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In state-of-the-art stellarators, turbulence is a major cause of the degradation of plasma confinement. To maximize confinement, which eventually determines the amount of nuclear fusion reactions, turbulent transport needs to be reduced. Here we report the observation of a confinement regime in a stellarator plasma that is characterized by increased confinement and reduced turbulent fluctuations. The transition to this regime is driven by the injection of submillimetric boron powder grains into the plasma. With the line-averaged electron density being kept constant, we observe a substantial increase of stored energy and electron and ion temperatures. At the same time, the amplitude of the plasma turbulent fluctuations is halved. While lower frequency fluctuations are damped, higher frequency modes in the range between 100 and 200 kHz are excited. We have observed this regime for different heating schemes, namely with both electron and ion cyclotron resonant radio frequencies and neutral beams, for both directions of the magnetic field and both hydrogen and deuterium plasmas.

A predictor model of radiative collapse of stellarator-heliotron plasmas has been developed by means of a machine learning technique and the feature of radiative collapse has been extracted with sparse modeling. The dataset used for training the model is constructed based on density ramp-up experiments in the Large Helical Device. As a result of feature extraction, the line averaged electron density, visible line emissions of CIV and OV, and the electron temperature at the edge have been selected as key parameters of radiative collapse. The likelihood of occurrence of radiative collapse has been quantified by using these parameters and this likelihood has been assessed in terms of predicting capability of the occurrence of radiative collapse. The collapse likelihood also implies the underlying physics of radiative collapse, therefore, the knowledge obtained by this data-driven study is expected to facilitate elucidation of the physics of the radiative collapse. In validation with discharges outside of the dataset, the predictor based on the likelihood has predicted over 85% of radiative collapse about 100 ms prior to this event on average while about 5% of stable discharges have been detected falsely as collapse discharges. The discharges in which the predictor made faults are discussed in order to investigate the cause of failure.

Spectroscopic studies of emissions released from tungsten ions combined with a pellet injection technique have been conducted in the Large Helical Device. The tungsten Unresolved Transition Array (UTA) spectrum was observed in the wavelength ranges of extreme ultraviolet (EUV) 6–60 Å and 130–340 Å, and the electron temperature dependence of the UTA spectral shape was investigated in the electron temperature region < 4.3 keV. The UTAs of W24+–W33+ at 20–33 Å, W37+–W42+ at 45–47 Å, W27+–W29+ at 48–55 Å, and W7+– W27+ at 170–210 Å were observed. Unidentified UTAs were also found at 230–270 Å and 280–320 Å. As the electron temperature increased further above 4 keV, the W37+–W42+ UTA at 45–47 Å was maintained, while the other UTAs became less intense.

Toward real-time wall conditioning, impurity powder dropping experiments with boron powder were performed in the 22nd experimental campaign of the Large Helical Device. To examine the deposition and desorption process of boron, we focus on boron hydride (BH) molecules which presumably populate near plasma-facing components. We performed spatially-resolved spectroscopic measurements of emission by boron ions and BH molecules. From the measurement, we found that BH and B+ were concentrated on the divertor viewing chord, which suggest boron deposition in the divertor region. By comparing Hγ emissions with and without boron injection, neutral hydrogen shows uniform reduction in the SOL region, whereas less reduction of neutral hydrogen is confirmed in the divertor region. Although emissions from BH and B+ increased linearly, emissions by B0 and B4+ became constant after the middle of the discharge. Continuous reduction of carbon density in the core plasma was confirmed even after B0 and B4+ became constant. The results may show reduction of hydrogen recycling and facilitation of impurity gettering by boron in the divertor region and thus effective real-time wall conditioning.

An energy transfer phenomenon between energetic ions, which cannot be explained only considering the Coulomb scattering process, was observed on a large helical device (LHD). This phenomenon often occurs in fusion reactivity enhancement and fast-ion slowing-down process that can be observed as a delay in the decay time of the D(d,n)3He neutron generation rate. The transferred energy required to induce such a reactivity enhancement or delay in the fast-ion slowing-down time (neutron decay time) was examined based on the Boltzmann−Fokker−Planck analysis in which a discrete energy transfer process, called nuclear elastic scattering (NES), is included. It was shown that even though the cross section of the NES is smaller than that of the Coulomb scattering, enough knock-on population appears in the energetic region in ion distribution function to induce the observable NES effects; thus, enough energy is transferred from beam ions to fast component of bulk ion distribution function indirectly and the transferred energy per unit time via NES is comparable to the Coulomb scattering rate. This study analytically demonstrates that the observed phenomena on LHD can be explained smoothly by considering the alternative indirect energy transfer channel between energetic ions, which can be comparable with the one via Coulomb scattering.

The fast deuteron (non-Maxwellian component) diagnostic method, which is based on the higher resolution optical spectroscopic measurement, has been developed as a powerful tool. Owing to a decrease in the D-H charge-exchange cross section, the diagnostic ability of conventional optical diagnostic methods should be improved for ∼MeV energy deuterons. Because the

Controlled particulate injections from the PPPL impurity powder dropper (IPD) into the Large Helical Device have demonstrated positive effects on the wall conditions on both an intra and inter-shot basis. Injections over a range of densities, input powers, pulse lengths, heating schemes, injection quantities and main ion species show conclusive evidence of improvement to plasma wall conditions. Successful injections are confirmed by both spectroscopic measurements as well as real-time visible camera signals. In 7 s long plasmas the responses include a reduction in wall recycling as well as a reduction in native impurity content as observed over the course of several discharges. For plasmas longer than 40 s, improvements to the recycling rate and increased impurity control are observed in real time as a consequence of the extended particulate injections. These experiments demonstrate the extended applicability of this solid particulate conditioning technique to the control and maintenance of the plasma wall conditions. In addition they are an important initial step in the development of the real-time boronization technique as a supplement to standard conditioning scenarios.

The world’s first quasi-axisymmetric stellarator, CFQS, is now under construction. The CFQS will be dedicated to studies on the interaction between flow and turbulence, and confinement improvement by suppression of turbulence in connection with proof-of-principle experiment of quasi-axisymmetry. In order to conduct this experimental research, a heavy ion beam probe (HIBP) system is planned to be installed and utilized to measure the radial electric field and its fluctuation in a CFQS plasma. In this paper, an orbit calculation for a probe beam is performed to verify feasibility of the HIBP in the CFQS. The required beam energy, possible ion species, and the observable region in a CFQS plasma are investigated. The beam attenuation by a CFQS plasma is also estimated for different beam ion species. If we use 133Cs+ as a primary probe beam, the required beam energy is expected to be 30∼50 keV, which is relatively easy to handle. In this case the beam attenuation, evaluated by the ratio between the injected and detected beam currents, is 10−3∼10−2 in a CFQS plasma with a line-averaged electron density of 19 m−3. For a higher density plasma, usage of 85Rb+ is better in terms of low-beam-attenuation, and a high signal-to-noise ratio. The HIBP in the CFQS will provide a great opportunity to study physics experimentally, related to the radial electric field, poloidal flow, and turbulence suppression.

Isotope effects are one of the most important issues for predicting future reactor operations. Large helical device (LHD) is the presently working largest stellarator/helical device using super conducting helical coils. In LHD, deuterium experiments started in 2017. Extensive studies regarding isotope effects on transport have been carried out. In this paper, the results of isotope effect studies in LHD are reported. The systematic studies were performed adjusting operational parameters and nondimensional parameters. In L mode like normal confinement plasma, where internal and edge transport barriers are not formed, the scaling of global energy confinement time (τ E) with operational parameters shows positive mass dependence (M 0.27; where M is effective ion mass) in electron cyclotron heating plasma and no mass dependence (M 0.0) in neutral beam injection heating plasma. The non-negative ion mass dependence is anti-gyro-Bohm scaling. The role of the turbulence in isotope effects was also found by turbulence measurements and gyrokinetic simulation. Better accessibility to electron and ion internal transport barrier (ITB) plasma is found in deuterium (D) plasma than in hydrogen (H). Gyro kinetic non-linear simulation shows reduced ion heat flux due to the larger generation of zonal flow in deuterium plasma. Peaked carbon density profile plays a prominent role in reducing ion energy transport in ITB plasma. This is evident only in plasma with deuterium ions. New findings on the mixing and non-mixing states of D and H particle transports are reported. In the mixing state, ion particle diffusivities are higher than electron particle diffusivities and D and H ion density profiles are almost identical. In the non-mixing state, ion particle diffusivity is much lower than electron diffusivity. Deuterium and hydrogen ion profiles are clearly different. Different turbulence structures were found in the mixing and non-mixing states suggesting different turbulence modes play a role.

In order to explore the compatibility of good core plasma performance with divertor heat load mitigation, the interaction between cold edge plasma and core plasma transport, including the edge transport barrier (ETB), has been analysed in the divertor detachment discharges of deuterium plasmas in LHD with resonant magnetic perturbation (RMP) field application. The RMP application introduces a widened edge stochastic layer and sharp boundary in the magnetic field structure between the confinement region and the edge stochastic layer. The widened edge stochastic layer enhances impurity radiation and provides stable detachment operation as compared with the case without RMP. It is found that ETB is formed at the confinement boundary at the onset of detachment transition. However, as the detachment deepens, the resistive pressure gradient-driven MHD mode is excited, which degrades the ETB. At the same time, however, the core transport decreases to keep global plasma stored energy (W p) unchanged, showing clear core-edge coupling. After a gradual increase of density fluctuation during the MHD activity, a spontaneous increase of W p and the recovery of ETB are observed while the detachment is maintained. Then, the coherent MHD mode ceases and ELM-like bursts appear. In the improved mode, impurity decontamination occurs, and the divertor heat load increases slightly. Key controlling physical processes in the interplay between core and cold edge plasma are discussed. A comparison between deuterium and hydrogen plasmas shows that hydrogen plasmas exhibit similar features to the deuterium ones in terms of density and magnetic fluctuations, impurity decontamination towards higher confinement, etc. But most of the features are modest in the hydrogen plasmas and thus no clear confinement mode transition with clear ETB formation is defined. Better global confinement is obtained in the deuterium plasmas than the hydrogen ones at a higher radiation level.

Multi-species impurity seeding is an advanced operation scenario to mitigate the divertor heat load for the realization of future fusion reactors. In the large helical device, divertor detachment is successfully sustained using higher-Z (krypton, Kr) and lower-Z (neon, Ne) superimposed seeding. Emission from Kr impurities is drastically enhanced if it is followed by Ne seeding. Plasma radiation can be enhanced even at the upstream region in the edge plasma compared with Ne only seeded plasmas with suppression of impurity accumulation toward the central plasma. The characteristics of divertor heat load reduction and energy confinement are comparable between the Kr + Ne seeding and Ne only seeding under the same radiation fraction. However, while the detachment in Ne only seeding is transient, the detachment in Kr + Ne seeding is stable. It indicates that multi-species impurity seeding can be competitive for steady-state operation although further investigation is desired about the balance between divertor heat load reduction, impurity screening, and confinement degradation. The Kr emission enhancement is strongly affected by electron density and temperature at the last closed flux surface resulting in impurity penetration.

The isotope effect on impurities and bulk ion particle transport is investigated by using the deuterium, hydrogen, and isotope mixture plasma in the Large Helical Device (LHD). A clear isotope effect is observed in the impurity transport but not the bulk ion transport. The isotope effects on impurity transport and ion heat transport are observed as a primary and a secondary effect, respectively, in the plasma with an internal transport barrier (ITB). In the LHD, an ion ITB is always transient because the impurity hole triggered by the increase of ion temperature gradient causes the enhancement of ion heat transport and gradually terminates the ion ITB. The formation of an impurity hole becomes slower in the deuterium (D) plasma than the hydrogen (H) plasma. This primary isotope effect on impurity transport contributes the longer sustainment of the ion ITB state because the low ion thermal diffusivity can be sustained as long as the normalized carbon impurity gradient R/L n,c, where L c =-(∇n c/n c) -1 is above the critical value (∼-5). Therefore, the longer sustainment of the ITB state in the deuterium plasma is considered to be a secondary isotope effect due to the mitigation of the impurity hole. The radial profile of H and D ion density is measured using bulk charge exchange spectroscopy inside the isotope mixture plasma. The decay time of H ion density after the H-pellet injection and the decay time of D ion density after D-pellet injection are almost identical, which demonstrates that there is no significant isotope effect on ion particle transport.

The enhancement of the fusion reaction rate coefficient induced by energetic protons, which isone of the typical nuclear elastic scattering (NES) effects, was observed in the large helicaldevice (LHD) located at the National Institute for Fusion Science. An intense high purityhydrogen beam (the atomic ratio of the contained deuterium was less than 1 ppm) with∼170 keV-energy and ∼10 MW-power was injected into a deuterium plasma with the electrontemperature ∼9 keV and density ∼1019 m−3. After the hydrogen beam injection, the neutrongeneration rate by the D(d,n)3He fusion reaction immediately increased, and an increment ofover one order of magnitude was observed, even though there was no meaningful iontemperature variation. The reasons for the increment in the neutron generation rate arediscussed with reference to the Boltzmann–Fokker–Planck analysis along with LHDexperimental data. It is concluded that the increment was induced by the production ofenergetic deuterons due to the NES of energetic protons.

The fast deuteron (non-Maxwellian component) diagnostic method, which is based on the higher resolution optical spectroscopic measurement, has been developed as a powerful tool. Owing to a decrease in the D–H charge-exchange cross section, the diagnostic ability of conventional optical diagnostic methods should be improved for ∼MeV energy deuterons. Because the 3He–H charge-exchange cross section is much larger than that of D–H in the ∼MeV energy range, the visible light (VIS) spectrum of 3He produced by the dueteron–dueteron (DD) reaction may be a useful tool. Although the density of 3He is small because it is produced via the DD reaction, improvement of the emissivity of the VIS spectrum of 3He can be expected by using a high-energy beam. We evaluate the VIS spectrum of 3He for the cases when a fast deuteron tail is formed and not formed in the ITER-like beam injected deuterium plasma. Even when the beam energy is in the MeV energy range, a large change appears in the half width at half maximum of the VIS spectrum. The emissivity of the VIS spectrum of 3He and the emissivity of bremsstrahlung are compared, and the measurable VIS spectrum is obtained. It is shown that the VIS spectrum of 3He is a useful tool for the MeV beam deuteron tail diagnostics.

A new hydrometallurgical route was investigated in which a pure copper cathode was recovered from crude copper containing high amounts of impurity elements. As an example of crude copper, copper powder obtained from a top submerged lance furnace, which was pulverized by atomization from molten copper, was used. The selective leaching of copper was achieved using an ammoniacal alkaline solution containing divalent copper ammine complexes and ammonium chloride with most impurities (e.g. silver and gold) remaining in the residue. However, some impurities, such as nickel, arsenic, antimony, and lead were dissolved. Purification steps using hydroxyapatite and magnesium chloride were effective at removing lead, antimony, and arsenic. On the basis of these results, copper cathode recovery from crude copper was examined. As a result, a sufficiently pure copper cathode was finally obtained by monovalent copper electrolysis, which indicated the possibility of using this process as a new route for recovering pure copper from highly impure crude copper.

A radiative collapse predictor has been developed using a machine-learning model based on high-density plasma experiments in the Large Helical Device (LHD). Concurrently, the physical background of radiative collapse was discussed based on the distinct features extracted by a sparse modeling, which is one of the frameworks of data-driven science. Electron density, CIV and OV line emissions, and electron temperature at the plasma edge have been extracted as the key parameters of radiative collapse. Those parameters are relevant to the physical knowledge that the major cause of radiative collapse is the enhancement of radiative loss by light impurities in the plasma-edge region. Using these four parameters, the likelihood of occurrence of radiative collapse has been estimated. The behavior of plasma at the edge—in particular, the carbon impurities outside the last closed flux surface—has been evaluated using EMC3-EIRENE code for the phase with increasing likelihood, that is, the plasma is getting close to the collapse. It is shown that the radiation caused by the C3+ ion, which corresponds to the CIV emission, is enhanced in the region where electron temperature is around 10 eV.

The transport properties and line emissions of the intrinsic carbon in the stochastic layer of the Large Helical Device have been investigated with the three-dimensional edge transport code EMC3-EIRENE. The simulations of impurity transport and emissivity have been performed to study the dedicated experiment in which the carbon emission distributions are measured by a space-resolved EUV spectrometer system. A discrepancy of the CIV impurity emission between the measurement and simulation is obtained, which is studied with the variation of the ion thermal force, friction force and the perpendicular diffusivity in the impurity transport model. An enhanced ion thermal force or a reduced friction force in the modelling can increase the CIV impurity emission at the inboard X-point region. Furthermore, the impact of the perpendicular diffusivity Dimp is studied which shows that the CIV impurity emission pattern is very sensitive to Dimp. It is found that the simulation results with the increased Dimp tend to be closer to the experimental observation. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Divertor detachment using higher-Z (Kr) and/or lower-Z (Ne) is investigated. Using Kr+Ne superimposed seeding, plasma radiation could be enhanced at the upstream region in the edge plasma with suppression of impurity accumulation toward the core plasma. Here, the pre-seeded Kr emission was drastically enhanced after the subsequent Ne seeding. Moreover, the detachment using Kr+Ne seeding could be stably sustained while the detachment using single species seeding is short-lived. Reduction of edge electron temperature due to Ne seeding can promote the Kr emission at the upstream region. It indicates the availability of multi-species impurity seeding with different cooling rate.

A charge-coupled device (CCD) is widely used as a detector of vacuum spectrometers in fusion devices. Recently, a deuterium plasma experiment has been initiated in a Large Helical Device (LHD). Totally 3.7 × 10

Vision-based environment perception is an important research topic for autonomous driving and advanced driver assistance systems. Vision sensors, such as the monocular camera and stereo camera, are widely used for environment perception. The monocular camera provides the appearance information like intensity, and the stereo camera provides the depth information. The appearance and depth information are complementary, and their effective fusion would result in robust environment perception. Consequently, in this paper, we propose a novel deep learning framework, termed as the ChiNet, for the effective sensor fusion of the appearance and depth information for free space and road object estimation. The ChiNet has two input branches and two output branches. The ChiNet input branches contains separate branches for the intensity and depth information. For the output branches, the ChiNet contains separate branches for the free space and road object semantic segmentation. A comparative of the proposed framework with state-of-the-art baseline algorithms is performed using an acquired dataset. Moreover, a detailed parameter analysis is performed to validate the ChiNet architecture as well as the advantages of sensor fusion. The experimental results show that the ChiNet is better than baseline algorithms. We also show that the proposed ChiNet architecture is better than other variations of the ChiNet architecture.

Molecular typing of Mycoplasma pneumoniae is an important tool for identifying grouped cases and investigating outbreaks. In the present study, we developed a new genotyping method based on single nucleotide polymorphisms (SNPs) selected from the whole-genome sequencing of eight M. pneumoniae strains, using the SNaPshot minisequencing assay. Eight SNPs, localized in housekeeping genes, predicted lipoproteins, and adhesin P1 genes were selected for genotyping. These SNPs were evaluated on 140 M. pneumoniae clinical isolates previously genotyped by multilocus variable-number tandem-repeat analysis (MLVA-5) and adhesin P1 typing. This method was also adapted for direct use with clinical samples and evaluated on 51 clinical specimens. The analysis of the clinical isolates using the SNP typing method showed nine distinct SNP types with a Hunter and Gaston diversity index (HGDI) of 0.836, which is higher than the HGDI of 0.583 retrieved for the MLVA-4 typing method, where the nonstable Mpn1 marker was removed. A strong correlation with the P1 adhesin gene typing results was observed. The congruence was poor between MLVA-5 and SNP typing, indicating distinct genotyping schemes. Combining the results increased the discriminatory power. This new typing method based on SNPs and the SNaPshot technology is a method for rapid M. pneumoniae typing directly from clinical specimens, which does not require any sequencing step. This method is based on stable markers and provides information distinct from but complementary to MLVA typing. The combined use of SNPs and MLVA typing provides powerful discrimination of strains.

The deuterium (D) operation was initiated in the LHD in 2017. In the first campaign of the D experiments, we successfully extended the high temperature regime in the LHD. The new record of the ion temperature (Ti) of 10 keV associated with the ion internal transport barrier (ITB) was achieved due to several operational optimization. The thermal confinement characteristics of ITB plasmas were compared between hydrogen and D discharges. The effective ion thermal diffusivity of the ion-ITB plasmas was found to be smaller in the D discharges than that in the H discharges. The profiles of the Ti, the electron density, and the impurity of the high Ti plasmas strongly depended on the magnetic configuration and these profiles tended to peaked in the inward-shifted configuration. It was also found that the electron thermal confinement of the electron-ITB plasmas was clearly improved in the deuterium case. The GKV simulation showed the linear growth rate of TEM/ITG reduced in the plasmas with D both for the ion ITB and the electron ITB plasmas and qualitatively agreed with the tendency of the change in the thermal diffusivity obtained from the power balance analysis.

We have investigated the polarization of the Lyman-α line due to anisotropic electron collisions in the Large Helical Device (LHD). Optical components provided by the CLASP (Chromospheric Lyman-αlpha Spectro-Polarimeter) project [Kano R 2017 ApJL 839 L10] team have been incorporated into a VUV spectrometer so that linearly polarized light spectra at different angles can be obtained sequentially. The steady-state phase of an ECH (electron cyclotron heating) discharge has been analyzed, and it is confirmed that the Lyman-α line is polarized. From a temporal variation analysis of the intensity, integrated over the line profile, the polarization degree is evaluated to be 3.4%. A simple theoretical model calculation shows that this polarization degree can be explained by approximately 10% anisotropy in the electron temperature between the parallel and perpendicular directions with respect to the magnetic field.

In livestock, parthenogenic embryos are simple to produce, but androgenetic embryos have been successfully produced only in sheep and cows. In the present study, matured porcine oocytes were enucleated by micromanipulation and then fertilized with sperm in vitro, thereby producing porcine androgenetic embryos. Porcine androgenetic embryos, which had only sperm genomes, were assessed for cleavage and for blastocyst formation 2 and 6 d after IVF, respectively. There was no difference in cleavage rate between androgenetic embryos and biparental IVF embryos (mean ± SD androgenetic: 65.5 ± 5.4%; biparental IVF: 63.2 ± 3.6%), but there was a difference in the rate of blastocyst formation (androgenetic: 4.5 ± 0.7%; biparental IVF: 30.2 ± 2.6%, P < 0.05). The average number of cells in Day 6 androgenetic blastocysts (34.3 ± 18.2) was lower (P < 0.05) than that in biparental IVF blastocysts (44.1 ± 19.5), but did not differ from that in parthenogenetic embryos (35.7 ± 16.7). The androgenetic embryos were transferred into recipient mothers to examine the competence of post-implantation development. Androgenetic fetuses were present on Days 21 and 25, but not on Days 28, 31, or 35. Of the six androgenetic fetuses recovered on Day 21, five had normal, translucent bodies, and two of these five had beating hearts. The four fetuses recovered on Day 25 were all non-viable. In conclusion, porcine androgenetic embryos initiated embryogenesis and had reached a viable fetal stage 21 days after IVF.

The double-differential cross sections (DDXs) for the inclusive reactions producing heavy nuclei with Z = 2–9 (fragments) from carbon, aluminum, and silicon targets induced by 50 and 70 MeV protons are systematically measured at several angles (30°, 60°, 90°, and 135°) using a specially developed Bragg curve counter and the energy-time-of-flight method. The DDXs of a silicon target for the proton-induced reaction producing fragments heavier than lithium were measured for the first time. The present results are compared with past experimental data, the LA150 evaluated data by the Los Alamos group and several intranuclear cascade models (Bertini and ISOBAR), and the JAEA-version quantum molecular dynamics model (JQMD) coupled with the Generalized Evaporation Model (GEM), which are implemented in the Particle and Heavy Ion Transport code System (PHITS). The present results agree well with the past experimental data and LA150 data for α -particle production. For the fragments heavier than lithium, the present...

To improve the accuracy of the neutron emission data in the nat Li(d,xn) reaction, which will be used as the neutron source in the International Fusion Materials Irradiation Facility (IFMIF), we measured the double-differential neutron emission cross-sections (DDXs) of the d-Li reaction at 25 MeV at the cyclotron facility of Tohoku University. The DDXs were measured at ten laboratory angles between 0° and 110° by the time-of-flight method, using a beam-swinger system and a well-collimated neutron flight channel. We used a two-gain method to obtain over most of the energy range of secondary neutrons and reveal the shape of the overall emission spectra including the breakup peak of incident deuterons near half the incidence energy, and several peaks in the high-energy tail due to stripping reactions. The experimental results compared favorably with those obtained using the extended Serber model.

The accuracy and suitability of two Monte Carlo codes for the simulation of a Compton spectrometer response function were studied. The Compton-scattered photon spectra were measured with a Schottky CdTe detector for 10–60-keV monoenergetic primary beams, and compared with the calculations, using EGS5 and MCNP4C codes. The results confirmed the accuracy of the simulations; however, the accuracy of EGS5 was significantly higher due to its ability to simulate the Doppler broadening effect.

The behavior of carbon impurities in deuterium plasmas and its impact on thermal confinement were investigated in comparison with hydrogen plasmas in the Large Helical Device (LHD). Deuterium plasma experiments have been started in the LHD and high-ion-temperature plasmas with central ion temperature (T i) of 10 keV were successfully obtained. The thermal confinement improvement could be sustained for a longer time compared with hydrogen plasmas. An isotope effect was observed in the time evolution of the carbon density profiles. A transiently peaked profile was observed in the deuterium plasmas due to the smaller carbon convection velocity and diffusivity in the deuterium plasmas compared with the hydrogen plasmas. The peaked carbon density profile was strongly correlated to the ion thermal confinement improvement. The peaking of the carbon density profile will be one of the clues to clarify the unexplained mechanisms for the formations of ion internal transport barrier and impurity hole on LHD. These results could also lead to a better understanding of the isotope effect in the thermal confinement in torus plasma.

Summary The erythrocyte esterase-D (Es-D) of four European-American pig breeds, two Taiwan native pigs (Taoyuan and Short ear breeds), Philippine native pig and wild boar populations (Sus scrofa riukiuanus) in Japan was investigated by using starch gel electrophoresis. Analysis of parentage records of the pigs revealed that the phenotypic variation of erythrocyte esterase-D was controlled by two codomi-nant alleles Es-DA and Es-DB. The allele Es-Db was mostly found in three European -American pig breeds, Landrace (0.100), Hampshire (0.135) and Duroc (0.102). All of the wild boar populations were monomorphic for allele Es-DA.

Summary The gene frequencies were calculated to investigate genetic variation apparent in blood group and serum protein systems in Asian native pigs. The results revealed that gene frequencies were generally similar in the nine pig populations, except in some systems. Differences of gene frequencies were recognized in HpY and Cpc detected on Taoyuan pigs of Taiwan and Ohmini pigs of Japan, respectively. TfC and AmC alleles were found in eight pig populations except Ohmini pigs. The overall genetic distances were calculated by gene frequencies of 13 loci and it was observed that Taoyuan pigs are closer to Ohmini pigs than to Short-ear pigs of Taiwan and other East Asian native pigs. However, the genetic distances between Asian native pigs and European or American breeds were larger than those among East Asian native pig populations.

Equilibrium experiments were performed between molten lead and six combinations of two adjacent nickel phosphides (Ni–Ni3P, Ni3P–Ni5P2, Ni5P2–Ni12P5, Ni12P5–Ni2P, Ni2P–Ni5P4 and Ni5P4–NiP2) at 973, 1023, 1073 and 1123 K. After cooling, a lead sample was analysed for nickel and phosphorus. Both nickel and phosphorus contents increased with increasing temperature. Nickel concentration decreased and that of phosphorus increased with increasing phosphorus to nickel ratio in each combination of two phases. The standard Gibbs energies of the following three reactions, Ni5P2+Ni=2Ni3P, 2Ni12P5+Ni=5Ni5P2 and 5/2Ni2P+Ni=1/2Ni12P5, were evaluated and thermodynamically discussed using nickel activity obtained in this study.

The application of digital sampling technique for extracting the timing properties of parallel-plate avalanche counter (PPAC) is described. The preamplifier output signals of two identical avalanche counters were simultaneously digitized by using a digital storage oscilloscope (sampling rate up to 10 GS/s, 8-bit resolution) and analyzed offline. The offline analysis includes signal and noise discrimination, noise filtration and determination of pulse arrival time. A time resolution better than 398 ps was obtained which matches the best literature results using analog electronics. The effect of sampling rate of signals on the achievable time resolution is studied as well. The results of the investigation lead to a simple and flexible method of data analysis in experiments dealing with avalanche counters.