Development of operation scenarios for plasma breakdown and current ramp-up phases in JT-60SA tokamak

Urano, Hajime; Fujita, Takaaki*; Ide, Shunsuke; Miyata, Yoshiaki; Matsunaga, Go; Matsukawa, Makoto

Fusion Engineering and Design, 100, p.345 - 356, 2015/11

https://doi.org/10.1016/j.fusengdes.2015.06.138

The operation scenarios for plasma breakdown and current ramp-up phases in JT-60SA tokamak have been developed. The induced current in the in-vessel conducting elements such as vacuum vessel and stabilizing plate increases to the comparable level of plasma current of 600 kA during the breakdown phase and thus enhances the strength of error field. The optimized scenarios for half and full pre-magnetization cases satisfied the conditions required for the plasma initiation. At the initial plasma, the vertical magnetic field required to sustain the plasma position was controlled by the outer equilibrium field (EF) coil currents which compensate for a vertical field due to a large eddy current. The condition for the formation of divertor configurations given by the combination of the magnetic flux for plasma and the plasma current enables us to develop the operational scenarios with a smooth transition from a limiter to a divertor configuration.

Advance in integrated modelling towards prediction and control of JT-60SA plasmas

Hayashi, Nobuhiko; Honda, Mitsuru; Shiraishi, Junya; Miyata, Yoshiaki; Wakatsuki, Takuma; Hoshino, Kazuo; Toma, Mitsunori; Suzuki, Takahiro; Urano, Hajime; Shimizu, Katsuhiro; et al.

Europhysics Conference Abstracts (Internet), 39E, p.P5.145_1 - P5.145_4, 2015/06

http://ocs.ciemat.es/EPS2015PAP/pdf/P5.145.pdf

The Cauchy-condition surface (CCS) method for plasma equilibrium shape reproduction

Kurihara, Kenichi; Itagaki, Masafumi*; Miyata, Yoshiaki; Nakamura, Kazuo*; Urano, Hajime

Purazuma, Kaku Yugo Gakkai-Shi, 91(1), p.10 - 47, 2015/01

http://www.jspf.or.jp/Journal/PDF_JSPF/jspf2015_01/jspf2015_01-10.pdf

no abstracts in English

Validation of plasma shape reconstruction by Cauchy condition surface method in KSTAR

Miyata, Yoshiaki; Hahn, S. H.*; Suzuki, Takahiro; Ide, Shunsuke; Chung, J.*; Bak, J. G.*; Ko, W. H.*

Physics of Plasmas, 21(3), p.032502_1 - 032502_11, 2014/03

https://doi.org/10.1063/1.4867493

Cauchy condition surface (CCS) method is a numerical approach to reconstruct the plasma boundary precisely and calculate the quantities related to plasma shape using small number of magnetic diagnostics in real time. It has been applied to the KSTAR plasma in order to establish the plasma shape reconstruction with the high elongation of plasma shape and the large effect of eddy current flowing in the structure for the first time. Calculations have been performed to validate the plasma shape reconstruction in 2012 KSTAR experimental campaign. Comparison between the CCS calculation and non-magnetic measurements revealed that the CCS calculation can reconstruct the accurate plasma shape even with a small Ip. The application of CCS calculation to the KSTAR plasma and the validation results of the plasma shape reconstruction are reported.

Optimization of JT-60SA plasma operational scenario with capabilities of installed actuators

Ide, Shunsuke; Aiba, Nobuyuki; Bolzonella, T.*; Challis, C. D.*; Fujita, Takaaki; Giruzzi, G.*; Joffrin, E.*; Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Honda, Mitsuru; et al.

Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/03

http://www-naweb.iaea.org/napc/physics/FEC/FEC2012/papers/228_FTPP722.pdf

Development of a simulator for plasma position and shape control in JT-60SA

Miyata, Yoshiaki; Suzuki, Takahiro; Fujita, Takaaki; Ide, Shunsuke; Urano, Hajime

Plasma and Fusion Research (Internet), 7, p.1405137_1 - 1405137_9, 2012/10

https://doi.org/10.1585/pfr.7.1405137

The plasma position and shape control is important issue in JT-60SA, ITER and future fusion reactor. In order to study the plasma position and shape control, we have developed a simulator which consists of an equilibrium solver and an "isoflux" controller. It is possible to simulate the position and shape control by using the "isoflux" technique and optimize the control logic of coil current in JT-60SA. It was demonstrated that the simulator can simulate the position and shape control in response to prescribed change in the configuration and internal parameters.

Observation of radial particle transport induced by the fluctuation measured with a gold neutral beam probe

Kojima, Atsushi; Ishii, Kameo*; Miyata, Yoshiaki*; Kakiuchi, Hideto*; Kaido, Norihiro*; Yoshikawa, Masayuki*; Itakura, Akiyoshi*; Ichimura, Makoto*; Chujo, T.*

Fusion Science and Technology, 51(2T), p.274 - 276, 2007/02

https://doi.org/10.13182/FST07-A1373

no abstracts in English

Development of simulator for plasma position and shape control in JT-60SA

Miyata, Yoshiaki; Suzuki, Takahiro; Fujita, Takaaki; Ide, Shunsuke; Urano, Hajime

no journal, , 

The plasma position and shape control is important issue in JT-60SA, ITER and future fusion reactor which has a small number of coils. In order to study the plasma position and shape control, we are developing a simulator which consists of an equilibrium solver and an "isoflux" controller. The controller controls poloidal field (PF) coil currents so as to keep the poloidal flux is equal at all of specified locations. The equilibrium solver identifies an equilibrium under the specified PF coil current and implements the effect of eddy current. The position and shape control has been simulated in response to prescribed change in the poloidal beta and the internal inductance due to heating.

Investigation of JT-60SA operation scenario through development of equilibrium control simulator

Suzuki, Takahiro; Miyata, Yoshiaki; Ide, Shunsuke; Urano, Hajime; Fujita, Takaaki

no journal, , 

We have developed an equilibrium control simulator and investigated the JT-60SA operation scenario using the simulator. The simulator consists of an equilibrium construction component that solves temporal evolution of plasma coupled with conducting wall and a controller that controls the plasma current, position and shape via external coil current in the feedback manner. An operation scenario based on the feedback control has been developed, where the plasma current is raised by flux swing in center solenoids and plasma position and shapes are controlled in order to form divertor configuration and apply heating. Results on controllability of the position and shape during heating and flux swing and controllability of the vertical instability are presented as well.

Extending KSTAR operation regime for advanced operation scenario development

Suzuki, Takahiro; Kim, J. H.*; Na, Y. S.*; Ide, Shunsuke; Mueller, D.*; Miyata, Yoshiaki; Kim, H. S.*; Hahn, S. H.*; Yoon, S. W.*; Kim, W. C.*

no journal, , 

We have started advanced operation scenario development in KSTAR in this campaign, which opens up a new research area directly connecting to ITER and DEMO. The advanced scenario, which has higher performance than the standard H-mode, typically possesses lower internal inductance li (safety factor q above unity without sawtooth). In conventional KSTAR operation scenarios, divertor configuration with high elongation is realized after or near the end of Ip ramp-up, where sawtooth activity starts during the ramp-up before entering into the higher performance phase. Thus, we need a new KSTAR operation scenario without sawtooth during the Ip ramp-up and with lower li than unity. Our idea is to delay the inductive current penetration by simultaneous EC&NB heating application into the full-bore divertor plasma during the Ip ramp-up as early as possible. After the optimization, we have successfully established a start-up scenario without sawtooth throughout the Ip ramp-up. In a shot 7897, high reaching an advanced scenario regime has been achieved in ELM-free H-mode () at .