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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.

JAEA Reports

Establishment of X-ray reference fields for performance tests of radiation measuring instruments based on international standard(ISO4037-1)

Shimizu, Shigeru; Zhang, Q.; Kajimoto, Yoichi; Kawasaki, Tomokatsu; Fujii, Katsutoshi

JAERI-Tech 2003-095, 52 Pages, 2004/01

JAERI-Tech-2003-095.pdf:2.66MB

The International Standards ISO4037-1 of the International Organization for Standardization widely applied in the world to construct X-ray reference fields for performance tests of radiation measuring instruments. The application of the current JAERI's X-ray reference field constructed in accordance with the Japanese Standards should be limited for domestic purposes becase of the characterization technique different from the International Standards. Therefore,for application to international performance tests, X-ray reference fields in the narrow,wide and high air-kerma series based on the International Standards were established using the medium-hard X-ray generator of the Facility of Radiation Standards(FRS), JAERI. This report presents quality characterization, estimation of X-ray spectra of each dose units of the new FRS's fields,and comparison of the qualities and the X-ray spectra to those of the ISO's. The FRS's qualities show good agreement with ISO's: the reference fields should serve for performance tests for international radiation protection purposes.

Journal Articles

Theory of the Newcomb equation and applications to MHD stability analysis of a tokamak

Tokuda, Shinji; Aiba, Nobuyuki*

Journal of Plasma and Fusion Research SERIES, Vol.6, p.207 - 209, 2004/00

Recent progress in the theory of the Newcomb equation is reported. Emphasis is put on the analysis of external modes including peeling modes (high $$n$$ kink modes), where $$n$$ is the toroidal mode number. A theory for low $$n$$ external modes is developed so that it is also useful for the analysis of resistive wall modes.

Journal Articles

Inner layer problem for ideal MHD modes in a toroidal system

Tokuda, Shinji

Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00

When we solve the eigenvalue problem associated with the two-dimensional Newcomb equation, we can identify the stability of a tokamak plasma against ideal MHD perturbations. The eigenvalue problem does not give the physical growth rate when the plasma is unstable. However, we can determine the growth rate by constructing a dispersion relation that gives the relation between the growth rate and the eigenvalue. It is expected that the dispersion relation provides an effective and fast method of stability analysis of MHD modes close to the marginal stability against ideal MHD perturbations, and the relation can be extended for non-ideal MHD modes close to the marginal stability.

Journal Articles

First measurement of the quadrupole moment in the 2$$_1^+$$ state of $$^{84}$$Kr

Osa, Akihiko; Czosnyka, T.*; Utsuno, Yutaka; Mizusaki, Takahiro*; Toh, Yosuke; Oshima, Masumi; Koizumi, Mitsuo; Hatsukawa, Yuichi; Katakura, Junichi; Hayakawa, Takehito; et al.

Physics Letters B, 546(1-2), p.48 - 54, 2002/10

 Times Cited Count:10 Percentile:52.26(Astronomy & Astrophysics)

A $$^{84}$$Kr beam was Coulomb-excited on a $$^{98}$$Mo target and a $$^{nat}$$Ta target. Six reduced matrix elements for 5 low-lying states were derived from the analysis using the least-squares code GOSIA. The quadrupole moment of the 2$$_1^+$$ was newly obtained. The measured quadrupole moment and the $$B(E2)$$ values are consistent with large-scale shell-model calculations which give a systematic description of $$N$$,=,50 isotones.

Journal Articles

Singular point analysis

Tokuda, Shinji

Purazuma, Kaku Yugo Gakkai-Shi, 78(9), p.913 - 924, 2002/09

An introductory review is given on recent developments in the methods for stability analysis of a toroidally confined plasma. Emphasis is put on the perturbation analysis of a magnetohydrodynamic system that has the marginally stable state as a terminal point of continuous spectra. We address ourselves to the asymptotic matching method pertinent to such a problem. The Newcomb equation and inner-layer equations are essential ingredients in the methods and the numerical methods for solving them are discussed.

Journal Articles

Operational status of superconducting resonators of the JAERI tandem-booster

Takeuchi, Suehiro; Matsuda, Makoto; Ishizaki, Nobuhiro; Tayama, Hidekazu; Iijima, Akihiko*; Yoshida, Takahiro*

Proceeding of 10th Workshop on RF Superconductivity (SRF 2001), p.591 - 593, 2001/00

no abstracts in English

Journal Articles

Development of whole energy absorption spectrometer for decay heat measurement

Maekawa, Fujio; Wada, Masayuki*; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research A, 450(2-3), p.467 - 478, 2000/08

 Times Cited Count:6 Percentile:45.19(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Evaluation method of performance of siphon break value as core covering system for water-cooled test and research reactors

; Kumada, Hiroaki; Kaminaga, Fumito*

Nihon Genshiryoku Gakkai-Shi, 42(4), p.325 - 333, 2000/04

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

Journal Articles

A New approach to the two-dimensional Newcomb equation

Tokuda, Shinji

Journal of Accelerator and Plasma Research, 5(1), p.87 - 108, 2000/00

no abstracts in English

Journal Articles

A New eigenvalue problem associated with the two-dimensional Newcomb equation without continuous spectra

Tokuda, Shinji; *

Physics of Plasmas, 6(8), p.3012 - 3026, 1999/08

 Times Cited Count:55 Percentile:84.33(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

Subroutine library for error estimation of matrix computation, Ver.1.0

*; *; *

JAERI-Data/Code 99-016, 183 Pages, 1999/03

JAERI-Data-Code-99-016.pdf:4.87MB

no abstracts in English

Journal Articles

A New eigenvalue problem associated with the two-dimensional Newcomb equation without continuous spectra

Tokuda, Shinji; *

Tokei Suri Kenkyujo Kyodo Kenkyu Ripoto, 110, p.70 - 77, 1998/03

no abstracts in English

Journal Articles

Measurement of Q$$_{EC}$$-values of $$^{126}$$La isomers

Kojima, Yasuaki*; Asai, Masato*; Osa, Akihiko; Koizumi, Mitsuo; Sekine, Toshiaki; Shibata, M.*; *; Kawade, Kiyoshi*

Applied Radiation and Isotopes, 49(7), p.829 - 834, 1998/00

 Times Cited Count:3 Percentile:32.94(Chemistry, Inorganic & Nuclear)

no abstracts in English

JAEA Reports

MARG2D code, 1; Eigenvalue problem for two dimensional Newcomb equation

Tokuda, Shinji; *

JAERI-Data/Code 97-040, 105 Pages, 1997/10

JAERI-Data-Code-97-040.pdf:2.32MB

no abstracts in English

Journal Articles

Eigenvalue method for the outer-region matching data in resistive MHD stability analysis

Tokuda, Shinji; *

Purazuma, Kaku Yugo Gakkai-Shi, 73(10), p.1141 - 1154, 1997/10

no abstracts in English

JAEA Reports

JAEA Reports

Journal Articles

Beta-decay energies of $$^{121,123,125}$$Ba and $$^{121-124,126}$$Cs

Osa, Akihiko; *; Kawade, Kiyoshi*; Yamamoto, Hiroshi*;

Journal of the Physical Society of Japan, 65(4), p.928 - 934, 1996/04

 Times Cited Count:16 Percentile:72.01(Physics, Multidisciplinary)

no abstracts in English

31 (Records 1-20 displayed on this page)