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A high power density and a long pulse negative ion beam accelerator has been developed in QST to realize the ITER neutral beam accelerator. A main target was the H− ion beam acceleration up to 1 MeV with 200 A/m2 for 60 s. After the achievement of 1 MeV at a short pulse, the pulse length has been gradually extended by modifications of grid configurations to suppress grid heat loads due to negative ions and electrons. However, the beam energy was limited up to 0.7 MeV at 60 s operation. One issue was an unstable negative ion production for a long time due to arcing and excess temperature rise of a plasma grid for optimum negative ion production. To suppress arcing, a cathode filament shape was modified. The plasma grid was modified to have a large heat capacitance in order to suppress temperature rise for 60 s operation at high discharge power required for 1 MeV operation. Another issue is to optimize beam optics more precisely. Fine tuning of the 1st acceleration stage was carried to improve beam optics f...

In order to evaluate deposition of cesium (Cs) in the plasma grid (PG) and investigate the origin of the gradual degradation of the negative ion current in a 100 s long pulsed operation in the JT-60SA negative ion source, Cs behavior in the source is model. To do this, Cs adsorption/desorption coefficient with a wide range of temperature is experimentally measured by a surface ionization detector and a quartz crystal microbalance. As a result, both of the adsorption and desorption are drastically varied at temperature range from room temperature to 100 °C. Based on these data, the model calculates the amounts of the Cs mass in the chamber wall and PG. The calculation result shows that, in the operation, an increase of temperature in the chamber wall (Twall) causes the evaporation of the huge amount of Cs in it. This leads to over pilling-up of Cs in the PG and the slight degradation of the negative ion production. Therefore, it is found that the constant temperature operation is needed to sustain the thickness of the Cs monolayer in the PG, and the Twall is desired to be less than 60 °C to suppress the evaporation of Cs in the chamber wall. According to this model, it is showed that there are many combinations of the temperatures to achieve it with low Cs consumption.In order to evaluate deposition of cesium (Cs) in the plasma grid (PG) and investigate the origin of the gradual degradation of the negative ion current in a 100 s long pulsed operation in the JT-60SA negative ion source, Cs behavior in the source is model. To do this, Cs adsorption/desorption coefficient with a wide range of temperature is experimentally measured by a surface ionization detector and a quartz crystal microbalance. As a result, both of the adsorption and desorption are drastically varied at temperature range from room temperature to 100 °C. Based on these data, the model calculates the amounts of the Cs mass in the chamber wall and PG. The calculation result shows that, in the operation, an increase of temperature in the chamber wall (Twall) causes the evaporation of the huge amount of Cs in it. This leads to over pilling-up of Cs in the PG and the slight degradation of the negative ion production. Therefore, it is found that the constant temperature operation is needed to sustain the thic...

Thermal annealing effects on Zn + ion-implanted silica glass (a-SiO 2 ) have been studied in order to control void formation. Void formation in a-SiO 2 with Zn + ion implantation and subsequent oxidation has been observed using transmission electron microscopy (TEM). Zn + ions of 60 keV were implanted into a-SiO 2 to a fluence of 1.0 × 10 17 ions/cm 2 . After the implantation, thermal annealing at 600 or 700 °C for 1 h in oxygen gas was conducted. In as-implanted state, metal Zn nanoparticles (NPs) of 10–15 nm in diameter are formed in the depth region around the projected range. The size of the Zn nanoparticles increases after the annealing at 600 °C in oxygen gas. Annealing in oxygen gas at 700 °C for 1 h caused two processes: (1) the migration of Zn atoms which formed Zn NPs in as-implanted state to the surface of the a-SiO 2 substrate and (2) the transformation to the oxide phase on the substrate. The transportation of Zn NPs to the surface leaves voids of 10–25 nm in diameter inside the a-SiO 2 . These results indicate that the oxidation at 700 °C for 1 h causes the migration of Zn atoms to the surface without diffusion and recombination of vacancies which form the voids.

Nanoscopic network structure of N -isopropylacrylamide (NIPAM) gel cross-linked with N , N ′-methelenbisacrylamide (BIS) was replicated in sol–gel derived silica matrix. As a result of that, the silica became a nanoporous solid with a high-porosity, which reaches 60–80%. The porosity was totally due to mesopores whose size was within 10 nm. Electron microscope observation revealed that the nanoscale network structure were replicated in the silica matrix as considered to be constituted from the main polymer chains and their interconnecting cross-linkers. The mesh size observed in the TEM micrograph matches the span length estimated from the molar ratio (∼80) of the main chain moiety (NIPAM) to that of cross-linker (BIS). When the weight ratio of NIPAM to silica matrix is smaller than unity, the pore size distribution measured by nitrogen adsorption/desorption has a sharp peak at 2 nm indicating that the worm-like nanopore is formed as a replica of an individual NIPAM chain. The peak position in the pore size distribution shifts to a larger value as the weight ratio of NIPAM was increased, suggesting the nanoscale segregation of NIPAM chains in the silica matrix. Therefore, the resultant size of the nanopores are considered to be determined at the moment of the structural freezing caused by the completion of the cross-linking in NIPAM gel. The completion of cross-linking (gellation) eliminates the mobility both of silica and NIPAM/BIS moiety. The TEM micrograph of a sample prepared at a large weight ratio also shows that larger nanopores tend to be generated when the template NIPAM moiety is more abundant.

This study investigated the molecular and pharmacokinetic mechanisms of the enhanced antiviral efficacy associated with pegylated interferon (PEG-IFN) alpha-2b and ribavirin. The study involved comparing the expression of serial double-stranded RNA-activated protein kinase (PKR) before and during treatment in 26 PEG-IFN alpha-2b and 26 conventional IFN alpha-2b recipients matched for age, body weight and dose of ribavirin. The pharmacokinetics of PEG-IFN alpha-2b and ribavirin was analysed in 15 of the 26 PEG-IFN recipients. There was a rapid increase in PKR expression in both treatment groups, although expression from day 2 onwards was maintained at a significantly higher level in the PEG-IFN recipients (P < 0.05). C(max) of PEG-IFN occurred 12-48 h after the initial administration, with t(1/2) and C(min) being 49 h and 190 pg/mL, respectively. In contrast to ribavirin, accumulation of PEG-IFN was minimal. There was no association between serum PEG-IFN and ribavirin levels and virological response. Although baseline expression of PKR before treatment was marginally higher in nonresponders (NRs), from day 2 onwards, sequential PKR expression in response to PEG-IFN was higher in sustained viral responders compared with the NRs (P < 0.05). Significant correlations were found between kinetics of PKR expression and viral decline rates in each phase of hepatitis C virus dynamics (first phase, r = 0.67, P = 0.0006; second phase, r = 0.67, P = 0.001). In conclusion, improvement in pharmacokinetics following pegylation led to higher intracellular PKR expression, which was associated with enhanced virological efficacy of PEG-IFN-based combination therapy. The concentrations of both ribavirin and PEG-IFN alpha-2b were not associated with viral response and PKR expression.

The inner-valence excitations of a xenon 5s electron were investigated by the electron impact method with an electron-energy-loss spectrometer. The incident energies of the electron beam are varied between 500 eV, 100 eV, 50 eV and 30 eV in order to assign the resonances in the spectra. Besides the optically allowed excitations normally observed by photoabsorption methods, lots of optically forbidden transitions were studied in the present work. The autoionization Rydberg series 5s−1ns, 5s−1np, 5s−1nd have been observed. Their energy levels, resonant profiles and quantum defects were obtained from the electron-energy-loss spectra. Other than single excitations, there are many double excitations in this energy region, which needs further sophisticated calculations and higher resolution experiments to assign most of the resonant features.

Silica glasses (SiO 2 ) were implanted with Zn + ions of 60 keV to a fluence of 1.0 x 10 17 ions/cm 2 , and were annealed in oxygen gas flow at 700 °C for 1 h, to form ZnO nanoparticles (NPs). In as-implanted state, metallic Zn NPs of 10-15 nm in diameter are formed between 10 and 50 nm in depth. NPs are not observed on the surface and down to 10 nm in depth. After the annealing at 700 C for 1 h in oxygen gas, ZnO NPs of ∼ 10 nm in diameter are observed around 50 nm in depth. Moreover, droplet-like ZnO NPs larger than 30 nm in diameter grow on the surface of SiO 2 substrate. Migration of Zn atoms toward the surface, i.e., shallowing of the depth profile, is observed under the oxygen annealing, while vacuum annealing at the same temperature 700°C does not induce any prominent migration of Zn atoms. Mechanisms of the shallowing and the formation of ZnO NPs are discussed.

Implantation of 60 keV Cu − ions into LiNbO 3 resulted in formation of complex nanocomposites consisting of metal Cu nanoparticles distributed among nanodomains of the host medium. The nanodomains of the host medium correspond to regions of a few hundred naometers in diameter with a constant refractive index. Distributions of the Cu nanoparticles and nanodomains in the implanted region do not correlate with each other. Variations of linear and non-linear optical absorption of the nanocomposites are mainly determined by the change of chemical composition and structure of implanted regions of LiNbO 3 .

N-Isopropylacrylamide (NIPA) hydrogel was successfully incorporated with tributyl phosphate (TBP) which works as an extractant species of phenols. NIPA hydrogel was found to be favorable to prepare a monolithic hydrogel in the coexistence of TBP which requires using methanol as the polymerization medium. The hydrogel was found to be stably obtained at 333 K in methanol and the concentration of crosslinker (N,N′-methylenebisacrylamide) of 86 mM. The TBP-incorporated NIPA hydrogel was used for experiments for removal of phenol from aqueous solution. The removed amount of phenol using the NIPA hydrogel was markedly enhanced in proportion to the amount of incorporated TBP. Liquid–liquid solvent extraction of phenol using TBP dissolved in n-octane was examined for comparison of the distribution ratio D. From the proportional dependence of the distribution ratio on the amount of the incorporated TBP, phenol was found to form a 1:1 complex with TBP both in the cases of NIPA gel and liquid–liquid solvent extraction. At the corresponding concentration of phosphate moiety, the phenol removal performance by the TBP-incorporated NIPA hydrogel was found to be comparable to that by conventional liquid–liquid extraction.

Zinc-ion implantation combined with thermal oxidation was carried out to fabricate zinc-oxide (ZnO) nanoparticles (NPs) in silica glass (SiO2). A SiO2 substrate was implanted with Zn+ ions of 60 keV to 1.0×1017 ions/cm2. In as-implanted state, the sample shows a strong absorption peak at ∼4.8 eV and a weak one at ∼1.2 eV due to Zn metallic NPs. After annealing in oxygen gas at 700°C for 1 hour, the absorption in the visible region disappears and a new distinct absorption edge appears at ∼3.3 eV. The grazing-incident-angle x-ray diffraction (GXRD) confirms the formation of ZnO NPs. The ZnO NPs show a photoluminescence (PL) peak at 3.32 eV under pulsed nitrogen-laser excitation. Annealing at 900°C induces an additional shift of the absorption edge to ∼5.3 eV. The additional shift is due to the formation of a Zn2SiO4-phase which has been confirmed by GXRD.

Spectra of ion-induced photon emissions (IIPE) of silica glass were measured during implantation of 3 MeV Cu ions at a constant flux of 3–10 μA/cm2 up to a fluence of 9×1016 ions/cm2. Three bands compose the IIPE spectra: a tail of the oxygen-deficient center band, the band of Cu+ ions at 2.27 eV and the band of non-bridging oxygen hole center at 1.89 eV. Intrinsic defects of silica glass contribute to the IIPE at the onset of irradiation only. At fluences higher than 5×1014 ions/cm2, the fluence dependence of the Cu+-band of IIPE represents (a) the accumulation of Cu solutes preceding the nanoparticle formation and (b) no change of Cu solute concentration during nanoparticle growth. The intensity of the Cu+-band is proportional to the total concentration of Cu solutes. The balance of Cu solutes and Cu nanoparticles is sensitive to the ion flux. The concentration of Cu solutes necessary for nanoparticle formation cannot be attained at fluxes higher than 10 μA/cm2.

Negative ion implantation has been applied to fabricate metal nanocomposites of metals and polymers which are promising for nonlinear electronic, optical and biomedical applications. We have studied nanoparticle formation processes of Ag and their effects on surface properties of polymers, in comparison with those of Cu. Polycarbonate (PC) substrates were irradiated by negative Ag and Cu ions of 60 keV to various doses up to 3 × 1017 ions/cm2. Optical absorption spectra of the irradiated PC were measured in the range from 0.5 to 4.5 eV. Surface- and nanoparticle morphology of the PC were studied by AFM and cross-sectional TEM. Depth profiles of implant concentrations were evaluated by RBS. A surface-plasmon-resonance peak of Ag around 2 eV appears in the optical spectra of PC implanted to a dose of 1 × 1017 ions/cm2, whereas their defect absorption is not significant. The TEM and RBS measurements show that well-defined implantation is capable at this fairly low energy, though surface recession takes place because of ion sputtering. The structure of PC is stable enough for formation of Ag nanocomposites. Depth distribution of Ag nanoparticles significantly shifts towards the surface, differently from the case of Cu nanoparticles. Negative ion implantation provides nanoparticle formation for surface modification of polymers, with understanding the ion-induced precipitation processes in the polymers.

Kinetic behaviors of nanoparticle formation in LiNbO 3 have been studied with negative Cu ion implantation and the effects on nonlinear optical properties have been discussed. Negative Cu ions of 60 keV are implanted into LiNbO 3 disks at fluxes up to 50 μA/cm 2 . Ion-induced photon spectroscopy was applied to monitor the ion-substrate interactions and the nanoparticle morphology was studied by cross-sectional TEM. Metal precipitation behaviors as well as the matrix stability significantly depended on ion flux. In a flux range of 3–10 μA/cm 2 , LiNbO 3 showed spontaneous formation of Cu nanocrystals of ∼10 nm, including nonspherical shape. Crystallinity of the LiNbO 3 lattice implanted was sustained up to 3 × 10 16 ions/cm 2 . The Cu nanoparticles in LiNbO 3 showed a sub-picosec nonlinear optical response. However, significant Li-atom release to the vacuum was detected by ion-induced photon spectroscopy, indicating formation of a Li-depleted zone. Particularly above a flux of 30 μA/cm 2 , significant coarsening of Cu particles and amorphization of the LiNbO 3 lattice occurred. The results indicate that metal nanoparticle formation in LiNbO 3 is sensitive to the ion flux and that the optimization is requisite to fabricate well-defined nanocomposites.

Implantation of Cu negative ions of 60 keV induces frequency shifts of infrared (IR) vibration modes of SiO 2 . Since the penetration depth of IR light is much larger than the projectile range of Cu − ions, conventional IR reflection spectroscopy detects little shifts. To evaluate the true shifts induced by the implantation, the near-surface sensitive IR reflection spectroscopy (NSS-IRRS) was applied using a suitable sample structure. Distinct shifts of −5, +6 and −44 cm −1 , respectively, are observed in rocking, bending and stretching modes of Si–O–Si bonding of SiO 2 . Ion-flux dependence was examined in the flux range of 0.95–100 μA/cm 2 with keeping the total fluence 3×10 16 ions/cm 2 . Almost no ion-flux dependence is observed in the shifts of these modes, which is in contrast with the strong flux dependences of size- and depth-distributions of Cu nanoparticles in SiO 2 .

The injection performance of the negative-ion based NBI (N-NBI) system for JT-60U has been improved by correcting beamlet deflection and improving spatial uniformity of negative ion production. Beamlet deflection at the peripheral region of the grid segment due to the distorted electric field at the bottom of the extractor has been observed. This was corrected by modifying the surface geometry at the extractor to form a flat electric field. Moreover, beamlet deflection due to beamlet–beamlet repulsion caused by space charge was also compensated for by extruding the edge of the bottom extractor. This resulted in a reduction of the heat loading on the NBI port limiter. As a result of the improvement above, continuous injection of a 2.6 MW H0 beam at 355 keV has been achieved for 10 s. Thus, long pulse injection up to the nominal pulse duration of JT-60U was demonstrated. This has opened up the prospect of long pulse operation of the negative-ion based NBI system for a steady-state tokamak reactor. So far, a maximum injection power of 5.8 MW at 400 keV, with a deuterium beam, and 6.2 MW at 381 keV, with a hydrogen beam, have been achieved in the JT-60U N-NBI. Uniformity of negative ion production was improved by tuning the filament emission current so as to direct more arc power into the region where less negative ion current was extracted.

Metal nanoparticle formation and radiation resistance of polymers with heavy ion implantation have been studied to develop modification process of the optical properties of polymers. Negative Cu ions of 60 keV were implanted into high-density polyethylene (HDPE), polystyrene (PS) and polycarbonate (PC) at 1 μA/cm 2 up to a total dose of 1.5 × 10 17 ions/cm 2 . Optical absorption spectra at high total doses show surface plasmon resonance, indicating formation of Cu nanoparticles for all the polymers. The onset dose at which the plasmon peak appears depends on the polymer species. The metal nanoparticle formation in polymers is confirmed by cross-sectional TEM. Depth profiles of Cu atoms evaluated by RBS do not indicate distinct ion-induced diffusion. The FTIR-ATR spectra show fairly good resistance against radiation damage in the order of PC, PS and HDPE. These results indicate that low energy Cu − irradiation at appropriate doses does not cause serious damage on the polymer matrices, and that Cu atoms implanted into the polymers cause nanoparticle precipitation to be promising for optical application.

Metal nanoparticles embedded in insulators exhibit a strong surface resonance and have been studied for optical switching. In this study, negative Cu ions of 60 keV were implanted into a-SiO2, MgO · 2.4(Al2O3) and LiNbO3 at 10–50 μA/cm2 to 1 × 1017 ions/cm2. The resultant nanoparticle morphology was studied by cross-sectional TEM and shown to depend on the substrate species. The a-SiO2 showed the formation of spherical Cu nanocrystals of ∼10 nm. The MgO · 2.4(Al2O3) suppressed particle coarsening even at high dose rates, sustaining crystallinity of the lattice. On the other hand, the LiNbO3 exhibited non-spherical Cu nanocrystals of ∼10 nm. Ion-induced photon spectroscopy was applied to monitor the ion–substrate interactions from outside of the substrates. The non-linear optical properties were evaluated by a pump–probe method around the plasmon energy of about 2 eV. Although LiNbO3 exhibited a sub-picosec non-linear response, ion-induced photon spectroscopy revealed Li-atom release to the vacuum under ion implantation, influencing the Cu nanoparticle formation.

Ion irradiation induces a frequency shift of Si–O–Si stretching vibration (ω4 mode, ∼1100 cm−1) in SiO2. Since the penetration depth of IR light is much larger than the projectile range of low-energy heavy ions (∼200 keV or less), conventional IR reflection spectroscopy detects a smaller shift than the true one. The near-surface sensitive reflection spectroscopy (NSSRS) was applied using a suitable sample structure, and obtained the true shift of ∼44 cm−1. The coherent two-layer reflection model, with the true shift value, well reproduces the spectra of the irradiated SiO2, and indicates that the ion-induced ω4 peak shift obtained with NSSRS has the same origin with the ion-induced 1040 cm−1 shoulder obtained with conventional spectroscopy. The present results indicate that the ω4 peak shift is ascribed not to the compaction, but to the Si–O–Si bond-breaking.

Simultaneous laser irradiation under ion irradiation is conducted to control nanoparticle precipitation in amorphous (a-)SiO 2 . Copper ions of 3 MeV and photons of 532 nm by Nd:YAG laser are irradiated to substrates of a-SiO 2 . The ion dose rate and total dose are set at 2–10 μA/cm 2 and 3.0 × 10 16 –3.0 × 10 17 ions/cm 2 , respectively, and the laser power density is 0.05–0.2 J/cm 2 pulse at 10 Hz. The laser is simultaneously irradiated with ions in the co-irradiation mode, and the result is compared to that in the sequential and ion-only irradiation. Cross-sectional TEM of the irradiated specimens is conducted after measuring optical absorption spectra. In the case of co-irradiation of intense laser power and high dose (0.2 J/cm 2 pulse and 3.0 × 10 17 ions/cm 2 ), Cu nanoparticles precipitate much more extensively than in the sequential irradiation, increasing both the particle diameter and the total Cu atoms in the nanoparticles. The optical absorption spectra show a surface plasmon peak of the nanoparticles. The precipitation enhancement in the co-irradiation mode suggests that the electronic energy is absorbed by the dynamic electronic states and promotes the Cu precipitation via enhancing the atomic migration.

The temperature control system of the large-size plasma grid has been developed to realize the long pulse production of high-current negative ions for JT-60SA. By using this prototype system for the JT-60SA ion source, 15 A negative ions has been sustained for 100 s for the first time, which is three times longer than that obtained in JT-60U. In this system, a high-temperature fluorinated fluid with a high boiling point of 270 degree Celsius is circulated in the cooling channels of the plasma grids (PG) where a cesium (Cs) coverage is formed to enhance the negative ion production. Because the PG temperature control had been applied to only 10% of the extraction area previously, the prototype PG with the full extraction area (110 cm × 45 cm) was developed to increase the negative ion current in this time. In the preliminary results of long pulse productions of high-current negative ions at a Cs conditioning phase, the negative ion production was gradually degraded in the last half of 100 s pulse where the temperature of an arc chamber wall was not saturated. From the spectroscopic measurements, it was found that the Cs flux released from the wall might affect to the negative ion production, which implied the wall temperature should be kept low to control the Cs flux to the PG for the long-pulse high-current production. The obtained results of long-pulse production and the PG temperature control method contributes the design of the ITER ion source.

The 500-keV negative-ion based neutral beam injector for JT-60U started operation in 1996. The beam power has been increased gradually through optimizing operation parameters of the ion sources and conquering many troubles in the ion source and power supplies caused by a high voltage break-down in the accelerator. However, some issues remain to be solved concerning the ion source for increasing further the beam power and the beam energy. The most serious issue of them is non-uniformity of source plasma in the arc chamber. Various countermeasures have been implemented to improve the non-uniformity. Some of those countermeasures have been found to be partially effective in reducing the non-uniformity of the source plasma, and as the result the ion source, so far, has accelerated negative-ion beams of 17.4A at 403keV with deuterium and 20A at 360keV with hydrogen against the goal of 22A at 500keV. The neutral beam injection power into the plasma has reached 5.8MW at 400keV with deuterium. Further efforts to ...

Ion-induced surface modification processes of polystyrene (PS) and high-density polyethylene (HDPE) have been studied by either in situ photon-emission spectroscopy or ex situ surface analyses. Heavy Cuions of 60 keV irradiated the polymers at a dose rate of 1 lA/cm 2 and ion-induced photon emission was in situ measured in a spectral region of 250-850 nm. Ion-induced chemical reactions of the surface layers were ex situ evaluated by X-ray photoelectron spectroscopy (XPS). Intensity, spectral shape and dose dependence of the photon emission were significantly different between aromatic-containing polymers (PS) and linear polymers (HDPE) in the same irradiation condition. The emission spectrum of HDPE represented a broad band with a maximum at about 595 nm, while that of PS showed a sharp peak around 656 nm. The total emission yield observed for PS was much lower than that of HDPE, and the decay rates of emission intensity for PS were different from that of HDPE in a dose region less than 10 14 ions/cm 2 . The XPS analyses showed chemical change of the surface bonding. These results suggested that ion-induced processes caused hydrogen extraction, crosslinking and bond scission of the matrix. 2002 Elsevier Science B.V. All rights reserved.

Ion-induced photon emission under 60 keV Cu − implantation into the insulators of MgAl 2 O 4 and LiNbO 3 was in situ measured over a wide wavelength range from 200 to 900 nm. The formation of the Mg and Li deficient layers for the respective insulator was detected based on the dose dependence of the Al, Mg and Li atomic line intensities. The Al I and Mg I line intensities from spinel exhibit different behaviors depending on irradiation temperatures: they gradually decrease while the (Al I)/(Mg I) ratio increases up to dose of 3×10 17 ions/cm 2 at room temperature or exhibits a steady-state tendency at high temperature. Sharp decrease of Li I line intensity from LiNbO 3 under high dose rate bombardment indicates drastic changes of surface layer that may alter the phase stability and optical performance of insulators.

The several hundred keV neutral beamline which is now operating on JT-60U marks the first usage of negative ion sources to produce high power neutral beams. Because this was such a large advance in the state of the art with respect to all system parameters, many new physical processes appeared during the earlier phases of the beam injection experiments. The physical mechanisms responsible for these processes have been explored, and solutions have been implemented for some of them, in particular excessive beam stripping, the secular dependence of the arc and beam parameters, and the non-uniformity of the plasma illuminating the beam extraction grid. This has reduced the percentage of beam heat loading on the downstream grids by roughly a third and has permitted longer beam pulses at higher powers. Progress is being made in improving the negative ion current density and in coping with the sensitivity of the caesium in the ion sources to oxidation by tiny air or water leaks, and the cathode operation is being altered.

Silicon-thermal-oxide (a-SiO2) films of 115 nm thick on Si wafers are implanted by high-flux Cu negative-ions of 60 keV. Optical reflectivity measurements show that the Si substrates are transformed into an amorphous-like state after the implantation. The “amorphization” is ascribed to recoil atoms, not directly to the incident Cu ions. The crystallinity is recovered after a heat treatment at 900°C for 1 h in Ar gas. The interference fringes in the reflectivity spectra shift to high energy side at 60 μA / cm 2 and the higher fluxes, indicating decrease of the oxide thickness. At the same fluxes, AFM observation shows a prominent change of surface morphology and a large increase of step-height at implanted–unimplanted area boundaries, indicating enhanced sputtering under high-flux implantation.

The positive-ion based NB1 system for JT-60 began operation in 1986 with hydrogen beam, and had injected the neutral beam power of 27 MW at 75 keV. The beam species has been changed to deuterium through changing the ion sources and beam-line components in 1991. The NBI has injected a deuterium beam of 40 MW at 96 keV in 1996. In 2000, the computer control system for the beam operation has been changed from a mini-computer to a workstation system in order to match a great variety of beam injection parameters, and the operation capability has greatly improved.

In fabricating metal nanoparticles in insulators, high-current negative ions have been shown to cause efficient and spontaneous growth of nanospheres. The in-beam growth is inevitably subjected to rearrangement of implanted atoms, departing from initially deposited positions. For high-current techniques for insulators, we discuss important experimental factors and explore possible mechanisms of the in-beam growth and atomic rearrangement of nanoparticles. Experimental data of interest are for negative Cu ion implantation at 60 keV into insulators, amorphous(a-), crystalline (c-) SiO 2 and a spinel oxide, MgAl 2 O 4 . Dose rates ranged up to 260 μA/cm 2 , with a total dose of 3.0×10 16 ions/cm 2 . Nanoparticle morphology and surface morphology by AFM were significantly dependent not only on dose rate but also on the boundary conditions. With increasing dose rate, the in-beam growth of nanoparticles became pronounced and the atomic profile shifted toward the surface. Since beam heating, especially in vacuum, is of concern, thermal analysis was carried out with a one-dimensional simulation code. Candidate mechanisms are depth-oriented gradients of deposited nuclear/electronic energy, chemical/elastic potentials and thermal effects. The relevant mechanisms are explored among these candidates.

A method is proposed to synthesize oxide nanoparticles in insulators, using metal-ion implantation and following thermal oxidation, which introduces less damage compared to the sequential implantation of metal ions and oxygen ions. Ni-oxide nanoparticles are formed in O2 gas flow at ∼800°C for 1h, through thermal oxidation of Ni metal nanoparticles, which were introduced in SiO2 by charging-free negative ion implantation of 60keV. After the oxidation, optical absorption in the visible region, which is due to Ni metal nanoparticles in the specimen, disappears, and a steep absorption edge of insulator NiO appears around ∼4eV. Simultaneously, the large magnetization of Ni metal nanoparticles changes to a weak magnetization of antiferromagnetic NiO nanoparticles. The nanoparticle formation is confirmed by transmission electron microscopy observation.

This paper describes the development of the neutral beam (NB) systems on JT‐60SA, where 30–34 MW D0 beams are required to be injected for 100 s. A 30 s operation of the NB injectors suggests that existing beamline components and positive ion sources on JT‐60U can be reused without the modifications on JT‐60 SA. The JT‐60 negative ion source was modified to improve the voltage holding capability, which leads to a successful acceleration of 2.8 A H− ion beam up to 500 keV of the rated acceleration energy for JT‐60SA.

Excess heat loads to accelerator grids limit extension of pulse length in operation of the large negative ion sources with multi aperture accelerator. Part of the heat loads is caused by interception of deflected beamlets due to their space charge repulsion. In this paper, a beamlet steering technique using aperture offset was examined for compensation of the beamlet deflections utilizing a three dimensional beam analysis simulating the D− negative ion source of JT‐60 U. The beamlet deflection was analyzed in detail using fifty beamlets, which were extracted from apertures arranged in a lattice pattern of 10×5. The simulation showed successful compensation of the beamlet deflection by aperture offsets defined according to the thin lens theory. Even if the beam energy was changed, the necessary aperture offset would not be changed maintaining the perveance and a ratio of extraction and acceleration voltage. In JT‐60 U, it was shown that the aperture offset of less than 1.0 mm would be enough to compensate ...

This paper reports the recent activities at JAEA for the development of 1 MeV H− ion accelerator toward the ITER NBI. For the development of MAMuG accelerator, a 320 mA H− ion beam was successfully accelerated as the highest record in the world at the MeV class energy (796 keV). This was achieved by protecting the H− ion source from the high heat load by the backstream positive ions, which was produced during the high current H− ion acceleration. The SINGAP accelerator was tested at JAEA to compare the performance of the SINGAP and the MAMuG. This paper also reports the results of the SINGAP test and the comparison between the SINGAP and the MAMuG is discussed.

Background & Aims: Clinical significance of molecules involving innate immunity in treatment response remains unclear. The aim is to elucidate the mechanisms underlying resistance to antiviral therapy and predictive usefulness of gene quantification in chronic hepatitis C (CH-C). Methods: We conducted a human study in 74 CH-C patients treated with pegylated interferon α-2b and ribavirin and 5 nonviral control patients. Expression of viral sensors, adaptor molecule, related ubiquitin E3-ligase, and modulators were quantified. Results: Hepatic RIG-I, MDA5, LGP2, ISG15, and USP18 in CH-C patients were up-regulated at 2- to 8-fold compared with nonhepatitis C virus patients with a relatively constitutive Cardif. Hepatic RIG-I, MDA5, and LGP2 were significantly up-regulated in nonvirologic responders (NVR) compared with transient (TR) or sustained virologic responders (SVR). Cardif and RNF125 were negatively correlated with RIG-I and significantly suppressed in NVR. Differences among clinical responses in RIG-I/Cardif and RIG-I/RNF125 ratios were conspicuous (NVR/TR/SVR = 1.3:0.6:0.4 and 2.3:1.3:0.8, respectively). Like viral sensors, ISG15 and USP18 were significantly up-regulated in NVR (4-fold and 2.3-fold, respectively). Multivariate and receiver operator characteristic analyses revealed higher RIG-I/Cardif ratio, ISG15, and USP18 predicted NVR. Lower Cardif in NVR was confirmed by its protein level in Western blot. Also, transcriptional responses in peripheral blood mononuclear cells to the therapy were rapid and strong except for Cardif in not only a positive (RIG-I, ISG15, and USP18) but also in a negative regulatory manner (RNF125). Conclusions: NVR may have adopted a different equilibrium in their innate immune response. High RIG-I/Cardif and RIG-I/RNF125 ratios and ISG15 and USP18 are useful in identifying NVR.

This paper reports on the development of compact surface plasmon resonance (SPR) sensors to be used for mobile robot olfaction. The proposed sensor uses a periodic metal structure formed on top of the self-assembled layer of polystyrene particles of 200 nm in diameter. With the grating of this size, SPR can be excited even with an LED light source. The change in the absorbance is simply measured using a photodiode. The experimental results are presented on a silver nanostructure sensor and a gold nanostructure sensor to show the potential of these sensors.

High-porosity nanoporous silica was prepared by nanocasting method using N-isopropylacrylamide (NIPAm) cross-linked by N, N’-methelenbisacrylamide (BIS) as the templating agent. The obtained silica was a bulk silica with good transparency indicating that the characteristic length-scale of the obtained silica is in the nanoscopic scale being much smaller than that of the wave length of visible light. Nitrogen adsorption/desorption measurements revealed that the nano porosity increases up to 80% with the weight ratio of NIPAm to silica. The mean pore size (radius) also increased with the weight ratio in the region smaller than 10nm. TEM observation revealed that the nanoscopic network structure was replicated into tube-like nanopores randomly distributed in the silica matrix. The whole nanoscopic morphology of these tube-like nanopores was much like as the predicted for the cross-linked polymer.

Negative ion beams are assuming increasing significance in the field of controlled fusion research. The first generation of large high current negative ion sources has now operated successfully on the JT‐60U tokamak for some years, producing negative ions of hydrogen or deuterium at energies up to 400 keV for conversion to several megawatts of neutrals which are used for plasma heating and current drive. We report an unexpected intensification phenomenon, and some of the improvements made or planned. In the realm of inertial confinement fusion, interest has grown in the use of heavy negative ion driver beams formed from halogens such as bromine, iodine, or chlorine. We discuss the advantages of negative ions as heavy ion fusion drivers, and assess the technical feasibility of a halogen negative beam system. We also discuss the potential for photodetaching the negative ions to produce atomically neutral beams and reduce beam space charge effects within the target chamber.

The magnetic nanoparticles are fabricated in silica glass (SiO 2 ) using high-flux implantation of nickel negative-ions of 60 keV. Photo-absorption measurements and the cross-sectional transmission electron microscopy (XTEM) observation confirm formation of metallic Ni nanoparticles in SiO 2 , and exclude possible formation of Ni silicides (Ni 3 Si, Ni 2 Si, NiSi) and oxides (NiO) as major products. The mean diameter of the nanoparticles was in ~2.9 nm, and the depth distribution was similar to the prediction from the TRIDYN code with taking account of the sputtering. Temperature- and field- dependences of magnetization show that the nanoparticles are in the super-paramagnetic state with a blocking temperature of ~27 K.

The negative ion based neutral beam system now operating for plasma heating and current drive on the large JT-60U tokamak marked the first application of negative ion source technology to the production of high current, high voltage beams for conversion to neutral atomic beams. This pioneering system has demonstrated the technical feasibility of negative ion based neutral beams for future fusion devices. Because this was a very large advance in the state of the art with respect to all system parameters, the principal physical processes governing the performance of the ion source and accelerator were somewhat different than had been the case with earlier much smaller negative ion sources. We have explored the physical mechanisms limiting the power and pulse length capability of these large sources, and have implemented ameliorating changes to reduce power loading on the accelerator grids and increase the transmitted power fraction.

Negative Cu ions of 60 keV have been applied to generate metal nanocrystals embedded in insulators. Crystalline (c-), amorphous (a-)SiO2 and a spinel oxide, MgO·2(Al2O3), were irradiated at various dose rates up to about 100 µA/cm2, at a total dose of 3.O×1016 ions/cm2. In a-Sio2, morphology of nanoparticles and the resultant optical property changed with dose rate and, at a critical condition, showed in-plane arrangement of nanocrystals. The optical property of c-Si0 2 (a-quartz) was qualitatively similar to that of a-SiO2, but the implanted region of c-SiO2 showed different irradiation responses. The c-SiO2 was susceptible to radiation-induced amorphization but the nanoparticle morphology was still different from a-SiO2, suggesting a stronger depth-oriented driving force. Unlike SiO2, the spinel oxide showed good structural stability against the implantation and no tendency of the long-range atomic rearrangement. The results indicate that the crystallinity and the relevant interactions may play an important role in the nanoparticle growth during the implantation.

Nanoparticles of Cu were fabricated by negative-ion implantation, leading to spontaneous formation at high beam fluxes. Negative ions, alleviating surface charging, exhibit significant merits in carrying out low-energy implantation at high dose rates. The kinetic processes were studied by measuring dose-rate dependence of colloid formation and resultant optical properties. Negative-Cu ions of 60 keV were implanted into silica glasses at high-current densities, up to 260 μA/cm2, fixing the total dose at 3.0 × 1016 ions/cm2. Spherical nanocrystals of Cu atoms formed within a narrow region, near the projectile range of Cu ions. Simultaneously, much smaller particles spread out beyond a depleted zone, deeper than the projectile range. The nanocrystal growth and optical properties were greatly dependent on the dose rate and the specimen boundary condition. The growth process is explained by a droplet-model based on surface tension and radiation-induced diffusion. Beam-surface interactions also play an important role in the mass transport from the beam flux to the interior solid.

Nanocrystals (NCs) of cuprous oxide (Cu2O), cupric oxide (CuO), and copper metal (Cu) are fabricated in silica glasses (SiO2) by implantation of 60keV Cu− ions at different annealing conditions. At room temperature, Cu2O NCs show two sharp absorption peaks at 2.58 and 2.71eV due to autoionized exciton states, and Cu NCs show a broad peak at ∼2.2eV due to the surface plasmon resonance (SPR). With decreasing temperature down to 2.8K, the peaks of Cu2O NCs become much narrower, while the SPR peak of Cu NCs keeps almost the same peak width.

Silica glass implanted with Zn ions of 60 keV to 1.0x10(17) ions/cm(2) was annealed in oxygen gas to form ZnO nanoparticles (NPs). In as-implanted state, the implanted Zn atoms form Zn metallic NPs inside of the silica. After annealing at 600 degrees C, ZnO NPs form on the surface, while Zn metallic NPs still remain in the deep region. At 700 degrees C, most of Zn atoms move to the surface to form the droplet-shaped ZnO NPs which show two photoluminescence bands, i.e., an exciton band at 375 nm and a defect band at similar to 500 nm. The defect band almost disappears in the samples annealed at 600 degrees C, which include both ZnO NPs and Zn NPs.

Changes in the pH gradient and thickness of the mucus gel layer in the healing of acetic acid-induced gastric ulcers in rats were investigated. The maximum of the pH gradient and the thickness of mucus gel layer at the edge of ulcers and in the regenerated mucosa were higher, decreased gradually with the healing of the ulcers and finally reached normal values. This indicates that mucus and bicarbonate are secreted actively from the mucosa surrounding an ulcer and that they play an important role in protection of the base of ulcers and in acceleration of the healing of the ulcers.

This study was designed to investigate the effect of luminal H+ on alkali and mucus secretion in the isolated rat stomach. At various luminal pHs, the thickness and the pH gradient of the mucus gel layer were measured. The maximum pH and calculated alkali secretion showed that the latter was stimulated in parallel with an increase in luminal H+ concentration, especially when the luminal pH became less than 3.5. Mucus secretion, however, was not significantly affected by the luminal H+ concentration. These results suggest that alkali and mucus secretion in the stomach are not regulated by the same mechanism, but different ones.