研究者業績

石川 毅彦

イシカワ タケヒコ  (Takehiko Ishikawa)

基本情報

所属
国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 教授

J-GLOBAL ID
201901019246827999
researchmap会員ID
B000358321

外部リンク

論文

 184
  • Stephen K. Wilke, Abdulrahman Al-Rubkhi, Chihiro Koyama, Takehiko Ishikawa, Hirohisa Oda, Brian Topper, Elizabeth M. Tsekrekas, Doris Möncke, Oliver L. G. Alderman, Vrishank Menon, Jared Rafferty, Emma Clark, Alan L. Kastengren, Chris J. Benmore, Jan Ilavsky, Jörg Neuefeind, Shinji Kohara, Michael SanSoucie, Brandon Phillips, Richard Weber
    npj Microgravity 10(1) 2024年3月6日  
    Abstract The relationships between materials processing and structure can vary between terrestrial and reduced gravity environments. As one case study, we compare the nonequilibrium melt processing of a rare-earth titanate, nominally 83TiO2-17Nd2O3, and the structure of its glassy and crystalline products. Density and thermal expansion for the liquid, supercooled liquid, and glass are measured over 300–1850 °C using the Electrostatic Levitation Furnace (ELF) in microgravity, and two replicate density measurements were reproducible to within 0.4%. Cooling rates in ELF are 40–110 °C s−1 lower than those in a terrestrial aerodynamic levitator due to the absence of forced convection. X-ray/neutron total scattering and Raman spectroscopy indicate that glasses processed on Earth and in microgravity exhibit similar atomic structures, with only subtle differences that are consistent with compositional variations of ~2 mol. % Nd2O3. The glass atomic network contains a mixture of corner- and edge-sharing Ti-O polyhedra, and the fraction of edge-sharing arrangements decreases with increasing Nd2O3 content. X-ray tomography and electron microscopy of crystalline products reveal substantial differences in microstructure, grain size, and crystalline phases, which arise from differences in the melt processes.
  • Yuta Shuseki, Shinji Kohara, Tomoaki Kaneko, Keitaro Sodeyama, Yohei Onodera, Chihiro Koyama, Atsunobu Masuno, Shunta Sasaki, Shohei Hatano, Motoki Shiga, Ippei Obayashi, Yasuaki Hiraoka, Junpei T. Okada, Akitoshi Mizuno, Yuki Watanabe, Yui Nakata, Koji Ohara, Motohiko Murakami, Matthew G. Tucker, Marshall T. McDonnell, Hirohisa Oda, Takehiko Ishikawa
    The Journal of Physical Chemistry A 2024年1月18日  
  • Jannatun Nawer, Takehiko Ishikawa, Hirohisa Oda, Chihiro Koyama, Douglas M. Matson
    Journal of Astronomy and Space Sciences 40(3) 93-100 2023年9月30日  査読有り
    A study of uncertainty analysis was conducted on four key thermophysical properties of molten Platinum using a non-contacting levitation technique. More specifically, this work demonstrates a detailed reporting of the uncertainties associated with the density, volumetric thermal expansion coefficient, surface tension and viscosity measurements at higher temperatures for a widely used refractory metal, Platinum using electrostatic levitation (ESL). The microgravity experiments were conducted using JAXA’s Electrostatic Levitation Furnace (ELF) facility on the International Space Station and the terrestrial experiments were conducted using NASA’s Marshal Space Flight Center’s ESL facility. The performance of these two facilities were then quantified based on the measurement precision and accuracy using the metrological International Standards Organization’s Guide to the Expression of Uncertainty Measurement (GUM) principles.
  • Chihiro Koyama, Takehiko Ishikawa, Yuki Watanabe
    Journal of the American Ceramic Society 2023年6月23日  査読有り
  • Jannatun Nawer, Takehiko Ishikawa, Hirohisa Oda, Hideki Saruwatari, Chihiro Koyama, Xiao Xiao, Stephan Schneider, Matthias Kolbe, Douglas M. Matson
    npj Microgravity 9(1) 2023年5月24日  査読有り
    Abstract A new method for quantifying facility performance has been discussed in this study that encompasses uncertainties associated with thermophysical property measurement. Four key thermophysical properties: density, volumetric thermal expansion coefficient, surface tension, and viscosity of liquid Au have been measured in microgravity environment using two different levitation facilities. Levitation experiments were conducted using the Electrostatic Levitation Furnace (ELF) onboard the ISS in Argon and air, and the TEMPUS Electromagnetic Levitation (EML) facility on a Novespace Zero-G aircraft parabolic flight in Argon. The traditional Maximum Amplitude method was augmented through the use of Frequency Crossover method to identify the natural frequency for oscillations induced on a molten sample during Faraday forcing in ESL. The EML tests were conducted using a pulse excitation method where two techniques, one imaging and one non-imaging, were used to study surface oscillations. The results from both facilities are in excellent agreement with the published literature values. A detailed study of the accuracy and precision of the measured values has also been presented in this work to evaluate facility performance.

MISC

 134

講演・口頭発表等

 63

共同研究・競争的資金等の研究課題

 13

● 専任大学名

 1
  • 専任大学名
    総合研究大学院大学(SOKENDAI)

● 所属する所内委員会

 4
  • 所内委員会名
    安全委員会
  • 所内委員会名
    ISASニュース編集委員会
  • 所内委員会名
    宇宙環境利用専門委員会
  • 所内委員会名
    大気球専門委員会