With the objective of reducing the power consumption of radio frequency (RF) plasma cathodes, the effect of external magnetic field on electron emission performance of a RF plasma cathode was experimentally evaluated. In the operating range of magnetic flux density from 0 mT to 8 mT, the maximum anode current emitted from the RF plasma cathode does not depend on the magnetic field strength. In contrast, the anode voltage at which the anode current is maximized is strongly affected by the magnetic field strength. Because the plasma brightness between the orifice and the anode increases as the strength of the magnetic field increases, we consider that the change of the resistance in the plasma bridge is the reason for the reduction of the anode voltage. The electron production cost was reduced from 89 W/A to 77 W/A when the coil current for forming the external magnetic field was varied from 0 A to 0.2 A. As a result, the external magnetic field improves the power consumption for the electron extraction.

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In order to develop a dye-sensitized solar cell (DSSC) manufacturing process using low power atmospheric plasma spray (APS), porous TiO2 film deposition was performed by the developed low power APS equipment. Consequently, the porosity and Anatase/ rutile ratio of the TiO2 film increased with increasing spray distance. The DSSC included the deposited film as photo voltaic device generated higher open circuit voltage with increasing the spray distance: d. The open circuit voltage of the DSSC with the porosity of 26.5% was 241 mV at d= 220 mm. Besides, the DSSC included the porous TiO2 film of 18% porosity using NaCl powder addition of the feedstock TiO2, generated high open circuit voltage of 105 mV in comparison with that in case of pure TiO2 feed stock powder deposited at d= 100 mm. From these results, these techniques were proved to have high potential for deposition of porous TiO2 film for the photo voltaic device of the DSSC.

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Surface modification methods of dental implant materials have been conducted to increase affinity between implant materials and surrounding tissues. Our previous experiment on surface treatments of titanium (Ti) showed that a blasted surface had better cell adhesion and proliferation than polished or machined surfaces. In this study, the cell adhesion and proliferation on the substrate were studied for the different roughness of blasted Ti surface. Different roughness and shape were prepared by changing the size and amount of blasting particles. Analysis of the surface by a roughness tester and a scanning electron microscope showed that the surface roughness depended on the size of blasting particles, but not on the amount of particles. An increase in number of cultured cells was observed on the Ti surface with the smaller roughness. Besides, it was found that the number of cultured cells reduced with increasing the amount of blasting particles, because residual steel particles arising from blasting deteriorated the cell adhesion ability of Ti surface.

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Sterilization effect of Staphylococcus epidermidis on agar using dielectric barrier discharge (DBD) was evaluated. S. epidermidis was used as a specimen. The DBD reactor consisted of a glass plate and an aluminum foil. AC high-voltage with frequency of 1.2 kHz generated using a transformer driven by MOS-FETs and was applied to the aluminum foil. The reactor was put above the agar medium to generate the plasmas between the glass plate and the agar medium. To prevent current flow to the specimen, a metal mesh was set on the surface of the glass plate. The number of colony forming units (CFU) of S. epidermidis decreased with increasing input energy into the plasmas. The number of CFU decreased and ozone yield increased with increasing the number of wires of the metal mesh. On the other hands, energy efficiency for production of hydrogen peroxide in the purified water decreased with increasing the wire number of meshes. These results indicated that ozone produced by the discharges mainly contributed to the sterilization of S. epidermidis.

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A 200 W class Hall thruster has been developed for the small satellites main propulsion. In order to overcome the degradation owing to the miniaturization, it has a unique magnetic field configuration, similar to “magnetic shielding”. The thrust performance was measured using a pendulum thrust stand. The thrust, thrust to power ratio, thrust efficiency is achieved to 13.1 mN,56 mN/kW and 0.36, respectively at discharge voltage of 300 V, xenon mass flow rate of 1.0 mg/s. The obtained thrust performance is comparable to the other 200 W class thruster.

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Alumina was reduced using Nd:YAG laser ablation and generated aluminum was collected using cupper plate. The collected aluminum mass was estimated by volume of hydrogen gas evaporated in hydrochloric acid titration. Then, the energy conversion efficiency was calculated as the ratio of injected laser energy to that stocked in the collected aluminum. The efficiency was investigated as functions of the laser irradiation time, peak power and ambient pressure. For the irradiation time variation, the efficiency decreased after having taken a constant value for 500 sec. For the peak power variation, the efficiency became maximum as 25 % at 4.0 MW and decreased at 10 MW. For the pressure variation, the efficiency significantly decreased at 670 Pa though it was almost constant from the pressure of 1.3 Pa to 130 Pa.

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