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Akiyama T, Kawahata K, Tanaka K, Tokuzawa T, Ito Y, Okajima S, Nakayama K, Michael CA, Vyacheslavov LN, Sanin A, Tsuji-Iio S. Interferometer Systems on LHD. Fusion Science and Technology 2017. [DOI: 10.13182/fst10-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- T. Akiyama
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - K. Kawahata
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - K. Tanaka
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - T. Tokuzawa
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - Y. Ito
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - S. Okajima
- Chubu University, Kasugai 487-8501, Japan
| | | | - C. A. Michael
- Culham Science Centre, Oxfordshire OX14 3DB, United Kingdom
| | | | - A. Sanin
- Budker Institute of Nuclear Physics, 630090, Novosibirsk, Russia
| | - S. Tsuji-Iio
- Tokyo Institute of Technology, Meguro 152-8550, Japan
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Hatakeyma S, Yoshino F, Tsutsui H, Tsuji-Iio S. Flywheel induction motor-generator for magnet power supply in small fusion device. Rev Sci Instrum 2016; 87:043509. [PMID: 27131676 DOI: 10.1063/1.4945799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A flywheel motor-generator (MG) for the toroidal field (TF) coils of a small fusion device was developed which utilizes a commercially available squirrel-cage induction motor. Advantages of the MG are comparably-long duration, quick power response, and easy implementation of power control compared with conventional capacitor-type power supply. A 55-kW MG was fabricated, and TF coils of a small fusion device were energized. The duration of the current flat-top was extended to 1 s which is much longer than those of conventional small devices (around 10-100 ms).
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Affiliation(s)
- S Hatakeyma
- Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - F Yoshino
- Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - H Tsutsui
- Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - S Tsuji-Iio
- Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
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Nagayama Y, Kuwahara D, Yoshinaga T, Hamada Y, Kogi Y, Mase A, Tsuchiya H, Tsuji-Iio S, Yamaguchi S. Development of 3D microwave imaging reflectometry in LHD (invited). Rev Sci Instrum 2012; 83:10E305. [PMID: 23126965 DOI: 10.1063/1.4729259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Three-dimensional (3D) microwave imaging reflectometry has been developed in the large helical device to visualize fluctuating reflection surface which is caused by the density fluctuations. The plasma is illuminated by the probe wave with four frequencies, which correspond to four radial positions. The imaging optics makes the image of cut-off surface onto the 2D (7 × 7 channels) horn antenna mixer arrays. Multi-channel receivers have been also developed using micro-strip-line technology to handle many channels at reasonable cost. This system is first applied to observe the edge harmonic oscillation (EHO), which is an MHD mode with many harmonics that appears in the edge plasma. A narrow structure along field lines is observed during EHO.
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Affiliation(s)
- Y Nagayama
- National Institute for Fusion Science, Toki, Japan
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Yoshinaga T, Nagayama Y, Kuwahara D, Tsuchiya H, Yamaguchi S, Kogi Y, Tsuji-Iio S, Mase A. Simultaneous projection and detection system of four different frequencies for microwave imaging reflectometry in Large Helical Device. Rev Sci Instrum 2010; 81:10D915. [PMID: 21033947 DOI: 10.1063/1.3491197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A simultaneous projection/detection system of four different frequencies for microwave imaging reflectometry (MIR) was developed for three-dimensional observation of electron density fluctuations in the Large Helical Device (LHD). The microwave with four frequency components at 60.410, 61.808, 63.008, and 64.610 GHz is projected in a continuous-wave mode to illuminate the target LHD plasma. A two-dimensional horn-antenna mixer array (2D HMA) receives the reflected wave from the plasma as well as the wave from the local oscillator operating at 55.800 GHz. The first intermediate frequency (IF) signals at 4.610, 6.008, 7.208, and 8.810 GHz were confirmed to be obtained by downconversion of these microwaves using the 2D HMA. Each of these first IF components is filtered from each other and downconverted again for the superheterodyne detection. It was confirmed that both the amplitudes and the phases of the detected signals reflect the fluctuations in LHD plasmas.
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Affiliation(s)
- T Yoshinaga
- National Institute for Fusion Science, 322-6 Oroshi, Toki 509-5292, Japan.
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Kuwahara D, Tsuji-Iio S, Nagayama Y, Yoshinaga T, Tsuchiya H, Sugito S, Yamaguchi S, Kogi Y, Akaki K, Mase A. Development of electron cyclotron emission imaging system on Large Helical Device. Rev Sci Instrum 2010; 81:10D919. [PMID: 21033951 DOI: 10.1063/1.3491223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A combined system of microwave imaging reflectometry and electron cyclotron emission (ECE) imaging has been developed for the Large Helical Device. This system includes a wide-band two-dimensional horn-antenna mixer array (HMA). The HMA consists of horn antennas, waveguides, mixers, and intermediate frequency circuits. The frequency response of the HMA is between 50 and 110 GHz. The ECE signal is selected using a 95 GHz local oscillator and a 93 GHz high-pass filter.
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Affiliation(s)
- D Kuwahara
- Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8550, Japan.
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Mimata H, Tani K, Tobita K, Tsutsui H, Tsuji-Iio S, Shimada R. Finite Larmor radius effects on ripple diffusion in tokamaks. Progress in Nuclear Energy 2008. [DOI: 10.1016/j.pnucene.2007.11.071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Akiyama T, Kawahata K, Ashikawa N, Tokitani M, Okajima S, Nakayama K, Yoshida N, Ebihara A, Tokunaga K, Ohtawa Y, Tsuji-Iio S. Changes of optical properties of retroreflector installed in LHD. Rev Sci Instrum 2007; 78:103501. [PMID: 17979413 DOI: 10.1063/1.2786938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
This article describes changes of optical properties of retroreflectors installed on the inner wall of the vacuum vessel of the Large Helical Device. They were made of stainless steel and were used for a CO(2) laser polarimeter. The reflectivity for a CO(2) laser beam dropped up to 40% after the start of glow discharge cleanings and main plasma experiments. Then it decreased gradually. The reflectivity in a wavelength range shorter than 10 mum decreased significantly through one experimental campaign (about 4 months). On the other hand the reflectivity in a wavelength range longer than 50 mum was larger than 70%. Decrease in the reflectivity in the central region of mirrors was more significant (the reflectivity for visible beams became almost zero) than that in the edge. The distribution of the reflectivity along the radial direction is expected to be related to the shape of the retroreflector. The parallelism of the reflected beam to an incident one also deteriorated. The changes in the polarization angle and in the ellipticity of reflected light polarization were not observed from the visible to the far infrared range.
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Affiliation(s)
- T Akiyama
- National Institute for Fusion Science, 322-6 Oroshi-cho, Toki-shi, Gifu 509-5292, Japan.
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Shimomura K, Takenaga H, Tsutsui H, Mimata H, Tsuji-Iio S, Miura Y, Tani K, Kubo H, Sakamoto Y, Hiratsuka H, Ichige H, Sueoka M, Kawamata Y, Sakamoto R, Kobayashi S, Shimada R. Burn control simulation experiments in JT-60U. Fusion Engineering and Design 2007. [DOI: 10.1016/j.fusengdes.2007.07.059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Tsutsui H, Nomura S, Tsuji-Iio S, Shimada R. Conceptual design of spherical torus with TF–CS hybrid coils based on virial theorem. Fusion Engineering and Design 2005. [DOI: 10.1016/j.fusengdes.2005.06.244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Tsutsui H, Ito T, Nakayama K, Nomura S, Tsuji-Iio S, Shimada R. Design of compact high field tokamak based on virial theorem. Fusion Engineering and Design 2003. [DOI: 10.1016/s0920-3796(03)00319-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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