By using a particle code including ionization and atomic processes, we investigated the ionization dynamics of carbon film irradiated by an intense laser pulse. We found two types of ionization dynamics, namely, a fast time scaleconvective propagation of the ionization front with C⁴⁺ triggered by induced plasma waves, and a slow front with C⁵⁺ and C⁶⁺ triggered by heated electrons due to non-local thermal conduction. Thus, ionization dynamics in solids werefound to evolve through multiple stages.

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A 300°C heat-resistant neutron shielding material was newly developed. The material consists of phenol-based resin with 5 weight-% boron. The neutron shielding performance of the developed resin, which was examined by usinga ²⁵²Cf neutron source, was almost identical to that of polyethylene. The resin can be applied to the port section of the vacuum vessel of the DD plasma device to suppress the streaming neutrons and to reduce the nuclear heating of thesuperconducting coils.

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A new gas jet-type Z-pinch EUV light source having double gas jet electrodes has been developed. It has two nozzles and two diffusers. A xenon Z-pinch plasma that emits EUV light is produced between the inner nozzle and the corresponding diffuser. A cylindrical shell consisting of a He gas curtain produced by the outer nozzle is specially designed for shielding the debris and suppressing the inner gas expansion. We have succeeded in generating EUV energy of 1.22 mJ/sr/pulse (2% in-band at 13.5 nm) and EUV emitting plasma of 0.07 mm FWHM diameter and 0.34 mm FWHM length by using this He gas curtain.

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A poloidally rotating radiation belt with helical structure was observed during the high density discharges with detachment by photodiode fan arrays and a fast camera in LHD. The peak of radiation rotates inside the last closed flux surface, and the direction and mode number of the poloidal rotation are electron diamagnetic and one, respectively. During the recombination phase after termination of the plasma heating, the rotation continues, and its rotating radius shrinks with shrinking of the plasma column. The poloidal rotating frequency depends on the heating power, and increases from the orders of several tens of Hz to several hundreds of Hz with shrinking of the rotation radius. The mechanism of the rotation remains uncertain.

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The plasma-enhanced chemical vapor deposition method, which has such benefits as low synthesis temperature and vertical alignment control, was successfully applied to the single-walled carbon nanotube (SWNT) formation stage. By means of plasma sheath effects, the individual SWNT with a freestanding form was grown on a silicon-based flat substrate surface. The detailed plasma effects are also discussed in order to achieve more precise control of the growth of the carbon nanotube.

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Inductively coupled plasma chemical vapor deposition combined with substrate biasing using a gas mixture of methane and hydrogen was applied to low-temperature synthesis of aligned carbon nanotubes and nanofibers. We found that the resultant carbon nanotubes, which were grown at 500°C, were aligned perpendicular to the substrate, and the aligned carbon nanofibers were synthesized even at a growth temperature as low as 200°C. The growth mechanism of the aligned carbon nanotubes and carbon nanofibers is discussed in terms of the moderate etching of carbon deposit by hydrogen species in inductively coupled plasma.

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It is very important to control the growth orientation of carbon nanotubes (CNTs) on substrates for applications such as field emission devices and CNT-based FETs. Although chemical vapor deposition (CVD) is the most reliable means to this end, there have been few reports on the synthesis of vertically aligned single-walled carbon nanotubes (SWNTs) using the CVD method. In this study, we demonstrate the low temperature synthesis of extremelydense and vertically aligned SWNTs deposited by point-arc microwave plasma CVD.

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Carbon nanowalls, self-assembled two-dimensional carbon nanostructures standing vertically on the substrate, were fabricated using capacitively coupled, radio-frequency, fluorocarbon plasma-enhanced chemical vapor deposition assisted by H radical injection. The correlation between carbon nanowall growth and the fabrication conditions was investigated. The morphologies and growth rate of carbon nanowalls were dependent on the types of carbon source gases and the amount of H radicals injected. In addition, straight, aligned carbon nanowalls with regular spacing were fabricated by controlling the radical flow configuration.

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The effect of negative direct-current bias on vertically aligned growth of carbon nanotubes by plasma-enhanced chemical vapor deposition is investigated. The experimental results showed that negative direct-current bias to a substrate enhanced the aligned growth of carbon nanotubes, due to the electrostatic attraction of the negatively charged tips of the carbon nanotubes toward the plasma in the strong sheath electric field. It was also shown that the accelerated positive ions in the strong sheath electric field affected the suppression of growth of catalytic metal particles by sputtering, thereby contributing to the formation of carbon nanotubes.

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Basic concepts of Vlasov (or Eulerian) simulation methods for the plasma microturbulence are reviewed in focus on the symplectic properties of the collisionless kinetice quations. Importance of the phase mixing is emphasized not only in kinetic simulations of turbulent transport but also in construction of fluid closure models. The state of the art of the gyrokinetic simulation codes based on the Eulerian approaches is also introduced.

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Prospects of the microturbulence simulation study for the magnetic confinement fusion are described forclosing the Lecture Note. Key issues in constructing a global simulation model of the turbulent transport as well as subjects relating to multi-scale and multi-physics problems are discussed.

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Low-energy and high-flux plasma exposures on tungsten surfaces result in blister/hole formation. Subsequent He plasma exposure at 2,000 K on the blister-rich surface forms a hole structure on the surface, including the blister surface, and some blisters collapse due to recrystallization and bubble formation on the blister skin. Grain ejections were observed after deuterium plasma exposure at 550 K on a W surface on which a hole structure had formed due to He pre-exposure at 1,600 K.

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The D_α spectral lines emitted from the neutral beam colliding with residual D₂ in a beam chamber were observed. The Doppler shifts of these D_α spectral lines indicate that the neutral beam includes deuterium atoms with energies of E, E/2, E/3 and E/9 ˜ E/11 (E : beamaccelerationenergy), which originate from D⁺, D⁺₂, D⁺₃ and D_iO⁺ (i=1,2,3), respectively. From the intensity ratio of the D_α spectral lines, the fraction of oxygen atoms to deuterium atoms was determined by the analysis on atomic and molecular processes in the neutralizer for the neutral beam. The neutral beam has been found to contain more than 8% of oxygen atoms over deuterium when the neutral beam injection starts. About 50% of the oxygen ions in the core plasma originate from the neutral beam. The oxygen content in the neutral beam decreases gradulally with its injection, and it reaches ˜ 1% around 850 injections. At this time, the fraction of the oxygen ions in the core plasma originating from the neutral beam is less than 20%. In L-mode plasmas, the confinement time of the oxygen ions originating from the neutral beam is estimated to be 0.5 s, and is longer than that of the deuterium ions ( 0.3 s ).

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We propose a new application of information technology to recognize and extract expressions of atomic and molecular states from electrical forms of scientific abstracts. Present results will help scientists to understand atomic states as well as the physics discussed in the articles. Combining with the internet search engines, it will make one possible to collect not only atomic and molecular data but broader scientific information over a wide range of research fields.

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