A5091428424- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Fusion materials and technologies
- Particle accelerators and beam dynamics
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Laser-induced spectroscopy and plasma
- Particle Detector Development and Performance
- Superconducting Materials and Applications
- Atomic and Subatomic Physics Research
- Nuclear reactor physics and engineering
- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Molecular Physics
- Advanced X-ray and CT Imaging
- Ion-surface interactions and analysis
- Electron and X-Ray Spectroscopy Techniques
- Radiation Detection and Scintillator Technologies
- Gyrotron and Vacuum Electronics Research
- High-pressure geophysics and materials
- Advanced Semiconductor Detectors and Materials
- Astronomical Observations and Instrumentation
- Silicon and Solar Cell Technologies
- Microwave and Dielectric Measurement Techniques
University of Tsukuba
2015-2024
Plasma (Russia)
2013-2023
National Institute for Fusion Science
2016-2021
Chubu University
2021
Kyoto University
2021
Dutch Institute for Fundamental Energy Research
2021
National Institutes for Quantum Science and Technology
2021
Oak Ridge National Laboratory
2021
Tokyo University of Agriculture and Technology
2016
Kyushu University
2016
This paper describes the recent progress in divertor simulation research using GAMMA 10/PDX tandem mirror towards development of divertors fusion reactors. During a plasma flow generation experiment end cell 10/PDX, ICRF heating anchor successfully extended particle flux up to 3.3 × 1023 m2 s−1. Superimposing short pulse ECH also attained maximum heat ~30 MW m−2. We have succeeded achieving and characterizing detachment high-temperature plasma, which is equivalent SOL tokamaks, by...
In the tandem mirror GAMMA 10/PDX, molecular activated recombination (MAR) leading to plasma detachment has been observed by additional hydrogen gas injection divertor simulation (i.e. end loss plasma) which is exposed V-shaped target in experimental module (D-module). The temperature near corner of decreased from ∼23 eV ∼2 as neutral pressure D-module increased. A clear density rollover was at Pa. position maximum moves upstream with increase and decreases detach target. After occurrence...
The central cell density and the diamagnetic signal were doubled as a result of plug potential formation by ECRH in hot ion mode experiments on GAMMA 10 tandem mirror. In order to obtain these remarkable results, axisymmetrized heating patterns ICRF optimized. Furthermore, conducting plates installed adjacent surface plasma along flat shaped magnetic flux tube located anchor transition regions; may contribute reduction some irregular electric fields produced possibly with thin regions....
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.
We have investigated the synergistic effect of a combination various impurity gases and hydrogen gas on plasma detachment high temperature plasma, equivalent to scrape-off layer tokamaks in GAMMA 10/PDX end region, utilizing an open magnetic field configuration. A small puff (N2, Ne, Ar, Kr, Xe) with H2 is examined evaluate their formation detached plasma; following results are obtained. (i) N2 puffs showed clear decrease electron density ion flux; (ii) form strong gradient along axial...
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...
This paper describes the recent results of divertor simulation research toward realization detached plasma using end-mirror a large tandem mirror device. The additional ion cyclotron range frequency heating in anchor-cells for higher particle flux generation significantly increases density, which attained highest up to 1.76 × 1023 particles/·m2 at exit. Massive gas injection (H2 and noble gases) into experimental module (D-module) was performed, remarkable reduction electron temperature on...
The controlled formation of an internal transport barrier (ITB) is observed in GAMMA 10 [T. Cho et al., Nucl. Fusion 45, 1650 (2005)]. localized within a layer strongly sheared Er×B plasma rotation (5.5<rc⩽10cm). This high-vorticity formed and maintained by off-axis electron-cyclotron heating, which generates cylindrical (4<rc<7cm) with high-energy electron population that modifies the initial Gaussian radial potential profile into nonmonotonic one hump structure. local...
A novel configuration of the multi-pass Thomson scattering (TS) system is proposed to improve time resolution and accuracy electron temperature measurements by use a polarization control technique. This can realize perfect coaxial multi-passing at each pass, number round trips not limited optical configuration. To confirm feasibility new method, we installed this in GAMMA 10 plasma system. As result, integrated signal double-pass about two times larger than that single-pass These results are...
An alternative principle and method in x-ray diagnostics is proposed for measurements of plasma electron temperatures ${T}_{e}.$ The different from widely utilized standard methods pulse-height analysis absorption. This proposal based on three-dimensionally diffusing charges produced by x rays a field-free substrate semiconductor detector, although these have been ignored the measurements. theory corrects conventional response employed over past quarter century ${T}_{e}$ analyses....
In the energy range from 1 keV down to a few hundred eV, newly developed ‘‘ultralow-energy measurable’’ pure-Ge detector for pulse-height analysis and current-mode observation has been characterized using synchrotron radiation monochromatized by grasshopper monochromator at Photon Factory of National Laboratory High Energy Physics (KEK). X-ray measurements in this low-energy region were previously tried out several types ‘‘windowless’’ Si(Li) detectors. These detectors, however, had trouble,...
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...
Intermittent turbulent potential fluctuations in ion-cyclotron wave heated plasmas and effects of their suppression due to strongly sheared plasma rotation with electron-cyclotron heating (ECH) for formation are observed GAMMA 10. Such a shear effect on the central-cell data is demonstrated by use heavy ion beam probe (HIBP) first time The HIBP system gold neutral employed measuring profiles radially formed as well associated Er central cell. During application ECH, produced stronger results...
In the GAMMA 10 tandem mirror, typical electron density is comparable to that of peripheral plasma torus-type fusion devices. Therefore, an effective method increase Thomson scattering (TS) signals required in order improve signal quality. 10, yttrium-aluminum-garnet (YAG)-TS system comprises a laser, incident optics, light collection detection electronics, and data recording system. We have been developing multi-pass TS for polarization-based based on YAG TS. To evaluate effectiveness...
The divertor simulation experimental module (Dmodule) has been installed in the west end region GAMMA 10/PDX. By use of Langmuir probes and spectroscopic measurement intensity ratios He I lines, temporal evolution electron temperature that density plasma D-module with V-shaped tungsten target are obtained. When additional ICRF heating is applied to anchor cell, evaluated decreases from ~60 eV ~25 probe ~27 ~14 eV. difference between both measurements seems be attributed their positions....
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...
The improvement of potential confinement was attained in the GAMMA 10 tandem mirror [Phys. Rev. Lett. 55, 939 (1985); Proceedings 13th International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Washington, 1990 (International Atomic Energy Agency, Vienna, 1991), Vol. 2, p. 539] by axisymmetrization heating systems for plasma production, heating, formation. A significant increase density diamagnetism observed. In previous experiment, it difficult to central cell higher...
Measurement of fluctuation in plasma is important for studying the improvement confinement by formation potential. The density observed microwaves methods such as interferometry, reflectometry and Fraunhofer diffraction method. We have constructed a new multichannel microwave interferometer to measure radial profiles single shot. successfully measured time-dependent line-integrated shot using interferometer. Thus, we developed useful tool
In the new research plan of Plasma Research Center University Tsukuba, a high heat-flux divertor simulator (E-Divertor) was proposed by using an end-mirror exit large tandem mirror GAMMA 10/PDX device. Experiments for characterization end-loss plasma flux have been extensively performed at region and detailed behavior particles has investigated. standard hot-ion mode plasmas (ne0 ~ 2×1018 m-3, Ti0 5 keV), energy analysis ion analyzer (ELIEA). It found that temperature (100 - 400 eV) is...
A new antenna array is proposed in order to improve the sensitivity and complexity of microwave imaging diagnostics systems such as a reflectometry, interferometer, an electron cyclotron emission imaging. The consists five elements: horn antenna, waveguide-to-microstrip line transition, mixer, local oscillation (LO) module, intermediate frequency amplifier. By using LO optics can be removed, supplied power each element equalized. We report details characteristics prototype array.
Characterization experiments have been carried out so as to investigate the effects of fusion-produced neutrons on x-ray-energy responses semiconductor detectors for x-ray tomography in Joint European Torus (JET) tokamak (n-type silicon) and GAMMA 10 tandem mirror (p-type silicon). Neutron these are studied using synchrotron radiation from a 2.5 GeV positron storage ring at Photon Factory. Changes material properties investigated an impedance analyzer estimate neutron x-ray-sensitive...