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A 2998MHz, 60MW klystron has been developed for future linear accelerators of synchrotron radiation sources. In order to save development and construction time, the 2998MHz, 60MW klystron is a modified version of an existing 2856MHz klystron used in linear accelerator of Beijing Electron-Positron Collider II. Based on the simulations, it was shown that the scaled version klystron was able to produce more than 60MW at a 350kV beam voltage. A prototype was built and tested. It successfully produced 50MW output power with an RF pulse width of 4.0ms, which exceeded the operating requirement of China's High Energy Photon Source. It also produced 62MW with an RF pulse width of 1.6ms, which proved the validity of new RF circuit design. This paper describes the details of the progresses of this klystron and advantages of this tube development.

Modern accelerators are based on the rf technology and the klystron is the one of key components. Some special accelerator projects require their specified klystrons i.e., project-oriented klystrons. In this paper, project-oriented klystron developments for a decade in Japan are described. Related projects are ILC, cERL and SKEKB. Usually klystron is very expensive but has a finite life and needs to procure again. Trial to introduce the compatible tubes and have a competitive tender to reduce the cost is described. At the same time, since an efficiency improvement is one of the recent trend, such an attempt is also presented. International klystron collaboration among the Asian countries has been performed for a long time. In this paper, collaboration with China and India is introduced. Since topics are covered mainly author’s experience, related counties described are limited.

Radio frequency windows are developed and evaluated for a 650 MHz continuous-wave multibeam klystron. Thin-pillbox windows with alumina and beryllia disks are designed with an average RF power of CW 400 kW. Results of a cold test and tuning procedures are described. The final measured S11 curves under the required bandwidth are less than − 32.0 and − 26.9 dB for alumina and beryllia windows, respectively. The windows are tested up to CW 143 kW for traveling waves and CW 110 kW for standing waves using a solid-state amplifier as an RF power source. Multipactor simulations for windows and benchmark studies for the thermal analysis of ceramic disks are introduced.

An optical absorption study has been made on electrons trapped in alcohol clusters in γ-irradiated 1-propanol (PrOH) – 2,2,4-trimethylpentane (TMP) – 2,2-dimethylbutane (DMB), 1-butanol (BuOH) – TMP – DMB, and 1-pentanol (PnOH) –– TMP – DMB mixture glasses at 77 K. Hitherto electron transfer from the hydrocarbon region into alcohol clusters has been known to be a major process for formation in γ-irradiated alcohol–hydrocarbon glasses. However, in the present systems of PrOH–TMP–DMB, BuOH–TMP–DMB, and PnOH–TMP–DMB, this type of electron transfer was not observed and the formation was found to result only from the direct radiolysis of alcohols. In the alcohol concentration range lower than 0.2 electron fraction the yields of are less than those expected from the direct radiolysis of alcohols. The average number of alcohol molecules in a cluster in these systems is estimated to be four in the lower alcohol concentration range studied. The position of the absorption maxima for in these systems is constant within experimental uncertainties independent of alchohol concentration, which is consistent with the results of a semicontinuum model calculation.

The antiferroelectric properties and energy storage performance of (Pb0.02,Y0.98)(Sn x ,Zr1[?] x )O3 (0 [?] x [?] 0.6) thin films fabricated by chemical solution deposition (CSD) were investigated. The recoverable energy storage density U reco linearly decreased from 15.9 J/cm3 at x = 0 to 8.5 J/cm3 at x = 60 at. %. The energy storage efficiency e increased with increasing x up to 40 at. % and showed a maximum of 68.4% at x = 20 at. %. Time domain measurements of the charge response induced by an electric field pulse were performed to evaluate the energy performance of charging and discharging processes. The average discharging power density after applying E = 380 kV/cm was 4.4 kW/cm3 and the maximum discharging power density was evaluated to be 740 kW/cm3. The Sn-substituted (Pb,Y)(Sn x ,Zr)O3 thin films showed a well-defined antiferroelectric property and the 20 at. % Sn-substituted thin film exhibited great energy performance in this study.