527 research outputs found
Magnetic configuration effects on TAE-induced losses and a comparison with the orbit-following model in the Large Helical Device
No full textFast-ion losses from Large Helical Device (LHD) plasmas due to toroidal Alfvén eigenmodes (TAEs) were measured by a scintillator-based lost fast-ion probe (SLIP) to understand the loss processes. TAE-induced losses measured by the SLIP appeared in energy E ranges of around 50–180 keV with pitch angles χ between 35°–45°, and increased with the increase in TAE amplitudes. Position shifts of the magnetic axis due to a finite plasma pressure led not only to an increase in TAE-induced losses but also to a stronger scaling of fast-ion losses on TAE amplitudes. Characteristics of the observed fast-ion losses were compared with a numerical simulation based on orbit-following models in which the TAE fluctuations are taken into account. The calculation indicated that the number of lost fast ions reaching the SLIP increased with the increase in the TAE amplitude at the TAE gap. Moreover, the calculated dependence of fast-ion loss fluxes on the fluctuation amplitude became stronger in the case of large magnetic axis shifts, compared with the case of smaller shifts, as was observed in the experiments. The simulation results agreed qualitatively with the experimental observations in the LHD.journal articl
Time-resolved deuterium–deuterium fusion born 1 MeV triton confinement study in EAST deuterium plasma
No full textORCID 0000-0003-4555-1837A time-resolved deuterium–deuterium (D–D) fusion-born triton confinement study, aimed at understanding alpha particle confinement ability, was performed in Experimental Advanced Superconducting Tokamak (EAST) deuterium plasmas for the first time. A scintillating fiber detector was developed for measuring the secondary deuterium–tritium (D–T) neutrons, which provide evidence of triton slowdown, in EAST. The D–D fusion-born triton confinement experiment was performed by measuring secondary D–T neutrons in D-beam-heated D plasma with a plasma current of 400 kA. The secondary D–T neutron signal and its time evolution were obtained using pulse height discrimination analysis. The D–T neutron rate was calculated using the classical energetic ion confinement model to clarify the D–T neutron measurements. The secondary D–T neutron emission rate obtained from the numerical simulation closely agrees with the experimentally obtained results when considering the prompt loss of the tritons.journal articl
sj-tif-1-jet-10.1177_15266028221134886 – Supplemental material for Characteristics, Antithrombotic Patterns, and Prognostic Outcomes in Claudication and Critical Limb-Threatening Ischemia Undergoing Endovascular Therapy
No full textSupplemental material, sj-tif-1-jet-10.1177_15266028221134886 for Characteristics, Antithrombotic Patterns, and Prognostic Outcomes in Claudication and Critical Limb-Threatening Ischemia Undergoing Endovascular Therapy by Osami Kawarada, Kan Zen, Koji Hozawa, Hideaki Obara, Kentaro Matsubara, Yoshito Yamamoto, Tatsuki Doijiri, Nozomu Tamai, Shigenori Ito, Akihiro Higashimori, Daizo Kawasaki, Hideki Doi, Kensuke Matsushita, Kengo Tsukahara, Katsuo Noda, Masahisa Shimpo, Yuki Tsuda, Shinjo Sonoda, Takuya Taniguchi, Katsuhisa Waseda, Masato Munehisa, Eiji Taguchi, Tatsuya Kinjo, Yohei Sasaki, Kenichiro Yuba, Shinichiro Yamaguchi, Takuo Nakagami, Shinobu Ayabe, Shingo Sakamoto, Takeshi Yagyu, Soshiro Ogata, Kunihiro Nishimura, Hisashi Motomura, Teruo Noguchi, Masaharu Ishihara, Hisao Ogawa and Satoshi Yasuda in Journal of Endovascular Therapy</p
Predictive analysis for triton burnup ratio in HL-2A and HL-2M plasmas
No full text0000-0003-4555-1837The expected triton burnup ratio was analyzed based on numerical simulation to study the feasibility of demonstrating energetic particle confinement through 1 MeV triton burnup experiments in HL-2A and HL-2M. Calculations were conducted using LORBIT, a collisionless Lorentz orbit code, and FBURN, a neutron emission calculation code based on the classical confinement of energetic particles. First, the orbit loss and radial distribution of the tritons were evaluated using the LORBIT code. The LORBIT code revealed that all tritons were lost within ∼10−6 s in HL-2A, whereas in HL-2M, most of the tritons were still confined at 10−3 s. The FBURN code calculated the deuterium–tritium neutron emission rate using the radial distribution of 1 MeV tritons. The predictive analysis found that nearly no deuterium–tritium neutrons remained in HL-2A at a plasma current of 160 kA. Also, in HL-2M, a significant triton burnup ratio could be obtained at the relatively high plasma currents of 1MA, 2MA, and 3MA. This analysis predicts that the triton burnup ratio exceeds 1% under relatively high plasma current conditions.journal articl
A scintillating-fiber detector for making high-time-resolution secondary D–T neutron measurements in KSTAR
No full textORCID 0000-0003-4555-1837A scintillating fiber (Sci-Fi) detector for the middle neutron flux range was installed in KSTAR as part of a collaboration between the National Institute for Fusion Science and the Korea Institute of Fusion Energy. The detector could make relatively high-time-resolution measurements of secondary deuterium (D)–tritium (T) neutron fluxes to investigate the degradation of D–D-born triton confinement, which is crucial for demonstrating alpha particle confinement, particularly above 0.9 MA in KSTAR. The pulse-height spectrum of the Sci-Fi detector exhibited two peaks, the higher of which corresponded to D–T neutrons. A discrimination technique was applied to extract the D–T neutron signal, revealing the time evolution of the D–T neutron flux during relatively high plasma current discharges with a 50 ms temporal resolution. Future research will involve investigating the causes of the degradation of the triton burnup ratio above 0.9 MA in KSTAR.journal articl
Neutron yield calculation of thin and thick d-D targets by using PHITS with frag data table
No full text0000-0003-2254-3164The D(d, n)3He reaction is one of the common monoenergetic neutron sources. We compile the Frag Data table of D(d, n)3He reaction from the literature as an external cross-section data for PHITS. We confirm the validity of the Frag Data table by the calculation of the total and angular neutron yield calculations for an ideal deuterium thin target. Finally, PHITS with the Frag Data table is applied to the angular neutron yield and spectrum calculations of the gas target and the deuterium-loaded titanium target of the Tohoku University Fast Neutron Laboratory.journal articl
Study of first orbit losses of 1 MeV tritons using the Lorentz orbit code in the LHD
No full text0000-0003-4555-1837Shot-integrated measurement of the triton burnup ratio has been performed in the Large Helical Device. It was reported that the triton burnup ratio, defined as total DT neutron yield divided by total DD neutron yield, increases significantly in inward shifted configurations. To understand the magnetic configuration dependence of the triton burnup ratio, the first orbit loss fraction of 1 MeV tritons is evaluated by means of the Lorentz orbit code for various magnetic configurations. The first orbit loss of 1 MeV tritons is seen at t of less than 10−5 s and loss points of the triton are concentrated on the side of the helical coil case where the magnetic field is relatively weak. The significant decrease of the first orbit loss fraction by 15% is obtained with the inward shift of the magnetic axis position from 3.90 to 3.55 m. It is found that the decrease of first orbit loss is due to the reduction of the first orbit loss of transition and helically trapped tritons.journal articl
Development of SH type total hip prosthesis
No full textWe compared the conventional hip prosthesis with a newly developed SH-type hip prosthesis by examining the degree of true roundness, sphericality, and surface roughness of the joint, as well as evaluating the metal stem properties. The roundness, sphericality and surface roughness were evaluated using Ogawa's criteria. Ogawa classified these values into 3 cate-gories, A (5 points), B (3 points), and C (1 point), and the overall scores into 4 categories, A (21 points or more), B (20-18 points), C (17-15 points), and D (14 points or less). In class A, roundness was less than 0.1μm and for the femoral head and less than 20μm for the acetabular cup, sphericality was less than 5μm and less than 50μm, and surface roughness less than 0.1μm and less than 0.5μm (maximal roughness of the cup was 5μm), respectively. Applying these criteria, the total score for the SH-type hip prosthesis placed it in class A. The strength and micro-cleanliness of the stem itself were sufficiently satisfactory
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