For the purpose of aerospace applications of light materials, functional metal coatings such as Cu, Ni and Ti were formed on plastic substrates by using a gas tunnel type plasma spraying. Metal coatings with more than 100 um in thickness were successfully deposited on PET surfaces by the gas tunnel type plasma spraying under selective operating conditions using a power of 10 kW or less. The microstructure and mechanical properties of these high functional coatings were clarified under various conditions. Also, a small power of 3kW gas tunnel type plasma spraying apparatus was developed by improving the plasma torch design, and it was applied to plasma spraying of Cu metal materials. As a result, good quality Cu coatings of 50-100 um in thickness were obtained on the plastic substrate, with almost no oxidation of Cu under the small power operating condition.

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Regarding the CO2-O2 mixture gas (20% O2) as the arc quenching gas in a high-voltage circuit breaker, the predominant component species with high number fractions at temperatures of 300- 20,000 K are determined in consideration of the admixture of the vapor ablated from PTFE (polytetrafluoroethylene) nozzles. In the evaluation, not only 48 gaseous species but also the carbon atom in solid phase (graphite) are taken into account as component species. The evaluation results reveal that C, O, C+, O+, F, F+, CO, COF2 and CO2 in gaseous phase behave as the predominant component species at temperatures above 2,000 K, while not only CO2, O2 and CF4 in gaseous phase but also C in solid phase behaves as the predominant component species at temperatures of 2,000 K or lower. In addition to O2 and CF4 number fractions, the number fraction of C in solid phase also manifests very pronounced dependence on the PTFE vapor concentration. The same evaluations are made for CO2 gas to reveal the effect of O2 addition on the predominant component species, especially on less production of graphite.

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A miniature microwave discharge plasma thruster for microsatellites is under development, with the target power consumption, thrust and specific impulse of 10 W, 1 mN and 1000 s, respectively. We developed the numerical code using Finite Difference Time Domain method and Particle in Cell method to analyze the electron heating by microwave. In this study we analyzed the dependence of the electron heating on the antenna configuration. Results showed the ratio of ECR heating to the heating near the antenna is under 1 %, this means that the ECR heating is not effective in the current thruster configuration. The average absorption power of the super particle with L shape antenna, large disk antenna and small disk antenna are 5.2x10^19 J/timestep 8.2x10^19 J/timestep and 6.6x10^19 J/timestep respectively. These results don’t correspond to the tendency of the experimental results. We have to discuss about the antenna configuration including the plasma exhaust.

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In this study, development of a laser-electrostatic hybrid acceleration thruster was conducted, which is a combination of a laser propulsion system and an electrostatic propulsion system. Since this system can additionally accelerate ions by accelerating laser-ablation plasma by an external electrostatic field, highspeed ions can be generated. In this study, to obtain spatial and temporal plasma parameters for the optimum acceleration, Langmuir probe measurement of laser-ablation plasmas was firstly conducted, where focused Nd:YAG laser pulses were irradiated on a copper target in a vacuum chamber. Temporal changes of spatial distributions of the plasma parameters were obtained. As the results, the maximum electron temperatures varied from 6.4 eV to 1.5 eV at probe positions at 150 mm and 170 mm respectively.

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Alumina reduction by laser ablation has been tested using a kW-class continuous-wave CO2 laser. The laser beam was focused on a sintered alumina rod and laser ablation occurred on the rod surface in a test chamber with argon ambient gas. The laser intensity was changed from 0.36 GW/m^2 to 1.8 GW/m^2 at the ambient pressure of 30 kPa to 150 kPa. A copper plate was set in front of the alumina rod to collect ablation products. As a result, white and black substances were adhered to the plate. By quantitative analysis using EDX (energy dispersive X-ray spectroscopy), mole fraction (Al:O) of these substances were found 2:2.8 and 2:2.3, respectively. These data suggest that these substances are alumina and oxygen-deficient alumina, respectively. Herewith, it was certified that reduction reaction occurs by laser ablation and phenomena in the ablation plume was estimated.

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Emission spectroscopy is a unique method for accurately determining the total enthalpy of arc wind tunnels. However, the method can be applied to only the thermochemical equilibrium region. Because arc flows are generally rarefied, the applicable flows are very restricted. To remove this restriction, we propose a new approach in which an magnetohydrodynamic shock layer enlargement is used to produce the thermochemical equilibrium region in rarefied arc flows. This study designs a magnet-mountable water cooling probe, and conducted the preliminary heating test of the nonmagnetized probe and emission spectroscopy from the shock layer using the ISAS arc wind tunnel. As a result, the probe had no damage despite the long heating time of 60 sec and strong heating rate of 3.6 MW/m^2. The temperature of the probe inside was under 31 °C. Therefore, the probe was found to be reusable and to be free from the thermal demagnetization. Moreover, the emission spectra show that the shock layer in front of the non-magnetized probe is in thermal non-equilibrium.

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