Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Nagayama, Shota; Kinsho, Michikazu; Harada, Hiroyuki; Yamada, Ippei; Chimura, Motoki; Kojima, Kunihiro; Yamamoto, Kazami; Shimogawa, Tetsushi*; Sato, Atsushi*
Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.1025 - 1028, 2025/11
Slow extraction method of synchrotrons is used in nuclear and particle physics experiments, radiation therapy, and many other applications. In the slow extraction process, beam loss at the septum electrode, which separates the extracted beam from the circumferential side, induces activation and damage to the device. To solve this problem, we have devised an electric field measurement device named "Beam separation test device" to evaluate the two-dimensional electric field distribution of the nondestructive electrostatic septum that we are developing. The device consists of a prototype septum, horizontal and vertical wire scanners, and an electron gun installed on a movable stage fixed to a drive unit. This device measures the electric field by injecting an electron beam into the electric field and measuring the bending angle of the beam orbit. In developing this device, an additional optics system was designed to make a narrow electron beam to improve the measurement accuracy of the electric field distribution. In addition, we designed a beam dump that reduces secondary electron emission by utilizing energy loss when particles collide with materials. According to calculations of secondary electron emission, this beam dump can reduce secondary-emission into the chamber by up to 98%.
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.
Nagayama, Shota; Harada, Hiroyuki; Shimogawa, Tetsushi*; Yamada, Ippei; Chimura, Motoki; Yamamoto, Kazami; Kinsho, Michikazu
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.503 - 507, 2023/01
Synchrotron accelerators realize physics experiments and radiation cancer treatment using the slow extraction technique, in which beams are stored in the ring and gradually delivered. We have devised and are currently developing a "non-destructive electrostatic septum" based on a new method, which in principle cannot be solved by conventional methods and is a cause of equipment failure and output limitation. It is ideal to generate a force distribution similar to a staircase function with discontinuous gaps at the boundary. In this presentation, we will show the calculation method for optimizing the electrode and wire configuration to generate a Lorentz force with a distribution similar to a staircase function in vacuum, and the calculation results of the beam breakup due to the generated Lorentz force. The compact proof-of-principle machine developed for the ongoing demonstration of this method will also be introduced.
Shimogawa, Tetsushi*; Harada, Hiroyuki
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1156 - 1158, 2019/07
A particle beam from accelerators has been applied not only to physics experiments but also medical applications. In the slow extraction which extract beam from a synchrotron during a large number of turns, the accelerated beam is blown up and extracted by the electrostatic septum. The septum consists of electrode and septum for separating between extraction and circulating beam. Generally, the wire and plate are used for septum. In this case, the beam hits on septum. Consequently, the extraction efficiency and the beam power are limited. We propose the non-destructive electrostatic septum. The multiple electrodes arrange surround the beam and produce the electric field for separation and deflect the beam. There are no materials in the beam orbit area. This will be reported introduction of our proposed non-destructive electrostatic septum.
Zhang, B.*; Harada, Tetsushi*; Hirahara, Daisuke*; Matsumoto, Tatsuya*; Morita, Koji*; Fukuda, Kenji*; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu
Nuclear Engineering and Design, 241(1), p.366 - 377, 2011/01
Times Cited Count：37 Percentile：91.09(Nuclear Science & Technology)Zhang, B.*; Harada, Tetsushi*; Hirahara, Daisuke*; Matsumoto, Tatsuya*; Morita, Koji*; Fukuda, Kenji*; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu
Journal of Nuclear Science and Technology, 47(4), p.384 - 395, 2010/04
Times Cited Count：40 Percentile：90.93(Nuclear Science & Technology)Zhang, B.*; Harada, Tetsushi*; Hirahara, Daisuke*; Matsumoto, Tatsuya*; Morita, Koji*; Fukuda, Kenji*; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu
Proceedings of 13th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-13) (CD-ROM), 15 Pages, 2009/09
Although the decay heat from fuel debris drives the coolant boiling in fast reactor accident conditions, the present experiments were conducted by employing depressurization boiling of water to simulate axially increasing void distribution in a debris bed instead of conventional heating or gas injection from the debris bottom. Good agreements on self-leveling occurrence were obtained between model predictions and experimental results. Extrapolation of the present model was also discussed against reactor conditions.
Zhang, B.*; Harada, Tetsushi*; Hirahara, Daisuke*; Matsumoto, Tatsuya*; Morita, Koji*; Fukuda, Kenji*; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu
Proceedings of 6th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-6) (USB Flash Drive), 8 Pages, 2008/11
In the present study, characteristics of self-leveling behaviors were investigated experimentally with simulant materials. The present experiments employed depressurization boiling of water to simulate axially increasing void distribution in a debris bed, which consists of solid particles of alumina or lead with different density. The particle size (from 0.5 mm to 6 mm in diameter) and shape (spherical or non-spherical particles) were also taken as experimental parameters. A rough criteria for self-leveling occurrence is proposed and compared with the experimental results.
Fukahori, Tokio; Kunieda, Satoshi; Chiba, Satoshi; Harada, Hideo; Nakashima, Hiroshi; Mori, Takamasa; Shimakawa, Satoshi; Maekawa, Fujio; Watanabe, Yukinobu*; Shigyo, Nobuhiro*; et al.
no journal, ,
The latest version of JENDL High Energy File (JENDL/HE) and JENDL Photonuclear Data File (JENDL/PD) is being planed to be released as JENDL/HE-2007 and JENDL/PD-2007. In JENDL/HE-2007, nuclear data for about 100 nuclides, which are newly ecaluated and revised from JENDL/HE-2004 will be stored. The JENDL/PD-2007 will have nuclear data for about 170 nuclides.
Nagayama, Shota; Harada, Hiroyuki; Shimogawa, Tetsushi*; Sato, Atsushi*; Yamada, Ippei; Chimura, Motoki; Kojima, Kunihiro; Yamamoto, Kazami; Kinsho, Michikazu
no journal, ,
no abstracts in English
Harada, Tetsushi*; Hirahara, Daisuke*; Zhang, B.*; Matsumoto, Tatsuya*; Morita, Koji*; Fukuda, Kenji*; Suzuki, Toru; Yamano, Hidemasa; Tobita, Yoshiharu
no journal, ,
no abstracts in English
Nagayama, Shota; Harada, Hiroyuki; Shimogawa, Tetsushi*; Sato, Atsushi*; Yamada, Ippei; Chimura, Motoki; Kojima, Kunihiro; Yamamoto, Kazami; Kinsho, Michikazu
no journal, ,
no abstracts in English
