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The electrical insulation of the Megavolt ITER Injector and Concept Advancement (MITICA) beam source (BS) at 1 MV in vacuum is a challenging issue, which could not be fully addressed so far on the basis of experimental results and of theoretical models available in literature. A specific high-voltage (HV) test campaign is being prepared to validate and optimize the voltage holding capability of the BS insulation under realistic conditions, using full-size mockup electrodes reproducing in detail the geometry of the BS and accelerator. The proposed test strategy will address both the single-gap and the multistage insulation, so as to obtain a verification of voltage holding at 1 MV before the installation of the real components. This approach is intended to reduce the risk related to the HV insulation at 1 MV and, if necessary, to allow the development of effective corrections. In this article, the test motivations and requirements are defined, and the electrode implementation and diagnostic setup are described. Finally, the test configurations and the experimental procedure are discussed.

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.

Enhancement of surface plasmon resonance (SPR) in optical absorption has been found on Cu ion-implanted SiO 2 substrate modified by micro-indentation and post-annealing. Micro-indentation effects on surface plasmon resonance (SPR) in optical absorption have been studied to control nanoparticle formation in Cu ion-implanted SiO 2 substrate. The SiO 2 was firstly implanted with 2 MeV Cu 2+ ions at an ion flux of 4 μA/cm 2 , up to a fluence of 6 × 10 16 ions/cm 2 . After the ion implantation, dot-array patterns of micro-indents were made by a micro-Vickers hardness tester, and followed by annealing at 600 °C in vacuum for 1 h. The optical absorption spectra of the indented region and the non-indented flat region were measured and compared with each other. After post-annealing at 600 °C, the indented area showed higher absorbance of SPR at 2.2 eV than that of the flat region annealed under the same annealing conditions. The TEM study shows larger and denser Cu precipitates inside the indentation than those in the flat area. The results indicate that the defects produced by indentation enhance the atomic migration in the plastic zone during thermal relaxation process, resulting in promoting the enhanced precipitation of Cu nanoparticles.

The optical propagation property of a planar waveguide with a periodic nanoparticle grating layer is characterized by using sliding prism method. Here, Cu nanoparticle grating was fabricated on a-SiO 2 substrate by periodic heavy-ion irradiation technique. The pitch of these gratings was 2 μm and 3 μm, respectively. The flux and fluence were at the range of 6–10 μA/cm 2 and 6 × 10 16 –1 × 10 17 ions/cm 2 , respectively. The grating effect, mainly including the mode selection effect, is observed. The effect depends on the pitch of the grating and the morphology of nanoparticles. The propagation loss of the waveguide induced by nanoparticle layer is evaluated.

症例1は44歳女性．人間ドックにて肝腫瘍を指摘され，精査目的に入院．HBV, HCVなどウイルスマーカー陰性で肝機能異常は認めず，各種画像診断から肝血管筋脂肪腫（AML）を考え，経皮的腫瘍生検にて診断確定した．経過観察中にて腫瘍径の増大は認めていない．症例2は40歳女性．健診にて肝腫瘍を指摘され，各種画像診断でも肝細胞癌が否定できず，短期間に腫瘍径が増大したため左葉外側切除術を施行した．病理組織より肝血管筋脂肪腫と診断された．症例1, 2は最終診断では肝血管筋脂肪腫であったが，症例1では脂肪成分に富み典型的なAML所見であったのに対し，症例2は脂肪成分に乏しく診断困難であった．両者ともに肝静脈が流出血管として描出され，造影超音波検査が有用であった．

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.

A precise grating profile evaluation method for distributed-feedback (DFB) laser diodes was achieved using a simple optical metrology. Spectroscopic scatterometry, an optical-wavelength light-diffraction technique, is emerging as a fast, accurate, and nondestructive means of monitoring profiles. A photoresist grating pattern on an InP substrate and an etched InP grating with periods of 0.2 and 0.24 mum were successfully evaluated by using unpolarized simple optical metrology. A precise grating profile evaluation technique with an accuracy of nanometers enabled us to obtain an accurate coupling coefficient (kappaL) for DFB laser diodes. DFB laser diodes with well-controlled kappaL are very promising for practical use in cost-effective optical networks.

SUMMARYNeobenedenia girellae, a capsalid monogenean, is a significant pathogen due to both its ability to cause high mortality in fishes and its low host specificity. Established control methods have both advantages and disadvantages. Biological control measures with no unfavourable effects on the environment should be incorporated into the control strategy. The response ofN. girellaeoncomiracidia to brightness and black-and-white contrast was investigated to search for an alternative approach of disease prevention or control. Japanese flounder,Paralichthys olivaceus(Paralichthyidae), were exposed to oncomiracidia in an aquarium divided into areas of different brightness (∼1·3, 41·3 and 138·0 lux). The number of parasites on the fish group reared in 138·0 lux was significantly higher than on those reared in the lower brightness levels. Thus, the fish tended to be more vulnerable to infection byN. girellaeunder brighter conditions. Challenge trials using host fish mucus and whole live fish were established to detect the response by oncomiracidia to black-and-white contrast on a whiteversusa black background. Markedly moreN. girellaeoncomiracidia attached to black-painted areas and dark-coloured fish (normal spotted halibut,Verasper variegatus(Pleuronectidae) compared with white-painted areas and light-coloured fish (mal-colouredV. variegatus) on a white-coloured background. On a black-coloured background, moreN. girellaeoncomiracidia tended to attach to white-painted areas and light-coloured fish. Thus, black-and-white contrast is considered important for host finding byN. girellaeoncomiracidia. The simplicity of the positive phototactic behaviour and the response to black-and-white contrast may lead to the development of a simple, practical and inexpensive method to controlN. girellaeoutbreaks.

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.

Enhancement of surface plasmon resonance (SPR) in optical absorption has been found on Cu ion-implanted SiO2 substrate modified by micro-indentation and post annealing. The SiO2was firstly implanted with 2 MeV Cu2+ ions, at an ion flux of 4 μA/cm2, up to a fluence of 6 × 1016 ions/cm2 at room temperature. After the ion implantation, dot-array patterns of micro-indents were made by a micro-Vickers machine, and annealed at 600 °C, 700 °C and 800 °C in vacuum for 1 h. The optical absorption spectra of the indented region and the non-indented flat region were measured by a dual beam spectrometer. After post annealing at different temperatures, all the indented areas showed higher absorbance of SPR at 2.2 eV, comparing to the flat region annealed under the same annealing conditions. In particular, the SPR enhancement reached maximum after 600 °C annealing, and decreases with further increasing annealing temperature. The result of SPR enhancement by the micro-indentation suggests that the indentation-induced deformation enhances the atomic migration, resulting in promoting the precipitation under thermal annealing.

A new method for nanoparticle planar control has been proposed based on optical laser-lithography technique. With this method, the planar spatial resolution of the lithography is improved. Combining the lithography with subsequent ion-irradiation technique, a two-dimensionally (2D) patterned structure of Cu nanoparticles in a silica substrate is obtained with a sub-micrometer spatial resolution. The size of each “spot” is 500 × 500 nm 2 , and the pitch is 2 μm. Planar TEM image and the result of scanning near-field optical microscopy (SNOM) verify the nanoparticle 2D-patterned distribution. Further improvement of the processing may enable 2D nanoparticle patterning with a pitch on a sub-micrometer scale.

In the present study, 10 greater amberjack Seriola dumerili held individually were given free access to self-feeder, and trigger actuations were continuously monitored. Most (80%) of greater amberjack developed stable self-feeding activity within 1 week. The fish was a rigidly diurnal feeder under a 12L:12D cycle, with a feeding peak of 1–3 h occurring just after the onset of lights. Under constant conditions, all 10 individual fish exhibited free-running self-feeding rhythms, which persisted for 43 days without a sign of damping out. As far as is known, this seems to be the longest record of free-running behavioural rhythms in fishes. Except one fish free-ran at a period length (τ) of 25·2 h, τ of free-running self-feeding rhythms in the other nine fish was shorter than 24 h, ranging from 20·0 h to 21·5 h. In addition, phase transients of feeding activity were observed in response to the advancement of lights on. It is concluded that feeding activity in greater amberjack is mediated by endogenous circadian oscillators.

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.

Optical properties of Au nanoparticle composites and a grid structure of Cu nanoparticle composite were studied. Negative ion implantation was applied to synthesize Au and Cu nanoparticles in amorphous SiO2 and Al2O3. Au nanoparticles were embedded within a depth of 30 nm by 60keV Au− implantation. The surface plasmon resonance (SPR) of Au:SiO2 and Au: Al2O3 composites shifted to red and to blue, respectively, compared to calculated ones by the Mie theory. Optical nonlinearity was measured with pump-probe femtosecond spectroscopy and the transient spectrum of Au: Al2O3 composite presented a large red shift from the SPR peak. Image mapping of far-field transmitted intensity of Cu-implanted SiO2 with a fine grid structure drawn by laser-lithography was observed by a scanning near-field optical microscopy (SNOM) system.

Surface recession due to sputtering under low-energy and high-fluence heavy-ion implantation makes shallower and broader depth profile of implanted ions than those calculated by conventional ion-range simulation-codes such as SRIM. Depth profiles of Zn atoms in silica glasses (SiO2) implanted with Zn+ ions of 60 keV up to 1.0×1017 ions/cm2 were evaluated using both experimental methods as Rutherford backscattering spectrometry (RBS), sputtering depth-profiling by X-ray photoelectron spectroscopy (XPS), and an advanced numerical simulation code TRIDYN, which includes the sputtering loss effects. The TRIDYN code predicts the shallowing of the projectile range from ∼46 to ∼27 nm with increasing the fluence up to 1×1017 ions/cm2, and very high-concentration (∼20 at%) of Zn atoms close to the surface. However, RBS and XPS results exclude such high concentration close to the surface. These results suggest remarkable redistribution of Zn atoms from the nearer surface to the deeper region during the implantation. In fact, Zn-atom concentration near the surface and that near the projectile range are, respectively, lower and higher than those by the SRIM code predictions.

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.

Kinetic processes of nanoparticle formation by ion implantation was studied for the insulators of a-SiO 2 , LiNbO 3 , MgO · 2.4(Al 2 O 3 ) and PMMA, either by changing ion flux or by using a co-irradiation technique of ions and photons. Under Cu-implantation of 60 keV Cu − , nanoparticles spontaneously formed without thermal annealing, indicating radiation-induced diffusion of implants. The high-flux implantation caused instable behaviors of nanoparticle morphology in a-SiO 2 , LiNbO 3 and PMMA, i.e. enhanced atomic rearrangement or loss of nanoparticles. The spinel MgO · 2.4(Al 2 O 3 ) also showed nanoparticle precipitation at 60 keV, but the precipitation tendency is less than the others. Combined irradiation of 3 MeV Cu ions and photons of 2.3 eV or 3.5 eV indicates that the electronic excitation during ion implantation significantly enhances nanoparticle precipitation, greatly depending on photon energy and fluence. The selectivity for photons can be applied to control nanoparticle precipitation.

In the negative ion based neutral beam injector (N-NBI) for JT-60U, an extension of the pulse duration up to 30 s has been intended to study quasi-steady state plasmas, where the NBI pulse duration is significantly longer than the plasma current diffusion time. Achieving long pulse injection requires a reduction of the heat load on the grids of the ion source. The ion source was modified to reduce the pressure within the grid structure by increasing the vacuum conductance of the acceleration grids. The acceleration efficiency was improved from 0.74 to 0.79. The heat load of the grounded grid, which was the main heat load of the acceleration grids, decreased from 9.2 to 7.0% at a constant arc chamber pressure of 0.3 Pa. These improvements seemed to be caused by the reduction of beam ion stripping loss. Up to now, a long pulse injection of 17 s at the power of 1.6 MW with beam energy of 366 keV was obtained by using one ion source. The temperature rise of the cooling water from the grounded grid saturated at less than 35 °C during operation, so the heat load of the grid is significantly reduced for steady state operation at this power level.

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 .

Negative ion implantation has been applied to polymers in order to modify the surface and to fabricate nanoparticles. Metal nanoparticles in the vicinity of a polymeric surface are promising for biomedical applications as well as nonlinear optical applications. Substrates of polymethyl methacrylate (PMMA) were implanted with Ag− and Cu− of 60 keV at 3 μA/cm2 up to 3×1017 ions/cm2. Optical absorption spectra of the implanted PMMA were measured in a photon range from 0.5 to 4.5 eV. A peak of surface plasmon resonance (SPR) emerges in the absorption spectra above about 1×1017 ions/cm2, both for the Ag− and Cu− cases. A coexisting absorption slope, due mostly to defects, increases but tends to saturate with ion fluence. The SPR peak of Ag-implanted PMMA is much broader than that of the Cu-implanted one. Corresponding to the SPR spectra, metal nanoparticles are observed by cross-sectional TEM. With increasing ion fluence, the Ag nanoparticles spread out towards the surface, in contrast to the localized Cu nanoparticles. The results demonstrate that metal nanoparticle fabrication in polymers is capable by using appropriate low-energy ions and provides a variety of spatial distributions dependent on ion species and fluence. In particular, Ag− ion implantation fabricates surface-exposed/gradient nanoparticles, which are suitable for biomedical applications such as anti-microbial effects.

Spectra of the optical transmission and ion-induced photon emission (IIPE) of silica glass were measured during implantation of 60 keV Cu − ions at ion fluxes from 1 to 75 μA/cm 2 up to a fluence of 2 × 10 17 ions/cm 2 , aimed at monitoring the formation of Cu nanoparticles. The precipitation threshold of Cu atoms is flux-dependent. At fluxes from 1 to 10 μA/cm 2 , the formation of nanoparticles is efficient up to fluences of 2 × 10 17 ions/cm 2 . The efficiency of IIPE of Cu + solutes in silica glass (band at 2.25 eV) is proportional to a total concentration of Cu solutes. In a single-phase region (solid solution of Cu atoms), the efficiency of IIPE of Cu + solutes is flux-independent. In a two-phase region (solid solution and Cu nanoparticles), the dynamic balance between the nanoparticles and Cu solutes determines the flux-dependent behavior of the efficiency of IIPE.

Silica glass was implanted with negative 60 keV Cu ions at an ion flux from 5 to 75 μA/cm2 up to a fluence of 1 × 1017 ions/cm2 at initial sample temperatures of 300, 573 and 773 K. Spectra of ion-induced photon emission (IIPE) were collected in situ in the range from 250 to 850 nm. Optical absorption spectra of implanted specimens were ex situ measured in the range from 190 to 2500 nm. IIPE spectra showed a broad band centered around 560 nm (2.2 eV) that was assigned to Cu+ solutes. The band appeared at the onset of irradiation, increased in intensity up to a fluence of about 5 × 1015 ions/cm2 and then gradually decreased indicating three stage of the ion beam synthesis of nanoclusters: accumulation of implants, nucleation and growth nanoclusters. The IIPE intensity normalized on the ion flux is independent on the ion flux below 20 μA/cm2 at higher fluences. The intensity of the band increased with increasing samples temperature, when optical absorption spectra reveal the increase of Cu nanoparticles size.

In the neutral beam injection (NBI) system, an extension of the pulse duration up to 30 sec has been intended to study quasi-steady state plasma on JT-60U. The four positive-ion based (P-NBI) units, which tangentially inject neutral beam to plasma, were mainly modified on the electric power supplies and the beam limiters to extend the pulse duration up to 30 sec with 2 MW at 80 keV per each. The seven P-NBI units, each of which perpendicularly injects for 10 sec, were conducted to operate in series for the total pulse duration of 30 sec. The ion source of the negative-ion based (N-NBI) unit, whose target beam energy is 500 keV for 10 sec, was also modified to reduce the heat load of the grid for long pulse operation. The reduction of the re-ionization of the neutral beam in the beam drift duct was a key to achieve a long pulse injection. It was found that the pressure rise in the beam drift duct, which gives the re-ionization rate, depended on the temperature of the re-ionization plates during NBI injection. Up to now, it was attained successfully that the pulse duration of the tangential P-NBI unit was extended up tomore » 30 sec. 310 MJ of the total integrated injection energy into JT-60U plasma was achieved, including the negative-ion based NBI operation for 17 sec at 366 keV.« less

Formation processes of nickel oxide (NiO) nanoparticles (NPs) in silica glass (SiO2) by implantation of 60 keV Ni− ions combined with thermal oxidation are studied using cross-sectional transmission electron microscopy (XTEM) and Rutherford backscattering spectrometry. In as-implanted state, Ni metallic NPs form within the surface layer of ∼80 nm thick. The mean depth 〈z〉 and the standard deviation 〈(Δz)2〉1/2 of Ni atom distribution determined by XTEM were 43 and 15 nm, respectively. After the oxidation at 800 °C for 1 h, 〈z〉 and 〈(Δz)2〉1/2 became 47 nm and 20 nm, respectively, i.e. the distribution was almost the same except a small diffusional shift to the deeper region. Mean volume of Ni- and NiO-NPs after heat treatments at 800 °C were 27 and 43 nm3, respectively. The larger mean volume of NiO-NPs is explained from the fact that NiO-NPs include both Ni and O atoms, i.e. approximately 2N atoms, while Ni-NPs include Ni atoms only, i.e. N atoms. Both the Ni- and NiO-NPs include 2.4 × 103 Ni atoms per NP in average. These results indicate that NiO-NPs are formed by oxidation of Ni-NPs without pronounced redistribution of Ni atoms.

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.

Magnetic nanoparticles are fabricated in silica glass (SiO2) using high-flux implantation of 60 keV negative nickel ions Ni−. Photo-absorption measurements and cross-sectional transmission electron microscopy (XTEM) observation confirm the formation of metallic Ni nanoparticles in SiO2, and exclude the possible formation of Ni silicides (Ni3Si, Ni2Si, NiSi) and oxides (NiO) as major products. The mean diameter of the nanoparticles was ∼2.9 nm, and the observed depth distribution was similar to a prediction from the TRIDYN code when sputtering was accounted for. Temperature- and field-dependences of magnetization show that the nanoparticles are in the superparamagnetic state at T>∼50 K. From the peak temperature of the zero-field cooling (ZFC) magnetization, which is ∼27 K, and the mean diameter determined from XTEM, it is suggested that the magnetic anisotropy constant K of the nanoparticles is enhanced by ∼8 times as compared to the bulk value.

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 .

Although ion implantation has a unique merit in fabricating immiscible metal–insulator composites being promising for non-linear optical applications, high-flux implantation especially is subject to pronounced atomic transports, either inside or outside the solid. Negative Cu ions of 60 keV irradiated substrates of a-SiO 2 and MgO · 2.4(Al 2 O 3 ) at fluxes up to 100 μA/cm 2 . Atomic redistribution of Cu nanoparticles inside the substrate was observed by cross-sectional TEM. Atomic release of Cu implants out of the substrate was detected by ion-induced photon spectroscopy, with fast-response CCD cameras. Spontaneous metal precipitation in insulators is attained at high flux. The ion-induced photon spectra of a-SiO 2 consist of sharp line spectra and a broad luminescence. The presence of line spectra demonstrated the outward transport into vacuum and loss of Cu atoms via the surface to the vacuum. Cations in MgO · 2.4(Al 2 O 3 ) are also significantly released to the vacuum via the surface. The outward mass transport results from ion-induced sputtering/sublimation of implants, concurrently with radiation-induced diffusion towards the surface.

This paper reports results on the progress in steady-state high-βp ELMy H-mode discharges in JT-60U. A fusion triple product, nD(0)τETi(0), of 3.1 × 1020 m−3 s keV under full non-inductive current drive has been achieved at Ip = 1.8 MA, which extends the record value of the fusion triple product under full non-inductive current drive by 50%. A high-beta plasma with βN ~ 2.7 has been sustained for 7.4 s (~60τE), with the duration determined only by the facility limits, such as the capability of the poloidal field coils and the upper limit on the duration of injection of neutral beams. Destabilization of neoclassical tearing modes (NTMs) has been avoided with good reproducibility by tailoring the current and pressure profiles. On the other hand, a real-time NTM stabilization system has been developed where detection of the centre of the magnetic island and optimization of the injection angle of the electron cyclotron wave are done in real time. By applying this system, a 3/2 NTM has been completely stabilized in a high-beta region (βp ~ 1.2, βN ~ 1.5), and the beta value and confinement enhancement factor have been improved by the stabilization.

The negative-ion based neutral beam injection system developed by JAERI for JT-60U has been intended to generate a 500 keV and 10 MW beam for 10 seconds with two ion sources. Technical efforts to d...

Two pilot facilities of advanced negative-ion-based neutral beam injection heating system have been working successfully on the JT-60U tokamak and the LHD heliotron in Japan. These were the first applications of negative-ion technology to the production of high current neutral beam for plasma heating as well as current drive. High energy deuterium beam of 400 keV (5.8 MW) was injected in JT-60U for efficient current drive, and high power hydrogen beam of 9.0 MW (160 keV) was injected in LHD producing high performance plasmas. These results demonstrate the feasibility of negative ion beam system for future fusion reactors such as ITER.

High energy accelerator and high current ion source development have been carried out at JAERI for negative-ion based neutral beam (N-NB) systems of JT-60U and ITER. One of R&D issues on the ITER prototype 5-staged electrostatic accelerator was voltage holding capability of the accelerator insulator column. By installing a stress ring, which reduces electric field concentration at the triple junction (interface of metal flange, insulator, and vacuum), 300 kV is held at each stage instead of rated voltage of 200 kV. At present the accelerator insulator column sustains 900 kV stably with the rings in all five stages. In the JT-60U N-NB system, a beamlet deflection by distorted electric field was found at the bottom of the extractor. Correcting the distorted field, reduction in beam divergence was confirmed for the overall beam. As the result, the heat load on the NB port limiter of JT-60U, located about 20 m away from the accelerator, was reduced to less than a half of the previous value before the correction. Consequently, we have succeeded in 10 s continuous injection of H 0 beam with the NB power of 2.6 MW at 355 keV.

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.

Amorphous (a-) SiO2 substrates were irradiated with 30 keV Au−, 60 keV Au− and Au2− ions up to total dose 1 × 1017 atoms/cm2. The growth of metal nanoparticles in the implanted layer was observed by cross-sectional transmission electron microscopy. Optical absorbance spectra of all implanted specimens exhibited a distinctive peak associated with a surface plasmon resonance of Au nanoparticles. The resonance energy and spectral shape of the absorbance spectra are similar in case of monoatomic and diatomic Au ion bombardment. The spectral similarity in the low-energy implanted samples reflects the importance of post-collision processes, such as diffusion and thermodynamic processes in metal nanoparticle formation.

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 ...

The positive-ion based neutral beam injection (NBI) system for JT-60, which consists of 14 beamline units and has a beam energy of 70 to 100 keV, started operation in 1986 with hydrogen beams and injected a neutral beam power of 27 MW at 75 keV into the JT-60 plasma. In 1991, the NBI system was modified to be able to handle deuterium beams as part of the JT-60 upgrade modification. After executing some research and developments, deuterium beams of 40 MW at 95 keV were injected in 1996. As a result, NBI has contributed to the achievement of the highest performance plasmas, a DT-equivalent fusion power gain of 1.25 and a fusion triple product of 1.55 x 10{sup 21} keVs/m{sup 3}, in the world on JT-60U.