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Tojo, Hiroshi; Hatae, Takaki; Sakuma, Takeshi; Hamano, Takashi; Itami, Kiyoshi; Aida, Yoshiaki*; Suito, Satoshi*; Fujie, Daijiro*
Review of Scientific Instruments, 81(10), p.10D539_1 - 10D539_3, 2010/10
Times Cited Count：10 Percentile：42.60(Instruments & Instrumentation)Designs of collection optics for JT-60SA Thomson scattering system are presented. By using tangential (to the toroidal direction) YAG laser injection, three collection optics without strong chromatic aberrations generated by the wide viewing angle and small design volume measure almost all the radial space. For the edge plasma measurements, we optimized the channel number and wavelength ranges of band-pass filters in polychromator to reduce relative error in the electron temperature by considering the all spatial channels and double-pass laser system with different geometric parameters.
Ikaida, Riku*; Sekikawa, Takuya; Toigawa, Tomohiro; Ono, Yoshiaki*; Kai, Takeshi
no journal, ,
The organic molecule called Tetra-Octyl-DiGlycol-Amide (TODGA) is used to extract minor actinides (MA) and rare earth elements (RE) from high-level radioactive liquid waste. In the actual extraction process, MAs and REs bound to TODGA are extracted from the organic layer by stirring an oily organic solvent in which TODGA is dissolved and a high-level liquid waste. However, it has been reported that the extraction performance of TODGA decreases after prolonged use due to 
-radiolysis. In addition, the physical and physicochemical processes related to radiolysis of TODGA have not been fully elucidated. In this study, we used the first-principles calculation software OpenMX to calculate the molecular structural changes in the physical and physicochemical processes of TODGA induced by ionization. As a result, we found molecular conformational changes and intramolecular proton transfer corresponding to the degradation products obtained experimentally. The elucidation of this process will lead to the clarification of the degradation behavior of TODGA and the mechanism of -ray induced hydrogen evolution.
based on the first-principles calculations; Analysis using Tetrahedron Method IIIkaida, Riku*; Sekikawa, Takuya; Ono, Yoshiaki*; Sano, Kazuhiro*; Masuda, Yoshimi*
no journal, ,
The SrTiO, a dilute mixture of Nb and other elements, has been studied as one of the most dilute free electron superconductors. At the same time, SrTiO has a huge dielectric constant at low temperatures, and ferroelectric transition occurs due to the substitution of O18 for O16 and Ca for Sr. Furthermore, an increase in the superconducting transition temperature Tc has been observed at substitution concentrations near where the ferroelectric transition occurs. However, the relationship between ferroelectricity and superconductivity is not clarified. In this study, we calculated the physical quantities related to ferroelectricity and superconductivity in the free electron density region near the highest superconducting transition temperature using the first-principles calculation software Quantum ESPRESSO. In the result, we found that the frequency of crystal oscillation decreases with decreasing free electron density, which is an indication of the ferroelectric transition. Furthermore, we found that Tc increases with decreasing free electron density. These results lead to a theoretical clarification of the relationship between ferroelectricity and superconductivity in SrTiO.
Tojo, Hiroshi; Hatae, Takaki; Sakuma, Takeshi; Hamano, Takashi; Shinohara, Koji; Itami, Kiyoshi; Aida, Yoshiaki*; Suito, Satoshi*; Fujie, Daijiro*
no journal, ,
Conceptual designs of the collection optics for JT-60SA Thomson scattering have been done. Adapting four glass materials of the lenses used for the collection optics enables to correct the chromatic aberrations with good resolution (
1 mm). The whole radial profile can be measured using three designed collection optics in Port-P1, P2 and P5. The collection optics will be installed in port-plugs accessing from the cryostat to vacuum vessel. In a disruption with a decrease of the plasma current by a time scale of 5 MA/8 ms, the eddy current (
0.1 MA/m
) is strongly generated in the area of 500 mm from the edge of the port-plug with the thickness of 30 mm. Even if the thickness is reduced to 20 mm decreasing the current in the area, the maximum principal stress is still under the limit value for the design.
Yatsuka, Eiichi; Hatae, Takaki; Suito, Satoshi*; Aida, Yoshiaki*; Kusama, Yoshinori
no journal, ,
no abstracts in English
based on the first-principles calculationsIkaida, Riku*; Sano, Kazuhiro*; Masuda, Yoshimi*; Sekikawa, Takuya; Ono, Yoshiaki*
no journal, ,
The superconductivity of SrTiO, which is used in solar cells and as a photocatalyst, is observed in systems doped with electrons such as Nb, but it also exhibits crystal instability due to doping, and the realization of superconductivity is in competition with doping and crystal instability. Since the crystal instability is not well understood, we calculated the electronic structure of SrTiO with electron doping as a parameter using the first-principles calculation software Quantum ESPRESSO. As a result, we succeeded in obtaining a solution for the decrease in frequency of crystal vibration (softening), which is considered to be caused by the ferroelectric transition, by reducing the amount of electron doping, and at the same time, we obtained the result that the superconducting transition temperature increases. This result is consistent with the experimental results of previous studies. This study provides new insight into the mechanism of superconductivity in SrTiO, which has been an unsolved problem for many years.
