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Journal Articles

ITB-events and their triggers in T-10 and JT-60U

Neudatchin, S. V.*; Takizuka, Tomonori; Sakamoto, Yoshiteru; Hayashi, Nobuhiko; Isayama, Akihiko; Kislov, A. Ya.*; Krylov, S. V.*; Pavlov, Yu. D.*; Shirai, Hiroshi; Borshegovskii, A. A.*

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03

Non-local transport bifurcations inside and around ITB were found in various JT-60U reverse shear (RS) and normal shear (NrS) plasmas and called ITB-events. The abrupt reduction of transport in the central part of the plasma column often interrupts a slow diffusive inward cold pulse propagation (CPP) in T-10. CPP is created by a cut-off of the off-axis ECRH. This phenomenon may referred to ITB-events as well. In many cases these events occur, when the central safety factor q decreases below unity. In JT-60U low-power heated RS plasmas, ITB-events are observed at the crossing of minimum of q equal to 3.5, 3, 2.5 values. Internal MHD n=1 activity has been reported earlier as ITB-events trigger in JT-60U. The present paper shows that an ITB-event is triggered by a series of small internal disruptions probably associated with q=2.5 surface in RS plasmas. In a high-poloidal-beta NrS shot, an ITB-event occurs in correlation with the start of ELMs series. The total heat flux reduces abruptly in the zone 0.3$$<$$r/a$$<$$0.7. This new finding of this ITB event suggests the possibility to control the ITB formation by inducing the ELM-like MHD activity.

Journal Articles

Role of low order rational $$q$$-values in the ITB events in JT-60U reverse shear plasmas

Neudatchin, S. V.*; Takizuka, Tomonori; Hayashi, Nobuhiko; Isayama, Akihiko; Shirai, Hiroshi; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Suzuki, Takahiro

Nuclear Fusion, 44(9), p.945 - 953, 2004/09

The formation of internal transport barriers (ITBs) near q=3 surfaces in normal shear (NrS) discharges of JT-60U is known. In reverse shear (RS) JT-60U plasmas, the role of q minimum (qmin) equal to 3.5,3,2.5,2 was not obvious for ITB formation. ITB-events (non-local confinement bifurcations inside and around ITB) are found in various NrS and RS plasmas. Under sufficient heating power, ITB-events are seen at rational and not rational values of qmin. The space-time evolution of Te and Ti is similar, suggesting the same mechanism of Te and Ti transport. The temporal formation of strong ITB under passing of qmin=3 (after periodical improvements and degradations via ITB-events) in RS mode is presented. Under smaller power, ITB-events are observed only at rational values of qmin. In a weak RS shot, abrupt rise of Te is seen at qmin=3.5, while more cases of Ti rise are observed. The difference of Te and Ti evolutions seen regularly under the low power, suggests decoupling of Te and Ti transport.

Journal Articles

Role of low order rational ${it q}$-values in the ITB events in JT-60U reverse shear plasmas

Neudatchin, S. V.*; Takizuka, Tomonori; Hayashi, Nobuhiko; Isayama, Akihiko; Shirai, Hiroshi; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Suzuki, Takahiro

Nuclear Fusion, 44(9), p.945 - 953, 2004/09

 Times Cited Count:14 Percentile:45.23(Physics, Fluids & Plasmas)

The formation of internal transport barriers (ITBs) near ${it q}$ =2,3 surfaces in normal shear (NrS) discharges of JT-60U and JET is known. In reverse shear (RS) JT-60U plasmas, the role of ${it q}$ minimum (${it q}$$$_{min}$$) equal to 3.5,3,2.5,2 is not obvious for ITB formation. In this paper, the effect of low rational ${it q}$ values on ITB-events in JT-60U NrS and RS plasmas is investigated. Under sufficient neutral beam power (${it P}$$$_{nbi}$$$$>$$8MW for 1.2-1.5MA/3.8T pulses), ITB-events are seen at rational and non-rational values of ${it q}$$$_{min}$$. The space-time evolutions of ${it T}$$$_{e}$$ and ${it T}$$$_{i}$$ are similar, suggesting the same mechanism for ${it T}$$$_{e}$$ and ${it T}$$$_{i}$$ transports. The temporal formation of stronger ITB under passing ${it q}$$$_{min}$$=3 (after periodical improvements and degradations via ITB-events) in RS H-mode with ${it P}$$$_{nbi}$$=8MW is presented. Under smaller power, ITB-events are observed only at rational ${it q}$$$_{min}$$ values. In a weak RS shot with ${it P}$$$_{nbi}$$=4MW, the abrupt rise of ${it T}$$$_{e}$$ is seen at ${it q}$$$_{min}$$=3.5, while more cases of ${it T}$$$_{i}$$ rise are observed. The difference between the ${it T}$$$_{e}$$ and ${it T}$$$_{i}$$ evolutions for the low power suggests the decoupling of ${it T}$$$_{e}$$ and ${it T}$$$_{i}$$ transports.

Journal Articles

Dynamics and interplay of L-H-L transitions and ITB events in reversed shear plasmas with internal barrieres in JT-60U

Neudatchin, S. V.; Takizuka, Tomonori; Shirai, Hiroshi; Fujita, Takaaki; Isayama, Akihiko; Kamada, Yutaka; Koide, Yoshihiko; Suzuki, Takahiro; Takeji, Satoru

Plasma Physics and Controlled Fusion, 44(5A), p.A383 - A389, 2002/05

 Times Cited Count:13 Percentile:42.53(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

Dynamic behavior of transport in normal and reversed shear plasmas with internal barriers in JT-60U

Neudatchin, S. V.; Takizuka, Tomonori; Shirai, Hiroshi; Fujita, Takaaki; Isayama, Akihiko; Kamada, Yutaka; Koide, Yoshihiko; Dnestrovskij, Y. N.*

JAERI-Research 2001-056, 32 Pages, 2001/12

JAERI-Research-2001-056.pdf:1.31MB

no abstracts in English

Journal Articles

Analysis of internal transport barrier heat diffusivity from heat pulse propagation induced by ITB event in JT-60U reverse shear plasmas

Neudatchin, S. V.; Takizuka, Tomonori; Shirai, Hiroshi; Fujita, Takaaki; Isayama, Akihiko; Koide, Yoshihiko; Kamada, Yutaka

Plasma Physics and Controlled Fusion, 43(5), p.661 - 675, 2001/05

 Times Cited Count:8 Percentile:28.51(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Dynamic behavior of transport in normal and reversed shear plasmas with internal barriers in JT-60U

Neudatchin, S. V.; Takizuka, Tomonori; Dnestrovskij, Y. N.*; Shirai, Hiroshi; Fujita, Takaaki; Isayama, Akihiko; Kamada, Yutaka; Koide, Yoshihiko

Proceedings of IAEA 18th Fusion Energy Conference (CD-ROM), 5 Pages, 2001/00

no abstracts in English

JAEA Reports

Analysis of internal transport barrier heat diffusivity from heat pulse propagation created by abrupt variation of diffusivity in JT-60U reverse shear plasmas

Neudatchin, S. V.; Takizuka, Tomonori; Shirai, Hiroshi; Fujita, Takaaki; Isayama, Akihiko; Koide, Yoshihiko; Kamada, Yutaka

JAERI-Research 99-063, p.38 - 0, 1999/11

JAERI-Research-99-063.pdf:1.7MB

no abstracts in English

Journal Articles

Abrupt in time and wide in space variations of heat diffusivity during ITB formation in JT-60U reverse shear discharges

Neudatchin, S. V.*; Takizuka, Tomonori; Shirai, Hiroshi; Fujita, Takaaki; Isei, Nobuaki; Isayama, Akihiko; Koide, Yoshihiko; Kamada, Yutaka

Plasma Physics and Controlled Fusion, 41(10), p.L39 - L47, 1999/00

 Times Cited Count:17 Percentile:57.89(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

Analysis of space-time structure of internal transport barrier in JT-60U

Neudatchin, S. V.*; Takizuka, Tomonori; Shirai, Hiroshi; Fujita, Takaaki; Takeji, Satoru; Isei, Nobuaki; Kamada, Yutaka

JAERI-Research 97-052, 27 Pages, 1997/08

JAERI-Research-97-052.pdf:1.1MB

no abstracts in English

Journal Articles

Analysis of transient transport processes on JT-60U tokamak

Neudatchin, S. V.*; Shirai, Hiroshi; Takizuka, Tomonori; Fujita, Takaaki; Takeji, Satoru; Isei, Nobuaki; Ishida, Shinichi; Kamada, Yutaka

Proc. of 24th European Physical Society Conf. on Controlled Fusion and Plasma Physics, 21A, p.497 - 500, 1997/00

no abstracts in English

Journal Articles

Time behavior of heat diffusivity during L-H-L transitions in JT-60U

Neudatchin, S. V.*; Takizuka, Tomonori; Shirai, Hiroshi; Isei, Nobuaki; Kamada, Yutaka; Koide, Yoshihiko; Sato, Masayasu; Azumi, Masafumi

Japanese Journal of Applied Physics, 35(6A), p.3595 - 3602, 1996/06

 Times Cited Count:9 Percentile:46.57(Physics, Applied)

no abstracts in English

JAEA Reports

Time behavior of heat diffusivity during L-H-L transitions in JT-60U

Neudatchin, S. V.*; Takizuka, Tomonori; Shirai, Hiroshi; Isei, Nobuaki; Kamada, Yutaka; Koide, Yoshihiko; Sato, Masayasu; Azumi, Masafumi

JAERI-Research 95-060, 31 Pages, 1995/09

JAERI-Research-95-060.pdf:1.07MB

no abstracts in English

Journal Articles

The time behavior of the heat conductivity during L-H-L transitions in JT-60U

Neudatchin, S. V.*; Shirai, Hiroshi; Takizuka, Tomonori; Isei, Nobuaki; Kamada, Yutaka; Koide, Yoshihiko; Muir, D. G.*; Sato, Masayasu; Azumi, Masafumi

Europhysics Conference Abstracts, 19C(Part3), p.029 - 032, 1995/00

no abstracts in English

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