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Here, we report on role of pre-ionization using non-resonant 2.45 GHz microwave heating (P 2.45 GHz < 20 kW) in plasma start-up of neutral beam injection (NBI) for heliotron configurations in low beam power (P NB) under non-resonant heating condition. A rapid electron heating towards burn-through of the low-Z impurities was observed experimentally in the early phase of beam injection when the seed plasma density produced by the non-resonant heating was enough for the plasma start-up. Beam heating time to the burn-through increased with decreasing the seed plasma density and a critical density condition of the seed plasma for successful start-up was observed experimentally. Proper timing of the gas fuelling is critical for plasma expansion because the beam fuelling is not significant. A 0-dimensional (0D) model analysis of the NBI start-up developed in this study well reproduces the experimental results. The 0D model clarifies the physical mechanism of the NBI start-up using pre-ionization described as follows: (1) the seed plasma produces sufficient beam ions immediately after beam injection, (2) the beam ions heat up electrons that promote the ionization/dissociation of the background neutrals, (3) this process acts as a positive feedback loop resulting in further electron heating towards burn-through. The 0D model analysis shows that the critical density corresponds to the state at which the electron heating by the beam ions is equal to electron power loss due to conduction and ionization/dissociation.

Background It has been reported that decreased nitric oxide bioavailability due to increased reactive oxygen species (ROS) is one of the most important causes of coronary artery spasm (CAS). Xanthine oxidoreductase (XOR) is the rate-limiting enzyme for uric acid (UA) production and plays a pivotal role in generating ROS. It was reported that the gender differences exist in the impact of serum UA levels on cardiovascular risks. We previously demonstrated that increased plasma XOR activity is significantly associated with the incidence of CAS. However, the gender differences in the impact of plasma XOR activity on CAS remain unclear. Purpose The aim of this study was to examine the gender differences in the clinical impact of plasma XOR activity on CAS. Methods We investigated plasma XOR activity in 132 patients suspected for CAS (male, n=78; female, n=54), and underwent intracoronary acetylcholine provocation test. XOR activity assay was performed using stable isotope-labeled substrate and liquid chromatography-triple quadrupole mass spectrometry. Provoked CAS was defined as total or subtotal occlusion (≥90%) with accompanying symptoms of chest pain and/or ischemic ST-segment changes on the electrocardiogram. We excluded the patients who had significant coronary artery stenosis (≥50%) and/or were taking XOR inhibitors. Results Plasma XOR activity was significantly lower in female compared with male patients (30.3 pmol/h/mL, interquartile range (IQR) 22.8–42.7 vs. 51.7 pmol/h/mL, IQR 34.7–101.8; P Conclusions Plasma XOR activity was an independent predictor for the incidence of CAS in both genders. The impact of plasma XOR activity on CAS was stronger in female patients than in male patients. Funding Acknowledgement Type of funding sources: None. Figure 1Figure 2

A case of the application of Non Evaporable Getter (NEG) pumps to fusion devices is discussed. Compared with other pumping technologies used in fusion devices, the NEG pumps have advantages in terms of operation temperature at 100–200 °C (in which there is a high tolerance of the temperature increase due to a plasma radiation and/or an unexpected heat load from heating devices), low power consumption and compactness. Moreover, in the case of a power outage getters continue pumping and do not release hydrogen and its isotopes. The NEG pumps have been installed as an in-vessel pump into the divertor region in the Large Helical Device (LHD) for the first time. The pumping performance test shows that the effective pumping speed is 10 m3/s in hydrogen, which is close to the target value. In addition, the exposure of the NEG pumps to boronization and glow discharge treatments have been tested. While the boronization and glow discharge under noble gases do not show effect on the pumping performances of the NEG pumps, the establishment of an operational scenario including hydrogen and deuterium glow discharges consistent with other pumping facilities is still an aspect to be refined. However, the use of NEG pumps in LHD divertor is a milestone for the possibility of using this technology in future fusion devices.

Three sets of tungsten coated graphite divertor tiles (VPS-W tiles) were installed in the closed helical divertor of the Large Helical Device (LHD) instead of the graphite divertor tiles in the 2012FY plasma campaign for examining the plasma wall interaction (PWI) with divertor plasma. The first wall panels and divertor tiles of the LHD consist of stainless steels (SUS316L) and graphite, respectively. The carbon based mixed-material deposition layer including a very small amount of Fe element has been formed on not only the divertor tiles but also the first walls near the divertor tiles through the PWI processes. Such a mixed layer often causes undesirable influences for maintaining a long pulse discharge in LHD, e.g., changing the particle recycling properties and dust generation. After the single plasma campaign of the 2012FY, we confirmed drastic suppression of the mixed-material deposition layer on the first wall panels just under the VPS-W tiles. On the other hand, carbon based mixed-material deposition layer was formed on the VPS-W tile surface, where the amount of the hydrogen retention was estimated to be over ∼4 × 1021 H/m2. If we would want further suppression of the hydrogen retention on the VPS-W tiles, the plasma facing components should be replaced to a full metal wall to avoid formation of the carbon co-deposition layer. Keywords: Tungsten divertor, Dust, Hydrogen retention

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.

A 1280×960 floating diffusion storage global shutter image sensor is implemented in a 3D stacked back illuminated indirect time of flight sensor (iToF). The sensor, achieves 18,000e- full well capacity and 32% quantum efficiency (QE) with a pyramid surface for diffraction (PSD) structure [1], utilizing a 3.5µm pixel. Low power consumption is also achieved, due to low leakage current for the iToF pixel and low resistance Cu-Cu connection metal wiring. These device architectures enable high resolution and wide dynamic range 3D depth sensing for both near and far objects.

We developed a 3-D hybrid parallel finite element method with the process parallelization by MPI and the thread parallelization by OpenMP for the purpose of improving parallel performance using PCs having many core CPUs. In this paper, we clarify the performance of block multicolor ordering preprocessing as a thread parallelization method through the torque analysis of an IPM motor using the 3-D hybrid parallel finite element method on a PC cluster with a 12-core processor.

Density control is crucial for maintaining stable confined plasma. Divertor pumping, where neutral particles are compressed and exhausted in the divertor region, was developed for this task for the Large Helical Device. In this study, neutral particle pressure, which is related to recycling, was systematically scanned in the magnetic configuration by changing the magnetic axis position. High neutral particle pressure and compression were obtained in the divertor for a high plasma electron density and the inner magnetic axis configuration. Density control using divertor pumping with gas puffing was applied to electron cyclotron heated plasma in the inner magnetic axis configuration, which provides high neutral particle compression and exhaust in the divertor. Stable plasma density and electron temperature were maintained with divertor pumping. A heat analysis shows that divertor pumping did not affect edge electron heat conductivity, but it led to low electron heat conductivity in the core caused by electron-internal-transport-barrier-like formation.

Thermal and flow analyses on the cartridge-type molten salt blanket named the CARDISTRY-B (CARtridges Divided and InSerTed RadiallY – Blanket) for the compact helical fusion reactor FFHR-c1 have been carried out. As a result, it is shown that the maximum local temperature in the cartridges can be kept below 550 °C, which is an allowable temperature of the structure material, under the neutron wall loading condition of FFHR-c1. The CARDISTRY-B is composed of the tritium breeder (Breeding Blanket: BB) and the neutron shield (Shielding Blanket: SB). Both of them are toroidally segmented every two degrees. From a safety perspective, the molten salt FLiNaBe (melting point ∼305 °C) is chosen as the first option of the breeder material. In the case of FLiNaBe BB cartridge made of RAFM (Reduced Activation Ferritic/Martensitic steel), it is necessary to suppress the maximum temperature of BB cartridges to 550 °C or below. In this study, a finite volume method code considering beryllium (Be) pebbles inside a flow channel has been used to evaluate the cooling characteristics of a BB cartridge. By estimating the pressure drop through pebbles with the porous medium model, we have investigated how the temperature of BB cartridge change depends on the mass flow rate of FLiNaBe. The volumetric heating profile was modeled according to the neutronics calculation results obtained by the MCNP (Monte Carlo Neutron and Photon Transport) code.

A quasi-axisymmetric stellarator, the CFQS, has been designed as a joint project of the National Institute for Fusion Science and Southwest Jiaotong University to prove intrinsic advantages of quasi-axisymmetry. Principal parameters of the CFQS are as follows: the major radius is 1 m, the magnetic field strength is 1 T, the aspect ratio is 4, and the toroidal periodic number is 2. The magnetic field configuration is designed based on that of the CHS-qa. Enhanced confinement properties within the context of neoclassical theory are achieved by its quasi-axisymmetric configuration. In the entire radial range, the magnetic well is retained to keep favourable stability features in the magnetohydrodynamic equilibrium. A magnetic field coil system was designed for the CFQS, which consists of 16 modular coils, 12 toroidal field coils, and 4 poloidal field coils. The supporting structure is designed to withstand strong electromagnetic force under 1 T operation, maintaining enough space for heating and diagnostic systems. The mock-up modular coil with the most complicated shape was constructed by Hefei Keye Electro Physical Equipment Manufacturing Co., Ltd. to check manufacturability and the achieved accuracy. A heat-run test was performed to check the temperature rise of conductors, and the capability of 1 T operation was confirmed. After various tests for the mock-up coil, construction of actual modular coils and the vacuum vessel has begun.

A new liquid metal divertor system named the REVOLVER-D (Reactor-oriented Effectively VOLumetric VERtical Divertor) is proposed for the helical fusion reactor FFHR-d1. The REVOLVER-D is composed of molten tin shower jets stabilized by internal flow resistances of wire/tape/chain. These shower jets are inserted into the ergodic layer surrounding the main plasma. Tin is selected as the liquid metal because of its low melting point, low vapor pressure, low material cost, and high safety. The liquid metal pumps, cryopumps, and turbo molecular pumps are installed in the central vacuum vessel connected to the main vacuum vessel via 10 inner ports equipped with maze neutron shields. Central solenoid coils made of high-temperature superconductors are installed inside the central vacuum vessel to shield the pumps from the strong magnetic field. The REVOLVER-D has a good possibility to satisfy important characteristics required for the divertor system in a fusion reactor, that is, high heat load tolerance, high maintainability, sufficient vacuum pump speed, high level of safety, and a small amount of radioactive wastes.

We evaluated the two dimensional (2D) distribution of the divertor heat flux in LHD. The Infrared (IR) thermography was performed to measure the surface temperature at a divertor plate. The 3D heat conduction equation was solved using the finite element method (FEM) by taking into account the practical divertor geometry including the heat sink behind the graphite tile and the cooling system. The FEM analysis successfully reconstructs heat load distribution from the measured temperature pattern. Significant difference was found between the temperature and the heat load patterns. The FEM analysis shows that the highest heat deposition is observed at the strike line with 5–10 MWm−2 of ∼ 10 mm width in NBI heated discharge. In addition to the strike line there is also found the lower heat deposition region of ∼ 1 MW m−2 with wide channel width ∼ 30 mm. The detailed heat transport analysis inside the divertor components shows that the heat transport process is different between the strike line and the other region due to the heat channel width and to the divertor component structure. The comparison between the heat flux obtained by the thermography and that by the Langmuir probes shows reasonable agreement, except that the peak value of the heat load is higher in the IR thermography than in the Langmuir probe. By relaxing the assumption that electron temperature, Te, equal to be ion temperature, Ti, in the sheath model for the Langmuir probe analysis, the agreement becomes better for the case with Ti > Te.

Divertor pumping was applied to plasma discharges for superior fuel particle control in the Large Helical Device (LHD). The LHD is equipped with two different pumping systems. One is the main pumping system, in which the pumping speed is 260 m3/s in hydrogen. The other pumping system is the divertor pumping system in which the pumping speed is 70 m3/s in hydrogen. Divertor pumping was applied to 40-second long pulse Electron Cyclotron Heating (ECH) discharges to assess the improvement in particle control provided by divertor pumping. The results show that without divertor pumping, the electron density was not controlled by gas puffing using the feedback signal of line-averaged electron density. Then, the plasma confinement deteriorated, finally leading to radiation collapse. On the other hand, with divertor pumping, the density was well-controlled by gas puffing using the feedback signal. The results indicate that divertor pumping is one of the key tools for controlling the particles in fusion plasmas.

The design activity on the CFQS quasi-axisymmetric stellarator which is conducted as a joint international project is ongoing by National Institute for Fusion Science (NIFS) in Japan and Southwest Jiaotong University (SWJTU) in China. The CFQS magnetic field generating coils consist of sixteen modular coils (MCs) in total with four different types, four poloidal field coils (PFCs), and twelve toroidal field coils (TFCs). In designing fusion devices, eddy currents and electromagnetic (EM) forces on the vacuum vessel (VV) have to be evaluated to verify the mechanical confidence and reliability. In this work, we consider the following three issues, (1) Influence of eddy current induced by external coil current change on the CFQS magnetic confinement, (2) Evaluation of EM force on VV by eddy current under a typical current of the MC and the PFC, and (3) Feasibility check of whether it is possible to heat the CFQS VV by using induction current.

The Chinese First Quasi-axisymmetric Stellarator (CFQS) will be the first operational quasi-axially symmetric stellarator in the world. The physical and engineering complexities led to the cancellation of two famous quasi-axisymmetric stellarators, CHS-qa and NCSX. Therefore, the major mission of the CFQS is to experimentally achieve the canonical quasi-axisymmetric configuration. The CFQS has been designed to possess a number of advanced features in fixed and free-boundary equilibria. It is a compact stellarator with an aspect ratio R/a ∼4.0. The neoclassical diffusion coefficient is similar to that of tokamaks in the collisionless regime. The MHD equilibrium of the CFQS configuration is stable up to volume-averaged normalized pressure β ∼1.1%. A region of the second ballooning stability exists in this facility with a large region of plasma, becoming second stable for β ∼2.7% in free-boundary equilibria. The gap between the first and second stability boundaries is very narrow, which is greatly beneficial for the CFQS operation in the second stable regime with high β plasma. A modular coil system with 16 coils is designed which robustly reproduces the standard quasi-axisymmetric magnetic field.

The Chinese First Quasi-axisymmetric Stellarator (CFQS) is now under design and construction. It will be the first quasi-axisymmetric (QA) configuration device to be operated in the world. The main parameters of the CFQS are as follows: the toroidal periodic number Np = 2, major radius R = 1.0 m, aspect ratio Ap = 4.0 and magnetic field strength Bt = 1.0 T. The low Ap makes it quite challenging to design a supporting structure because of the limited space and strong electromagnetic (EM) force. In this paper, a cage-like supporting structure is proposed for the CFQS modular coil (MC) system to sustain the EM force and the weight of entire device. A finite element analysis is carried out for ensuring the reliability of the supporting structure. The analysis results of the CFQS global model indicate that the cage-like supporting structure can basically satisfy the requirement.

The world's first quasi-axisymmetric stellarator CFQS (China First Quasi-axisymmetric Stellarator) will be constructed as the joint project of National Institute for Fusion Science (NIFS) in Japan and Southwest Jiaotong University (SWJTU) in China [1]. Physics design of CFQS plasma was completed [2, 3], and numerous efforts are now being made to finalize engineering design of CFQS [4]. The CFQS vacuum vessel (VV) will be made of thin plates of SUS316L with thickness of 6 mm. The thickness is determined by considering fabricability and manufacturing cost. In this report, analyses have been performed to confirm the structural reliability of VV and evaluate the influence of eddy current using finite element method software ANSYS/MechanicalTM and ANSYS/MaxwellTM.

The cartridge-type helical blanket system called the CARDISTRY-B has been proposed for the helical fusion reactor FFHR-d1. The CARDISTRY-B is aimed at easy construction and maintenance. However, there remain many issues in the design. For example, these include a large number of cartridges, no tangential ports, low compatibility with the helical divertor, and others. To solve these issues, an improved design of the cartridge-type blanket is proposed and named the CARDISTRY-B2. This is composed of the tritium breeding blanket (BB) filled with the flowing molten salt and the neutron shielding blanket (SB) filled with the tungsten-carbide. The number of the BB (or, SB) cartridges in the 1/10 section of the full torus are reduced from 32 to 17 (or, from 44 to 17). Tangential ports for the neutral beam injection heating are newly equipped together with the multi-purpose blanket cartridge. Compatibility with the helical divertor is also improved. The BB cartridges are fixed on the fixing units set on the top of the SB. No other part of the BB is touching the SB except the fixing ribs. The SB cartridges surround the superconducting magnet coils and work as the cryostat inside the vacuum vessel. This makes the large bellows for the large maintenance ports unnecessary. Details of the CARDISTRY-B2 designed for a small helical fusion reactor FFHR-b1 are described in this paper.

In the Large Helical Device (LHD), studies of divertor heat and particle control have been conducted with a helical divertor magnetic structure which exists naturally in the heliotron-type magnetic configuration to explore operation scenarios in a heliotron-type fusion reactor. Reduction of the divertor heat load has been one of the focused studies in the recent LHD experiment. Impurity seeding and modification of the edge magnetic structure with a resonant magnetic perturbation field have been investigated to enhance radiation power. To control the fueled particles and impurities, the helical diveror will be closed with a baffle structure and in-vessel cryo-sorption pump in 2012. For the examination of the baffle structure, it was partially installed in LHD in 2010. Comparison of the neutral particle pressure in the divertor with the baffle structure and with the existing open divertor shows that the baffle structure efficiently compresses fueled particles in the divertor.

An outbreak of a disease characterized by a peculiar spiral movement in farmed greater amberjack, Seriola dumerili (Risso), occurred in Kagoshima Prefecture, Japan, in May 2008, immediately after importing the fish from China. Although neither bacteria nor viruses were detected in routine diagnostic tests, histopathological observations of the affected fish revealed severe inflammation in the tegmentum of the brain including the medulla oblongata and the anterior part of the spinal cord. In addition, a microsporidian parasite was observed in the nerve cell bodies or axons in the inflamed tissues. We identified a microsporidian small subunit rRNA gene (SSU rDNA) from the lesion, and the sequence showed 96.1% identity with that of Spraguea lophii. Subsequent in situ hybridization using probes presumably specific to the SSU rRNA confirmed that the parasite observed in histopathology harboured the identified SSU rRNA. Apparently degenerated microsporidian cells or spores were also frequently observed in tissue sections. Thus, the disease was most probably caused by the infection of a hitherto unknown microsporidian parasite that has a genetic affinity to the genus Spraguea, in the central nervous system of the amberjack.

Neutral particle behavior in the Large Helical Device heliotron has been investigated to conduct the effective particle control using the intrinsic helical divertor. It was revealed that the torus in–out asymmetry observed in the neutral pressure distribution depended on the divertor particle flux distribution, and thus, on the operational magnetic configuration. It was also revealed that the neutral pressure in the vacuum vessel in LHD was below 0.1 Pa. Degradation of the plasma confinement with increasing of the neutral pressure was observed, and that suggested the effective particle control is necessary for the sustaining of long discharge with high performance plasma and the further improvement of the confinement. The modification of the open helical divertor to the closed one was investigated for the particle control using helical divertor by using EIRENE code. Results of the calculation showed that proper rearrangement of divertor plates and additional components, such as dome structure make the neutral particles to be compressed well in the divertor region, and effective divertor pumping to be possible. Based on the simulation and experimental results, design of the closed helical divertor was completed and it will be partially installed in the Large Helical Device before the experimental campaign in 2010.

To understand the edge plasma transport in the complex magnetic field lines structure in the LHD heliotoron, the heat and particle fluxes profiles on divertor plates were investigated experimentally and theoretically by using EMC3-EIRENE code. The heat flux profiles on a divertor plate in different magnetic configuration were measured and the main channel of the heat transport was revealed to be the field lines with long connection lengths which connect the divertor plate and the stochastic field lines layer. A comparison of the heat and the ion fluxes profiles on the divertor plates between the experimental data and the results of the calculation using EMC3-EIRENE code was conducted. It was revealed that the change of the cross-field transport in the edge plasma region causes not only the change of the heat and particle flux profiles on divertor plates, but also the changes of the intrinsically non-uniform global heat and particle deposition profiles on the helical diveror. The cross-field transport seems to be larger in the higher edge electron temperature discharge in the experimental conditions in this paper (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The stabilization effect of the Internal Flow Resistances (IFR) inserted into water jets has been investigated in order to apply the liquid metal divertor to the helical fusion reactor, FFHR. A high heat load exceeding 20 MW/m2 is one of the important issues for the divertor in the nuclear fusion reactor. A new concept of ergodic limiter/divertor called the REVOLVER-D has been proposed for FFHR. This divertor is expected to tolerate a high heat load larger than a few tens of MW/m2. Jets narrow after acceleration by gravity and transform to droplets due to the surface tension instability. Stabilization of jets is an important issue for realizing the REVOLVER-D. In this paper, stabilization of jet by various IFR has been examined. Here, the “sheath jet” is defined as a jet with an IFR inside. Experiments on sheath jet have been carried out and the stabilization effect of IFR has been confirmed. Numerical simulations on sheath jet using ANSYS have been carried out. It is shown that the velocity of the sheath jet reaches the terminal velocity, which is proportional to 0.36 ± 0.01 power of the flow rate and −0.26 ± 0.01 power of the outer circumference of the IFR.

We have developed a 4-channel multi-anode MCP-PMT, SL10, which exhibits a performance of sigma_TTS ~ 30 ps for single photons with G ~ 10^6 and QE=20% under a magnetic field of B, 14 pages, 14 figures

For condensation of binary mixtures where the less volatile constituent has the higher surface tension the condensate film is potentially unstable and various “modes” of condensation are seen depending primarily on composition and vapour-to-surface temperature difference. Of particular interest is the so-called “pseudo-dropwise” mode of condensation where the appearance of the condensate closely resembles that of dropwise condensation of a pure fluid on a hydrophobic surface. In recent years the so-called Marangoni condensation problem has been studied experimentally in great detail by Utaka and co-workers [4] , [5] , [6] , [7] , [8] , [11] for condensation of steam–ethanol mixtures on small vertical plane surfaces. It has been found that very small concentrations of ethanol in the liquid phase can give rise to significantly larger heat-transfer coefficients than found with pure steam. In the present investigation the problem has been studied using a horizontal condenser tube. Heat flux and vapour-to-surface temperature difference have been measured for steam–ethanol mixtures over a wide range of composition at atmospheric pressure. The results show the same trends as those found by Utaka for vertical surfaces. Differences in detail can be explained by geometry considerations and strong dependence of heat-transfer coefficient on vapour-to-surface temperature difference and vapour velocity, both of which vary around the perimeter of the horizontal tube.

Ovarian leiomyoma is very rare type of ovarian tumor. This benign tumor is seen in the pediatric age group to premenopausal women.A 76-year-old woman had a huge leiomyoma (19 x 11 x 10 cm) of the right ovary. The preoperative diagnosis was difficult to distinguish from a broad ligament leiomyoma or ovarian cancer.Although theses tumors are benign, its extreme rarity led us to report an additional and rather unusual case of ovarian leiomyoma, and to focus some attention on this type of tumor.

The paper presents new measurements on the effect of inundation during condensation of steam in tubes banks. Most of the data relate to wire-wrapped enhanced tubes but measurements are also reported for low-finned and smooth tubes. The technique of artificial inundation has been used where liquid is supplied above a single horizontal test condenser tube to simulate condensate draining from higher tubes. Inundation rates have been used to simulate a column of up to almost 30 tubes. The surface temperature of the condenser tube was measured at four locations around the tube using buried thermocouples. The heat transfer and hence condensation rate was determined from the mass flow rate and temperature rise from coolant. The temperature and flow rate of the simulated inundation was carefully controlled. All tests were carried out at atmospheric pressure with constant vapour downflow approach velocity and constant coolant flow rate. For the given coolant and vapour flow rates and temperatures (same for all tests), and in the absence of inundation, the vapour-side heat-transfer coefficient for the finned tube was around four times that of the smooth tube while the heat-transfer coefficient for the wire-wrapped tubes was independent of winding pitch and around 30% higher than for the smooth tube. For inundation conditions the smooth tube data are in line with the widely used Kern equation relating the heat-transfer coefficient to the depth of a tube in the bank. The heat-transfer coefficient for the finned tube was virtually unaffected by inundation up to the maximum used which was equivalent to a depth of about 20 finned tubes in a bank. At this depth level the heat-transfer coefficient for the finned tube was around six times that of the smooth tube. For the wire-wrapped tubes the deterioration in performance with increasing inundation was least for the smallest winding pitch used for which the heat-transfer coefficient fell by around 9% at an equivalent depth in a bank of 25 tubes. At this depth level the heat-transfer coefficient for the wire-wrapped tube was almost twice that of the smooth tube.

We have measured depth profiles of N isotopes by Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) before and after implantation of 100 keV N isotopes into Si 3 N 4 films on SiO 2 -glass substrates, which were prepared by using RF-magnetron-reactive-sputtering deposition method in N 2 gas. The film thickness is ∼200 nm and comparable with the calculated projected range, 180 nm (TRIM1997) of 100 keV N ions. We find that the nitride film thickness has increased after N implantation with nearly stoichiometric composition. Optical absorption spectra also show the increase of the film thickness. According to NRA, the implanted 15 N are found to be located around the Si 3 N 4 film–substrate interface. It also appears that the increase of the film thickness multiplied by the film density approximately equals to the implantation dose. These results imply reaction of implanted nitrogen with the substrate and growth of Si 3 N 4 .

Partial-ion-yield (PIY) spectra using ion time-of-flight (TOF) method and near-edge absorption fine structure (NEXAFS) spectra were measured for 2-(perfluorooctyl)ethanethiol [CF 3 (CF 2 ) 7 (CH 2 ) 2 SH] self-assembled monolayer (F8-SAM) on Au(1 1 1) near carbon K-edge. The PIY spectra of the F8-SAM at the magic angle, where –CF 3 groups exist at the surface were compared with those of the rubbed polytetrafluoroethylene (PTFE) thin film. The F + intensity from the F8-SAM at the photon energy of the sharp peak of the NEXAFS, which originates from the excitation of C1s electron to σ * (C–F) states at –CF 2 – chain, was extremely smaller than that from the rubbed PTFE film. This result clearly indicates that the ions observed by PIY do not originate from the film inside but from the surface. This was confirmed by changes in ion-TOF mass spectra during soft X-ray induced etching of the F8-SAM. The NEXAFS peaks of the F8-SAM were also assigned by considering PIY results.

Hydrogen introduction into p + silicon was carried out by boiling in water to reduce the surface carrier concentration due to the formation of boron-hydrogen pairs. Carrier concentration profiles were estimated from Schottky diodes fabricated successfully on the hydrogenated surfaces. Boiling for times longer than 30 min was not effective for the reduction of the carrier concentration near the surface. Instead, the repetition of the process, which consists of removal of the oxide and boiling in water for 15 min, was found to introduce a large quantity of hydrogen. For the total boiling time of 28 h, the carrier concentration decreased from the original value of mid 10 18 to 2 x 10 16 cm -3 at the depth of 170 nm. Iron-boron pairs (E v + 0.1 eV) were detected by deep-level transient spectroscopy measurements on hydrogenated p + silicon, which was intentionally iron-contaminated.

Superior control of particle recycling and hence full governance of plasma density has been established in the Large Helical Device (LHD) using largely enhanced active pumping of the closed helical divertor (CHD). In-vessel cryo-sorption pumping systems inside the CHD in five out of ten inner toroidal divertor sections have been developed and installed step by step in the LHD. The total effective pumping speed obtained was 67?????5 m3 s?1 in hydrogen, which is approximately seven times larger than previously obtained. As a result, a low recycling state was observed with CHD pumping for the first time in LHD featuring excellent density control even under intense pellet fueling conditions. A global particle confinement time () is used for comparison of operation with and without the CHD pumping. The was evaluated from the density decay after the fueling of hydrogen pellet injection or gas puffing in NBI plasmas. A reliably low base density before the fueling and short after the fueling were obtained during the CHD pumping, demonstrating for the first time full control of the particle balance with active pumping in the CHD.

A new cartridge-type blanket named the CARDISTRY-B is proposed for the helical fusion reactor FFHR-d1. This blanket is composed of the neutron shield and the tritium breeder using molten salt. Both of these are toroidally segmented every two degrees. At each toroidal angle, the segmented parts are divided further into several cartridges in order to make it possible to assemble these cartridges after completion of the superconducting magnet coils. The neutron shield is basically assembled by using mortise and tenon prepared on each of the cartridges and the lower port, instead of the wide area welding. After assembly, the plasma side of the neutron shield is welded to form a vacuum vessel. Another side of the neutron shield facing on the superconducting magnet coils is covered with the thermal shield, which was already attached before assembly. The tritium breeder cartridges can be replaced without cutting or welding of cooling pipes inside the vacuum vessel, where severe radiation dose is expected. Details of the CARDISTRY-B, including the results of motion analysis for all cartridges and estimation of the cartridge weight, are discussed.

An outbreak due to Shiga toxin-producing Escherichia coli O26[ratio ]H11 (STEC) occurred at a nursery in southeastern Japan in 1997. Thirty-two children had watery or bloody diarrhoea but none of them suffered from haemolytic-uremic syndrome. All of the STEC O26 were isolated during the period from 23 July to 22 August from 24 children, 3 nurses, and 2 food samples. These organisms had stx1 and eae genes but none of the other genes for which we tested (stx2, bfp, and EAF plasmid). They also possessed multiple antimicrobial resistances, which were encoded by a transmissible plasmid, and showed mostly identical genomic pulsed-field gel electrophoretic patterns. The results of this investigation suggested that contaminated food was the main contributing factor to this multiple antimicrobial-resistant STEC O26 infection, and person-to-person transmission also contributed to the spread of this outbreak.

Transport channels of the X-ray beamlines of SPring-8 are evacuated by restricted types of pump units that have been achieved the standardization of beamline components. This report describes selection of the pump unit in some characteristic beamlines that have long or large ducts.