Explanipedia

Impact of material-dependent energy reflection coefficient on divertor heat flux in the Large Helical Device Open

Y. Hayashi, Y. Hamaji, M. Tokitani, S. Masuzaki, M. Kobayashi , et al. · 2025

Review of Contributions of Image Observations Using Visible Cameras to Advancements in Sustaining Long-pulse Discharges in LHD Open

M. Shoji, Hiroshi Kasahara, Tesuo Seki, R. Seki, M. Tokitani , et al. · 2025

This paper reviews the contributions of image observations to extending the duration of Ion Cyclotron Range of Frequencies (ICRF)-heated long-pulse discharges in the Large Helical Device (LHD). The plasma discharges were monitored using ov…

Helium plasma-induced surface modifications of unirradiated and pre-ion irradiated tungsten at LHD divertor leg position Open

Mingzhong Zhao, S. Masuzaki, M. Tokitani, Miyuki Yajima, Makoto Kobayashi , et al. · 2025

Understanding helium (He) plasma-induced tungsten (W) surface modifications and the effect of irradiation defects on He plasma-induced W surface modifications under a real divertor environment are important for the operation of fusion reac…

Surface modifications on unirradiated and ion-irradiated tungsten after exposed to deuterium plasma at LHD divertor-leg position Open

Mingzhong Zhao, S. Masuzaki, M. Tokitani, Miyuki Yajima, Makoto Kobayashi , et al. · 2025

In order to clarify the divertor plasma-induced tungsten (W) surface modifications as well as the irradiation defects effect, two kinds of ITER grade W were exposed to the large helical device (LHD) deuterium (D) plasma at the divertor-leg…

Impact of Material-Dependent Energy Reflection Coefficient on Divertor Heat Flux in the Large Helical Device Open

Yuki Hayashi, M. Tokitani, Suguru Masuzaki, Masahiro Kobayashi, Y. Hamaji , et al. · 2025

Glow Discharge Boronization and Real-Time Boronization Using an Impurity Powder Dropper in LHD Open

S. Masuzaki, M. Shoji, F. Nespoli, R. Lunsford, G. Motojima , et al. · 2024

Effect of nanosecond laser irradiation on tungsten grain structure Open

Haotian Yang, Ryo Yasuhara, Hiroyuki Noto, Daisuke Nagata, M. Tokitani , et al. · 2024

The laser-induced grain structure of pure tungsten was evaluated using a nanosecond Q-switched Nd:YAG laser. The grain structure, crystal orientation, and grain boundary angular distribution were analyzed through electron backscatter diffr…

Co-deposited layers on gap surfaces of bulk tungsten divertor tiles in JET ITER-like wall: Directional effects and nanostructures Open

M. Tokitani, M. Miyamoto, S. Masuzaki, Yuji Hatano, Sun Eui Lee , et al. · 2024

Reply to Comment on ‘Deuterium supersaturated surface layer in tungsten: ion energy dependence’ Open

D. Nishijima, M. Tokitani, Daisuke Nagata, T. Schwarz‐Selinger, A. Založnik , et al. · 2024

We reply to the comment by Li et al (submitted to Nucl. Fusion with this response) on our recent paper Nishijima et al (2023 Nucl. Fusion 63 126003). In this response, we address the existence of an incident ion energy, E i , threshold for…

Signal-Distribution-Based Crack Detection for Divertor Monoblock Inspection Using Eddy Current Testing Open

Fanwei Yu, Takuma Tomizawa, Noritaka Yusa, M. Tokitani · 2024

Formation of corrugated nano-fuzz tungsten thin film on silicon via helium plasma irradiation Open

Shuangyuan Feng, Shin Kajita, Ryo Yasuhara, M. Tokitani, Quan Shi · 2023

Tungsten thin films were deposited onto silicon substrates using sputtering techniques, and helium plasma irradiation was performed in a linear plasma device. Observations of the surface and cross-sectional morphology revealed the presence…

Overview of tritium retention in divertor tiles and dust particles from the JET tokamak with the ITER-like wall Open

Y. Torikai, Goro Kikuchi, A. Owada, S. Masuzaki, Teppei Otsuka , et al. · 2023

Divertor tiles after Joint European Torus-ITER like wall (JET-ILW) campaigns and dust collected after JET-C and JET-ILW operation were examined by a set of complementary techniques (full combustion and radiography) to determine the total, …

Deuterium supersaturated surface layer in tungsten: ion energy dependence Open

D. Nishijima, M. Tokitani, Daisuke Nagata, T. Schwarz‐Selinger, A. Založnik , et al. · 2023

Properties of deuterium (D) supersaturated surface layers (DSSLs) formed in tungsten (W), such as thickness, internal microstructures, and D retention, are experimentally investigated as a function of the incident ion energy, E i . W sampl…

The Effect of the Grain Size of Divertor’s Cooling Pipe on the Capability of High-Frequency Ultrasonic Tests to Evaluate the Quality of the Bond between Divertor’s Cooling Pipe and Armor Open

Mohammadjavad Faridafshin, Noritaka Yusa, Ryouji SUZUKI, Takashi FURUKAWA, M. Tokitani , et al. · 2023

This study evaluated the effect of the grain size of the divertor's cooling pipe on the capability of high-frequency ultrasonic tests to evaluate the quality of the bonded interface between the divertor's cooling pipe and armor. First, sim…

Fabrication of tungsten-based optical diffuser using fiberform nanostructure via efficient plasma route Open

Shuangyuan Feng, HIROKI NATSUME, Shin Kajita, Enhao Li, Ryo Yasuhara , et al. · 2023

Optical diffusion is an essential process used to manage photons in a wide range of photoelectric systems. This work proposes an approach to fabricate novel optical diffusers by a plasma-processing technique, using fiberform nanostructures…

Novel optical diffuser based on fiberform nanostructure by efficient plasma route Open

Shuangyuan Feng, HIROKI NATSUME, Shin Kajita, Enhao Li, Ryo Yasuhara , et al. · 2023

Optical diffusion is an essential process used to manage photons in a wide range of photoelectric systems. This work proposes an approach to fabricate novel optical diffusers by a plasma-processing technique, using helium plasma to form fi…

Novel optical diffuser based on fiberform nanostructure by efficient plasma route Open

Shuangyuan Feng, HIROKI NATSUME, Shin Kajita, Enhao Li, Ryo Yasuhara , et al. · 2023

Optical diffusion is an essential process used to manage photons in a wide range of photoelectric systems. This work proposes an approach to fabricate novel optical diffusers by a plasma-processing technique, using helium plasma to form fi…

Tritium distributions in castellated structures of Be limiter tiles from JET-ITER-like wall experiments Open

S. Lee, Yuji Hatano, S. Masuzaki, Yasuhisa Oya, M. Tokitani , et al. · 2023

Tritium retention in the castellated structure of beryllium limiters used in JET with the ITER-like wall (ILW) during the first (ILW1), third (ILW3) and all three (ILW1-3) campaigns were examined and evaluated. Tritium was deposited on the…

Mechanical Properties and Hydrogen Embrittlement Resistance in 3, 4, and 5 Element Media and Cocrfemnni High-Entropy Alloys Open

Qiu Xu, Huaqing Guan, Shaosong Huang, Zhihong Zhong, Koichi Sato , et al. · 2023

Effects of titanium concentration on microstructure and mechanical properties of high-purity vanadium alloys Open

Jingjie Shen, Takuya Nagasaka, M. Tokitani, T. Muroga, Ryuta Kasada , et al. · 2022

Validation of the plasma-wall interaction simulation code ERO2.0 by the analysis of tungsten migration in the open divertor region in the Large Helical Device Open

M. Shoji, G. Kawamura, J. Romazanov, A. Kirschner, S. Masuzaki , et al. · 2022

Tungsten migration in the open divertor region in the Large Helical Device is analyzed for validating the three-dimensional plasma-wall interaction simulation code ERO2.0. The ERO2.0 simulation reproduced the measurement of localized tungs…

Evaluation of heat removal property in W/Cu/RAFM steel joint by using electron beam facility Open

Tetsuya Yamashita, M. Tokitani, Y. Hamaji, Jingjie Shen, Hiroyuki Noto , et al. · 2022

A reliable technique for creating joints between tungsten (W) and Reduced Activated Ferritic/Martensitic (RAFM) steel with a pure-copper (Cu) interlayer (W/Cu/RAFM steel) has been explored for developing the heat removal component in the b…

Distributions of deposits and hydrogen on the upper and lower TDUs3 target elements of Wendelstein 7-X Open

Mingzhong Zhao, S. Masuzaki, G. Motojima, M. Tokitani, Miyuki Yajima , et al. · 2022

Distributions of deposits and hydrogen (H) on the graphite divertor target elements TM4h4 and TM3v5 in the test divertor units 3 (TDUs3) of Wendelstein 7-X (W7-X) are studied. The TM4h4 and TM3v5 are located at the magnetically symmetric p…

Application of High-Frequency Ultrasonic Test to the Non-Destructive Inspection of W-Cu Bonded Interface Open

Noritaka Yusa, Ryouji SUZUKI, Takashi FURUKAWA, M. Tokitani, S. Masuzaki · 2022

This study evaluated the applicability of high-frequency ultrasonic tests to the non-destructive inspection of the bonded interface between a cooling pipe and a divertor monoblock. Samples prepared in this study were an ITER-grade tungsten…

Optical Properties of Fiberform Nanostructured Tungsten in the Infrared Wavelength Range Open

Shuangyuan Feng, Shin Kajita, Ryo Yasuhara, Ryota Imazawa, M. Tokitani · 2021

Fiberform nanostructured tungsten (FN-W) samples were synthesized by helium plasma irradiation with different irradiation times. It is shown that the optical reflectivity decreases significantly with the increase of the irradiation time, e…

Enhanced D retention in RAFM steel caused by D bubbles formed inside Cr-rich surface layer Open

D. Nishijima, M. Tokitani, R.P. Doerner, S. Masuzaki, M. Miyamoto , et al. · 2021

To identify the cause for an enhanced D retention in RAFM (reduced-activation ferritic/martensitic) steels with decreasing incident D fluence, $\\phi_D$, CLAM steel samples were exposed to D plasma at a low $\\phi_D$ ~ 3 x 10²³ …

Global distribution of tritium in JET with the ITER-like wall Open

S.E. Lee, Yuji Hatano, M. Tokitani, S. Masuzaki, Yasuhisa Oya , et al. · 2021

Nondestructive analysis of tritium (T) distribution was performed by means of imaging plate technique on specimens cut from the Be limiters, W-coated carbon tiles and bulk W lamellae retrieved from the JET tokamak after the first and third…

Investigation on tritium retention and surface properties on the first wall in the large helical Device Open

Miyuki Yajima, S. Masuzaki, N. Yoshida, M. Tokitani, Teppei Otsuka , et al. · 2021

In the Large Helical Device (LHD), the first deuterium plasma experiment was conducted in 2017. To investigate tritium migration in the LHD vacuum vessel, long-term material probes were installed on the first wall before the deuterium plas…

DAMAGING OF PURE TUNGSTEN WITH DIFFERENT MICROSTRUCTURE UNDER SEQUENTIAL QSPA AND LHD PLASMA LOADS Open

S.S. Herashchenko, O.V. Byrka, V.A. Makhlaj, M. Wirtz, N.N. Aksenov , et al. · 2020

The cracking thresholds were evaluated for tungsten samples with different microstructure in the course of QSPA Kh-50 repetitive plasma loads. No damage has been observed on the exposed surfaces under 0.1 MJ/m2. Nevertheless, cracks were d…

Investigation of the distribution of remaining tritium in divertor in LHD Open

S. Masuzaki, Miyuki Yajima, K. Ogawa, G. Motojima, Masahiro Tanaka , et al. · 2020

To reveal the triton transport and the tritium migration in a deuterium plasma experiment in the Large Helical Device (LHD), the distribution of the remaining tritium in divertor tiles made of graphite after the first deuterium plasma expe…

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