JOPSS - Search Results

Journal Articles

Role of anomalous transport in onset and evolution of neoclassical tearing modes

Konovalov, S. V.; Mikhailovskii, A. B.*; Ozeki, Takahisa; Takizuka, Tomonori; Shirokov, M. S.*; Hayashi, Nobuhiko

Plasma Physics and Controlled Fusion, 47(12B), p.B223 - B236, 2005/12

https://doi.org/10.1088/0741-3335/47/12B/S17

Times Cited Count：7 Percentile：24.58(Physics, Fluids & Plasmas)

Neoclassical Tearing Modes, NTMs, are known to limit the maximum attainable plasma pressure, degrade confinement and, at worst, culminate in disruption of the tokamak discharges. Key role in NTM evolution belongs to the radial profiles of the plasma flow, temperature and density which are determined by the conjunction of the longitudinal and cross-filed transport arising from thermal conduction, particle diffusion, and viscosity. In this report the influence of anomalous perpendicular heat transport and anomalous ion perpendicular viscosity on early stage of the NTM evolution is studied theoretically.

Journal Articles

Infuluence of anomalous transport phenomena on onset of neoclassical tearing modes in tokamaks

Konovalov, S. V.; Mikhailovskii, A.*; Ozeki, Takahisa; Takizuka, Tomonori; Shirokov, M. S.*; Hayashi, Nobuhiko

Proceedings of 20th IAEA Fusion Energy Conference (FEC 2004) (CD-ROM), 8 Pages, 2004/11

http://www-naweb.iaea.org/napc/physics/fec/fec2004/datasets/TH_P4-43.html

Influence of anomalous perpendicular heat transport and anomalous perpendicular viscosity on conditions of Neoclassical Tearing Mode onset is studied theoretically. Series of different parallel transport mechanisms competitive to anomalous cross-island heat conductivity in the perturbed temperature profile are considered.In the transport threshold model, magnetic curvature effect is as much important as bootstrap drive weakened by the finite perpendicular heat transport. Perpendicular viscosity brings island-rotation-frequency dependence of the transport threshold model.

Journal Articles

Charge-ordered state in single-crystalline CaFeO $_{3}$ thin film studied by X-ray anomalous diffraction

Akao, Tadahiro*; Azuma, Yusuke; Usuda, Manabu; Nishihata, Yasuo; Mizuki, Junichiro; Hamada, Noriaki*; Hayashi, Naoaki*; Terashima, Takahito*; Takano, Mikio*

Physical Review Letters, 91(15), p.156405_1 - 156405_4, 2003/10

https://doi.org/10.1103/PhysRevLett.91.156405

Times Cited Count：34 Percentile：79.55(Physics, Multidisciplinary)

X-ray anomalous diffraction, together with a band structure calculation, was employed to obtain a quantitative comprehension of the charge-ordering state in a single-crystalline CaFeO $_{3}$ thin film. The experimental results show a characteristic energy dispersion of the near inhibited reflection at 150, implying Fe atoms split into two distinct states. The energy dispersion is in good agreement with the calculated spectrum based on LDA+U scheme. The calculation reveals an electronic configuration of the Fe 3d orbital follows a localization in the oxygen orbital surrounds one of the distinct Fe atoms.

JAEA Reports

Study of ultra-high gradient wakefield excitation by intense ultrashort laser pulses in plasma

Kotaki, Hideyuki

JAERI-Research 2002-031, 88 Pages, 2002/12

JAERI-Research-2002-031.pdf:3.33MB

We investigate a nonlinear phenomena in laser-plasma interaction, a wakefield excited by intense laser pulses, and a possibility of generating an electron beam by an intense laser pulse. Ionization of gas with a self-focusing causes a broad continuous spectrum with blueshift. The normal blueshift depends on the laser intensity and the plasma density. We have found the spectrum shifts to fixed wavelength independent of the laser power and gas pressure. We call the phenomenon "anomalous blueshift". An intense laser pulse excites a wakefield in plasma. The wakefield excited by 2TW, 50fs laser pulses in a gas-jet plasma is measured with a time-resolved frequency domain interferometer (FDI). This is the first time-resolved measurement of the wakefield of 20GeV/m in a gas-jet plasma. The FDI and the anomalous blueshift will be modified to an optical injection system as an electron beam injector. In a simulation we obtain a high quality intense electron beam. The result illuminates the possibility of a high energy and a high quality electron beam acceleration.

Journal Articles

Structural physics with synchrotron radiation; Focus on a use of resonant effect

Mizuki, Junichiro

Bussei Kenkyu, 79(3), p.481 - 490, 2002/12

http://ci.nii.ac.jp/naid/110006408717

The content of the text is focused on a use of resonant effect of X-rays from Synchrotron Radiation. The resonant effect of X-rays is one of the advantages of Synchrotron radiation to be used for structural studies on condenced matters. We will show some recent studies employed with this effect.

Journal Articles

Energetic particles in spherical torus

Tobita, Kenji

Denki Gakkai Kenkyukai Shiryo, Pulazuma Kenkyukai (PST-01-73), p.43 - 46, 2001/09

Behavior of energetic particles in spherical torus (ST) is summarized in comparison with that in tokamaks. The issues treated in this article are neoclassical transport, ripple loss, Alfven eigenmodes and Magetohydrodynamic- instability-induced anomalous transport. ST is expected to be favorable in terms of neoclassical transport and ripple loss. On the other hand, Alfven eigenmodes and the resulting energetic particle loss can be serious concerns in a ST reactor because of a high volume-averaged beta and a super-Alfvenic speed of alpha particles.

Journal Articles