A5101731709- Gyrotron and Vacuum Electronics Research
- Particle accelerators and beam dynamics
- Microwave Engineering and Waveguides
- Pulsed Power Technology Applications
- Superconducting Materials and Applications
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Plasma Applications and Diagnostics
- Combustion and Detonation Processes
- Antenna Design and Analysis
- Fusion materials and technologies
- Spacecraft Design and Technology
- Magnetic and Electromagnetic Effects
- Energy Harvesting in Wireless Networks
- Satellite Communication Systems
- Millimeter-Wave Propagation and Modeling
- Semiconductor Quantum Structures and Devices
- Nuclear Materials and Properties
- Advancements in Semiconductor Devices and Circuit Design
- Electromagnetic Simulation and Numerical Methods
- Power Line Communications and Noise
- Vibration and Dynamic Analysis
- Antenna Design and Optimization
- Energetic Materials and Combustion
- Engineering Applied Research
Setsunan University
2019-2024
Japanese Red Cross Society, Japan
2021
National Institutes for Quantum Science and Technology
2016-2019
Japan Atomic Energy Agency
2008-2017
Niigata University
2012-2016
National Institute for Fusion Science
2014-2015
Aoyama Gakuin University
2015
Sapienza University of Rome
2015
NTT (Japan)
1997-2013
The University of Tokyo
2004-2011
Regular two-dimensional plasma filamentary arrays have been observed in gas breakdown experiments using a pulsed 1.5 MW, 110 GHz gyrotron. The gyrotron Gaussian output beam is focused to an intensity of up 4 MW/cm2. filaments develop array with spacing about one quarter wavelength, elongated the electric field direction. was imaged photodiodes, slow camera, which captures entire event, and fast camera 6 ns window. These diagnostics demonstrate sequential development propagating back toward...
For the purposes of long-term use tungsten divertor walls, formation process fuzzy nanostructure induced by exposure to helium plasma was studied. In present paper, nanostructure's has been successfully reproduced new hybrid simulation method in which deformation material due pressure bubbles simulated molecular dynamics and diffusion atoms random walk based on Monte Carlo method. By results, surface height increased only when retention under steady state. It proven that growth brought about...
Propagation of an ionization front in the beam channel was observed after plasma generated using a 170GHz millimeter-wave atmosphere. The propagation velocity found to be supersonic when power density greater than 75kWcm−2. momentum coupling coefficient Cm, ratio propulsive impulse input energy, measured conical and cylindrical thruster models. A Cm value 350NMW−1 recorded propagated with velocity.
Recent progress on the high power gyrotron development in JAEA is presented. The featured to have a triode-type magnetron injection gun, cylindrical resonator working at 170 GHz with TE 31,8 mode, water-cooled diamond window and depressed collector. After demonstration of ITER basic performance, has been operated for 3 years, recorded ∼200 GJ total output energy. Next, which oscillates higher order 31,12 , designed fabricated study long pulse oscillation greater than 1 MW. In parallel,...
Ten patients with spinal arteriovenous malformations (AVMs) were examined high-field-strength (1.5-T) magnetic resonance (MR) imaging and a surface coil (eight patients) or head (two patients). Four AVMs intramedullary, six extramedullary. There was one case of Foix-Alajouanine disease (subacute necrotizing myelitis; thrombosed AVM). Three important pathologic findings--myelomalacia, total thrombosis, wall thickening the draining vein--were clearly demonstrated at MR confirmed autopsy. A...
The transmission line (TL) subsystem associated with the ITER electron cyclotron heating and current drive system has reached conceptual design maturity. At this stage responsibility of finalizing been transferred from Organization to U.S. Domestic Agency. purpose TL is transmit microwaves generated by 170-GHz gyrotrons installed in radio-frequency building launchers located one equatorial four upper tokamak ports. Each consists evacuated HE11 waveguides, direct-current breaks, power...
This paper proposes an advanced line-of-sight path-loss model incorporating characteristics of actual urban environment. Accurate results are obtained by using a two-path with shadowing caused obstacles that would appear in environment and rising reflection area vehicular traffic. By applying the environment, microcellular path loss can be predicted from ultra-high-frequency to microwave bands.
An experiment was conducted on a microwave rocket (repetitive-pulse millimeter-wave-beam-powered thruster) with repetitive pulses. A thruster model forced-breathing system used. The supplies fresh air from the thrust wall into thruster. pressure histories in weremeasured and propagation velocity of shock wave impulse were deduced. Results show that although identical to result for single-pulse operation at first pulse, increased after second pulse. Similarly, decreased dependence performance...
A high power dual-frequency gyrotron is designed and tested. The design based on a 170 GHz single-frequency with triode magnetron injection gun (MIG). MIG enables to choose variety of oscillation modes for different frequencies suitable pitch factor, which the great advantage multi-frequency gyrotron. Another frequency 137 selected in order use 1.853-mm-thick single-disk output window. Cavity are TE31,11 TE25,9 GHz, respectively, have mode conversion efficiency RF beam similar radiation...
Megawatt power gyrotrons are being developed for collaborative electron cyclotron heating (ECH) studies of advanced fusion devices and demonstration plant (DEMO). (1) In the first experiment a 300 GHz gyrotron, an output above 0.5 MW in TE32,18 single mode was achieved with pulse width 2 ms. This observation MW-scale oscillations DEMO-relevant gyrotron mode. It also found that reflection at window affected determination oscillation Furthermore, several 226–254 range were confirmed, which is...
This paper presents the frequency dependence of propagation loss and multipath characteristics for urban mobile communications based on measurement results in Japanese areas. Path reference frequencies from 457.2 MHz to 15.45 GHz increases according free space power law terms both macrocell microcell environments. The standard deviation each band exhibits similar values. Wide-band measurements show analogous among bands 3 15 propagation. These that dominant difference is found only UHF...
Megawatt (MW) gyrotrons, with a wide frequency range from 14 to 300 GHz, are being developed as part of collaborative electron cyclotron heating (ECH) study for advanced fusion devices and demonstration power plant (DEMO). (1) Detailed designs GHz 1 MW gyrotron fabrication. For radio (RF) beam high divergence, calculated transmission efficiency 94% the corrugated waveguide coupling position was obtained initially by introducing design concept (direct RF built-in waveguide) minimize path....
A new gyrotron operation technique to increase oscillation efficiency was developed using the JT-60 electron cyclotron range of frequency (ECRF) system. In order without a significant in anode leakage current by trapped electrons that limits gyrotrons with collector potential depression technology, we actively optimized pitch factor controlling only voltage within ∼0.1 s after start operation, and high-efficiency so-called hard-self-excitation region achieved from oscillation. As an...
This paper presents a summary of recent progress pertaining to the manufacturing and inspection ITER gyrotrons operation system in QST. Major achievements are as follows. (i) The final design gyrotron was accomplished two completed. Then test QST prior shipment has started with relevant high voltage power supply configuration. 1st achieved 1.05 MW for 300 s 51% efficiency. Measured cooling channel waveform pulse demonstrated thermally stable condition representing sufficient performance 1 CW...
A shock wave in a tube supported by atmospheric millimeter-wave plasma is discussed. After breakdown, the millimeter propagates at constant velocity tube. In this study, driving model of proposed. The consists normal propagating heat-supply area which an ionization front located. flow properties predicted show good agreement with measured generated using 170 GHz beam. propagation Ushock identical to Uioniz when supersonic. Then pressure increment end independent power density.
High power, long pulse millimeter (mm) wave experiments of the RF test stand (RFTS) Japan Atomic Energy Agency (JAEA) were performed. The system consists a 1 MW/170 GHz gyrotron, and short distance transmission line (TL), an equatorial launcher (EL) mock-up. RFTS has ITER-relevant configuration, i.e., consisted by MW-170 mm TL, EL TL is composed matching optics unit, evacuated circular corrugated waveguides, 6-miter bends, in-line waveguide switch, isolation valve. EL-mock-up fabricated...
This paper presents the progress of performance tests ITER gyrotrons developed at QST and design dual-frequency (170 GHz 104 GHz) to enhance various operation scenarios in ITER, such as characteristics studies H-mode/ELM low magnetic fields. The major achievements developing are follows: (i) Manufacturing eight their auxiliary components has been completed. Performance have progressing four achieved required test criteria—1 MW / 300 s 50 %, 5 kHz modulation with ≥ 0.8 MW. Excitation LP01...
A 5 kHz full power modulation experiment is demonstrated on a 170 GHz gyrotron. high-power and beam on/off achieved by employing fast short-circuited switch between the anode cathode of triode-type electron gun (single switch). Lower heat load cavity collector compared with continuous-wave operation realizes more than 1 MW oscillation designed The maximum 1.16 an electrical efficiency 48%. In high-efficiency operation, unwanted mode observed at start-up phase each pulse, which induced slow...