•This research investigates the effect of Argon (Ar) and Neon (Ne) injection on the plasma parameters in the end-cell of GAMMA 10/PDX numerically by using a multi-fluid code.•Temperature reduction in ...the electrons and ions during Ar injection is higher than those of the Ne injection.•Particularly in the electron temperature a remarkable reduction is observed during Ar injection.•The electron density shows a tendency of roll-over phenomenon for Ar injection.•It is also observed that the radiative power loss due to the Ar injection is much higher than that of the Ne injection.
This research investigates the effect of Argon (Ar) and Neon (Ne) injection on the plasma parameters in the end-cell of GAMMA 10/PDX numerically by using a multi-fluid code. Reduction in the temperature of the electrons and ions is observed according to the increment of impurity injection. The electron density and the particle flux show tendency of roll-over phenomena for Ar injection. Temperature reduction in the electrons and ions during Ar injection is higher than those of the Ne injection. It is also observed that the charge-exchange (CX) loss and radiative power loss for Ar injection is higher than that of the Ne injection. These outcomes indicate that Ar is more effective radiative gas for generating detached plasma.
Divertor simulation study has been started as a new research plan, by making best use of a large linear plasma device. The experiment of generating the plasma flow with high heat and particle flux ...was successfully performed at an end-mirror exit of the GAMMA 10 tandem mirror. In typical hot-ion-mode plasmas, the heat-flux density of 0.6MW/m2 and the particle-flux density of 1022particles/sm2 were simultaneously achieved in the case of only ICRF heating and superimposing the 300kW ECH pulse attained the peak value of the net heat-flux up to 8MW/m2 on axis. The above experimental results and the simulation analysis of ICRF heating using the Fokker–Planck code give a clear prospect of generating the required performance for divertor studies by building up the plasma heating systems to the end-mirror cell. Detailed behavior of the plasma flow and the future research plan are also described.
Abstract
The scintillation decay time constant in liquid xenon was measured using the XMASS-I detector and its calibration setup. The scintillation decay time constants of both electron recoil and ...nuclear recoil were evaluated by comparing the observed photon detection times with Monte Carlo simulations. Two exponential components, corresponding to the singlet and triplet state of the xenon excited dimer, are needed to reproduce the observed photon detection times. In this paper, we report the measurement of the electron recoil and the nuclear recoil scintillation decay time constants with the XMASS-I detector.
Abstract
A new ultra-low background high-purity germanium (HPGe) detector has been installed at the Kamioka underground experimental site. The background count rate in the energy range from 40 keV to ...2700 keV is about 25% lower than that of the first HPGe detector installed in 2016, which has the same detector specification and similar shielding geometry. This paper describes the shielding configuration, including the cleaning of the material surface, the comparison of calibration data and simulation, the time variation of the background spectra, the sample measurement procedure, and some results of the radioactivity in the selected samples.
In this work, the high temperature oxidation behavior of selected MCrAlY overlay coatings has been investigated using the elemental concentration profile analysis. Emphasis is placed upon the ...influence of chemical composition on the oxidation. The results show that the oxide scale formation on coatings is considerably influenced by the microstructure of coating, the chemical composition of M as well as CrAlY, and the interdiffusion from substrate. If an element exists only in the one side of the overlay coating system, the diffusion amount of that particular element becomes higher. The vacancies which formed near the substrate/coating interface after thermal exposure could be generated by the diffusion of Ni and Al. A seriously diffusion-affected zone between substrate and coating are observed within 80
μm from the substrate/coating interface toward the coating surface. The cobalt-including CoCrAlYs and CoNiCrAlYs outperform the nickel-based system under the high temperature oxidizing condition.
In this paper, detailed results on spectral measurement are reported and the argument on impurity transport is presented from the comparison of the spectral measurements in the end-cell and the ...plug/barrier-cell. Spectroscopic measurement in the plug/barrier-cell was carried out for the first time. Ionization behavior in the plug/barrier-cell showed a significant difference from that in the end-cell. Discussion of detached plasma generation from the change of the electron temperature, density and emission spectrum by the gas injection conditions is also presented. In the case that the plenum pressure of noble gas was increased, the radiation of hydrogen neutrals decreased by 20~90% and the ion saturation current decreased by 90~95%, which indicated that electron density is reduced by recombination. It is suggested that the effect of molecular activated recombination may have appeared.
Aluminum alloys are widely used as materials for engineering components of automobiles and airplanes because of their light weight and high corrosion resistance. However, cracks may develop sometimes ...in aluminum components, which have to be repaired by welding. It is difficult to weld aluminum components due to its high specific thermal conductivity and high coefficient of thermal expansion. The low-pressure cold-spray technique can be used instead of welding for repairing cracks. However, the effects of surface conditions on particle deposition and the mechanical properties of cold-sprayed coatings have not been investigated thus far. In this study, the effect of surface conditions focusing on active newly formed surface on aluminum particle deposition is studied and the mechanical properties of low-pressure cold-sprayed aluminum coatings are investigated by four-point bending tests. It is found that for efficient particle deposition it was necessary to obtain active newly formed surface of the substrate and particle surfaces by several impingements because the existence of inactive native oxide films has an adverse effect on the deposition. Furthermore, the strength of a cold-sprayed specimen is found to be higher than that of a cold-rolled specimen under compressive loading.
We successfully developed a new photomultiplier tube (PMT) with a three-inch diameter, convex-shaped photocathode, R13111. Its prominent features include good performance and ultra-low radioactivity. ...The convex-shaped photocathode realized a large photon acceptance and good timing resolution. Low radioactivity was achieved by three factors: (1) the glass material was synthesized using low-radioactive-contamination material; (2) the photocathode was produced with 39K-enriched potassium; and (3) the purest grade of aluminum material was used for the vacuum seal. As a result each R13111 PMT contains only about 0.4 mBq of 226Ra, less than 2 mBq of 238U, 0.3 mBq of 228Ra, 2 mBq of 40K and 0.2 mBq of 60Co. We also examined and resolved the intrinsic leakage of Xe gas into PMTs that was observed in several older models. We thus succeeded in developing a PMT that has low background, large angular acceptance with high collection efficiency, good timing resolution, and long-term stable operation. These features are highly desirable for experiments searching for rare events beyond the standard model, such as dark matter particle interactions and neutrinoless double beta decay events.
A new micropatterning technique based on photoinduced mass transport in a polymer film is presented. The Figure shows a rod‐like dye crystallized aligned along a surface relief grating (SRG) on an ...azobenzene polymer film produced by photoirradiation through a photomask. The uniaxial alignment is achieved by one‐dimensional diffusion—restricted by the grating geometry—of the dye molecule.
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