[en] Laser spectroscopy has been developed to investigate the temporal and spatial behaviours of hydrogen and impurity atoms in fusion plasma. Among various schemes, tunable lasers were developed. The importance of the development of tunable VUV laser sources is based on the fact that the resonance-wavelengths of such hight-elements as hydrogen, carbon and oxygen are all in this range of wavelength. The frequency conversion method of tunable dye laser light by the third harmonic generation or two-photon resonance four-wave-sum-mixing in gaseous media was adopted. The maximum output was about 30 W in Kr/Ar mixture. The velocity distribution function of metal atoms and light elements was measured shot-by-shot by varying the spectrally narrowed pulse laser source. A fast-frequency-scan dye laser with the duration of the laser emission of 5 microsecond has been constructed. The system was applied to the measurement of the velocity distribution function of iron atoms sputtered by iron beam. The result was satisfactory. The system was applied for the studies of particle behaviour in various plasma, such as in linear machines like RFC-XX-M at the Institute for Plasma Physics, Nagoya University. A marked decrease of neutral hydrogen at the center of plasma in RFC-XX-M was for the first time confirmed in linear machines. The capability of measuring the density and velocity distribution functions of species, in situ, is fully exploited. (Kato, T.)

No abstract available

[en] In order to assist in understanding the particle and energy confinements in the RFC-XX-M axisymmetric mirror-cusp system, plasma wave and turbulence were measured using the Fraunhofer-diffraction method. In this method, fluctuations for whose wave-numbers SMM lasers would be required in a conventional scattering can be measured using a CO/sub 2/ laser, and the absolute fluctuation-intensity is directly obtainable by a simple comparison of the intensity of a diffracted signal with that of a carrier wave. Plasmas were produced by an ECH breakdown upon puffed gases and heated by an ICRF using the Nagoya type III antenna. Typical plasma in the central mirror section was with T/sub e/ ≅25 eV, T/sub i/ ≤500eV and n/sub e/ ≅6x10/sup 18/ m/sup -3/. Energy confinement time was typically a few hundred μs. The wave measurements were performed at the central section using a cw CO/sub 2/ laser with an output power of 3 W. The beam- waist was adjusted at w/sub o/= 2 mm and the Fraunhofer profiles at the front local plane of the collecting lens were measured on a shot-to-shot basis by traversing a HgCdTe detector. The detector outputs were first passed through a preamplifier and were then AD converted to be stored on a floppy disk. The data were later FFT-analyzed by a micro-computer to yield spectral information. The spatial intensity distribution at each ω gives a wave-number k, thus enabling to obtain wave-dispersion relations

[en] Laser Thomson scattering was applied to plasma diagnostics almost as soon as laser was invented in 1960. Extensive developments of the technique have been made to meet various measurement requirements, not only in high-temperature plasmas but in plasmas for industrial applications. In this article, these developments are briefly reviewed, followed by the work of the author and its implications for understanding various plasma phenomena

[en] Sizes and densities of nano catalysts for carbon nanotube synthesis, formed by the plasma breaking method of thin Fe films deposited using pulse laser deposition (PLD) were controlled by the changes of operating parameters. At the best optimum condition, nano catalysts with a density of 1.9x10¹⁵ m^-2 and a diameter of about 15 nm were obtained. Carbon nanotubes (CNTs) synthesized on these catalysts were shown to have almost the same size and density as those of the catalysts

[en] Iron thin films deposited by pulse laser deposition (PLD) were broken into uniform nano-sized catalysts by plasma bombardment for carbon nanotube (CNT) synthesis. Size distributions of broken catalysts were obtained in terms of plasma discharge conditions. Vertically arranged high-density (10¹³ per m²) CNTs were synthesized using microwave plasma chemical vapor deposition (MP-CVD) system and the gas mixture of N₂ and CH₄ on optimally broken catalysts with few carbonaceous particles on a large area Si substrate. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy (RS) were used to evaluate the obtained CNTs

[en] Understanding plasmas for materials processing requires information on many quantities characterizing the plasmas, starting from charged particle density and temperature, to constituent gas compositions, and electric and magnetic fields. In this contribution, the authors first outline the various methods which are available or are now being developed for these measurements, and then show results from their own experiments in which laser-aided plasma diagnostics are extensively used. (orig.)

[en] The systematic efforts at Kyushu University are described from the necessary laser developments to actual particle measurements for laser fluorescence spectroscopy measurements of plasma-surface interactions necessary in controlled fusion research or in glow-discharge characterization. (author)

[en] The angular distribution of sputtered atoms for normal incidence ions has been investigated theoretically and by computer simulation. For low energy ions the angular distribution is under-cosine, while for relatively high energy ions we obtain an over-cosine angular distribution for the sputtered atoms. It is found that the outward-peakness of the angular distribution for relatively high energy ions is due to the geometrical asymmetry near the surface. Using the Monte Carlo simulation code ACAT, which is based on the binary collision approximation, the angular distributions of sputtered atoms are calculated for various incident energies of Ar ions incident normally on a Fe target. It is found that one needs to take into account the surface roughness in order to obtain good agreement with experiment. The surface roughness is believed to reduce the degree of the over-cosine distribution because a rough surface has a larger effective surface area as compared with an unirradiated surface. (orig.)

[en] An experiment is described in which the emission from a tokamak plasma in the region of the electron cyclotron frequency and its low harmonics (up to the sixth) is measured. The results are compared with the predictions of the theory of cyclotron emission