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Nagayama, Shota; Harada, Hiroyuki; Shimogawa, Tetsushi*; Sato, Atsushi*; Yamada, Ippei; Chimura, Motoki; Kojima, Kunihiro; Yamamoto, Kazami; Kinsho, Michikazu
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.526 - 530, 2023/11
We have been developing "Non-destructive electrostatic septum" for a slow extraction. This septum has multiple electrodes placed around the region without the beam hitting and separate the beam by its electric field. To evaluate its electric field, we have built a prototype septum and a test machine, which consists of an electron gun and monitors. This test machine can measure the electric field indirectly by using a narrow electron beam. The experiment results of prototype septum is good agreement with the calculation one. However, this electric field distribution is not enough to separate the beam. A step function-like electric field distribution is ideal for the beam separation with minimal negative effect on the beam. We have studied to improve the electrode configuration to match the beam shape. In this paper, we present the result of the electric field measurements and the septum improvement. Additionally, we describe the future plan of this development.
Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Nishimura, Koji*; Hashimoto, Taishi*; Tanaka, Yoshimasa*; Kadokura, Akira*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Ogawa, Yasunobu*; et al.
Journal of Space Weather and Space Climate (Internet), 12, p.18_1 - 18_16, 2022/06
Times Cited Count：1 Percentile：22.72(Astronomy & Astrophysics)We identified two energetic electron precipitation (EEP) events during the growth phase of moderate substorms and estimated the mesospheric ionization rate for an EEP event for which the most comprehensive dataset from ground-based and space-born instruments was available. The mesospheric ionization signature reached below 70 km altitude and continued for ~15 min until the substorm onset, as observed by the PANSY radar and imaging riometer at Syowa Station in the Antarctic region. We also used energetic electron flux observed by the Arase and POES 15 satellites as the input for the air-shower simulation code PHITS to quantitatively estimate the mesospheric ionization rate. Combining the cutting-edge observations and simulations, we shed new light on the space weather impact of the EEP events during geomagnetically quiet times, which is important to understand the possible link between the space environment and climate.
-ray for improvement neutron emission profile measurementUchida, Yuki*; Takada, Eiji*; Fujisaki, Akihiro*; Isobe, Mitsutaka*; Ogawa, Kunihiro*; Shinohara, Koji; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*
Review of Scientific Instruments, 85(11), p.11E118_1 - 11E118_4, 2014/11
Times Cited Count：9 Percentile：40.01(Instruments & Instrumentation)Shiihara, Katsunori*; Makino, Yoshinobu*; Ogawa, Tsuyoshi*; Asai, Satoru*; Kanahara, Toshio*; Senda, Ikuo*; Okuno, Kiyoshi; Koizumi, Norikiyo; Matsui, Kunihiro
Proceedings of 26th International Congress on Applications of Lasers & Electro-Optics (ICALEO 2007) (CD-ROM), p.316 - 324, 2007/10
The toroidal field coil is manufactured as one of superconducting coil systems in the ITER. For welding the cover plate of TF coil, the prevention of the thermal effect on the coil and the deformation of the whole coil are required. Moreover, the application of high efficient welding is required in consideration for the productivity. Therefore, laser-arc hybrid welding process was investigated for the application to the cover plate welding, because its process is superior in the tolerance of the joint gap and the ease of the control for the heat input. In the experiment, it was confirmed that the application of laser-arc hybrid welding with the double gas shielding for high concentration arc and the filler wire for controlling the deposit amount is effective in the joint gap up to 0.8mm. Besides, twin spot laser head with the arc was developed in order to weld the both sides of cover plate simultaneously. By the optimization of welding condition for twin spot laser-arc hybrid welding process, it was confirmed to be effective in the prevention of the gap movement during welding and the acquisition of the proper penetration without the weld defect. Finally, the effectiveness of laser-arc hybrid welding for the welding deformation and the weldability on the quality was verified by the scale model test with the actual shape.
Asai, Satoru*; Ogawa, Takeshi*; Makino, Yoshinobu*; Shiihara, Katsunori*; Senda, Ikuo*; Okuno, Kiyoshi; Koizumi, Norikiyo; Matsui, Kunihiro
no journal, ,
no abstracts in English
Ogawa, Tsuyoshi*; Asai, Satoru*; Makino, Yoshinobu*; Shiihara, Katsunori*; Senda, Ikuo*; Okuno, Kiyoshi; Koizumi, Norikiyo; Matsui, Kunihiro
no journal, ,
no abstracts in English
Asai, Satoru*; Ogawa, Tsuyoshi*; Makino, Yoshinobu*; Shiihara, Katsunori*; Senda, Ikuo*; Okuno, Kiyoshi; Koizumi, Norikiyo; Matsui, Kunihiro
no journal, ,
no abstracts in English
Hayashi, Shota*; Takada, Eiji*; Isobe, Mitsutaka*; Ogawa, Kunihiro*; Kawarabayashi, Jun*; Tomita, Hideki*; Iguchi, Tetsuo*; Sato, Satoshi
no journal, ,
no abstracts in English
Nakada, Naoki*; Takada, Eiji*; Isobe, Mitsutaka*; Ogawa, Kunihiro*; Nishitani, Takeo*; Iguchi, Tetsuo*; Tomita, Hideki*; Sato, Satoshi; Kawarabayashi, Jun*
no journal, ,
In order to measure the profile of the neutron generation in LHD at NIFS, we have developed the directional fast neutron detector based on scintillating optical fibers by using the forward direction of the probability of the recoil proton generation by the neutron and the scintillating optical fibers. We have enhanced the directional quality by optimizing the configuration of the scintillating optical fibers. In case 14 MeV neutrons were incident to the detector, we calculated the number of the energy deposition events with the energy of more than threshold value by PHITS. In case they were incident to the detector parallel, the number of the events at the rear part lessened due to the self-shielding. Even if the scintillating optical fiber was shortened, the angular dependency was not so changed. In case it was thin downed, it was found that the angular dependency was enhanced. We performed the neutron measurement experiment by using the developed detector and the DT neutron source at JAEA/FNS. The angular dependencies by the experiment were worse than those by the calculation. It is thought to be causally related to the high sensitivity to the -ray of the detector. In the future, we will redesign the detector for the neutron and -ray field in LHD.
