ITPA (International Tokamak Physics Activity) meeting report, 53

Kawano, Yasunori; Akiyama, Tsuyoshi*; Ishikawa, Masao; Isobe, Mitsutaka*; Itami, Kiyoshi; Ejiri, Akira*; Peterson, B.*

Purazuma, Kaku Yugo Gakkai-Shi, 92(2), P. 145, 2016/02

http://www.jspf.or.jp/Journal/PDF_JSPF/jspf2016_02/jspf2016_02-145.pdf

no abstracts in English

Development of instrumentation and control systems for the ITER diagnostic systems in JADA

Yamamoto, Tsuyoshi; Hashimoto, Yasunori*; Kitazawa, Sin-iti; Yatsuka, Eiichi; Hatae, Takaki; Sugie, Tatsuo; Ogawa, Hiroaki; Takeuchi, Masaki; Kawano, Yasunori; Itami, Kiyoshi

Fusion Engineering and Design, 96-97, p.1012 - 1016, 2015/10

https://doi.org/10.1016/j.fusengdes.2015.06.119

Japan Domestic Agency (JADA) is responsible for six diagnostic systems in the ITER project. We have successfully developed an instrumentation and control (I&C) system for the diagnostic systems. The I&C system manages internal operations for measurement such as health checks of sensors, configuration of measurement parameters, and consistency checks between measurement parameters. We developed a conversion tool to convert operational flowcharts to EPICS records. The sequencing management function coordinates the execution of operation steps by monitoring changes in the record values. It was designed so that the relationship between the records and steps is determined automatically according to the flowcharts as much as possible. We validated the performance of the I&C system for the thermocouple measurement system, and are continuing the development of even more complex I&C systems for other JADA diagnostic systems.

Meshless method for solving fixed boundary problem of plasma equilibrium

Imazawa, Ryota; Kawano, Yasunori; Itami, Kiyoshi

Journal of Computational Physics, 292, p.208 - 214, 2015/07

https://doi.org/10.1016/j.jcp.2015.03.035

no abstracts in English

Profile measurement of current density, electron density and electron temperature using laser polarimetry on burning plasma

Imazawa, Ryota; Kawano, Yasunori; Itami, Kiyoshi

Purazuma, Kaku Yugo Gakkai-Shi, 90(11), p.743 - 747, 2014/11

http://www.jspf.or.jp/Journal/PDF_JSPF/jspf2014_11/jspf2014_11-743.pdf

no abstracts in English

Magnification of a polarization angle with a Littrow layout brazed grating

Sasao, Hajime; Arakawa, Hiroyuki*; Kubo, Hirotaka; Kawano, Yasunori; Itami, Kiyoshi

Review of Scientific Instruments, 85(8), p.086106_1 - 086106_3, 2014/08

https://doi.org/10.1063/1.4892478

Role of the electron temperature in the current decay during disruption in JT-60U

Shibata, Yoshihide; Isayama, Akihiko; Matsunaga, Go; Kawano, Yasunori; Miyamoto, Seiji*; Lukash, V.*; Khayrutdinov, R.*; JT-60 Team

Plasma and Fusion Research (Internet), 9(Sp.2), p.3402084_1 - 3402084_5, 2014/06

https://doi.org/10.1585/pfr.9.3402084

We performed the disruption simulation using DINA code to investigate the effect of the electron temperature on the plasma current decay after the initial phase of current quench (CQ). In this calculation, we used the measured profile during the initial phase of CQ. After the initial phase of CQ, we assumed that the profile does not change in time and used the value at the end of the initial phase of current quench because profile could not be measured after the initial phase of CQ. From the simulation results, it was found that the time evolution of plasma current calculated by DINA was similar to experimental one in this calculation. However, the time evolution of profile in this calculation was different from the measured profile because Te after first mini-collapse rapidly decreased until the value below a measurement limit (less than 0.1 keV). Moreover, the time evolution of poloidal cross-section S calculated by DINA code was rapidly decreased although the experimental one was gradually decreased. The plasma current decay during the disruption is determined by various parameters, , and S. It is necessary to evaluate the effect of profile on the plasma current decay after the initial phase of CQ by using various assumed model and DINA code.

Progress of preparation for ITER divertor thermocouple in JADA

Kitazawa, Sin-iti; Yamamoto, Tsuyoshi; Kawano, Yasunori; Itami, Kiyoshi

Plasma and Fusion Research (Internet), 9(Sp.2), p.3405049_1 - 3405049_4, 2014/05

https://doi.org/10.1585/pfr.9.3405049

The Japan Domestic Agency (JADA) is scheduled to procure a divertor thermocouple (DTC) system for the divertor outer vertical targets in the ITER project. The DTC is a diagnostic device that will directly measure the surface temperature of the divertor, a plasma-facing component, and will be installed on the surface of the divertors which are in the scope of JADA procurement sharing. A thermocouple itself is a conventional device used for measuring temperature, however, for the DTC to be able to take highly reliable operation under the ultrahigh vacuum and high radiation field of the ITER environment. Therefore various advanced research and development is necessary. Development of the DTC control system, which is based on ITER standards, should also be performed since it is included within the scope of JADA procurement. In this presentation, we will show the current status of research & development on the DTC.

ITPA meeting report, 43

Kawano, Yasunori; Itami, Kiyoshi; Kawahata, Kazuo*; Kusama, Yoshinori; Sasao, Mamiko*; Peterson, B.*; Mase, Atsushi*

Purazuma, Kaku Yugo Gakkai-Shi, 90(2), P. 164, 2014/02

http://www.jspf.or.jp/Journal/PDF_JSPF/jspf2014_02/jspf2014_02-164.pdf

no abstracts in English

Effect of resistivity profile on current decay time of initial phase of current quench in neon-gas-puff inducing disruptions of JT-60U

Kawakami, Sho*; Shibata, Yoshihide; Watanabe, Kiyomasa*; Ono, Noriyasu*; Isayama, Akihiko; Takizuka, Tomonori*; Kawano, Yasunori; Okamoto, Masaaki*

Physics of Plasmas, 20(11), p.112507_1 - 112507_6, 2013/11

https://doi.org/10.1063/1.4830103

According to an early work on the behavior of the plasma current decay in the JT-60U disruptive discharges caused by the radiative collapse with a massive neon-gas-puff, the increase of the internal inductance mainly determined the current decay time of plasma current during the initial phase of current quench. To investigate what determines the increase of the internal inductance, we focus attention on the relationship between the electron temperature (or the resistivity) profile and the time evolution of the current density profile, and carry out numerical calculations. As a result, we find the reason of the increase of the internal inductance: The current density profile at the start of the current quench is broader than an expected current density profile in the steady state, which is determined by the temperature (or resistivity) profile. The current density profile evolves into peaked one and the internal inductance is increasing.

Designing a prototype of the ITER pulse scheduling system

Yamamoto, Tsuyoshi; Yonekawa, Izuru*; Ota, Kazuya*; Hosoyama, Hiroki*; Hashimoto, Yasunori*; Wallander, A.*; Winter, A.*; Sugie, Tatsuo; Kusama, Yoshinori; Kawano, Yasunori; et al.

Fusion Engineering and Design, 87(12), p.2016 - 2019, 2012/12

https://doi.org/10.1016/j.fusengdes.2012.08.005

The ITER pulse scheduling system creates, approves and manage parameters that characterize plasma operation of ITER. JAEA analyzed requirements on the ITER plasma operations based on experience operating the JT-60U and designed essential functions. This system was designed to enable the change and reuse of parameters. The functions to support to check consistency between parameters and to assign parameter values are calculated by the system were proposed. These functions are useful to support operators.