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Park, P.*; Cho, W.*; Kim, C.*; An, Y.*; Avdeev, M.*; Iida, Kazuki*; Kajimoto, Ryoichi; Park, J.-G.*
Physical Review B, 109(6), p.L060403_1 - L060403_7, 2024/02
Times Cited Count：6 Percentile：84.81(Materials Science, Multidisciplinary)Maurer, C.*; Galmarini, S.*; Solazzo, E.*; Ku
mierczyk-Michulec, J.*; Bar
, J.*; Kalinowski, M.*; Schoeppner, M.*; Bourgouin, P.*; Crawford, A.*; Stein, A.*; et al.
Journal of Environmental Radioactivity, 255, p.106968_1 - 106968_27, 2022/12
Times Cited Count：5 Percentile：33.52(Environmental Sciences)After performing multi-model exercises in 2015 and 2016, a comprehensive Xe-133 atmospheric transport modeling challenge was organized in 2019. For evaluation measured samples for the same time frame were gathered from four International Monitoring System stations located in Europe and North America with overall considerable influence of IRE and/or CNL emissions. As a lesion learnt from the 2nd ATM-Challenge participants were prompted to work with controlled and harmonized model set ups to make runs more comparable, but also to increase diversity. Effects of transport errors, not properly characterized remaining emitters and long IMS sampling times (12 to 24 hours) undoubtedly interfere with the effect of high-quality IRE and CNL stack data. An ensemble based on a few arbitrary submissions is good enough to forecast the Xe-133 background at the stations investigated. The effective ensemble size is below five.
Kim, S. B.*; Zhang, Y.*; Won, S. M.*; Bandodkar, A. J.*; Sekine, Yurina; Xue, Y.*; Koo, J.*; Harshman, S. W.*; Martin, J. A.*; Park, J. M.*; et al.
Small, 14(12), p.1703334_1 - 1703334_11, 2018/03
Times Cited Count：128 Percentile：96.23(Chemistry, Multidisciplinary)Luce, T. C.*; Challis, C. D.*; Ide, Shunsuke; Joffrin, E.*; Kamada, Yutaka; Politzer, P. A.*; Schweinzer, J.*; Sips, A. C. C.*; Stober, J.*; Giruzzi, G.*; et al.
Nuclear Fusion, 54(1), p.013015_1 - 013015_15, 2013/12
Times Cited Count：45 Percentile：87.18(Physics, Fluids & Plasmas)Pace, D. C.*; Austin, M. E.*; Bass, E. M.*; Budny, R.*; Heidbrink, W. W.*; Hillesheim, J. C.*; Holcomb, C. T.*; Gorelenkova, M.*; Grierson, B. A.*; McCune, D. C.*; et al.
Physics of Plasmas, 20(5), p.056108_1 - 056108_18, 2013/05
Times Cited Count：35 Percentile：81.13(Physics, Fluids & Plasmas)Energetic ion transport due to microturbulence is investigated in MHD-quiescent plasmas by way of neutral beam injection in the DIII-D tokamak. A range of on-axis and off-axis beam injection scenarios are employed to vary relevant parameters such as the character of the background microturbulence and the value of Eb/Te, where Eb is the energetic ion energy and Te the electron temperature. In all cases it is found that any transport enhancement due to microturbulence is too small to observe experimentally. These transport effects are modeled using numerical and analytic expectations that calculate the energetic ion diffusivity due to microturbulence. It is determined that energetic ion transport due to coherent modes, including possible reductions in neutral beam current drive, is a considerably larger effect and should therefore be considered more important for ITER.
Suzuki, Takahiro; Akers, R.*; Gates, D. A.*; G
nter, S.*; Heidbrink, W. W.*; Hobirk, J.*; Luce, T. C.*; Murakami, Masanori*; Park, J. M.*; Turnyanskiy, M.*; et al.
Nuclear Fusion, 51(8), p.083020_1 - 083020_8, 2011/08
Times Cited Count：19 Percentile：60.06(Physics, Fluids & Plasmas)Joint experiments investigating the off-axis neutral beam current drive (NBCD) capability to be utilized for advanced operation scenario development in ITER was conducted in 5 tokamaks (AUG, DIII-D, JT-60U, MAST and NSTX) through the ITPA. We discuss results obtained in the joint experiments, where the toroidal field, 
, covered 0.3-3.7 T, the plasma current, 
, 0.6-1.2 MA, and the beam energy, Eb, 67-350 keV. A current profile broadened by off-axis NBCD was observed in MAST. In DIII-D, good agreement between the measured and calculated NB driven current profile was observed. In JT-60U, agreement between measured and calculated NBCD location was obtained, when the NBCD location (0.3-0.6 in 
/
), heating power (6-13 MW), triangularity 
(0.25-0.45), and 
(85 and 350 keV) were widely scanned. In AUG (at low 
0.2) and DIII-D, introduction of a fast ion diffusion coefficient of 
0.3-0.5 m
/s in the calculation gave better agreement at high heating power (5 and 7.2 MW), suggesting anomalous transport of fast ions by turbulence. It was found through these ITPA joint experiments that NBCD related physics quantities reasonably agree with calculations (with = 0-0.5 m/s) in all devices when there is no MHD activity except ELMs. Proximity of measured off-axis beam driven current to the corresponding calculation with = 0 has been discussed for ITER in terms of a theoretically predicted scaling of fast-ion diffusion that depends on /
for electrostatic turbulence or 
for electromagnetic turbulence.
Suzuki, Takahiro; Akers, R.*; Gates, D. A.*; Gnter, S.*; Heidbrink, W. W.*; Hobirk, J.*; Luce, T. C.*; Murakami, Masanori*; Park, J. M.*; Turnyanskiy, M.*; et al.
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2010/10
Joint experiments investigating the off-axis neutral beam current drive (NBCD) capability to be utilized for advanced operation scenario development in ITER was conducted in 4 tokamaks (AUG, DIII-D, JT-60U and MAST) through the ITPA. We discuss results obtained in the joint experiments, where the toroidal field, Bt, covered 0.3-3.7 T, the plasma current, Ip, 0.6-1.2 MA, and the beam energy, Eb, 67-350 keV. A current profile broadened by off-axis NBCD was observed in MAST. In DIII-D, good agreement between the measured and calculated NB driven current profile was observed. In JT-60U, agreement between measured and calculated NBCD location was obtained, when the NBCD location (0.3-0.6 in r/a), heating power (6-13 MW), triangularity d (0.25-0.45), and Eb (85 and 350 keV) were widely scanned. In AUG (at low d 0.2) and DIII-D, introduction of a fast ion diffusion coefficient of Db 0.3-0.5 m/s in the calculation gave better agreement at high heating power (5 and 7.2 MW), suggesting anomalous transport of fast ions by turbulence. It was found through these ITPA joint experiments that NBCD related physics quantities reasonably agree with calculations (with Db=0-0.5 m/s) in all devices when there is no MHD activity except ELMs.
Oikawa, Toshihiro; Park, J. M.*; Polevoi, A. R.*; Schneider, M.*; Giruzzi, G.*; Murakami, M.*; Tani, Keiji*; Sips, A. C. C.*
no journal, ,
The author has been leading a neutral beam current drive code benchmark in the ITPA IOS topical group frame. Presently, the orbit following Monte-Carlo codes OFMC, NUBEAM and SPOT and the Fokker-Planck codes ACCOME and ASTRA have been compared. The NB fast ion source profile agrees well among the codes that employ different beam models and beam stopping models. The heating profile generally agrees, but there is visible discrepancy. This is considerted to result from finite orbit width effects. Large differenence is observed in the NBCD profile. OFMC and ACCOME calculates the initial pitch angle of a fast ion against the toroidal magnetic field, which should correctly be against the equilibrium field. By correcting this the difference is expected to be resolved to some degree. ASTRA's deviation from other codes results from its too simplified NBI geometry and a Fokker-Planck equation derived for a cylinder plasma being used, which does not accordingly include toroidal effects.
Kim, W. J.*; Seo, M.-R.*; Park, J. Y.*; Sumita, Junya; Shibata, Taiju; Sawa, Kazuhiro
no journal, ,
Carbon-carbon (C/C) composites have been widely used for high-temperature structural applications because they possess excellent mechanical properties such as high specific strength and thermal shock resistance. In the nuclear industry, the composites have also been considered for plasma facing materials in fusion reactors and high-temperature structural parts in gas cooled reactors. In the high-temperature gas cooled reactor, the composites are being considered for the application of various high-temperature structural parts such as control rod components, core restraint belts, tie rods, upper plenum shroud, hot duct insulation cover sheets, and floor blocks. However, the carbon based materials are susceptible to oxidation at temperatures above 400 
C. Therefore, the oxidation behavior and property degradation at high temperature under impure He or in air in case of accidental air ingress should be evaluated before the deployment of composites. In this study, the oxidation behavior of several nuclear-grade C/C composites was evaluated at various temperatures. Thermal and mechanical properties of the composites were also measured before and after oxidation. The oxidation experiments were performed in range of 500 to 1100 C under air or Ar atmosphere. Thermal diffusivity, flexural strength, tensile strength, and interlaminar shear strength of as-received and oxidized specimens were evaluated.
V nuclear magnetic resonance study of the triangular Kondo lattice system YbV
SnSakai, Hironori; Park, S.*; Dioguardi, A. P.*; Furukawa, Tetsuya*; Sasaki, Takahiko*; Kimata, Motoi; Kambe, Shinsaku; Tokunaga, Yo; Thomas, S. M.*; Thompson, J. D.*; et al.
no journal, ,
YbVSn has a HfFeGe-type structure, in which V atoms form a Kagome lattice and Yb atoms form a triangular lattice. This rare Yb-based Kondo triangular lattice system has attracted much attention as an essential model to explore the relationship between quantum magnetism and topological properties. To microscopically clarify the quantum criticality of this system, we have performed V nuclear magnetic resonance (NMR) studies using a single crystal of YbVSn. In this talk, I will report on the spectral assignments of V nuclei revealed from V NMR measurements in the paramagnetic state.
Suzuki, Takahiro; Akers, R.*; Gates, D. A.*; Gnter, S.*; Heidbrink, W. W.*; Hobirk, J.*; Luce, T. C.*; Murakami, Masanori*; Park, J. M.*; Turnyanskiy, M.*; et al.
no journal, ,
Joint experiments investigating the off-axis neutral beam current drive (NBCD) capability to be utilized for advanced operation scenario development in ITER was conducted in 5 tokamaks (AUG, DIII-D, JT-60U, MAST and NSTX) through the ITPA. We discuss results obtained in the joint experiments, where the toroidal field, Bt, covered 0.3-3.7 T, the plasma current, Ip, 0.6-1.2 MA, and the beam energy, Eb, 67-350 keV. A current profile broadened by off-axis NBCD was observed in MAST. In DIII-D, good agreement between the measured and calculated NB driven current profile was observed. In JT-60U, agreement between measured and calculated NBCD location was obtained, when the NBCD location (0.3-0.6 in r/a), heating power (6-13 MW), triangularity d (0.25-0.45), and Eb (85 and 350 keV) were widely scanned. In AUG (at low d 0.2) and DIII-D, introduction of a fast ion diffusion coefficient of Db 0.3-0.5 m/s in the calculation gave better agreement at high heating power (5 and 7.2 MW), suggesting anomalous transport of fast ions by turbulence. It was found through these ITPA joint experiments that NBCD related physics quantities reasonably agree with calculations (with Db=0-0.5 m/s) in all devices when there is no MHD activity except ELMs.
Tanimoto, Masataka; Cho, M.*; Shibata, Akira; Lee, C.*; Nakamura, Jinichi; Park, S.*; Tsuchiya, Kunihiko; Choo, K.*
no journal, ,
The JMTR in JAEA and HANARO in KAERI are the foremost testing/research reactors in the world and these are expected to contribute to many nuclear fields. As a part of instrument development in irradiation field, information exchange of instruments started from 2010 under the cooperation agreements between KAERI and JAEA. To get measurement data with high accuracy for fuel and material behavior studies in irradiation tests, many types of measuring equipments have been developed; these are the multi-paired thermocouples, the Linear Voltage Differential Transformer (LVDT) type gas pressure gauge and Self-Powered Neutron Detector (SPND). In this presentation, the instruments developed in JMTR and HANARO are introduced and cooperation experiments as future plan are discussed for international standardization of the instruments in the Material Testing Reactors.
