http://hdl.handle.net/10098/1223 2013-05-23T08:09:25Z http://hdl.handle.net/10098/7324 タイトル: 高強度テラヘルツ電磁波を用いた半導体超格子の伝導制御 著者: 平川, 一彦 2012-06-01T00:00:00Z http://hdl.handle.net/10098/7323 タイトル: フラストレートしたデルタ鎖化合物ユークロアイトのスピンギャップ 著者: KIKUCHI, Hikomitsu; FUJII, Yutaka; TAKAHASHI, Daisuke; AZUMA, Masaki; SHIMAKAWA, Yuichi; TANIGUCHI, Toshifumi; MATSUO, Akira; KINDO, Koichi 抄録: We find Cu2(AsO4)(OH)·3H2O (euchroite) is a model compound for the frustrated delta chain which is composed of corner-sharing triangles. Magnetic susceptibility, specific heat, high field magnetization and 1H-NMR measurements are carried out using natural mineral samples of euchroite to study magnetic properties. Large spin gap of about 100 K is shown to be presented　in this compound. 2011-06-01T00:00:00Z http://hdl.handle.net/10098/6967 タイトル: formation of a laminar electron flow for 300GHz high-power pulsed gyrotron 著者: YAMAGUCHI, Yuusuke; TATEMATSU, Yoshinori; SAITO, Teruo; IKEDA, Ryosuke; MUDIGANTI, Jagadish C.; OGAWA, Isamu; IDEHARA, Toshitaka 抄録: This paper describes the design of a triode magnetron injection gun for use in a 200 kW, 300 GHz gyrotron. As power and frequency increase, the performance of the gyrotron becomes quite sensitive to the quality of the electron beam. Formation of a laminar electron flow is essential for the realization of a high quality beam with a small velocity spread. In this study, a new method is developed for a quantitative evaluation of the laminarity and is applied to optimize the electrode design. The laminarity depends not only on conventional design parameters such as the cathode slant angle but also on the spatial distribution of the electric field along the beam trajectory. In the optimized design, the velocity pitch factors, a, larger than 1.2 are obtained at 65 kV, 10A with spreads, Da, less than 5%. 2012-11-01T00:00:00Z http://hdl.handle.net/10098/6937 タイトル: Formation of Laminar Electron Flow for a High-Power Sub-THz Gyrotron 著者: YAMAGUCHI, Yuusuke; TATEMATSU, Yoshinori; SAITO, Teruo; IKEDA, Ryosuke; MUDIGANTI, Jagadish C.; OGAWA, Isamu; IDEHARA, Toshitaka 抄録: This paper describes the design of a magnetron-injection gun for a 100kW, 300 GHz gyrotron. With an increase in power and frequency, performance of the gyrotron becomes quite sensitive to the quality of the electron beam. Formation of a laminar electron flow is essential for the realization of a high quality beam with small velocity spread. In this study, a new method is proposed for the evaluation of the laminarity, and applied to the design optimization of the electrodes. It is found that the laminarity depends not only on the conventional design parameter of the cathode slant angle, but also on the spatial distribution of the electric field inside the beam. 2012-01-01T00:00:00Z