A5112638218- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Nuclear Materials and Properties
- Plasma Diagnostics and Applications
- Combustion and Detonation Processes
- Fire dynamics and safety research
- Nuclear Engineering Thermal-Hydraulics
- Atomic and Subatomic Physics Research
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Laser-induced spectroscopy and plasma
- Geophysical Methods and Applications
- Bluetooth and Wireless Communication Technologies
- Solar and Space Plasma Dynamics
- Thermal and Kinetic Analysis
- Risk and Safety Analysis
- Magnetic Field Sensors Techniques
- Semiconductor materials and devices
- Combustion and flame dynamics
Japan Atomic Energy Agency
2019-2024
The University of Tokyo
2010-2016
A double-pass Thomson scattering system, in which a laser pulse makes round trip through the plasma, was constructed. Using same optics and fast detection unit, we can resolve backward forward pulses signal. Because these scatterings reflect velocity distribution along different directions, electron temperature anisotropy be estimated from system.
We have developed a multi-point Thomson scattering system with double-pass configuration for the TST-2 device and installed new collection optics same. Temperature density can now be measured simultaneously at four points by using fibers polychromators. Herein, we present results of off-axis temperature anisotropy measurements performed this system, in which no beyond error bar was observed ohmic plasmas.
In this research, the profiles of electron temperature Te and density ne for a spherical tokamak with plasma current sustained by lower hybrid waves alone have been measured first time using Thomson scattering diagnostics in TST-2 device. The profile was hollow like bell-shaped. near center were 6 eV × 1017 m−3, respectively, leading to pressure 0.6 Pa. On other hand, whole at calculated an equilibrium reconstruction code EFIT around 20 Therefore, it is suggested that fast electrons play...
The RF central solenoid operation is a method for generating an inductive electric field in device by which plasma can be produced and ohmically heated. Furthermore, it may drive the DC current via heating. Experiments were carried out TST-2 to clarify this potential under limited amount of flux swing (±0.5 mVs) solenoid. It was found that produce up approximately 0.6 kA on average when external equilibrium applied. In addition, ramped applied ECW power-sustained plasmas.
Non-inductive plasma current start-up experiments using RF power in the lower hybrid frequency range is being conducted on TST-2 spherical tokamak. Plasma currents of up to 15 kA have been achieved. The effect direct drive can be seen by comparing cases with co-drive and counter-drive. X-rays various energy ranges were measured investigate interaction between wave electrons. Soft X-ray (SX) measurements revealed that perpendicular SX emission increased significantly as increased, tangential...
A local current diagnostic using a small Rogowski coil was developed in the TST-2 spherical tokamak device (R = 0.38 m, 0.25 Bt 0.3 T, Ip 0.1 MA). is cost effective tool for that can detect signal directly. new (outer diameter 20 mm, inner 12 number of turns 360) with sensitivity to external magnetic fields, such as and Bp, successfully installed TST-2. The measured at edge just inside last closed flux surface ohmic heating about 15 A.
For successful plasma current (Ip) ramp-up by the lower hybrid wave (LHW), density must be kept at a low level. In TST-2 Ip experiment using LHW, application of electron cyclotron (ECW) was found to reduce about 10%. This allowed for further later in discharge.
For sodium-cooled fast reactors, understanding sodium combustion behaviour is crucial for managing leakage accidents. In this study, we perform benchmark analyses of the Sandia National Laboratories (SNL) T3 experiment using multi-dimensional thermal hydraulic code AQUA-SF. Conducted in an enclosed space with a large vessel volume 100 m3 and mass flow rate 1 kg/s, highlighted effects local temperature increase shortly after injection. This study aims to extend capabilities AQUA-SF by...
RF magnetic probes can be used to measure not only the wavevector, but also polarization of waves in plasmas. A 5-channel probe (5ch-RFMP) was installed TST-2 spherical tokamak and were studied detail during lower hybrid wave injection experiments. From measurements, poloidal field is found dominant. In addition polarization, components k perpendicular major radial direction obtained from phase differences among five channels. The wavenumber by scanning position 5ch-RFMP on a shot basis....
Edge electron temperature fluctuation is evaluated by the use of fast voltage sweeping technique on TST-2. The validity obtained current-voltage characteristic curve was checked comparing time evolutions floating potential between that from and measured with probe method. Good agreement them confirmed. We also found fitting errors in evaluation itself are less than 10% levels temperature. Therefore accuracy applicable to study plasma fluctuations.
A new technique is used to estimate the amplitude of temperature fluctuation in edge plasma on TST-2. Langmuir probe current-voltage characteristic curves are conditionally reconstituted terms intensity floating potential. High/low electron temperatures obtained low/high potential phases. As a result, normalized levels found be about 19 % or larger.
In order to investigate the effect of sodium combustion, Sandia National Laboratories (SNL) and Japan Atomic Energy Agency (JAEA) have exchanged information combustion modelling related experimental data in framework Civil Nuclear Research Development Working Group (CNWG). This collaboration includes a benchmark analysis SNL Surtsey spray experiment (SNL T3/T4 experiments) using AQUA-SF SPHINCS JAEA CONTAIN-LMR SNL. is multi-dimensional code, zone model (lumped mass model) applied both codes...
Abstract In order to investigate the effect of sodium combustion, Sandia National Laboratories (SNL) and Japan Atomic Energy Agency (JAEA) have exchanged information combustion modeling related experimental data in framework Civil Nuclear Research Development Working Group (CNWG). This collaboration includes a benchmark analysis SNL Surtsey spray experiment (SNL T3 experiments) using AQUA-SF SPHINCS JAEA. this paper, investigation into multi-dimensional best estimate for with are conducted...
In sodium-cooled fast reactors (SFRs), it has been pointed out that molten fuel may be discharged from the core during a severe accident (SA) accompanied by damage, and solidify into debris particles with diameters ranging several millimeters to hundred micrometers due interaction sodium coolant accumulate at bottom of reactor vessel. Therefore, is necessary understand behavior such appropriately evaluate SA event progression. To meet these requirements, analysis code using dissipative...
Sodium combustion analysis is one of the most important issues in development safety measurements sodium cooled fast reactors. However, conservative assumptions that lead to excessive margins and expensive designs were made previous evaluations. In order evaluate effects three dimensions, an code AQUA-SF has been developed, which enables more detailed elucidation phenomena evaluation effectiveness measures. this paper, we examine multidimensional spray for SNL-T3 test as a benchmark...
The amplitudes of electron temperature fluctuations are evaluated in the edge plasma TST-2 using a new technique. Langmuir probe current-voltage characteristic curves conditionally reconstituted terms magnitude floating potential. High/low temperatures obtained low/high floating-potential phases. relationship between and time-averaged gradient is discussed.
This paper presents initial results from experimental observation of edge turbulence structures in ohmically heated plasmas on Tokyo Spherical Tokamak-2 (TST-2). The experiment was conducted using two-dimensionally movable Langmuir probes. With monitoring floating potential Vf and ion saturation current Iis, the radial poloidal are obtained. high coherence fluctuations at 10-100kHz frequency observed by use probes 90° toroidally ∼75° poloidally distant each other, suggesting that have long...
Progress of severe accidents (SAs) has been previously evaluated by transferring analytical results between multiple analysis codes. In this study, a new code, SPECTRA was developed for integrated in- and ex-vessel phenomena during SAs. consists modules which have thermal hydraulics (TH) module as base part. The in-vessel TH computes complicated multi-dimensional behavior liquid sodium gas using the multi-fluid model considering compressibility. Relocation molten core is computed dissipative...