A5022697720- Particle accelerators and beam dynamics
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Ionosphere and magnetosphere dynamics
- Laser-induced spectroscopy and plasma
- Fusion materials and technologies
- Gyrotron and Vacuum Electronics Research
- Plasma and Flow Control in Aerodynamics
- Electrohydrodynamics and Fluid Dynamics
- Electrostatic Discharge in Electronics
- HVDC Systems and Fault Protection
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Ion-surface interactions and analysis
- Plasma Applications and Diagnostics
- Gas Dynamics and Kinetic Theory
- Vacuum and Plasma Arcs
- Silicon Carbide Semiconductor Technologies
- High voltage insulation and dielectric phenomena
- Muon and positron interactions and applications
- Quantum and electron transport phenomena
- Nanopore and Nanochannel Transport Studies
- Astrophysics and Cosmic Phenomena
National Institutes for Quantum Science and Technology
2016-2023
National Agency for New Technologies, Energy and Sustainable Economic Development
2021
University of Padua
2021
Japan Atomic Energy Agency
2007-2016
Princeton Plasma Physics Laboratory
2010-2015
Saitama University
2015
Saitama Prefecture
2015
University of Milan
2013
Princeton University
2010-2011
CEA Cadarache
2009
The ITER Neutral Beam Test Facility (NBTF), called PRIMA (Padova Research on Megavolt Accelerator), is hosted in Padova, Italy and includes two experiments: MITICA, the full-scale prototype of heating neutral beam injector, SPIDER, full-size radio frequency negative-ions source. NBTF realization exploitation SPIDER MITICA have been recognized as necessary to make future operation injectors efficient reliable, fundamental achievement thermonuclear-relevant plasma parameters ITER. This paper...
The ITER project requires additional heating by two neutral beam injectors, each accelerating to 1 MV a 40 A of negative deuterium ions, deliver the plasma power about 17 MW for one hour. As these requirements have never been experimentally met, it was recognized as necessary setup test facility, PRIMA (Padova Research on Megavolt Accelerator), in Italy, including full-size ion source, SPIDER, and prototype whole injector, MITICA, aiming develop injectors be installed ITER. This realization...
Heating neutral beam (HNB) injectors, necessary to achieve burning conditions and control plasma instabilities in ITER, are characterized by such demanding parameters that a test facility (NBTF) dedicated their development optimization is being realized Padua (Italy) with direct contributions from the Italian government (through Consorzio RFX as host entity) ITER international organization (with kind domestic agencies of Europe, Japan India) technical scientific support various European...
Hydrogen negative ion beams of 507 keV, 1 A and 486 2.8 have been successfully produced in the JT-60U source with a three-stage accelerator by overcoming poor voltage holding large-size grids ∼2 m 2 . This is first result H − beam acceleration up to 500 keV at high current over A. In order improve capability, breakdown voltages small-size electrodes uniform locally strong electric fields were examined changing gap length. It was found that below half field which used design accelerator....
Significant progress in the extension of pulse durations powerful negative ion beams has been made to realize neutral beam injectors for JT-60SA and ITER. In order overcome common issues long-pulse production/acceleration ITER, new technologies have developed source MeV accelerator Japan Atomic Energy Agency.
Developments of the large negative ion source have been progressed in high-energy, high-power, and long-pulse neutral beam injector for JT-60 Super Advanced. Countermeasures studied tested critical issues grid heat load voltage holding capability. As acceleration grids, direct interception D- ions was reduced by adjusting beamlet steering. a result, below an allowable level injections. capability, local electric field mitigated tuning gap lengths between large-area grids accelerator....
A high-density and high-speed flowing helium-plasma is produced quasi-steadily (1 ms) by use of a magneto-plasma-dynamic arcjet (MPDA) in various external magnetic field configurations. In uniform configuration, an ion acoustic Mach number Mi the plasma flow limited to be nearly unity. divergent nozzle on other hand, increases up almost 3. The proportion gradient field. Spatial variations are well predicted isentropic model compressible flow. decreases downstream region due charge-exchange...
The first neutral beam (NB) injection system of the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak was partially completed in 2010 with only 1∕3 its full design capability, and NB heating experiments were carried out during KSTAR operation campaign. ion source is composed a JAEA bucket plasma generator KAERI large multi-aperture accelerator assembly, which designed to deliver 1.5 MW, power deuterium at 95 keV. Before experiments, discharge, extraction characteristics...
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...
The megavolt ITER injector and concept advancement experiment is the prototype test bed of heating current drive neutral beam injectors, currently in final design phase, view installation Padova Research on Injector Megavolt Accelerated facility Padova, Italy. source key component system, as its goal generation 1 MeV accelerated deuterium or hydrogen negative ions. This paper presents highlights latest developments for finalization MITICA design, together with a description most recent...
In order to clarify the acceleration mechanism of applied-field magneto-plasma-dynamic arcjet (MPDA) plasma, spatial profiles flow field and electromagnetic near outlet MPDA were measured using magnetic probes spectroscopic method. The plasma current densities Lorentz forces acting on evaluated experimentally. It was found that azimuthal rotation exhausted in applied is determined by a balance among E×B drift, diamagnetic centrifugal force drift. Three components force, i.e., radial,...
Procurement of a dc −1 MV power supply system for the ITER neutral beam injector (NBI) is shared by Japan and EU. The Atomic Energy Agency as Domestic (JADA) contributes to procurement ultra-high voltage (UHV) components such generator, transmission line insulating transformer NBI supply. inverter frequency 150 Hz in major circuit parameters have been proposed adopted NBI. UHV insulation has carefully designed since long pulse quite different from conventional ac or short systems. A...
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...
The influence of magnetic filter configuration on the beam uniformity was examined to improve in a large Cs-seeded negative-ion source. By reducing strength transverse field used typical source, largely improved with improvement plasma while intensity kept be nearly constant. However, coextracted electron current greatly increased. To suppress current, tent-shaped applied together modifications cusp magnets form multicusp positive-ion source arrangement. longitudinal profile deviation local...
At JAEA, as the Japan Domestic Agency (JADA) for ITER, a MAMuG (multi-aperture multi-grid) accelerator has been developed to perform required R&D ITER neutral beam (NB) system. As result of countermeasures handle excess heat load ion source by backstreaming positive ions, H − current was increased 0.32 A (the density 140 m −2 ) at energy 796 keV. This high power acceleration simulated operation condition maintaining perveance (H density/beam 3/2 accelerator. After operation, pulse length...
The production and transport processes of H0 atoms are numerically simulated using a three-dimensional Monte Carlo code. code is applied to the large JAEA 10ampere negative ion source under Cs-seeded condition obtain spatial distribution surface-produced H− ions. In this analysis, amount produced through dissociation H2 molecules calculated from electron temperature density obtained by Langmuir probe measurements. high-energy tail electrons, which greatly affects atom production, taken into...
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,...
Based on previous studies the spatial uniformity of negative ion beam, external magnetic filter was replaced to a novel tent-shaped in JAEA 10 A source. The line-cusp field configuration source chamber also changed form symmetric like many positive sources aiming at high proton yield. This allows fast electrons emitted from filament cathodes rotate azimuthally inside chamber. thus prevents localization due their B x grad drift field. As result, H(-) beam profile extracted wide region 340 170...
Vacuum insulation on a large size negative ion accelerator with multiple extraction apertures and acceleration grids for fusion application was experimentally examined designed. In the experiment, vacuum characteristics were investigated in JT-60 source &gt;1000 grid surface area of ∼2 m2. The sustainable voltages varied square root gap lengths between grids, decreased number grids. Based obtained results, JT-60SA (super advanced) is designed to produce 22 A, 500 keV D− beams 100 s.