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Ejiri A, Oosako T, Tsujimura J, Shimada Y, Takase Y, Torii Y, Sasaki M, Tojo H, Masuda T, Nuga H, Sumitomo N, Kainaga S, Sugiyama J, Tsujii N. ECH and HHFW Start-Up Experiments on the TST-2 Spherical Tokamak. Fusion Science and Technology 2017. [DOI: 10.13182/fst07-a1341] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [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)
- A. Ejiri
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - T. Oosako
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - J. Tsujimura
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - Y. Shimada
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - Y. Takase
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - Y. Torii
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - M. Sasaki
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - H. Tojo
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - T. Masuda
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - H. Nuga
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - N. Sumitomo
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - S. Kainaga
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - J. Sugiyama
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
| | - N. Tsujii
- Grad. School of Frontier Sciences and Grad. School of Science, the Univ. Tokyo, Kashiwa 277-8561, Japan
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Furui H, Nagashima Y, Takase Y, Ejiri A, Kakuda H, Sonehara M, Oosako T, Tsujii N, Hiratsuka J, Imamura K, Inada T, Nakamura K, Nakanishi A, Shinya T, Togashi H, Tsuda S, Wakatsuki T, Yamaguchi T. Local current density measurement using a Rogowski probe in Tokyo Spherical Tokamak-2. Rev Sci Instrum 2014; 85:11D813. [PMID: 25430226 DOI: 10.1063/1.4887277] [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: 06/04/2023]
Abstract
A Rogowski probe consisting of a small multi-layer Rogowski coil, five magnetic pick-up coils, and a Langmuir probe was developed to measure the local current density and its direction. It can be moved along the major radius and can be turned around its axis. This probe was used to measure the current density profile near the last closed flux surface of Ohmic plasmas in Tokyo Spherical Tokamak-2. The current density profile was measured successfully with a signal to noise ratio of greater than 20.
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Affiliation(s)
- H Furui
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Y Nagashima
- Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8680, Japan
| | - Y Takase
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - A Ejiri
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - H Kakuda
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - M Sonehara
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - T Oosako
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - N Tsujii
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - J Hiratsuka
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - K Imamura
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - T Inada
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - K Nakamura
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - A Nakanishi
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - T Shinya
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - H Togashi
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - S Tsuda
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - T Wakatsuki
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - T Yamaguchi
- The University of Tokyo, 5-1-5 Kasshiwanoha, Kashiwa, Chiba 277-8561, Japan
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Togashi H, Ejiri A, Hiratsuka J, Nakamura K, Takase Y, Yamaguchi T, Furui H, Imamura K, Inada T, Kakuda H, Nakanishi A, Oosako T, Shinya T, Sonehara M, Tsuda S, Tsujii N, Wakatsuki T, Hasegawa M, Nagashima Y, Narihara K, Yamada I, Tojo H. Demonstration of improvement in the signal-to-noise ratio of Thomson scattering signal obtained by using a multi-pass optical cavity on the Tokyo Spherical Tokamak-2. Rev Sci Instrum 2014; 85:11D846. [PMID: 25430259 DOI: 10.1063/1.4891707] [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: 06/04/2023]
Abstract
The multi-pass Thomson scattering (TS) scheme enables obtaining many photons by accumulating multiple TS signals. The signal-to-noise ratio (SNR) depends on the accumulation number. In this study, we performed multi-pass TS measurements for ohmically heated plasmas, and the relationship between SNR and the accumulation number was investigated. As a result, improvement of SNR in this experiment indicated similar tendency to that calculated for the background noise dominant situation.
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Affiliation(s)
- H Togashi
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - A Ejiri
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - J Hiratsuka
- Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - K Nakamura
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - Y Takase
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - T Yamaguchi
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - H Furui
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - K Imamura
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - T Inada
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - H Kakuda
- Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - A Nakanishi
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - T Oosako
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - T Shinya
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - M Sonehara
- Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - S Tsuda
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - N Tsujii
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
| | - T Wakatsuki
- Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - M Hasegawa
- Research Institute of Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
| | - Y Nagashima
- Research Institute of Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
| | - K Narihara
- Research Institute of Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
| | - I Yamada
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - H Tojo
- Japan Atomic Energy Agency, Naka 311-0193, Japan
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Togashi H, Ejiri A, Hiratsuka J, Nakamura K, Takase Y, Yamaguchi T, Furui H, Imamura K, Inada T, Kakuda H, Nakanishi A, Oosako T, Shinya T, Sonehara M, Tsuda S, Tsujii N, Wakatsuki T, Hasegawa M, Nagashima Y, Narihara K, Yamada I, Tojo H. Note: Multi-pass Thomson scattering measurement on the TST-2 spherical tokamak. Rev Sci Instrum 2014; 85:056103. [PMID: 24880428 DOI: 10.1063/1.4878260] [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: 06/03/2023]
Abstract
In multi-pass Thomson scattering (TS) scheme, a laser pulse makes multiple round trips through the plasma, and the effective laser energy is enhanced, and we can increase the signal-to-noise ratio as a result. We have developed a coaxial optical cavity in which a laser pulse is confined, and we performed TS measurements using the coaxial cavity in tokamak plasmas for the first time. In the optical cavity, the laser energy attenuation was approximately 30% in each round trip, and we achieved a photon number gain of about 3 compared with that obtained in the first round trip. In addition, the temperature measurement accuracy was improved by accumulating the first three round trip waveforms.
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Affiliation(s)
- H Togashi
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - A Ejiri
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - J Hiratsuka
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - K Nakamura
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - Y Takase
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - T Yamaguchi
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - H Furui
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - K Imamura
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - T Inada
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - H Kakuda
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - A Nakanishi
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - T Oosako
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - T Shinya
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - M Sonehara
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - S Tsuda
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - N Tsujii
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - T Wakatsuki
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - M Hasegawa
- Kyushu University, Kasuga 816-8580, Japan
| | | | - K Narihara
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - I Yamada
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - H Tojo
- Japan Atomic Energy Agency, Naka 311-0193, Japan
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Kasahara H, Seki T, Kumazawa R, Saito K, Mutoh T, Kubo S, Shimozuma T, Igami H, Yoshimura Y, Takahashi H, Yamada I, Tokuzawa T, Ohdachi S, Morita S, Nomura G, Shimpo F, Komori A, Motojima O, Oosako T, Takase Y, Zhao Y, Kwak J. The observation of nonlinear ion cyclotron wave excitation during high-harmonic fast wave heating in the large helical device. Rev Sci Instrum 2008; 79:10E722. [PMID: 19044539 DOI: 10.1063/1.2973325] [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: 05/27/2023]
Abstract
A wave detector, a newly designed magnetic probe, is installed in the large helical device (LHD). This wave detector is a 100-turn loop coil with electrostatic shield. Comparing a one-loop coil to this detector, this detector has roughly constant power coupling in the lower frequency range of 40 MHz, and it can easily detect magnetic wave in the frequency of a few megahertz. During high-harmonic fast wave heating, lower frequency waves (<10 MHz) were observed in the LHD for the first time, and for the power density threshold of lower frequency wave excitation (7.5 MHz) the power density of excited pumped wave (38.47 MHz) was approximately -46 dBmHz. These lower frequencies are kept constant for electron density and high energy particle distribution, and these lower frequency waves seem to be ion cyclotron waves caused by nonlinear wave-particle interaction, for example, parametric decay instability.
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Affiliation(s)
- H Kasahara
- National Institute for Fusion Science, Toki 509-5292, Japan.
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Adachi Y, Ejiri A, Takase Y, Watanabe O, Oosako T, Tojo H, Kainaga S, Masuda T, Sasaki M, Sugiyama J, Yamaguchi T. Detection of a new parametric decay instability branch in TST-2 during high harmonic fast wave heating. Rev Sci Instrum 2008; 79:10F507. [PMID: 19044652 DOI: 10.1063/1.2955574] [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: 05/27/2023]
Abstract
Parametric decay instability (PDI) is often observed in the TST-2 spherical tokamak during high harmonic fast wave heating by rf pickup probes. The frequency spectrum exhibits lower and upper sideband peaks in addition to the pump wave at f(0)=21 MHz. Two types of PDI are observed. One is the well-known decay into the ion-cyclotron quasimode (nf(ci)) and the ion Bernstein wave (f(0)-nf(ci)). The other is a newly found decay with the sideband frequency between f(0) and f(0)-f(ci). The frequency difference between this sideband and the pump increases in proportion to B(t). Moreover, high-speed visible light measuring systems with photomultiplier tubes or hybrid photodetectors viewing the plasma core detected oscillation of light emission at around f(0).
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Affiliation(s)
- Y Adachi
- The University of Tokyo, Kashiwa 277-8561, Japan.
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Yamada T, Ejiri A, Shimada Y, Oosako T, Tsujimura J, Takase Y, Kasahara H. Direct measurement of density oscillation induced by a radio-frequency wave. Rev Sci Instrum 2007; 78:083502. [PMID: 17764321 DOI: 10.1063/1.2769351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
An O-mode reflectometer at a frequency of 25.85 GHz was applied to plasmas heated by the high harmonic fast wave (21 MHz) in the TST-2 spherical tokamak. An oscillation in the phase of the reflected microwave in the rf range was observed directly for the first time. In TST-2, the rf (250 kW) induced density oscillation depends mainly on the poloidal rf electric field, which is estimated to be about 0.2 kV/m rms by the reflectometer measurement. Sideband peaks separated in frequency by ion cyclotron harmonics from 21 MHz, and peaks at ion cyclotron harmonics which are suggested to be quasimodes generated by parametric decay, were detected.
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Affiliation(s)
- T Yamada
- Research Institute for Applied Mechanics, Kyushu University, Kasuga, Japan.
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Masuda A, Saito Y, Sato T, Oosako T, Fukunaka M, Nonoyama A, Kagawa T. [Chronic pulmonary embolism--report of a successfully embolectomized case with reference to collective review of the literature]. Nihon Kyobu Geka Gakkai Zasshi 1984; 32:1886-92. [PMID: 6520458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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