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DEVELOPMENT OF FRASTA SIMULATION SOFTWARE

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Acta Metallurgica Sinica(English Letters) 2006年第3期19卷 165-170页

作者： k. tanaka Department of Mechanical Systems Engineering Toyama Prefectural University Toyama 939-0398 Japan

Fracture-surface topography analysis （FRASTA） was successfully used to simulate the process of crack.and calculate parameters of crack.such as the crack.opening angle （COA） and crack.tip opening angle （CTOA）. But because the amount of calculation is large, errors are often made during the course of calculation. FRASTA simulation software, namely fracture surface analyst （FSA ） is developed and a series of center-crack.d tension （CCT） and double edge notched （DEN） specimens of different materials with different sizes are tested, their fracture surfaces are scanned by non-contact 319 scanning system and the elevation data of the fracture surfaces is recorded. FSA used the recorded elevation data of fracture surfaces to simulate the process of crack.based on the principle of FRASTA. Results show that FSA can accurately simulate the process and calculate the parameters of crack.

关键词： FRASTA (fracture-surface topography analysis) COA (crack.opening angle) CTOA (crack.tip opening angle) CCT (center-crack.d tension) DEN (double edge notched)

Analysis Scheme for Density Modulation Experiments to Study Particle Confinements

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Plasma Science and Technology 2006年第1期8卷 65-71页

作者： k. tanaka C. MICHAEL k. k.WANATA T. TOk.ZAWAI M. SHOJI k. TOI 高翔揭银先 National Institute for Fusion Science Toki 509-5292 Japan Institute of Plasma Physics Chinese Academy of Science Hefei 230031 China

Density modulation experiments are powerful experimental schemes for the study of particle transport. The diffusion coefficients （D） and convection velocity （V）, which cannot be evaluated from the particle balance in the equilibrium state, can be obtained separately. Further, the estimated values of D and V are determined independent of the absolute value of the particle source rate, which is difficult to obtain experimentally. However, the sensitivities and interpretation of D and V from the modulation experiments need to be considered. This paper describes numerical techniques for solving the particle balance equation of the modulation components. Examples of the analysis are shown regarding the data of LHD experiments, and the results of the modulation experiments are discussed.

关键词： density modulation, particle confinements, diffusion coefficient convection velocity

RELATIONSHIP BETWEEN J-INTEGRAL AND FRACTURE SURFACE AVERAGE PROFILE

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Acta Metallurgica Sinica(English Letters) 2007年第1期20卷 40-48页

作者： Y.G. Cao S.F. Xue k. tanaka Department of Engineering Mechanics College of Architecture and Transport and Storage Engineering China University of Petroleum Dongying 257061 China Department of Mechanical Systems Engineering Toyama Prefectural University Toyama 939-0398 Japan

To investigate the causes that led to the formation of crack. in materials, a novel method that only considered the fracture surfaces for determining the fracture toughness parameters of J-integral for plain strain was proposed The principle of the fracture-surface topography analysis （FRASTA） was used. In FRASTA, the fracture surfaces were scanned by laser microscope and the elevation data was recorded for analysis. The relationship between J-integral and fracture surface average profile for plain strain was deduced. It was also verified that the J-integral determined by the novel method and by the compliance method matches each other well.

关键词： FRASTA (fracture-surface topography analysis) J-integral fracture surface

Novel wide band gap alloyed semiconductors, x(LiGaO_2)_(1/2)-(1-x)ZnO, and fabrication of their thin films

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Science China(Technological Sciences) 2009年第1期52卷 111-115页

作者： T. OMATA k. tanaka A. TAZUk. k. NOSE S. OTSUk.-YAO-MATSUO Division of Materials and Manufacturing Science Graduate School of Engineering Osaka University 2-1 Yamada-oka Suita

Oxide semiconductor alloys of x(LiGaO2)1/2-(1−x)ZnO were fabricated by the solid state reaction between β-LiGaO2 and ZnO and rf-magnetron sputtering. For the solid state reaction, the wurtzite-type single phases were obtained in the composition range of x⩽0.38. The formation range of the alloys was wider than that of the (Mg1−x Zn x )O system, because the β-LiGaO2 possesses a wurtzite-derived structure and approximately the same lattice constants with ZnO. The electrical resistivity and energy band gap of the 0.38(LiGaO2)1/2-0.62ZnO alloyed ceramic were 0.45 Ωcm and 3.7 eV, respectively, at room temperature. For the alloying by sputtering, the films consisting of the wurtzite-type single phase were obtained over the entire composition range of x(LiGaO2)1/2-(1−x)ZnO. The energy band gap was controllable in the range from 3.3 to 5.6 eV. For the as-deposited film fabricated using the 0.4(LiGaO2)1/2-0.6ZnO alloyed ceramic target, the energy band gap was 3.74 eV, and the electrical resistivity, carrier density and the Hall mobility at room temperature were 3.6 Ωcm, 3.4×1017 cm−3 and 5.6 cm2 V−1 s−1, respectively.

关键词： zinc oxide transparent conductor ultraviolet light band gap engineering oxide electronics

Contribution of the Large Helical Device Plasmas to Alfvén Eigenmode Physics in Toroidal Plasmas

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Plasma Science and Technology 2009年第4期11卷 377-380页

作者： k. TOI M. ISOBE M. OSAk.BE F. WATANABE k. OGAWA T. TOk.ZAWA A. SHIMIZU T. IDO k. IDA, T. ITO S. MORITA k. NAGAOk. k. NARIHARA M. NISHIURA S. OHDACHI S. SAk.k.BARA k. tanaka LHD Experiment Group National Institute for Fusion Science Toki 509-5292 Japan Department of Energy Engineering and Science Nagoya University Nagoya 464-8601 Japan

In the large helical device （LHD） having three dimensional configuration, Alfven eigenmodes （AEs） destabilized by energetic ions are widely investigated using neutral beam heated plasmas with monotonic and non-monotonic rotational transform （l/2π） profiles. In a plasma with monotonic l/2π-profile, core-localized toroidicity-induced Alfven eigenmode （TAE） as well as global one are often observed. With the increase in the averaged toroidal beta value, defined as the ratio of total plasma pressure to toroidal magnetic pressure, core-localized TAE with low toroidal mode number becomes global. In a relatively high beta plasma with monotonic l/2π-profile, two TAEs with different toroidal mode number often interact nonlinearly and generate another modes through three wave coupling. In a plasma with non-monotonic l/2π-profile generated by intense counter neutral beam current drive, reversed shear Alfven eigenmode （RSAE） and geodesic acoustic mode （CAM） excited by energetic ions were observed for the first time in a helical plasma. Nonlinear coupling was also observed between RSAE and GAM.

关键词： alpha particles Alfven eigenmodes geodesic acoustic mode helical/stellarator

Formation of Edge Transport Barriers by L-H Transition and Large Reversed Plasma Current on LHD

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Plasma Science and Technology 2006年第1期8卷 5-9页

作者： k. TOI S. OHDACHI F. WATANABE k. NARIHARA T. MORISAk. 高翔 M. GOTO k. IDA S. MASUZAk. k. MIYAZAWA S. MOR.ITA S. SAk.k.BARA k. tanaka T. TOk.ZAWA k.W. WATANABE 严龙文 M. YOSHINUMA National Institute for Fusion Science Toki Japan Department of Energy Science and Engineering Nagoya University Nagoya Japan Institute of Plasma Physics Chinese Academy of Science Hefei 230031 China Southwestern Institute of Physics Chengdu 610041 China

On the Large Helical Device （LHD） where nested magnetic surfaces are surrounded by the ergodic field layer, edge transport barrier （ETB） was produced in neutral-beam-injection （NBI） heated plasmas through transition and non-transition processes. The former case is the ETB formation by L-Htransition, where characteristics of L-H transition observed in a tok.mak.plasma are clearly recognized. The confinement improvement is the modest （- 10%）, compared with the ISS95 international stellarator scaling. The threshold power for the transition is comparable or slightly lower than the ITER scaling law established by tok.mak. and compact tori. The ETB is formed inside the ergodic field layer of the vacuum field. The ETB formation destabilizes edge coherent modes such as m/n = 1/1, 2/3 and 1/2, of which rational surfaces are in the magnetic hill. The formed ETB is partially and transiently destroyed by these coherent edge MHD modes and edge localized modes （ELMs） typically observed in Ha signals. The latter ETB is observed in a plasma with large reversed NBI-driven current more than 100 k. at Bt = 1 T. In these plasmas, the edge magnetic shear is enhanced by the current and the rotational transform in the core region is expected to be appreciably reduced. Thus reduced rotational transform in the plasma central region will enhance outward heat and particle fluxes toward ergodic edge layer. The ETB with steep electron temperature gradient up to - 5 k.V/m is formed by block.ng enhanced outward heat flux.

关键词： edge transport barrier ergodic field layer L-H transition ELMs edge MHD modes

Review of Divertor Studies in LHD

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Plasma Science and Technology 2006年第1期8卷 14-18页

作者： T. MORISAk. S. MASUZAk. A. k.MORI N. OHYABU M. k.BAYASHI J. MIYAZAWA M. SHOJI 高翔 k. IDA k. Ik.DA O. k.NEk. k. k.WAHATA S. k.BO S. MORITA k. NAGAOk. H. NAk.NISHI k. NARIHARA Y. Ok. M. OSAk.BE B. J. PETERSON S. SAk.k.BARA R. SAk.MOTO T. SHIMOZUMA Y. TAk.IRI k. tanaka k. TOI, k. TSUMORI k. Y. WATABABE T. WATARI H. YAMADA I. YAMADA 严龙文杨青巍杨愚 Y.YOSHIMURA M. YOSHINUMA O. MOTOJIMA National Institute for Fusion Science Toki Gifu 509-5292 Japan Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 China Southwesteru Institute of Physics Chengdu 610041 China

In the Large Helical Device （LHD）, two different divertor configurations, i.e. helical divertor （HD） and local island divertor （LID）, are utilized to control the edge plasma. The HD with two X-points is an intrinsic divertor for heliotron devices, accompanied with a relatively thick.ergodic layer outside the confinement region. Edge and divertor plasma behavior from low density to high density regimes is presented, referring to the divertor detachment. The effect of the ergodic layer on the edge transport is also discussed. On the other hand, the LID is an advanced divertor concept which realizes a high pumping efficiency by the combination of an externally induced magnetic island and a closed pumping system. Experimental results to confirm the fundamental divertor performance of the LID are presented.

关键词： LHD divertor ergodic layer magnetic island edge plasma

STUDY ON THE RELATIONSHIP BETWEEN J-INTEGRAL AND COD

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Acta Metallurgica Sinica(English Letters) 2007年第6期20卷 417-424页

作者： Y. G. Cao X. Y. Sun k. tanaka Department of Engineering Mechanics College of Architecture and Transport andStorage Engineering China University of Petroleum Dongying 257061 China Department of Mechanical Systems Engineering Toyama Prefectural UniversityToyama 939-0398 Japan

J-integral arid crack.opening displacement 8 （COD） were important parameters for characterization of fractures in engineering materials. The relationship between J-integral arid COD has been investigated for a long time and was generally represented as J = m σy, δ, where σy is the yield strength arid m is a function of specimen geometry arid material properties. To determine the value of m, extensive studies and experiments have been performed. The method that used the fracture-surface topography analysis （ FRASTA ） for determining J-integral from fracture surfaces of materials was introduced. On the basis of the relationship between COD arid fracture surface average profile, the relationship between J-integral arid COD was deduced arid compared with the generally used equation. The method was experimentally confirmed to be able to provide a new way to determine the relationship between J-integral and COD.

关键词： FRASTA (fracture-surface topography analysis) J-integral COD (crack.opening displacement)

Quantum electrodynamics experiments with colliding petawatt laser pulses

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High Power Laser Science and Engineering 2019年第1期7卷 74-81页

作者： I. C. E. Turcu B. Shen D. Neely G. Sarri k. A. tanaka P. Mck.nna S. P. D. Mangles T.-P. Yu W. Luo X.-L. Zhu Y. Yin STFC Rutherford Appleton Laboratory Central Laser Facility School of Electronic Science and Engineering Nanjing University ELI-NP Extreme Light Infrastructure – Nuclear Physics National Institute of Physics and Nuclear Engineering (IFIN HH) State k.y Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences School of Physical Science and Technology ShanghaiTech University Shanghai Normal University School of Mathematics and Physics Queen’s University Belfast SUPA Department of Physics University of Strathclyde The John Adams Institute for Accelerator Science Imperial College London Department of Physics National University of Defense Technology School of Nuclear Science and Technology University of South China k.y Laboratory for Laser Plasmas (MOE) School of Physics and Astronomy Shanghai Jiao Tong University

A new generation of high power laser facilities will provide laser pulses with extremely high powers of 10 petawatt(PW)and even 100 PW, capable of reaching intensities of 1023 W/cm^2 in the laser focus. These ultra-high intensities are nevertheless lower than the Schwinger intensity IS= 2.3×1029 W/cm^2 at which the theory of quantum electrodynamics(QED) predicts that a large part of the energy of the laser photons will be transformed to hard Gamma-ray photons and even to matter, via electron–positron pair production. To enable the investigation of this physics at the intensities achievable with the next generation of high power laser facilities, an approach involving the interaction of two colliding PW laser pulses is being adopted. Theoretical simulations predict strong QED effects with colliding laser pulses of 10 PW focused to intensities 10^(22) W/cm^2.

关键词： colliding petawatt laser pulses electron-positron pairs creation nonlinear Breit-Wheeler process petawatt laser facilities quantum electrodynamics