは,知識転化を中心とし,プロジェクト組織を横断した緊密な協力を行い,ユーザ企業が最低限の基本的な管理水準を持ち,成熟した基本モデルと何処でも通用可能なシステムを採用するということが指摘できる。

The diamond amplified photocathode has the potential to dramatically increase the average current available from photoinjectors, perhaps to the amphere-class performance necessary for flux-competitive fourth-generation light sources. Electron emission from a diamond amplifier has been observed from hydrogen-terminated diamond, using both photons and electrons to generate carriers. The diamond electron amplifier has been demonstrated, with an emission gain of 40. Very high average current densities (>10 A/cm²) have been transported through the diamond using x-ray generated carriers. The device relies on high-purity intrinsic diamond with low crystalline defect density, as well as a negative electron affinity achieved by hydrogen termination. The effects of diamond purity and crystalline defects on charge transport in the material, and emission from the diamond surface have been studied using a number of techniques and the process is now well understood. The electron affinity of diamond has been measured to be -1.1 eV; the fraction of the electrons produced in the material which are emitted from the surface has also been measured., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

The proposed electron ion collider, eRHIC, requires large average polarized electron current of 50mA, which is more than 20 times higher than the present experiment results of single polarization source, such as GaAs. To achieve the current requirement of eRHIC, we have designed the multi-cathode DC electron gun for injection. 24 GaAs cathodes will be prepared and emit electrons at the arranged pattern. Despite of ultra-high vacuum and precise timing, multi-cathode DC electron gun has high demand on the electric field symmetry, magnetic field shielding, and arcing prevention. In the paper, we present the 3D simulation results of the latest model for the multi-cathode DC electron gun. The results will give guidance to the actual design in the future., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan