A5043490376- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Fusion materials and technologies
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Polymer Nanocomposites and Properties
- Nuclear Materials and Properties
- Nuclear reactor physics and engineering
- High voltage insulation and dielectric phenomena
- Nuclear Physics and Applications
- Diamond and Carbon-based Materials Research
- Particle Accelerators and Free-Electron Lasers
- High-pressure geophysics and materials
- Surfactants and Colloidal Systems
- Solar and Space Plasma Dynamics
- Synthesis and properties of polymers
- Polymer crystallization and properties
- Ion-surface interactions and analysis
- Dielectric materials and actuators
- Advanced Polymer Synthesis and Characterization
- Advanced Sensor and Energy Harvesting Materials
- Metal and Thin Film Mechanics
- Gyrotron and Vacuum Electronics Research
National Institute of Technology, Ube College
2024
Tokyo University of Science
2023
Yamaguchi University
2001-2021
Tokyo City University
2008-2020
Tokiwa Park
2019
Ibaraki University
2019
National Institutes for Quantum Science and Technology
2017
Japan Proton Accelerator Research Complex
2017
Japan Atomic Energy Agency
2007-2016
Saitama University
2015
We studied the trapping of positive and negative charges in chemical structures polymers under a high electric field using space charge measurement system. Positive accumulated low-density polyethylene (LDPE), whereas polyimide (Kapton) also ethylene tetrafluoroethylene (ETFE) subjected to electron beam irradiation. To determine charge-trapping sites structures, quantum calculation was carried out Density Function Theory (DFT) with Gaussian 09. The relationship between energy band isosurface...
Vortexlike turbulent structures in hot-ion mode plasmas with several keV are observed the case a radially produced weak shear of electric fields ${E}_{r}$. However, strong ${E}_{r}$ formation due to high ion-confining potential ${\ensuremath{\phi}}_{c}$ production clears up these vortices together plasma-confinement improvement and disappearance both drift-wave turbulencelike Fourier spectral signals. These findings based on three-time progress comparison attained 1992--2002. The significant...
Charge trap in amorphous perfluoro-polymer electret is studied, focusing on electron site and energy. Low-energy inverse photoelectron spectroscopy adopted to measure solid-state affinity (EA) of cyclic transparent optical polymer (CYTOP). EA CYTOP CTL-S discovered by compensating the unwanted charge-up effect. Negatively-charged materials (polyethylene, ethylene-tetra-fluoro-ethylene, poly-tetra-fluoro-ethylene, CYTOP) are analyzed quantum mechanical calculation. Density functional theory...
The main operations from 1979 to 2000 in the GAMMA 10 tandem-mirror, characterized terms of high-potential mode having kV-order plasma-confining potentials and hot-ion yielding fusion neutrons with 10-20 keV bulk-ion temperatures, are summarized generalized as a result scalings formation effects potentials. wide validity potential-formation physics Cohen's theory Pastukhov's for thermal-barrier on electron confinement verified consolidated through electron-energy balance.
High power and long-pulse negative ion extractor, which is composed of the plasma grid (PG) extraction (EXG), newly developed toward neutral beam injector for heating current drive future fusion machines such as ITER, JT-60 Super Advanced DEMO reactor. The PG designed to enhance surface production ions efficiently by applying chamfered aperture. efficiency discharge increased a factor 1.3 against that conventional PG. EXG also with thermal analysis upgrade cooling capability long pulse...
Off-axis electron-cyclotron heating in an axisymmetric barrier mirror produces a cylindrical layer with energetic electrons, which flow through the central cell and into end region. The layer, producing localized bumped ambipolar potential ${\ensuremath{\Phi}}_{C}$, forms strong shear of radial electric fields ${E}_{r}$ peaked vorticity direction reversal ${E}_{r}\ifmmode\times\else\texttimes\fi{}B$ sheared near ${\ensuremath{\Phi}}_{C}$ peak. Intermittent vortexlike turbulent structures are...
Abstract In the negative-ion-based neutral beam injector (N-NBI) of JT-60SA, a hydrogen negative ion with energy 500 keV and current density 154 A m −2 for 118 s has been successfully demonstrated. This achievement exceeds requirements (500 keV, 130 , 100 s) first time. To maintain stable production long pulse, optimal temperatures chamber wall plasma grid were analytically examined experimentally It was confirmed that temperature during pulse should be <50 °C >200 grid. Damage to...
Design techniques for the vacuum insulation have been developed in order to realize a reliable voltage holding capability of multi-aperture multi-grid (MAMuG) accelerators fusion application. In this method, nested multi-stage configuration MAMuG accelerator can be uniquely designed satisfy target within given boundary conditions. The evaluation capabilities each acceleration stages was based on previous experimental results about area effect and effect. Since found extension by total facing...
In order to realize negative ion sources and accelerators be applicable International Thermonuclear Experimental Reactor JT-60 Super Advanced, a large cesium (Cs)-seeded source multi-aperture multi-stage electric acceleration have been developed at Japan Atomic Energy Agency (JAEA). Long pulse production of the beams independently carried out. The long high current has achieved 100 s beam 15 A by modifying source. duration time is increased three times longer than that before modification....
Long pulse acceleration of hydrogen negative ion beams with the power density over 70 MW/m2 and length 100 s has been demonstrated for first time by using a multi-aperture 3-stage accelerator. Such long was achieved integrating design beam optics voltage holding capability to meet requirements JT-60SA. By newly designed accelerator JT-60SA, at 500 kV stably sustained even after 5 g cesium seeded, heat load on each grid reduced below allowable level pulse, less than 5% total power. As result,...
Non-uniformity of the negative ion beams in JT-60 source with world-largest extraction area was improved by modifying magnetic filter from plasma grid (PG) to a tent-shaped filter. The design via electron trajectory calculation showed that expected suppress localization primary electrons emitted filaments and created uniform positive ions atoms parent particles for ions. By filter, uniformity defined as deviation averaged beam intensity reduced 14% PG ∼10% without reduction production.
In this study, a hydrogen ionic plasma with relatively low residual fractional electron concentration (ne/n+ ∼ 10−2) is generated using an aluminum grid for the production of negative ions and control ion extraction removal. The composed positive ions, containing molecular ions. Negative are in part produced several volts. A beam 50 eV or more contributes to increase density plasma. energy bias voltage tuned such way that high-density maintained.
Scaling laws of potential formation and associated effects along with their physical interpretations are consolidated on the basis experimental verification using GAMMA 10 tandem mirror. A proposal extended consolidation generalization two major theories—(i) Cohen's strong electron cyclotron heating (ECH) theory for physics plasma confining potentials (ii) generalized Pastukhov effectiveness produced confinement is made through use energy balance equation. This then followed by data from...
Following the 19th IAEA Fusion Energy Conference (Lyon, 2002), (1) three-time progress in formation of ion-confining potential heights ϕc including a record 2.1 kV comparison to those attained 1992–2002 is achieved for tandem-mirror plasmas hot-ion mode with ion temperatures several kiloelectronvolts. (2) The advance gives bases finding remarkable effects radially produced shear electric fields Er, or non-uniform sheared plasma rotation on suppression intermittent vortex-like turbulent...
An innovative magnetic configuration called ADCM (Asymmetric Deflection Compensation Magnets) has been recently proposed for the cancellation of "criss-cross" deflection ion trajectories in multi-beamlet negative accelerators. Such undesired occurs due to transverse field, which is necessary suppression co-extracted electrons. In view application this concept ITER Heating Neutral Beam Injector, new experimentally tested first time 2016, framework a research collaboration between Consorzio...
Mercury(ii) ions act as catalyst in the substitution of cyanide ion hexacyanoruthenate(ii) by pyrazine (Pz) an acidic medium. This property Hg(ii) has been utilized for its determination aqueous solutions. The progress reaction was followed spectrophotometrically measuring increase absorbance yellow colour product, [Ru(CN)5Pz]3- at 370 nm (λmax, ε = 4.2 × 103 M-1 s-1) under optimized conditions; 5.0 10-5 M [Ru(CN)64-], 7.5 10-4 [Pz], pH 4.00 ± 0.02, ionic strength (I) 0.05 (KCl) and temp....
Generalized scaling laws for the formation of plasma confining potentials and associated effectiveness produced are systematically investigated to find physics essentials common representative tandem mirror operational modes GAMMA 10, explore novel extended from bases constructed. (a) The potential scalings generalized using a finding wider validity Cohen's strong ECH theory covering modes. (b) produced, in turn, provide favourable increase central cell electron temperatures Te with...
To understand the physics of cesium (Cs) recycling in large Cs-seeded negative ion sources relevant to ITER and JT-60SA with extraction area 45-60 cm × 110-120 cm, time evolution profile was precisely measured where is longitudinally segmented into 5. The Cs seeded from oven at 180 °C source. After 1 g input, surface production ions appeared only central segment a nozzle located. Up 2 Cs, expanded over full area. has similar tendency distribution atoms that calculated. From results, it...