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Shibata, Yoshihide; Isayama, Akihiko; Miyamoto, Seiji*; Kawakami, Sho*; Watanabe, Kiyomasa*; Matsunaga, Go; Kawano, Yasunori; Lukash, V.*; Khayrutdinov, R.*; JT-60 Team
Plasma Physics and Controlled Fusion, 56(4), p.045008_1 - 045008_8, 2014/04
Times Cited Count：3 Percentile：15.17(Physics, Fluids & Plasmas)In JT-60U disruption, the plasma current decay during the initial phase of current quench has been calculated by a disruption simulation code (DINA) using the measured electron temperature 
profile. In the case of fast plasma current decay, has a peaked profile just after thermal quench and the profile doesn't change significantly during the initial phase of current quench. On the other hand, in the case of the slow plasma current decay, the profile is border just after the thermal quench, and the profile shrinks. The results of DINA simulation show that plasma internal inductance 
increases during the initial phase of current quench, while plasma external inductance 
does not change in time. The increase of is caused by current diffusion toward the core plasma due to the decrease of in intermediate and edge regions. It is suggested that an additional heating in the plasma periphery region has the effect of slowing down plasma current decay.
Kawakami, Sho*; Shibata, Yoshihide; Watanabe, Kiyomasa*; Ono, Noriyasu*; Isayama, Akihiko; Takizuka, Tomonori*; Kawano, Yasunori; Okamoto, Masaaki*
Physics of Plasmas, 20(11), p.112507_1 - 112507_6, 2013/11
Times Cited Count：2 Percentile：8.81(Physics, Fluids & Plasmas)According to an early work on the behavior of the plasma current decay in the JT-60U disruptive discharges caused by the radiative collapse with a massive neon-gas-puff, the increase of the internal inductance mainly determined the current decay time of plasma current during the initial phase of current quench. To investigate what determines the increase of the internal inductance, we focus attention on the relationship between the electron temperature (or the resistivity) profile and the time evolution of the current density profile, and carry out numerical calculations. As a result, we find the reason of the increase of the internal inductance: The current density profile at the start of the current quench is broader than an expected current density profile in the steady state, which is determined by the temperature (or resistivity) profile. The current density profile evolves into peaked one and the internal inductance is increasing.
molecular beamKawakami, Yasunori; Teraoka, Yuden; Yoshigoe, Akitaka; Harries, J.
no journal, ,
We observed real-time O1s photoemission spectrum for oxidation of Ni(111) Surface at Room Temperature induced by Supersonic O
Molecular Beam which kinetic energy from 0.03 eV to 2.3 eV, and we found out clear difference of profile depend on translational motion energy. Compare HOMB (translational motion energy is about 2.3 eV) with backfilling (translational motion energy is 0.03 eV), we guess there are not less than three components in spectrum each other. Generation rate of each component depends on amount of oxidation exposure. Especially, we see large effect of kinetic energy on component peak of 531.5 eV. This effect is large on backfilling exposure, so it indicates that adsorption site formed by way of physical adsorption.
Kawakami, Yasunori; Teraoka, Yuden; Yoshigoe, Akitaka; Harries, J.
no journal, ,
no abstracts in English
molecular beamsTeraoka, Yuden; Kawakami, Yasunori; Yoshigoe, Akitaka; Harries, J.; Hiraya, Atsunari*
no journal, ,
Chemical bonding states of oxygen, adsorbed on Ni(111) via supersonic O beams have been analyzed by low energy electron diffraction and synchrotron radiation X-ray photoemission spectroscopy. The oxygen-adsorbed structure in the early stages of O irradiation was assigned to be an three-folded near-fcc site. The oxide layer consisted of peroxide, suboxide, and NiO components depending on O incident energy and dose. In the 0.6 eV case, the three-folded near-fcc site changed finally to the NiO through suboxide and peroxide. The oxide layer was NiO(111) regardless of kinetic energy. With increasing kinetic energy, NiO formed in the lower O dose and the three-folded near-fcc sites decreased in the earlier stages. Especially, the kinetic energy of 2.3 eV was effective to form NiO in the extreme early stages. This implies that the activated adsorption occurs in the oxidation of Ni(111) by energetic O molecules.
molecular beams on Ni(111) surfaceTeraoka, Yuden; Inoue, Keisuke*; Kawakami, Yasunori*; Hiraya, Atsunari*
no journal, ,
The oxidation states of Ni(111) surface, which were made by irradiation of supersonic O molecular beam (SSOMB), were analyzed by synchrotron radiation photoemission spectroscopy (SR-XPS). After irradiation of SSOMB on the Ni(111) surface to some extent, the evolution of surface oxides were observed by core level photoemission spectra of Ni2p and O1s using SR-XPS. The surface temperature was kept to be 300 K during SSOMB irradiation and SR-XPS measurements. The SR energy was 680 eV. Oxygen uptake curves were measured at every translational energy of O beam. Although the sticking probability was almost constant in the range of 0.6 eV to 2.0 eV, the remarkable increase was observed in the region over 2.0 eV. A threshold was found to be 2.0 eV.
molecular beams on Ni(111) surfaceInoue, Keisuke*; Teraoka, Yuden; Kawakami, Yasunori*; Hiraya, Atsunari*
no journal, ,
In this study, the oxidation states of Ni(111) surface, made by irradiation of a supersonic O molecular beam (SSOMB), were analyzed using synchrotron radiation photoemission spectroscopy (SR-XPS). The surface temperature was 300 K during both SSOMB irradiation and SR-XPS measurements. After irradiation of SSOMB on the Ni(111) surface to some extent, the evolution of the surface oxides were observed by core level photoemission spectra of Ni3p and O1s, and oxygen uptake curves were measured at every translational energy of O beam. The initial sticking rate increased with increasing translational energy from 0.5 eV to 1.0 eV, slightly decreased up to 2.2 eV, and a remarkable re-increase was observed in the region around 2.3 eV. These results imply that high speed O molecules adsorb by new adsorption mechanisms.
beam on Ni(111) surface depending on kinetic energyInoue, Keisuke*; Teraoka, Yuden; Kawakami, Yasunori*; Hiraya, Atsunari*
no journal, ,
The oxidation states of Ni(111) surface, which were made by irradiation of supersonic O molecular beam, were analyzed by synchrotron radiation photoemission spectroscopy. After irradiation of SSOMB on the Ni(111) surface to some extent, the evolution of surface oxides were observed by core level photoemission spectra of Ni3p and O1s using SR-XPS. The surface temperature was kept to be 300 K during SSOMB irradiation and SR-XPS measurements. The SR energy was 680 eV. Oxygen uptake curves were measured at every translational energy of O beam. The initial sticking probability increased as translational energy increased from 0.3 eV to 1.0 eV, slightly decreased toward 2.2 eV, and a remarkable re-increase was observed in the region around 2.3 eV. These result show existence of two potential barriers.
Kawakami, Sho*; Shibata, Yoshihide*; Watanabe, Kiyomasa*; Ono, Noriyasu*; Kajita, Shin*; Okamoto, Masaaki*; Isayama, Akihiko; Sugihara, Masayoshi*; Kawano, Yasunori; Lukash, V. E.*; et al.
no journal, ,
no abstracts in English
Kawakami, Sho*; Ono, Noriyasu*; Watanabe, Kiyomasa*; Shibata, Yoshihide; Okamoto, Masaaki*; Miyamoto, Seiji; Isayama, Akihiko; Sugihara, Masayoshi*; Kawano, Yasunori; Lukash, V. E.*; et al.
no journal, ,
no abstracts in English
