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.

Study of JT-60SA operation scenario using a plasma equilibrium control simulator

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

Plasma and Fusion Research (Internet), 8(Sp.1), p.2405109_1 - 2405109_6, 2013/08

https://doi.org/10.1585/pfr.8.2405109

The precise control of the plasma position is a key issue in safe and stable plasma operation. A plasma equilibrium control simulator has been developed in order to study the techniques of plasma equilibrium control for JT-60SA. The simulator consists of an equilibrium solver and controller. The equilibrium solver identifies the plasma equilibrium under the given coil current and unknown eddy current by iteration. The function which calculates the self-consistent with magnetic flux consumption has been incorporated in order to simulate the control. The waveforms of JT-60SA plasma operation scenario during the ramp-up and the controllability of the plasma equilibrium control using the equilibrium control simulator were reported.

Model validation and integrated modelling simulations for the JT-60SA tokamak

Giruzzi, G.*; Garcia, J.*; Hayashi, Nobuhiko; Schneider, M.*; Artaud, J. F.*; Baruzzo, M.*; Bolzonella, T.*; Farina, D.*; Figini, L.*; Fujita, Takaaki; 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/34_THP203.pdf

Energy confinement of hydrogen and deuterium H-mode plasmas in JT-60U

Urano, Hajime; Takizuka, Tomonori*; Fujita, Takaaki; Kamada, Yutaka; Nakano, Tomohide; Oyama, Naoyuki; JT-60 Team

Nuclear Fusion, 52(11), p.114021_1 - 114021_10, 2012/11

https://doi.org/10.1088/0029-5515/52/11/114021

Energy confinement properties for hydrogen and deuterium H-mode plasmas are investigated. The stored energy for deuterium becomes larger approximately by a factor of 1.7-2.0 than that for hydrogen at a given heating power. When the stored energy is fixed for both cases, the required power differs roughly a factor of and the identical spatial profiles of electron density , electron temperature and ion temperature are obtained. Despite almost the same power crossing the separatrix, type-I ELM frequency for hydrogen becomes approximately in double from that for deuterium. The pedestal pressure differs approximately by a factor of for the cases between hydrogen and deuterium plasmas at a given absorbed power. The relation between and is almost identical regardless of the difference of the isotropic composition.

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.

Energy confinement characterization of hydrogen and deuterium H-mode plasmas in JT-60U tokamak

Urano, Hajime; Takizuka, Tomonori*; Kikuchi, Mitsuru; Nakano, Tomohide; Fujita, Takaaki; Hayashi, Nobuhiko; Oyama, Naoyuki; Kamada, Yutaka; JT-60 Team

Europhysics Conference Abstracts (Internet), 36F, p.P1.016_1 - P1.016_4, 2012/00

http://ocs.ciemat.es/EPSICPP2012PAP/pdf/P1.016.pdf

Energy confinement properties for hydrogen and deuterium H-mode plasmas were examined in JT-60U. The energy confinement time became larger by a factor of 1.2-1.3 for deuterium than for hydrogen at a given . When the plasma energy was fixed, the profiles of density and temperature became identical for both cases while higher heating power was required for hydrogen. The ion conductive heat flux for hydrogen became approximately two times that for deuterium. Hence, the ion heat diffusivity for hydrogen was higher than for deuterium. It was found that the ion-temperature-gradient scale length became smaller by a factor of 1.2 for deuterium than for hydrogen.

Core transport properties in JT-60U and JET identity plasmas

Litaudon, X.*; Sakamoto, Yoshiteru; de Vries, P. C.*; Salmi, A.*; Tala, T.*; Angioni, C.*; Benkadda, S.*; Beurskens, M. N. A.*; Bourdelle, C.*; Brix, M.*; et al.

Nuclear Fusion, 51(7), p.073020_1 - 073020_13, 2011/07

https://doi.org/10.1088/0029-5515/51/7/073020

A variety of triggering mechanisms and structures of internal transport barrier (ITB) has been observed in various devices or depending on operation scenarios. Thus identity experiments on ITB in JT-60U and JET have been performed to shed light on the physics behind ITBs. Because of their similar size, the dimensionless parameters between both devices are the same. These experiments were performed with near identical magnetic configurations, heating waveforms and normalized quantities such as safety factor, magnetic shear, normalized Larmor radius, normalized collision frequency, beta, temperatures ratio. Similarities of the ITB triggering mechanism and the ITB strength have been observed when a proper match is achieved of the most relevant profiles of the normalized quantities. This paper will report on the detail comparison of transport properties of ITBs obtained in these JET/JT-60U identity experiments.

Fast dynamics of type I and grassy ELMs in JT-60U

Kojima, Atsushi; Oyama, Naoyuki; Sakamoto, Yoshiteru; Kamada, Yutaka; Urano, Hajime; Kamiya, Kensaku; Fujita, Takaaki; Kubo, Hirotaka; Aiba, Nobuyuki; JT-60 Team

Nuclear Fusion, 49(11), p.115008_1 - 115008_8, 2009/11

https://doi.org/10.1088/0029-5515/49/11/115008

In order to understand the physics of the ELM trigger and determining the ELM size, the fast ELM dynamics of type I and grassy ELMs have been studied in JT-60U, using new fast diagnostics with high spatial and temporal resolutions. The evolution of the ion pressure profile in the pedestal region is evaluated for the first time by detailed edge profile measurements. Type I ELMs observed in co-rotating plasmas exhibited larger and wider ELM affected area than ctr-rotating plasmas. Just before type I ELM crash, the pedestal ion pressure and its maximum gradient in co-rotating plasmas are 20% and 12% higher than those in ctr-rotating plasmas, respectively. It is found that the radial extent of the ion pressure gradient at the pedestal region in co-rotating plasmas is 14% wider than that in ctr-rotating plasmas. The experimental results suggest that the ELM size is determined by the structure of the plasma pressure in the whole pedestal region.

Status of JT-60SA tokamak under the EU-JA broader approach agreement

Matsukawa, Makoto; Kikuchi, Mitsuru; Fujii, Tsuneyuki; Fujita, Takaaki; Hayashi, Takao; Higashijima, Satoru; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Ide, Shunsuke; Ishida, Shinichi; et al.

Fusion Engineering and Design, 83(7-9), p.795 - 803, 2008/12

https://doi.org/10.1016/j.fusengdes.2008.06.047

no abstracts in English

Dependence of heat transport on toroidal rotation in conventional H-modes in JT-60U

Urano, Hajime; Takenaga, Hidenobu; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Oyama, Naoyuki; Yoshida, Maiko; JT-60 Team

Nuclear Fusion, 48(8), p.085007_1 - 085007_9, 2008/08

https://doi.org/10.1088/0029-5515/48/8/085007

Relation between heat transport in the plasma core and toroidal rotation profile was examined in conventional ELMy H-mode plasmas in JT-60U. Energy confinement improvement is observed with toroidal rotation which increases in co-direction with respect to the plasma current. Heat transport in the plasma core varies while sustaining self-similar temperature profile in the variation of toroidal rotation profiles. Large increase in heat conduction imposes the resilient profile of ion temperature, under which local effect of toroidal rotation profile on the scale length of ion temperature gradient is very weak. When the pedestal temperature was fixed between the cases of co and counter-NBI by adjusting the plasma density, the identical temperature profiles were obtained in spite of totally different toroidal rotation profiles.