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Although ICRF heating has achieved the high heating efficiency necessary to achieve high-performance plasmas, it has not overcome the reliability and economic problems associated with the antenna structure inside the vacuum vessel in fusion reactors. We suggested a slit ICRF antenna that uses the blanket surface as a transmission line to solve these problems. With a single slit ICRF antenna with a width of 3 m and a height of 15 cm, the electric field strength to the magnetic field direction was successfully suppressed to 5 kV/cm when 20 MW of power radiation was achieved from the single slit. The slit ICRF antenna had a bending angle in the electromagnetic wave transmission path to prevent direct neutron impact on the first wall and a vacuum gate from rapidly preventing water or air leakage accidents. The slit ICRF antenna has a simple structure that allows heating at high power density while minimizing blanket volume reduction.

Recent advances in the high power and steady state heating system and experiment results of the Large Helical Device (LHD) are reviewed in this paper. Plasma performance is extended largely through...

Electron Cyclotron Resonance Heating (ECRH) has contributed to the achievement of high performance plasma production, high electron temperature plasmas and sustainment of steady-state plasmas in the Large Helical Device (LHD). Our immediate targets of upgrading the ECRH system are 5 MW several seconds and 1 MW longer than one hour power injection into LHD. The improvement will greatly extend the plasma parameter regime. For that purpose, we have been promoting the development and installation of 77 GHz/1-1.5 MW/several seconds and 0.3 MW/CW gyrotrons in collaboration with University of Tsukuba. The transmission lines are re-examined and improved for high and CW power transmission. In the recent experimental campaign, two 77 GHz gyrotrons were operated. One more gyrotron, which was designed for 1.5 MW/2 s output, was constructed and is tested. We have been promoting to improve total ECRH efficiency for efficient gyrotron-power use and efficient plasma heating, e.g. a new waveguide alignment method and mode-content analysis and the feedback control of the injection polarization. In the last experimental campaign, the 77 GHz gyrotrons were used in combination with the existing 84 GHz range and 168 GHz gyrotrons. Multi-frequency ECRH system is more flexible in plasma heating experiments and diagnostics. A lot of experiments have been performed in relation to high electron temperature plasmas by realization of the core electron-root confinement (CERC), electron cyclotron current drive (ECCD), Electron Bernstein Wave heating, and steady-state plasma sustainment. Some of the experimental results are briefly described. © 2009 American Institute of Physics.

To sustain plasmas with higher parameters and with longer pulse duration in LHD, ECH system has been upgraded by introducing newly developed 77 GHz gyrotrons. The designed output power and operation duration time are over 1 MW for several seconds and 0.3 MW for continuous operation, respectively. Owing to the upgrade of gyrotrons and improved power supply operation procedure, total injection power of EC-waves to LHD increased up to 3.7 MW at the last LHD experimental campaign in 2010. Application of the high-power 77 GHz EC-waves of 3.4 MW as focused beams to the center of plasma with low line-average electron density of ∼0.2×10 19m -3 causes highly steep electron temperature profile and the central electron temperature reached up to 20 keV, which highly exceeds the former record of 15 keV. At higher density region of 1×10 19m -3, central electron temperature reached 8.6 keV. Additional electron Bernstein wave heatings, O-X-B and slow X-B heatings, using a 77 GHz ECH system caused clear increase in plasma stored energy even for the high-density plasmas over plasma cutoff (>7. 35×10 19m -3) sustained with NBI. For the O-X-B scenario, the 77 GHz EC-wave was obliquely injected from low-field side in O-mode polarization, aiming at the point where high mode-conversion efficiency was expected. For realizing slow X-B scenario, new inner-vessel mirrors were installed in LHD just close to a helical coil, that is, at the high-field side (HFS) region. Using the inner-vessel mirror, X-mode waves were injected from HFS, showing evident increase in plasma stored energy. Oblique injection of long-pulse 0.77 MW/8 s 77 GHz wave with various N ∥ clearly demonstrated ECCD in LHD. The EC-driven current changes its direction with the sign of N ∥, and the highest EC-driven current reached up to 42 kA. © 2011 American Institute of Physics.

The electron cyclotron resonance heating (ECRH) system on the Large Helical Device (LHD) has been in stable operation for ∼11 yr in numerous plasma experiments. During this time, many upgrades to the system have been made, such as reinforcement of the gyrotron tubes, modification of the power supply depending on gyrotron type, and increase in the number of transmission lines and antennas. These efforts allow the stable injection of millimeter-wave power in excess of 2 MW. In parallel, various transmission components were evaluated, and antenna performance was confirmed at a high power level. The coupling efficiency of the millimeter wave from the gyrotron to the transmission line and the transmission efficiency through the waveguide were further improved in recent years. The feedback control of the wave polarization has also been tried to maximize the efficiency of wave absorption. The gyrotron oscillation frequency was reconsidered in order to extend the flexibility of the magnetic configuration in plasma experiments. The development of 77-GHz gyrotrons with the output of 1 MW per few seconds in a single tube is currently taking place in collaboration with the University of Tsukuba. Two such gyrotron tubes already have been installed and were used for plasma experiments recently. An ECRH system with a capability of the steady operation is required, because the LHD can continuously generate confinement magnetic fields using superconducting magnets. Not only the gyrotron but also the transmission system and components must withstand continuous power operation. Further acceleration of both the power reinforcement and a steady-state capability will allow the sustainment of high-performance plasmas.

Production and heating of over-dense plasmas by 2.45 GHz microwave system under very low field condition was performed and demonstrated on CHS. In this experiment, microwave systems were arranged to aim at taking place mode conversion of launched electron cyclotron wave effectively into electron Bernstein wave (EBW). The power deposition profiles in produced over-dense plasmas were measured directly by using power modulation technique at various magnetic configurations. The power deposition took place dominantly in overdense region. To clarify wave trajectories, power absorption mechanism and mode conversion, a numerical analysis by a ray-tracing method was performed. Calculated ray-trajectories accessed to the region where the experimentally obtained deposition profile has a peak (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Pharmacokinetic analyses of three kinds of benzodiazepines--midazolam (MDZ), triazolam (TRZ) and alprezolam (APZ)--were performed in rats with cannulated portal and jugular veins. Each drug was administered to the double-cannulated rats, and pharmacokinetic data for the parent drugs and their 1'- and 4-hydroxylated metabolites were compared with those obtained in non-cannulated mice. In bioavailability, the drugs ranked APZTRZ = MDZ in rats, and APZTRZMDZ in mice, with the values for MDZ remarkably different between rats and mice (19% in rats versus 2.3% in mice). In contrast, hepatic availability (Fh) was similar (APZTRZMDZ) in both species. Highly significant relationships were found between the ratio of the area under the plasma concentration-time curve (AUC) for the parent drugs in portal blood (AUC(por)) to that in systemic blood (AUC(sys)) and Fh in rats and mice. The double-cannulated rat is useful for estimating the hepatic availability of drug candidates by determining the AUC values for the parent drugs in portal and systemic blood samples.

Achieving steady-state plasma operation at high plasma temperatures is one of the important goals of worldwide magnetic fusion research. High temperatures of approximately 1–2 keV, and steady-state plasma sustainment operations have been reported. Recently the steady-state operation regime was greatly extended in the Large Helical Device (LHD). A high-temperature plasma was created and maintained for 54 min with 1.6 GJ in the 2005FY experimental programme. The three-dimensional heat-deposition profile of the LHD helical divertor was modified, and during long-pulse discharges it effectively dispersed the heat load using a magnetic axis swing technique developed at the LHD. A sweep of only 3 cm in the major radius of the magnetic axis position (less than 1% of the major radius of the LHD) was enough to disperse the divertor heat load. The steady-state plasma was heated and sustained mainly by hydrogen minority ion heating using ion cyclotron range of frequencies and partially by electron cyclotron of fundamental resonance frequency. By accumulating the small flux of charge-exchanged neutral particles during the long-pulse operation, a high energy ion tail which extended up to 1.6 MeV was observed. This is the first experimental evidence of high energetic ion confinement of MeV range in helical devices. The long-pulse operations lasted until a sudden increase in radiation loss occurred, presumably because of metal wall flakes dropping into the plasma. The sustained line-averaged electron density and temperature were approximately 0.8 × 1019 m−3and 2 keV, respectively, at a 1.3 GJ discharge (#53776) and 0.4 × 1019 m−3and 1 keV at a 1.6 GJ discharge (#66053). The average input power was 680 kW and 490 kW, and the plasma duration was 32 min and 54 min, respectively. These successful long operations show that the heliotron configuration has a high potential as a steady-state fusion reactor.

呼吸困難が出現し緊急手術にて救命しえた慢性特発性大腸偽性腸閉塞症の1例を経験したので報告する. 症例は60歳男性. 以前より便秘にて近医通院中であった. 腸閉塞症状が出現し近医入院, 保存的加療を行うも増悪するため当院緊急入院となった. 腹部は著明に膨満し, 腸雑音は消失していた. 徐々に内視鏡的ガス抜きを施行するも腹部膨満の増悪と呼吸障害が出現, 全身状態が悪化, 緊急手術を施行した. 大腸は盲腸から直腸まで著明に拡張し, とくにS状結腸に顕著であった. 大腸亜全摘術, 回腸人工肛門造設術を施行した. 術翌日には呼吸状態, 循環動態ともに改善し, 術後1年以上経過した現在特記すべき障害は認めていない.本症は腸管に器質的閉塞・狭窄や原因となる基礎疾患がないにもかかわらず, 大腸のみに腸閉塞様の症状を繰り返す疾患であるが, 保存的加療抵抗性の場合には外科的切除術も治療の選択肢の一つにあげるべきであると考えられた.

The polarizer is one of the critical components in a high-power millimeter-wave transmission line. It requires full and highly efficient coverage of any polarization states, high-power tolerance, and low-loss feature. Polarizers with rounded shape at the edge of the periodic groove surface are designed and fabricated by the machining process for a mega-watt long-pulse millimeter-wave transmission line of the electron cyclotron resonance heating system in the large helical device. The groove shape of λ/8- and λ/4-type polarizers for an 82.7 GHz transmission line is optimally designed in an integral method developed in the vector theories of diffraction gratings so that the efficiency to realize any polarization state can be maximized. The dependence of the polarization states on the combination of the two polarizer rotation angles (Φλ/8, Φλ/4) is examined experimentally in a low-power test with the newly developed polarization monitor. The results show that the measured polarization characteristics are in good agreement with the calculated ones.

ICRF heating in the Large Helical Device is studied applying two global simulation codes; a drift kinetic equation solver, GNET, and a wave field solver, TASK/WM. Characteristics of energetic ion distributions in the phase space are investigated changing the resonance heating position; i.e. the on-axis and off-axis heating cases. A clear peak of the energetic ion distribution can be seen in the off-axis heating case because of the stable orbit of resonant energetic ions. The simulation results are also compared with experimental results evaluating the count number of the neutral particle analyzer and a relatively good agreement is obtained.

Steady state divertor operation with high performance plasmas (ne ~ 0.7 × 1019 cm−3, Ti ~ 2 keV) was demonstrated for half an hour in the Large Helical Device (LHD), the superconducting helical device (R = 3.6–3.9 m, a = 0.6 m, B = 3 T, l/m = 2/10). The high performance plasmas have been sustained with an averaged heating power of 680 kW and achieved an injected energy of 1.3 GJ. This required both advanced technological integration of heating systems and divertor heat flux control. In particular, optimization of divertor heat flux distribution along the divertor leg trace on divertor plates and real-time magnetic axis sweeping (R = 3.67–3.7 m) have allowed LHD to access a steady state regime with a margin of safety for the actively cooled divertor plates. The distribution of divertor heat load along the traces was investigated with calorimetric measurements and it was found that there was a localized heat load connected with the loss of high-energy ions produced by ion cyclotron radio frequency near-fields. Orbit analysis shows that the behaviour of high-energy ions is qualitatively in good agreement with the experimental result. Long-pulse discharges were terminated by radiation collapse due to penetration of metallic flakes into the plasma.

A long-pulse plasma discharge of more than 30 min duration was achieved on the Large Helical Device (LHD). A plasma of ne = 0.8 × 1019 m−3 and Ti0 = 2.0 keV was sustained with PICH = 0.52 MW, PECH = 0.1 MW and averaged PNBI = 0.067 MW. The total injected heating energy was 1.3 GJ. One of the keys to the success of the experiment was a dispersion of the local plasma heat load to divertors, accomplished by sweeping the magnetic axis inward and outward. Causes limiting the long pulse plasma discharge are discussed. An ion impurity penetration limited further long-pulse discharge in the 8th experimental campaign (2004).

The Large Helical Device (LHD) achieves high-performance plasma confinement by the coordination of the magnetic surface region and the chaotic field line layer. It is theoretically and experimentally shown that drift surfaces exist for highly energetic particles being extended over the last closed flux surface (LCFS) in the LHD. These particles are considered lost particles due to the loss-cone in the previous theories, where the analyses are limited inside the LCFS. The present theory predicts that the loss-cone is strongly reduced in the LHD and that highly energetic particles confined over the LCFS exist. These are consistent with the LHD experimental results in both the ICRF heating experiments and the low magnetic field neutral beam injection heating experiments. From particle orbit analyses and studies on the connection length of diverter field lines, it is also shown that plasma can exist in the chaotic field line layer located outside the LCFS in the LHD. The plasma in the chaotic field line layer is clearly detected by CCD-cameras in the LHD experiment. This ambient plasma might be expected to play the role of a kind of impregnable barrier for the core plasma, which suppresses both the MHD instabilities and the cooling of the core plasma due to charge exchange processes. The line-tying effects of diverter field lines that are slipped out from the chaotic field line layer can also stabilize the ballooning mode and the vertical displacement events of the plasma column.

A long-pulse plasma discharge for more than 30 min. was achieved on the Large Helical Device (LHD). A plasma of ne = 0.8× 1019 m−3 and Ti0 = 2.0 keV was sustained with PICH = 0.52 MW, PECH = 0.1 MW and averaged PNBI = 0.067 MW. Total injected heating energy was 1.3 GJ, which was a quarter of the prepared RF heating energy. One of the keys to the success of the experiment was a dispersion of the local plasma heat load to divertors, accomplished by shifting the magnetic axis inward and outward.

Two types of improved core confinement were observed during centrally focused electron cyclotron heating (ECH) into plasmas sustained by counter (CNTR) and Co neutral beam injections (NBI) in the Large Helical Device. The CNTR NBI plasma displayed transition phenomena to the high-electron-temperature state and had a clear electron internal transport barrier, while the Co NBI plasma did not show a clear transition or an ECH power threshold but showed broad high temperature profiles with moderate temperature gradient. This indicated that the Co NBI plasma with additional ECH also had an improved core confinement. The electron heat transport characteristics of these plasmas were directly investigated using heat pulse propagation excited by modulated ECH. These effects appear to be related to the m/n = 2/1 rational surface or the island induced by NBI beam-driven current.

This paper reports on the results of an experimental investigation into electron cyclotron resonance heating (ECRH) using the fundamental O-mode in the large helical device (LHD). The aim of the experiment is to understand the mechanism of the selective excitation of the O-mode EC wave and, thereby, optimize the performance of the ECRH. The polarization angle and the ellipticity of the electric field of the incident high power millimetre waves were varied in the experiment using a pair of grating polarizers. The responses of the plasma stored energy and electron temperature were measured to evaluate the effects. The optimum values of the polarization angle and the ellipticity for the ECRH were identified experimentally. A simple model of power branching between the O- and X-modes is introduced in order to interpret the observed experimental results. Specific to the ECRH in the LHD configuration, the effect of magnetic shear in the plasma peripheral region is considered.

The potential of continuous plasma sustainment of Large Helical Device (LHD) was successfully demonstrated by a one hour discharge with 110 kW electron cyclotron heating (ECH) power. The ECH power of frequency 84 GHz generated by a continuous-work (CW) gyrotron is transmitted through an evacuated waveguide transmission line and injected to the LHD vacuum vessel using waveguide antenna. The plasma density was kept at about 1.5 × 1018/m3 and the electron temperature at the plasma center over 1 keV. Due to the low injection power the density was not so high but the plasma was quite stable. The power injection was terminated manually at 3900 seconds from the limitation of the setting of data acquisition, not for any troubles on devices.

The behaviour of helical ripple-trapped particles in large helical device (LHD) have been investigated by two line-of-sights natural diamond detector measurements in plasma sustained with ICRF for two types of resonance configurations, i.e. on-axis and saddle-shaped resonances. The tail temperature increases linearly as the Stix-temperature increases and then saturation follows, indicating the effect of the finite confinement time of the energetic ions. In the linear region, the tail readily increases when the line-of-sight is focused on the larger resonance area. The confinement time of the energetic ions is obtained from the empirical relation based on the Stix theory. The configuration with a saddle-shaped resonance has a longer confinement time than the on-axis resonance. Analyses of experimental measurements are consistent with the theoretical calculations including collisional ripple-induced transport.

Characteristics of MHD instabilities and their impacts on plasma confinement are studied in current free plasmas of the Large Helical Device. Spontaneous L?H transition is often observed in high beta plasmas close to 2% at low toroidal fields (Bt ? 0.75?T). The stored energy starts to rise rapidly just after the transition accompanying the clear rise in the electron density but quickly saturates due to the growth of the m = 2/n = 3 mode (m and n: poloidal and toroidal mode numbers), the rational surface of which is located in the edge barrier region, and edge localized mode (ELM) like activities having fairly small amplitude but high repetition frequency. Even in low beta plasmas without L?H transitions, ELM-like activities are sometimes induced in high performance plasmas with a steep edge pressure gradient and transiently reduce the stored energy up to 10%. Energetic ion driven MHD modes such as Alfv?n eigenmodes (AEs) are studied in a very wide range of characteristic parameters (the averaged beta of energetic ions, ?b?, and the ratio of energetic ion velocity to the Alfv?n velocity, Vb?/VA), of which range includes all tokamak data. In addition to the observation of toroidicity induced AEs (TAEs), coherent magnetic fluctuations of helicity induced AEs (HAEs) have been detected for the first time in NBI heated plasmas. The transition of a core-localized TAE to a global AE (GAE) is also observed in a discharge with temporal evolution of the rotational transform profile, having a similarity to the phenomenon observed in a reversed shear tokamak. At low magnetic fields, bursting TAEs transiently induce a significant loss of energetic ions, up to 40% of injected beams, but on the other hand play an important role in triggering the formation of transport barriers in the core and edge regions.

Significant progress has been made with ion cyclotron range of frequencies (ICRF) heating in the Large Helical Device. This is mainly due to better confinement of the helically trapped particles and less accumulation of impurities in the region of the plasma core. During the past two years, ICRF heating power has been increased from 1.35 to 2.7 MW. Various wave-mode tests were carried out using minority-ion heating, second-harmonic heating, slow-wave heating and high-density fast-wave heating at the fundamental cyclotron frequency. This fundamental heating mode extended the plasma density range of effective ICRF heating to a value of 1×1020 m−3. This use of the heating mode was its first successful application in large fusion devices. Using the minority-ion mode gave the best performance, and the stored energy reached 240 kJ using ICRF alone. This was obtained for the inward-shifted magnetic axis configuration. The improvement associated with the axis-shift was common for both bulk plasma and highly accelerated particles. For the minority-ion mode, high-energy ions up to 500 keV were observed by concentrating the heating power near the plasma axis. The confinement properties of high-energy particles were studied for different magnetic axis configurations, using the power-modulation technique. It confirmed that with the inward-shifted configuration the confinement of high-energy particles was better than with the normal configuration. By increasing the distance of the plasma to the vessel wall to about 2 cm, the impurity influx was sufficiently reduced to allow sustainment of the plasma with ICRF heating alone for more than 2 min.

Internal transport barriers with respect to electron thermal transport (eITB) were observed in the large helical device, when the electron cyclotron resonance heating (ECH) power was highly localized on the centre of a plasma sustained by neutral beam injection. The eITB is characterized by a high central electron temperature of 6–8 keV with an extremely steep gradient, as high as 55 keV m−1 and a low electron thermal diffusivity within a normalized average radius ρ≈0.3 as well as by the existence of clear thresholds for the ECH power and plasma collisionality.

The behaviour of high-energy ions accelerated by an ion cyclotron range of frequency (ICRF) electric field in the large helical device (LHD) is discussed. A better confinement performance of high-energy ions in the inward-shifted magnetic axis configuration was experimentally verified by measuring their energy spectrum and comparing it with the effective temperature determined by an electron slowing down process. In the standard magnetic axis configuration a saturation of the measured tail temperature was observed as the effective temperature was increased. The ratio between these two quantities is a measure of the quality of transfer efficiency from high-energy ions to a bulk plasma; when this efficiency was compared with Monte Carlo simulations the results agreed fairly well. The ratio of the stored energy of the high-energy ions to that of the bulk plasma was measured using an ICRF heating power modulation method; it was deduced from phase differences between total and bulk plasma stored energies and the modulated ICRF heating power. The measured high energy fraction agreed with that calculated using the injected ICRF heating power, the transfer efficiency determined in the experiment and the confinement scaling of the LHD plasma.

Ion temperature at the plasma centre has been measured from Doppler broadening of Ti XXI (2.61 A) and Ar XVII (3.95 A) x-ray lines using a newly installed crystal spectrometer with CCD detector in ECH, NBI and ICRF plasmas of Large Helical Device (LHD). The ion temperature obtained in a range of 0.6 and 3.5 keV was analysed with electron density and compared with electron temperature. A new parameter range of Ti>Te was found in low-density (ne

Intrinsic impurity behaviour in neutral beam heated LHD long pulse discharges with a discharge duration of 10 s was investigated. Spectroscopic and bolometric measurements showed a remarkable temporal increase of core radiation due to metallic impurities. Central impurity accumulation was found in a narrow plasma density region (e = 1–3×1019 m−3) for both density ramp-up discharges and constant density discharges. In the density ramp-up discharges, high-Z impurities were accumulated in the low-density region and diffused out from the core plasma in the high-density region. The impurity behaviour was compared with neoclassical predictions.

Energetic tail formation by ion-cyclotron-range-of-frequencies (ICRF) heating was studied in the large helical device (LHD), by measuring high-energy charge-exchange atom spectra with a specially developed natural diamond detector, which views the LHD plasma perpendicularly. Comparison of measured effective perpendicular temperature of ICRF-driven H+ minority ions with the classical Stix model indicates that perpendicular ions with energy at least up to 150 keV are well confined in the centre region of the LHD. However, deviation from the classical prediction was observed for high-energy perpendicular protons in the outer region of the plasma, indicating ripple-induced transport and charge-exchange losses. With perpendicular fast atom spectrum and flux measurements, small yet notable differences were detected co-injected and counter-injected ICRF-driven beam ion confinement during combined neutral beam injection (NBI) and ICRF heating. These results can be explained by the differences in the orbit topology and ICRF-induced drift.

The experimentally optimized magnetic field configuration of the Large Helical Device [A. Iiyoshi et al., Nucl. Fusion 39, 1245 (1999)], where the magnetic axis is shifted inward by 15 cm from the early theoretical prediction, reveals 50% better global energy confinement than the prediction of the scaling law. This configuration has been investigated further from the viewpoints of high energy particle confinement and magnetohydrodynamic (MHD) stability. The confinement of high energy ions is improved as expected. The minority heating of ion cyclotron range of frequency was successful and the heating efficiency was improved by the inward shift. The confinement of passing particles by neutral beam injection was also improved under low magnetic field strength, and there could be obtained an almost steady high beta discharge up to 3% in volume average. This was a surprising result because the observed pressure gradient exceeded the Mercier unstable limit. The observed MHD activities became as high as beta but they did not grow enough to deteriorate the confinement of high energy ions or the performance of the bulk plasma, which was still 50% better than the scaling. According to these favorable results, better performance would be expected by increasing the heating power because the neoclassical transport can also be improved there.

Enhancement of the output power per gyrotron has been planned in the Large Helical Device (LHD). Three 77-GHz gyrotrons with an output power of more than 1 MW have been operated. In addition, a high power gyrotron with the frequency of 154 GHz (1 MW/5 s, 0.5 MW/CW) was newly installed in 2012 and the total injection power of ECRH reached 4.6 MW. The operational regime of ECRH plasma on the LHD has been extended due to the upgraded ECRH system such as the central electron temperature T{sub e0} = 13.5 keV with n{sub e} = 1×10{sup 19}m{sup −3}. In the LHD, an electron-internal-transport barrier (e-ITB) related to the production of high T{sub e} plasmas has been realized by strongly centre-focused ECRH. The electron thermal confinement clearly improved inside the e-ITB. The radial electric field was measured using the heavy ion beam probe. The formation of the positive E{sub r} was observed in the core region, which well agreed with the prediction of the neoclassical transport theory. The energy confinement characteristics have been investigated in the ECRH plasmas. It was found that higher plasma stored energy and lower radiation power was realized in the outward configuration. The plasma stored energy of 530more » kJ with n{sub e} = 3.2×10{sup 19}m{sup −3}, which is the 1.7 times larger than the previous record in the ECRH plasma in the LHD, has been successfully achieved.« less

Long-pulse discharge with the electron density ne0 of 1 × 1019 m−3, electron temperature Te0 of 2.5 keV, discharge length tdis of 19 minutes and heating power Pinject of 1MW, is demonstrated using the HAS antenna and the PA antenna for ion cyclotron heating (ICH) and increasing in the power of electron cyclotron heating (ECH). The HAS antenna is designed to phase dipole and excite ideal fast wave with parallel electric field kept small, and low impurity generation and accumulation are achieved on the steady-state discharge by weak parasitic heating around antennas. On the long-pulse discharge, the radiation measured by bolometer is kept smaller than 20% for injection power, and the heat load to divertor is approximately 60 % with low energetic particle losses. The heat load ratio to divertor is not as a function of injection power around 1MW, and energy confinement has been kept during the steady-state discharge.

During the first two years of the LHD experiment the following results have been achieved: (i) higher Te (Te(0) = 4.4 keV at ne = 5.3 × 1018 m-3 and Pabs = 1.8 MW); (ii) higher confinement (τE = 0.3 s, Te(0) = 1.1 keV at ne = 6.5 × 1019 m-3 and Pabs = 2.0 MW); (iii) higher stored energy, Wpdia = 880 kJ at B = 2.75 T. High performance plasmas have been realized in the inward shifted magnetic axis configuration (R = 3.6 m) where helical symmetry is recovered and the particle orbit properties are improved by a trade-off of MHD stability properties due to the appearance of a magnetic hill. Energy confinement was systematically higher than that predicted by the International Stellarator Scaling 95 by up to a factor of 1.6 and was comparable with the ELMy H mode confinement capability in tokamaks. This confinement improvement is attributed to configuration control (inward shift of the magnetic axis) and to the formation of a high edge temperature. The average beta value achieved reached 2.4% at B = 1.3 T, the highest beta value ever obtained in a helical device, and so far no degradation of confinement by MHD phenomena has been observed. The inward shifted configuration has also led to successful ICRF minority ion heating. ICRF powers up to 1.3 MW were reliably injected into the plasma without significant impurity contamination, and a plasma with a stored energy of 200 kJ was sustained for 5 s by ICRF alone. As another important result, long pulse discharges of more than 1 min were successfully achieved separately with an NBI heating of 0.5 MW and with an ICRF heating of 0.85 MW.

Semiconductor detectors based on natural diamonds have been installed on the Large Helical Device (LHD) heliotron to measure the energy distribution of charge exchange fast neutral particles from different viewing angles. Advantages of a natural diamond detector (NDD) are (1) very compact size, (2) relatively easy handling, and (3) high energy resolution. Although NDDs are sensitive to visible light, vacuum ultraviolet, and soft x rays, unfavorable pulses produced by such radiation were greatly reduced by choosing an appropriate stainless steel shield in this experiment. In LHD, the time-resolved energy distribution of counter-going beam ions and ion cyclotron range of frequency-produced energetic ions have been successfully obtained by means of an NDD. The performance of NDDs as a neutral particle analyzer and its good suitability to LHD plasmas were demonstrated throughout this work.

Ion cyclotron range of frequency (ICRF) heating on the large helical device (LHD) is characterized by high power (up to 12 MW) and steady state operation (30 min). The LHD is a helical device (with a major radius of 3.9 m and a minor radius of 0.6 m) with superconducting coil windings (l=2, m=10). The main purpose of physical research is to investigate currentless and disruption-free plasma. Research and development for steady state ICRF heating has been carried out in recent years: A high rf power transmission system consisting of stub tuners, a ceramic feedthrough, and an ion cyclotron heating loop antenna has been developed. In addition, steady state operation of a rf oscillator has been achieved at a power higher than 1 MW. A liquid stub tuner has been proposed as an innovation. The liquid stub tuner makes use of the difference between the rf wavelengths in liquid and in gas due to the different relative dielectric constants. The liquid stub tuner has been experimentally proved to be a reliable rf com...

The aim of this study was to evaluate the effects of halothane, enflurane, isoflurane, and sevoflurane on slowly adapting pulmonary stretch receptor (SAR) activity in dogs. Eight beagles were anesthetized with an intravenous injection of a mixture of urethane and alpha-chloralose as a basal anesthesia, then vagotomized, artificially ventilated, and chest opened. Single afferent activities from SARs were recorded from the peripheral nerve cut end of the left vagus. Changes in SAR activities with inhalation of halothane, enflurane, isoflurane, and sevoflurane at 1, 1.5, and 2 times the minimal alveolar anesthetic concentration (MAC) were measured, and differences in the discharges within and among four anesthetics were evaluated. As a result, two different types of SARs, low threshold SARs and high threshold SARs, were detected in this study. In all anesthetics, expiratory discharges of low threshold SARs decreased significantly in a dose-dependent manner, whereas inspiratory discharges did not change significantly at any anesthetic level. Discharges of high threshold SARs tended to decrease with increasing anesthetic level; however, no statistical significance was observed at any anesthetic level. Only one exception to these changes was observed at 1 MAC of halothane where no significant decrease in the expiratory discharge of low threshold SARs or significant increase in the discharge of high threshold SARs was induced against a control value. In conclusion, recent inhalation anesthetics, except for halothane at the light anesthetic level, tended to decrease SAR activities depending on the anesthetic level, suggesting attenuation of the Hering-Breuer inflation reflex.

1. To search an appropriate evaluation methodology for the intestinal first-pass metabolism of new drug candidates, grapefruit juice (GFJ)- and vehicle (tap water)-pretreated mice or rats were orally administered midazolam (MDZ) or triazolam (TRZ), and blood levels of the parent compounds and their metabolites were measured by liquid chromatography/MS/MS. A significant effect of GFJ to elevate the blood levels was observed only for TRZ in mice. 2. In vitro experiments using mouse, rat and human intestinal and hepatic microsomal fractions demonstrated that GFJ suppressed the intestinal microsomal oxidation of MDZ and especially TRZ. Substrate inhibition by MDZ caused reduction in 1'-hydroxylation but not 4-hydroxylation in both intestinal and hepatic microsomal fractions. The kinetic profiles of MDZ oxidation and the substrate inhibition in mouse intestinal and hepatic microsomal fractions were very similar to those in human microsomes but were different from those in rat microsomes. Furthermore, MDZ caused mechanism-based inactivation of cytochrome P450 3A-dependent TRZ 1'-hydroxylation in mouse, rat and human intestinal microsomes with similar potencies. 3. These results are useful information in the analysis of data obtained in mouse and rat for the evaluation of first-pass effects of drug candidates to be metabolized by CYP3A enzymes.

Application of Ion Bernstein Wave Heating (IBWH) into the Princeton Beta Experiment‐Modification (PBX‐M) [Phys. Fluids B 2, 1271 (1990)] tokamak stabilizes sawtooth oscillations and generates peaked density profiles. A transport barrier, spatially correlated with the IBWH power deposition profile, is observed in the core of IBWH‐assisted neutral beam injection (NBI) discharges. A precursor to the fully developed barrier is seen in the soft x‐ray data during edge localized mode (ELM) activity. Sustained IBWH operation is conducive to a regime where the barrier supports large ∇ne, ∇Te, ∇νφ, and ∇Ti, delimiting the confinement zone. This regime is reminiscent of the H(high) mode, but with a confinement zone moved inward. The core region has better than H‐mode confinement while the peripheral region is L(low)‐mode‐like. The peaked profile enhances NBI core deposition and increases nuclear reactivity. An increase in central Ti results from χi reduction (compared to the H mode) and better beam penetration. Boot...

Purpose We evaluated the safety of indocyanine green for use in fundus angiography. Methods We sent a questionnaire concerning complications of indocyanine green to 32 institutions in Japan, which were selected on the basis of the client list from the Topcon Company, which manufactures the indocyanine green fundus camera. Results Ophthalmologists at 15 institutions responded, reporting a total of 3,774 indocyanine green angiograms performed on 2,820 patients between June 1984 and September 1992. Before angiography, intradermal or intravenous indocyanine green testing, or both was performed at 13 of 15 institutions. For three patients, the decision was made not to proceed with angiography after positive preangiographic testing. The dosage of indocyanine green used for angiography varied from 25 to 75 mg, depending upon the institution. There were 13 cases of adverse reactions (0.34%), ten of which were mild reactions such as nausea, exanthema, urtication, itchiness, and urgency to defecate, and did not require treatment. Also recorded were one case of pain of the vein, which required treatment, and two cases of hypotension. The two hypotensive patients required treatment for shock. Conclusions A comparison of frequency of adverse reactions to indocyanine green with the previously reported frequency of such reactions to fluorescein sodium indicated that indocyanine green is as safe as fluorescein for use in angiography.

Millimeter-wave components were re-examined for high power (Mega-Watt) and steady- state (greater than one hour) operation. Some millimeter-wave components, including waveguide joints, vacuum pumping sections, power monitors, sliding waveguides, and injection windows, have been improved for high power CW (Continuous Waves) transmission. To improve transmission efficiency, information about the wave phase and mode content of high power millimeter-waves propagating in corrugated waveguides, which are difficult to measure directly, were obtained by a newly developed method based on retrieved phase information. To optimize the plasma heating efficiency, a proof-of-principle study of the injection polarization feedback control was performed in the low power test stand.

The large helical device (LHD) has fourteen experiment cycles so far. The ion cyclotron range of frequencies (ICRF) heating has been carried out successfully on LHD; High RF power heating up to 3MW and the long pulse plasma discharge up to about one hour (54 minutes) have been achieved using the poloidal array (PA) antennas. In the 14th experiment cycle (2010) a new one pair of ICRF heating antennas was installed in LHD. This pair consists of two antennas arrayed in the toroidal direction and has a controllability of the wave number along the magnetic field line k∥ with changing the phase difference between them. The target plasma consisted of the helium plasma as the majority with the hydrogen‐ion minority. Several experiment results were obtained and compared with those obtained using the PA antenna (no capability of changing k∥). The fast wave with a large k∥ is excited with (0, π) phasing between two antennas, and a small wave‐number of k∥ with (0, 0) phasing. The plasma loading resistance in (0, π) w...

Three Mega-Watt 77GHz gyrotrons were developed for an ECRH system in LHD. Their operation could be highly optimized by means of two-step rise of an anode voltage. Output power of 1.78MW with 37.9% efficiency were obtained in the 3rd gyrotron. The system improvement has been promoted including the development of a mmw-beam position and profile monitor. © 2011 IEEE.

In LHD, an ECH system for fusion-relevant plasma heating has been greatly progressed with the development of megawatt gyrotrons. Net power of 3.7 MW could be injected into LHD. For stable operation, a new position and profile monitor of the mmw-beams in evacuated transmission lines is developed. © 2010 IEEE.

The effect of severe generalized edema on respiratory system mechanics is not well described. We measured airway pressure, gastric pressure, and four vertical pleural pressures in 13 anesthetized paralyzed pigs ventilated in the upright position. Pressure-volume relationships of the respiratory system, chest wall, and lung were measured on deflation from total lung capacity to residual volume and during tidal breathing both before (control) and 50 min after one of two interventions. In one series of experiments, a volume equal to 15–20% of the pig's body weight was infused intravenously. In a second series, a balloon was placed in the peritoneal space to distend the abdomen to the same gastric pressures as achieved in the first series. Measurements were compared before and after either abdominal balloon inflation or volume infusion. Volume infusion increased the pleural pressure in dependent lung regions, decreased both total lung capacity (34%) and functional residual capacity (62%) (both P less than 0.05), and markedly shifted the respiratory system and chest wall pressure-volume curves to the right, but it only moderately affected the lung deflation curve. Tidal compliances of the respiratory system, chest wall, and lung decreased 36, 31, and 49%, respectively (all P less than 0.05). The effect of abdominal balloon inflation on respiratory system mechanics was similar to that of volume infusion. We conclude that infusing large volumes of fluid markedly alters chest wall mechanics, mainly by causing abdominal distension that prohibits descent of the diaphragm.

Production of over-dense plasmas by launching 2.45 GHz microwaves under very low field conditions has been successfully demonstrated on CHS.1 In the experiment, microwaves systems were arranged to aim at taking place mode conversion of launched electron cyclotron wave effectively into electron Bernstein wave (EBW). One system (ECH#1) is launched nearly perpendicularly to the toroidal field, where FX-B conversion scenario is expected. Another (ECH#2) is launched obliquely for O-X-B conversion scenario. This experiment aims at clarifying the excitation, propagate and absorption of mode converted EBW. Power deposition profiles in produced over-dense plasmas were measured directly by using power modulation technique at various magnetic configurations where electron cyclotron resonance (ECR) and upper hybrid resonance (UHR) layers were scanned in space widely.2 Figure 1 is radial profile of electron temperature T e , electron density n e and electron pressure p e . This figure also shows the response in p e to ECH#1 or ECH#2 source p e , and the coherence γp e 2 and phase difference between δ p e and the modulated ECH power Φ pe at B t /B res = 100%. Electron density exceeds 2–3 times O-mode cutoff density (n co ∼ 7.5×1016m−3). Power deposition profile corresponds to Φ pe -profile and the peak position is in over-dense region. Similarly, it was investigated in the cases of B t /B res = 70%, 50% and 20%.