電気学会論文誌A(基礎・材料・共通部門誌)
Online ISSN : 1347-5533
Print ISSN : 0385-4205
ISSN-L : 0385-4205
最新号
選択された号の論文の8件中1~8を表示しています
論文
  • Keita Tamura, Masafumi Muraji, Kenji Tanaka, Tatsuru Shirafuji
    2019 年 139 巻 8 号 p. 339-344
    発行日: 2019/08/01
    公開日: 2019/08/01
    ジャーナル 認証あり

    We observed the temperature dependence of nonlinearity in the response waveform from a yeast suspension when an alternating current (AC) voltage was applied. This observation is based on repeatable data of nonlinearity measured over time. The nonlinearity in the response of the living yeast suspension was unique, and a relationship between this nonlinearity and the growth state of yeast was identified. We suggest that this nonlinearity reflects the electrical properties inherent in living organisms. Measuring the nonlinearity of the yeast suspension response and accounting for temperature permits us to rapidly distinguish between living and dead yeast. Moreover, we found that the nonlinearity depended on the shape of the electrodes. For each electrode shape, we investigated the effects of field intensity and its distortion on the nonlinearity of the response using a computer simulation. We suggest that the nonlinearity is strongly related to the field intensity and its distortion near the electrodes.

  • 田川 亨, 山下 智彦, 佐久川 貴志, 勝木 淳, 福田 憲司, 坂本 邦博
    2019 年 139 巻 8 号 p. 345-350
    発行日: 2019/08/01
    公開日: 2019/08/01
    ジャーナル 認証あり

    Pulsed power generator using semiconductor switches have been developed. We have developed switching module using discrete type Silicon Carbide (SiC) Device for pulsed power circuit. We compare the switching module using SiC-MOSFETs with conventional module using IGBTs. Both of switching devices the switching loss increased when the voltage get higher. The switching module using SiC-MOSFETs can input higher voltage and has less switching loss in same input voltage. Also, we have investigate the switching loss depend on di/dt at switching. The permissible di/dt of SiC-MOSFETs were higher than IGBTs. However, there is a limit to the value of permissible di/dt. The loss in this module is reduced by applying magnetic assist. The advantage of SiC-MOSFET was confirmed in switching for pulsed power.

  • 佐藤 正寛, 熊田 亜紀子, 日高 邦彦
    2019 年 139 巻 8 号 p. 351-357
    発行日: 2019/08/01
    公開日: 2019/08/01
    ジャーナル 認証あり

    Recently, we have developed a first-principles based multi-scale modeling approach for computing the carrier mobilities in polymeric dielectric. In this work, time-of-flight transient current waveforms are simulated without adopting empirical or phenomenological models. Our calculations demonstrate that dispersive charge transport takes place in thin polyethylene films, and in line with experimental findings, the simulated current waveforms exhibit a peak, plateau, and a long tail. Dispersive transient currents in insulating polymers are often interpreted in terms of semi-phenomenological Scher-Montroll theory, owing to the somewhat satisfactory fitting to the experimental data. We show that even though the underlying assumption in the model is not fulfilled, the simulated current waveforms “happen to” obey the universality predicted by the Scher-Montroll theory as observed in experiments. Since, current waveforms have more information than the carrier mobilities, we believe that our computational approach will provide a more detailed understanding and insights on the carrier transfer properties in amorphous insulating polymers.

研究開発レター
  • 田中 遥暁, 小野 靖, 田辺 博士, 曹 慶紅
    2019 年 139 巻 8 号 p. 358-359
    発行日: 2019/08/01
    公開日: 2019/08/01
    ジャーナル 認証あり

    Global 2D characteristics of reconnection heating were investigated by an upgraded 2D ion Doppler tomography diagnostics in TS-6 tokamak merging experiment. The new system, which covers the whole area of two merging flux tubes, successfully detects a global structure formation due to balanced amount of a field-aligned motions of ions in the downstream. Under the influence of high toroidal field, the high T𝑖 area expands along the closed flux surface of the reconnected field lines because the ratio of parallel/perpendicular heat diffusivety 𝑥/𝑥 ∼ 2(ω𝑐𝑖τ𝑖𝑖)2 is higher than 10. The improvement of transport coefficient with high toroidal field strongly suppresses the perpendicular heat conduction and finally makes a globally hollow ion temperature profile.

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