This paper describes the photon stimulated desorption (PSD) apparatus using a laser plasma light source which we have developed, and the results of PSD experiments on rare gas solids. In order to reveal the mechanism of the desorption from two-component systems, we have investigated PSD of metastable atoms from Ne solid films on which 0.2-200 Ar layers were deposited. We have found that both the desorption yield and the kinetic energy of desorbed Ne metastables strongly depend on an Ar thickness. These results suggest that the deposition of Ar atoms leads to the formation of Ar-Ne mixed layers and the change in the cohesive energy of the sample solids.

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  The angular distribution of molecules emitted from rotating disks with a small gap was simulated using the Monte Carlo method. As the molecules have a circumferential velocity rω (r: distance from the rotating axis and ω: angular velocity), when they leave the surfaces of the rotating disks, they tend to be emitted toward the tangent lines of the rims of the disks. When the disks rotate with a velocity ratio η≡r₁/<v> (r₁: radius of the disk and <v>: mean velocity of the molecules) of 3.8, three quarters of the outgoing molecules gather within an angle of 0.4 radians from the tangent line. The angular distribution is related to the altitude almost independent of the revolution frequency with a value of η less than 2, where the rotating vector is specified to be oriented to zenith.

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  In this study, deuterium retention properties of SiC/SiC composites irradiated by deuterium ions at different temperatures in the range from 293 K to 923 K were investigated with thermal desorption spectroscopy, and the relationship between deuterium retention and the change of atomic composition was examined. Thermal desorption spectra of D₂ showed two major peaks which was regarded as deuterium released from its Si-D and C-D bonds, respectively. At the irradiation temperature of 673 K, the ratio of the amounts of desorbed D₂ at lower desorption peak (Si-D bond) increased compared to the room temperature case, owing to the decrease in carbon composition at the surface. On the other hand, at the irradiation temperatures at 823 and 923 K, the ratio of the amounts of desorbed D₂ at higher desorption peak (C-D bond) increased, and the hydrocarbon desorption also increased. The present data suggests that the fuel hydrogen retention properties of SiC/SiC composites are significantly affected by the surface temperature.

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  A novel quartz oscillator that has a temperature-stable output was investigated for outdoor hydrogen sensing. The output from the quartz oscillator remained almost constant for temperatures in the range of 15 to 50℃. Fluctuations of the output of the quartz oscillator in this temperature range were 0.3% at constant relative humidity of 0%RH, which corresponds to the change in the output when 0.3 vol% of hydrogen leaked in air. This change is thus sufficiently lower than the necessary minimum detection level of 1 vol% hydrogen concentration using the novel quartz oscillator's output during outdoor hydrogen sensing.

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  Measurements of silane concentration using a quartz friction pressure gauge (Q-gauge) in gas mixtures of hydrogen and silane were applied to the region of low pressure and low silane concentration. The measured conditions of pressures below 100 Pa and silane concentrations below 10 vol% are important because they are usually used for microcrystalline silicon film deposition in production of thin silicon solar cells. Output from the Q-gauge depended on silane concentration of 1-100 vol% in the gas mixtures at a constant pressure of 13 Pa and on silane concentrations of 1, 2, 3, 5, and 7 vol% in the gas mixtures at 13-1333 Pa. Present partial concentration measurement using the Q-gauge was shown to be applicable to gas mixtures of silane and hydrogen even at low pressures and low silane concentrations.

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