Takahiro Nagata
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View article: Experimental progress and future plans on spherical tokamak, QUEST
Experimental progress and future plans on spherical tokamak, QUEST Open
QUEST (Q-shu university experiment with steady state spherical tokamak) aims at effective plasma current start-up and stable maintenance of plasma discharge. To solve the inherent problems in a spherical tokamak (ST) arising from insuffici…
View article: A Method for LLM-Based Construction of a Materials Property Knowledge Graph: A Case Study
A Method for LLM-Based Construction of a Materials Property Knowledge Graph: A Case Study Open
In the field of materials science, experimental data or simulation results on material properties are often unevenly distributed. In addition to the vast unexplored material space, properties of lesser interest have not been measured even …
View article: Experimental demonstration of transient CHI start-up using a floating biased electrode configuration
Experimental demonstration of transient CHI start-up using a floating biased electrode configuration Open
Transient coaxial helicity injection (CHI) current start-up in a spherical tokamak (ST) has been demonstrated for the first time using a reactor-relevant floating single biased (FSB) electrode configuration on QUEST. Unlike previous applic…
View article: Automated analysis of photoelectron yield spectroscopy spectra interpreted via power laws
Automated analysis of photoelectron yield spectroscopy spectra interpreted via power laws Open
We propose an automated method for threshold analysis in photoelectron yield spectroscopy (PYS), a technique used for measuring the ionization energy of inorganic and organic semiconductors. PYS spectra can be interpreted using the power l…
View article: Impact of Low-Dose Narrowband UV Radiation on Skin Tissue and Mast Cells in a Canine Model
Impact of Low-Dose Narrowband UV Radiation on Skin Tissue and Mast Cells in a Canine Model Open
Narrowband ultraviolet radiation (NB-UVR) therapy is widely utilized in dermatology worldwide. While the immunosuppressive effects of ultraviolet radiation are well-documented, its non-inflammatory effects remain poorly understood. This st…
View article: Electron cyclotron current start-up using a retarding electric field in the QUEST spherical tokamak
Electron cyclotron current start-up using a retarding electric field in the QUEST spherical tokamak Open
The plasma current start-up experiment is conducted through electron cyclotron (EC) heating in the QUEST spherical tokamak. During the EC heating, the application of a toroidal electric field in the opposite direction to the plasma current…
View article: Crystal Structure Modification and Dielectric Properties of Sr- and La-Containing A<sub>2</sub>B<sub>2</sub>O<sub>7</sub> Thin Films for High-Temperature Operational Film Capacitors
Crystal Structure Modification and Dielectric Properties of Sr- and La-Containing A<sub>2</sub>B<sub>2</sub>O<sub>7</sub> Thin Films for High-Temperature Operational Film Capacitors Open
In order to obtain thermally stable thin-film materials with high dielectric constant, A2B2O7 thin films (Sr2Ta2O7, Sr2Nb2O7, La2…
View article: Giant piezoresponse in nanoporous (Ba,Ca)(Ti,Zr)O<sub>3</sub> thin film
Giant piezoresponse in nanoporous (Ba,Ca)(Ti,Zr)O<sub>3</sub> thin film Open
Nanoporous Ba 0.85 Ca 0.15 (Ti 0.9 Zr 0.1 )O 3 (BCZT) films, as lead-free piezoelectrics, exhibited a d 33 ∼10 times higher than nonporous BCZT, making them promising for high-density dielectric capacitors and energy harvesters.
View article: Demonstration of transient CHI startup using a floating biased electrode configuration
Demonstration of transient CHI startup using a floating biased electrode configuration Open
Results from the successful solenoid-free plasma startup using the method of transient coaxial helicity injection (transient CHI) in the QUEST spherical tokamak (ST) are reported. Unlike previous applications of CHI on HIT-II and on NSTX w…
View article: Effects of oxidant gas for atomic layer deposition on crystal structure and fatigue of ferroelectric HfxZr1−xO2 thin films
Effects of oxidant gas for atomic layer deposition on crystal structure and fatigue of ferroelectric HfxZr1−xO2 thin films Open
View article: Sudden Change Events of Plasma Current during Electron-Cyclotron Current Start-Up on the QUEST Spherical Tokamak
Sudden Change Events of Plasma Current during Electron-Cyclotron Current Start-Up on the QUEST Spherical Tokamak Open
Non-inductive plasma current start-up experiments have been conducted using 2nd harmonic electron-cyclotron resonance heating (ECRH) on the QUEST spherical tokamak. Sudden or abrupt changes in plasma current, referred to as sudden change e…
View article: Quaternion Analysis of Transient Phenomena of Motor-Generator
Quaternion Analysis of Transient Phenomena of Motor-Generator Open
A motor-generator slowly converts low electrical power to the large rotating energy of the induction motor, which is then converted to the higher electrical power of the synchronous generator through a pulse. Such a cycle is repeated in a …
View article: Spectroscopic measurement of increases in hydrogen molecular rotational temperature with plasma-facing surface temperature and due to collisional-radiative processes in tokamaks
Spectroscopic measurement of increases in hydrogen molecular rotational temperature with plasma-facing surface temperature and due to collisional-radiative processes in tokamaks Open
Spatially resolved rotational temperature of ground state hydrogen molecules desorbed from plasma-facing surface was measured in QUEST, LTX-β, and DIII-D tokamaks, and the increases of the rotational temperature with the surface temperatur…
View article: Unusual selective monitoring of N,N-dimethylformamide in a two-dimensional layered field-effect transistor
Unusual selective monitoring of N,N-dimethylformamide in a two-dimensional layered field-effect transistor Open
N,N-Dimethylformamide (DMF) is an essential solvent in industries and pharmaceutics. Its market size range was estimated to be 2 billion US dollars in 2022. Monitoring DMF in solution environments in real time is significant because of its…
View article: Initial testing of ohmic heating through double flux swing during electron cyclotron start-up in the QUEST spherical tokamak
Initial testing of ohmic heating through double flux swing during electron cyclotron start-up in the QUEST spherical tokamak Open
A power-supply system was developed for Ohmic heating (OH) to double × 10 18 the amount of change magnetic flux in the primary central solenoid (CS) on the QUEST spherical tokamak. Two power supplies are connected with stacks of insulated-…
View article: Role of Interface Reaction Layer between Ferroelectric Hfxzr1−Xo2 Thin Film and Tin Electrode on Endurance Properties
Role of Interface Reaction Layer between Ferroelectric Hfxzr1−Xo2 Thin Film and Tin Electrode on Endurance Properties Open
View article: Create the database of the photoemission yield spectroscopy(PYS)
Create the database of the photoemission yield spectroscopy(PYS) Open
有機・無機半導体材料のイオン化ポテンシャルの情報を与える光電子収量分光（PYS）のデジタルデータベース構築を行った．検索する際のキー（メタデータ）である，（1）計測機から得られる計測メタデータ，（2）データ解析メタデータ，（3）測定試料や実験手順などを記載した試料・実験メタデータ，（4）データの利用ライセンスに関するメタデータについて整理した．低分子有機材料については，材料名を一意に特定するために行列表記の構造ファイルから線形表記に変換したSMILESなどをメタデータに含め…
View article: Nf3 And F2 Gas Fluorination of Gan Surface and Pt/Gan Interface Analyzed by Hard X-Ray Photoelectron Spectroscopy
Nf3 And F2 Gas Fluorination of Gan Surface and Pt/Gan Interface Analyzed by Hard X-Ray Photoelectron Spectroscopy Open
View article: High-Throughput Methodology for the Realization of High-Entropy Sub-Nm Equivalent-Oxide-Thickness High-Dielectric-Constant Ba(Ti,Zr,Ta,Hf,Mo)O3 Film-Based Metal-Oxide-Semiconductor-Related Devices
High-Throughput Methodology for the Realization of High-Entropy Sub-Nm Equivalent-Oxide-Thickness High-Dielectric-Constant Ba(Ti,Zr,Ta,Hf,Mo)O3 Film-Based Metal-Oxide-Semiconductor-Related Devices Open
View article: The Non-Innocent Role of Cobalt in Manipulating the Magnetic and Electric Properties of Mesoporous Silica Thin Films
The Non-Innocent Role of Cobalt in Manipulating the Magnetic and Electric Properties of Mesoporous Silica Thin Films Open
View article: High-Throughput Methodology for the Realization of High-Entropy Sub-Nm Equivalent-Oxide-Thickness High-Dielectric-Constant Ba(Ti,Zr,Ta,Hf,Mo)O<sub>3</sub> Film-Based Metal-Oxide-Semiconductor-Related Devices
High-Throughput Methodology for the Realization of High-Entropy Sub-Nm Equivalent-Oxide-Thickness High-Dielectric-Constant Ba(Ti,Zr,Ta,Hf,Mo)O<sub>3</sub> Film-Based Metal-Oxide-Semiconductor-Related Devices Open
View article: Long-Range Frequency-Modulated Continuous-Wave Lidar Employing Wavelength-Swept Optical Frequency Comb
Long-Range Frequency-Modulated Continuous-Wave Lidar Employing Wavelength-Swept Optical Frequency Comb Open
View article: Construction of photoelectron yield spectroscopy (PYS) database
Construction of photoelectron yield spectroscopy (PYS) database Open
View article: Improvements to the High-Field-Side Transient CHI System on QUEST
Improvements to the High-Field-Side Transient CHI System on QUEST Open
View article: Stay at the University of California, Santa Barbara
Stay at the University of California, Santa Barbara Open
View article: Polarity Control of an All-Sputtered Epitaxial GaN/AlN/Al Film on a Si(111) Substrate by Intermediate Oxidization
Polarity Control of an All-Sputtered Epitaxial GaN/AlN/Al Film on a Si(111) Substrate by Intermediate Oxidization Open
The ability to control the polarity of an all-sputtered epitaxial GaN/AlN/Al film on a Si(111) substrate via intermediate oxidization was investigated. A stable surface of GaN on a Si substrate is a N-terminated surface (-c surface); hence…
View article: Quaternion Analysis of Transient Phenomena in Matrix Converter Based on Space-Vector Modulation
Quaternion Analysis of Transient Phenomena in Matrix Converter Based on Space-Vector Modulation Open
The space vector of an output voltage can be rotated smoothly in a matrix converter. However, a zero-sequence component appears causing problems in the load, such as a motor. A quaternion is a four-dimensional hypercomplex number with an i…
View article: Molecular beam epitaxy of single-crystalline bixbyite <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi mathvariant="normal">In</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mrow><mml:msub><mml:mi mathvariant="normal">Ga</mml:mi><mml:mi>x</mml:mi></mml:msub></mml:mrow><mml:mo>)</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math> films (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>x</mml:mi><mml:mo>≤</mml:mo><mml:mn>0.18</mml:mn></mml:mrow></mml:math>): Structural properties and consequences of compositional inhomogeneity
Molecular beam epitaxy of single-crystalline bixbyite films (): Structural properties and consequences of compositional inhomogeneity Open
In this work, we show the heteroepitaxial growth of single-crystalline\nbixbyite (In$_{1-x}$Ga$_x$)$_2$O$_3$ films on (111)-oriented yttria-stabilized\nzirconia substrates using plasma-assisted molecular beam epitaxy under various\ngrowth …
View article: Direct feature extraction from two-dimensional X-ray diffraction images of semiconductor thin films for fabrication analysis
Direct feature extraction from two-dimensional X-ray diffraction images of semiconductor thin films for fabrication analysis Open
We built a workflow for the fabrication analysis of thin films by applying machine-learning (ML) techniques directly to the measurement data. This will lower the problem in cost of synthesizing and analyzing samples to improve the fabricat…
View article: The electrical conductivity of cubic (In<sub>1−x </sub>Ga<sub> x </sub>)<sub>2</sub>O<sub>3</sub> films (x ≤ 0.18): native bulk point defects, Sn-doping, and the surface electron accumulation layer
The electrical conductivity of cubic (In<sub>1−x </sub>Ga<sub> x </sub>)<sub>2</sub>O<sub>3</sub> films (x ≤ 0.18): native bulk point defects, Sn-doping, and the surface electron accumulation layer Open
The alloying of the group-III transparent semiconducting sesquioxides In 2 O 3 and Ga 2 O 3 can lead to a modulation of the properties of the parent compounds, e.g. the shallow- and deep-donor character of the oxygen vacancy or the presenc…