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Gyrofluid Simulation of Ion-Scale Turbulence in Tokamak Plasmas

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Communications in Computational Physics 2008年第10期4卷 1245-1257页

作者： Jiquan Li Y.kishimoto Graduate School of Energy Science Kyoto UniversityUjiKyoto 611-0011Japan Institute for Fusion Theory and Simulation ZhejiangUniversityHangzhouChina

An improved three-field gyrofluid model is proposed to numerically simulate ion-scale turbulence in tokamak plasmas,which includes the nonlinear evolution of perturbed electrostatic potential,parallel ion velocity and ion pressure with adiabatic electron *** is benchmarked through advancing a gyrofluid toroidal global(GFT G)code as well as the local version(GFT L),with the emphasis of the collisionless damping of zonal *** nonlinear equations are solved by using Fourier decomposition in poloidal and toroidal directions and semi-implicit finite difference method along radial *** numerical implementation is briefly explained,especially on the periodic boundary condition in GFT L *** a numerical test and also practical application,the nonlinear excitation of geodesic acoustic mode(GAM),as well as its radial structure,is investigated in tokamak plasma turbulence.

关键词： Geodesic acoustic mode(GAM) zonal flow ion temperature gradient(ITG)turbulence gyrofluid simulation tokamak

In-flight(K^-,N) Reactions for Study of Kaon-nucleus Interaction

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原子核物理评论 2009年第S1期26卷 119-123页

作者： T.kishimoto Research Center for Nuclear Physics Osaka University

We would like to emphasize that the in-flight (K-,N) reactions are particularly useful for the study of the K-nucleus interaction. Since the reaction mechanism is well known,there is little ambiguity to derive the K-nucleus interaction from the measured missing mass spectra. Here we discuss the missing mass spectra of the (K-,N) reactions on the 12C and 16O targets. The spectra show an appreciable amount of strength below the K-nucleus threshold which indicates that the K-nuclear potential is strongly attractive. Comparison of the missing mass spectra with theoretical calculations leads to a potential depth of around -190 MeV for the 12C(K-,n) reaction. A less deep potential of around -160 MeV reproduces well that of the 12C(K-,p) reaction. The difference can be due to isospin dependence of the interaction. Our data show that the K-nucleus potential is very deep to realize kaon condensation in the core of neutron stars.

关键词： neutron star kaon condensation kaon-nucleus interaction

WAVE PROPAGATION IN TWO-DIMENSIONAL DISORDERED PIEZOELECTRIC PHONONIC CRYSTALS

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Acta Mechanica Solida Sinica 2008年第6期21卷 507-516页

作者： Jinqiang Li Fengming Li Yuesheng Wang Kikuo kishimoto P. O. Box 137 School of Astronautics Harbin Institute of Technology Harbin 150001 China Department of Mechanical Sciences and Engineering Tokyo Institute of Technology 2-12-1 O-okayama Meguro-ku Tokyo 152-8552 Japan Institute of Engineering Mechanics Beijing Jiaotong University Beijing 100044 China

The wave propagation is studied in two-dimensional disordered piezoelectric phononic crystals using the finite-difference time-domain （FDTD） method. For different cases of disorder, the transmission coefficients are calculated. The influences of disorders on band gaps are investigated. The results show that the disorder in the piezoelectric phononic crystals has more significant influences on the band gap in the low frequency regions than in the high frequency ones. The relation between the width of band gap and the direction of position disorder is also discussed. When the position disorder is along the direction perpendicular to the wave transmission, the piezoelectric phononic crystals have wider band gaps at low frequency regions than the case of position disorder being along the wave transmission direction. It can also be found that the effect of. size disorder on band gaps is analogous to that of location disorder. When the perturbation coefficient is big, it has more pronounced effects on the pass bands in the piezoelectric phononic crystals with both size and location disorders than in the piezoelectric phononic crystals with single disorder. In higher frequency regions the piezoelectric effect reduces the transmission coefficients. But for larger disorder degree, the effects of the piezoelectricity will be reduced.

关键词： phononic crystal piezoelectricity position disorder band gap FDTD method

Tuning of band gaps for a two-dimensional piezoelectric phononic crystal with a rectangular lattice

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Acta Mechanica Sinica 2009年第1期25卷 65-71页

作者： Yize Wang Fengming Li Yuesheng Wang Kikuo kishimoto Wenhu Huang School of Astronautics Harbin Institute of TechnologyP. O. Box 137 150001 Harbin China Institute of Engineering Mechanics Beijing Jiaotong University 100044 Beijing China Department of Mechanical Sciences and Engineering.Tokyo Institute of Technology 2-12-1 O-okayama.Meguro-ku Tokyo 152-8552 Japan

In this paper, the elastic wave propagation in a two-dimensional piezoelectric phononic crystal is studied by considering the mechanic-electric coupling. The generalized eigenvalue equation is obtained by the relation of the mechanic and electric fields as well as the Bloch-Floquet theorem. The band structures of both the in-plane and anti-plane modes are calculated for a rectangular lattice by the planewave expansion method. The effects of the lattice constant ratio and the piezoelectricity with different filling fractions are analyzed. The results show that the largest gap width is not always obtained for a square lattice. In some situations, a rectangular lattice may generate larger gaps. The band gap characteristics are influenced obviously by the piezoelectricity with the larger lattice constant ratios and the filling fractions.

关键词： Piezoelectricity Phononic crystal Rectangular lattice - Plane-wave expansion method Band gap

Magnetic-island-induced ion temperature gradient mode： Landau damping, equilibrium magnetic shear and pressure flattening effects

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Plasma Science and Technology 2018年第7期20卷 77-85页

作者： Wei WANG Zhengxiong WANG Jiquan LI Yasuaki kishimoto Jiaqi DONG Shu ZHENG Key Laboratory of Materials Modification by Beams of the Ministry of Education School of PhysicsDalian University of TechnologyDalian 116024People＇s Republic of China Graduate School of Energy Science Kyoto UniversityGokasyoUjiKyoto 611-0011Japan Southwestern Institute of Physics Chengdu 610041People＇s Republic of China Institute for Fusion Theory and Simulation Zhejiang UniversityHangzhou 310027People＇s Republic of China

Characteristics of the magnetic-island-induced ion temperature gradient （MITG） mode are studied through gyrofluid simulations in the slab geometry, focusing on the effects of Landau damping, equilibrium magnetic shear （EMS）, and pressure flattening. It is shown that the magnetic island may enhance the Landau damping of the system by inducing the radial magnetic field. Moreover, the radial eigenmode numbers of most MITG poloidal harmonics are increased by the magnetic island so that the MITG mode is destabilized in the low EMS regime. In addition, the pressure profile flattening effect inside a magnetic island hardly affects the growth of the whole MITG mode, while it has different local effects near the O-point and the X-point regions. In comparison with the non-zero-order perturbations, only the quasi-linear flattening effect due to the zonal pressure is the effective component to impact the growth rate of the mode.

关键词： magnetic island magnetic shear Landau damping MITG

WAVE LOCALIZATION IN RANDOMLY DISORDERED PERIODIC PIEZOELECTRIC RODS WITH INITIAL STRESS

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Acta Mechanica Solida Sinica 2008年第6期21卷 529-535页

作者： Yize Wang Fengming Li Kikuo kishimoto Yuesheng Wang Wenhu Huang P.O. Box 137 School of Astronautics Harbin Institute of Technology Harbin 150001 China Department of Mechanical Sciences and Engineering Tokyo Institute of Technology 2-12-1 O-okayama Meguro-ku Tokyo 152-8552 Japan Institute of Engineering Mechanics Beijing Jiaotong University Beijing 100044 China

The elastic wave localization in disordered periodic piezoelectric rods with initial stress is studied using the transfer matrix and Lyapunov exponent method. The electric field is approximated as quasi-static. The effects of the initial stress on the band gap characteristics are investigated. The numerical calculations of localization factors and localization lengths are performed. It can be observed from the results that the band structures can be tuned by exerting the suitable initial stress. For different values of the piezoelectric rod length and the elastic constant, the band structures and the localization phenomena are very different. Larger disorder degree can lead to more obvious localization phenomenon.

关键词： piezoelectric phononic crystal initial stress random disorder localization factor,localization length

An electron moir■ method for a common SEM

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Acta Mechanica Sinica 2006年第6期22卷 595-602页

作者： Y. M. Xing S. kishimoto Y. R. Zhao Department of Applied Mechanics Inner Mongolia University of Technology Hohhot 010051 China National Institute for Materials Sciences Tsukuba Ibaraki 305-0047 Japan

In the electron moiré method, a high-frequency grating is used to measure microscopic deformation, which promises significant potential applications for the method in the microscopic analysis of materials. However, a special beam scanning control device is required to produce a grating and generate a moiré fringe pattern for the scanning electron microscope （SEM）. Because only a few SEMs used in the material science studies are equipped with this device, the use of the electron moiré method is limited. In this study, an electron moiré method for a common SEM without the beam control device is presented. A grating based on a multi-scanning concept is fabricated in any observing mode. A real-time moiré pattern can also be generated in the SEM or an optical filtering system. Without the beam control device being a prerequisite, the electron moiré method can be more widely used. The experimental results from three different types of SEMs show that high quality gratings with uniform lines and less pitch error can be fabricated by this method, and moiré patterns can also be correctly generated.

关键词： Electron moiré Grating Multi-scanning Electron beam moiré

Dynamics of Secondary Large-Scale Structures in ETG Turbulence Simulations

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Plasma Science and Technology 2006年第1期8卷 110-113页

作者：李继全 Y.kishimoto 董家齐 N.MIYATO T.MATSUMOTO Southwestern Institute of Physics and SWIP-DUT Joint Lab for Fusion Plasma PhysicsChengdu 610041China Department of Fundamental Energy Kyoto University611-0011 GokashoUjiJapan Naka Fusion Research EstablishmentJAERINakaIbaraki 311-0193Japan Naka Fusion Research Establishment JAERINakaIbaraki 311-0193Japan

The dynamics of secondary large-scale structures in electron-temperature-gradient （ETG） turbulence is investigated based on gyrofluid simulations in sheared slab geometry. It is found that structural bifurcation to zonal flow dominated or streamer-like states depends on the spectral anisotropy of turbulent ETG fluctuation, which is governed by the magnetic shear. The turbulent electron transport is suppressed by enhanced zonal flows. However, it is still low even if the streamer is formed in ETG turbulence with strong shears. It is shown that the low transport may be related to the secondary excitation of poloidal long-wavelength mode due to the beat wave of the most unstable components or a modulation instability. This large-scale structure with a low frequency and a long wavelength may saturate, or at least contribute to the saturation of ETG fluctuations through a poloidal mode coupling. The result suggests a low fluctuation level in ETG turbulence.

关键词： large-scale structures ETG turbulence gyrofluid simulation tokamak

Permeabilities of rebamipide via rat intestinal membranes and its colon specific delivery using chitosan capsule as a carrier

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World Journal of Gastroenterology 2008年第31期14卷 4928-4937页

作者： Bei-Bei Huang Guo-Feng Li Jing-Hui Luo Lian Duan kishimoto Nobuaki Yamamoto Akira Department of pharmacy Nanfang Hospital Southern Medical University Guangzhou 510515 Guangdong Province China Department of Biopharmaceutics Kyoto Pharmaceutical University Misasagi Yamashinaku Kyoto 6078414 Japan

AIM: To investigate the permeability characteristics of rebamipide across intestinal mucosa, and examine the effects of some absorption enhancers on the permeability across the colonic tissue. Another purpose is to demonstrate the colon-specific delivery of rebamipide with or without absorption enhancers using chitosan capsule as a carrier. METHODS: The permeability of rebamipide was evaluated using an in vitro diffusion chamber system, and the effects of some absorption enhancers on the permeability via colon were further investigated. The release of rebamipide from chitosan or gelatin capsule was studied by Japan Pharmacopoeia rotating basket method. The colonic and plasma concentrations were analyzed by high performance liquid chromatography (HPLC) to evaluate colon-targeting action after oral administration of various dosage forms, and rebamipide with absorption enhancers in chitosan dosage forms. RESULTS: The permeability of rebamipide across the jejunal or ileal membranes was higher than the colonic membranes. Both sodium laurate (C12) and labrasol signifi cantly increased permeability across the colon membranes. On the other hand, the release of rebamipide from chitosan capsule was less than 10%totally within 6 h. The area under concentration-time profile of drug in the colon mucosa using chitosan capsules (AUCLI, 1 6011.2 ng·h/g) was 2.5 times and 4.4 times greater than using gelatin capsules and CMC suspension, respectively. Meanwhile, the area under concentration-time profile of drug in the plasma (AUCPL) was 1016.0 ng·h/mL for chitosan capsule, 1887.9 ng·h/mL for CMC suspension p and 2163.5 ng·h/mL for gelatin capsule. Overall, both AUCLI and AUCPL were increased when C12 was co-administrated, but the increase of AUCLI was much greater; the drug delivery index (DDI) was more than 1 compared with simple chitosan capsule group. CONCLUSION: There was a regional difference in the permeability of Rabamipide across the jejunum, ileum and the colon, and passive

关键词： Rebamipide Diffusion chamber Permeability Sodium laurate Chitosan capsule Colon-specific delivery