田原 弘一

同軸テフロン放電室パルスプラズマエンジンの性能特性の取得。(担当部分：作動実験、取りまとめ)

ホール型イオンエンジンの推力特性とプラズマ加速過程の研究。

直流アークジェットエンジンの噴射プラズマ流の研究。

材料窒化用超音速窒素水素混合ガスプラズマの噴流特性の研究。(担当部分：作動実験、取りまとめ)

Thermal plasma CVD is hoped to be made fit for practical use because this process is the process which can fabricate precisely structure and component controlled coatings. Especially, TPCVD will be used in the industrial fields where thermal spraying has been used so far since TPCVD come to be studied under an atmospheric environment recently. However, TPCVD coatings fabricated under an atmospheric environment is porous and brittle. So that, TPCVD has been mostly carried out under a low pressure environment and high equipment cost has been demanded. As for the method to solve this problem, according to the report on a gas-deposition process, improvement of the jet flow is thought to be useful. Therefore, in this study, in order to obtain dense and rigid film by TPCVD under an atmospheric environment, Dense oxide coating deposition by High velocity TPCVD utilizing boiling of metal alcoxide was carried out. Consequently, though only brittle coating was deposited on the condition without boiling of metal alcoxide, dense and rigid coating was deposited even under an atmospheric environment on the condition with boiling. From this result, TPCVD was found to have high potential for rapid deposition of dense and rigid coatings.

Spectroscopic and electrostatic probe measurements were made to examine plasma characteristics under nitriding for a 10-kW-class direct-current arc plasma jet generator with a supersonic expansion nozzle in a low pressure environment. Heat fluxes into the plate from the plasma were also evaluated. Ammonia and mixtures of nitrogen and hydrogen were used as the working gas. The H-atom electronic excitation temperature and the N-2 molecule-rotational excitation temperature intensively decreased downstream in the nozzle although the NE molecule-rotational excitation temperature did not show an axial decrease. As approaching the titanium plate, the thermodynamical nonequilibrium plasma came to be a temperature-equilibrium one. Both the electron number density near the plate and the heat flux increased with H-2 mole fraction for mixtures gases. In cases with mixtures of N-2 and H-2, a radical of NH with a radially Aide distribution is considered to contribute to the better nitriding as a chemically active and non heating process.

In magneto-plasma-dynamic (MPD) arcjet generators, plasma is accelerated by electromagnetic body forces. The MPD arcjet generator can produce higher-velocity, higher-temperature, higher-density and larger-area plasmas than those of conventional thermal plasma torches. Two types of MPD arcjet generator were developed for applications to ceramic spray coatings. One generator was installed with a cathode covered with mullite or zirconia ceramics and the other with a titanium cathode. The former was operated with Ar for mullite or zirconia coating by an ablation process of the cathode cover and the latter with N-2 for titanium nitride coating by a reactive process between ablated titanium particles and nitrogen plasma. The MPD spray process could successfully form dense, uniform and hard ceramic coatings. In titanium nitride reactive spraying, plasma diagnostic measurement and flowfield analysis were also carried out. A large amount of N and N+ was expected to be exhausted with a high velocity from the MPD generator. Both the electron temperature and the electron number density were kept high at a substrate position compared with those for conventional low-pressure thermal sprayings. A chemically active plasma with excited particles of N+, Ti, Ti+ and Ti2+ was expected to contribute to better titanium nitride coatings. All coating characteristics showed that the MPD arcjet generators had high potentials for ceramic spray coatings.

Spectroscopic and electrostatic probe measurements were made to examine plasma characteristics with or without a titanium plate under nitriding for a 10-kW-class. direct-current arc plasma jet generator with a supersonic expansion nozzle in a low-pressure environment. Heat fluxes into the plate from the plasma were also evaluated with a Nickel slug and thermocouple arrangement. Ammonia and mixtures of nitrogen and hydrogen were used as a working gas. The NH3 and N-2+3H(2) plasmas in the nozzle and in the downstream plume without a substrate plate were in thermodynamical nonequilibrium states.. As a result, the H-atom electronic excitation temperature And the N-2 molecule-rotational excitation temperature intensively decreased downstream in the nozzle although the NH molecule-rotational excitation temperature did not show an axial decrease. Each temperature was kept in a small range, in the plume without a substrate plate except,for the NH rotational temperature for NH3 working gas. On the other hand, as approaching the titanium plate, the thermodynamical, nonequilibrium plasma came to be a temperature-equilibrium one because the plasma flow tended to stagnate in front of the plate. The electron temperature had a small radial variation near the plate., Both the electron number density and the heat flux decreased radially outward, and an increase in H-2, Mole fraction raised them at a constant radial position. In cases with NH3 and N-2+3H(2), a radical of NH with a radially wide, distribution was considered to contribute to the better nitriding as a chemically active and non heating process.

マサチューセッツ工科大学（米国）との共同研究として、ホール型イオンエンジンの流れ場の準一次元流体解析が行われた。全体の質量・運動量・エネルギー保存式のほか、電子の運動量保存式とエネルギー保存式が使用された。また熱平衡の電離反応、放電室壁面上の質量・運動量・エネルギー損失の条件が考慮された。計算された結果は実験結果と定性的に一致し、内部の放電状態を十分模擬することができた。（担当部分：主な数値計算）

ホール型イオン推進機の流れ場の準一次元流体解析が行われた。既存のホール推進機と同じ形状と作動条件のもと計算が実行された。計算された推進性能は、放電電流は実験値とほぼ一致したが、推力は異なり、今後は計算モデルの改良が必要である。２次元粒子モデルによる計算コードの開発が提案、議論された。（担当部分：主な数値計算）

超音速プラズマジェットの下流に平板が配置され、その直前のプラズマ状態と平板に流入する熱流束が研究された。作動ガスとしてアンモニアガスと窒素・水素混合ガスが用いられた。平板の有無によって、平板設置位置でのプラズマ状態は大きく異なり、平板がある場合その近傍直前で各種の温度は近づいてくる（緩和方向に向かう）。また熱流束はタンク内圧の影響が大きいが、水素原子、水素を含む活性種の衝突効果も無視できないと推測された。（担当部分：主な実験研究）

基材表面洗浄機能を有する大気熱プラズマＣＶＤ装置の開発を目的として、基材を陽極とした移行性アークを用いた基材へのプラズマ照射、および基材設置型陽極を用いた非移行性アークを用いた基材へのプラズマ照射を行った。その結果、基材設置型陽極を用いた場合基材の表面を溶融させることなく、スパッタリングによる洗浄効果が確認できた。（担当部分：実験研究、全体の取りまとめ）

低電力ホール型イオンエンジンの磁場と加速チャネル最適化の研究。(担当部分：作動実験、取りまとめ)

ホール型イオンエンジン流れ場の簡易１次元計算。(担当部分：数値計算、取りまとめ)

材料加工用電磁プラズマ加速アークジェットのプラズマ特性の研究。(担当部分：作動実験、取りまとめ)

電磁加速プラズマエンジンの外部磁気ノズルの効果に関する研究。(担当部分：作動実験、取りまとめ)

シリンドリカル型ホールイオンエンジンの作動特性の取得。(担当部分：作動実験、取りまとめ)

荷電粒子衝突による宇宙用高分子材料の劣化現象とその帯電・放電現象に関する研究

ホール型イオンエンジンの性能と噴出流に与える磁場の影響の研究。(担当部分：作動実験、取りまとめ)

円形断面ホール型イオンエンジンの作動特性と性能に関する研究。(担当部分：作動実験、取りまとめ)

ベアテザー衛星による電子捕集の特性に関する研究。(担当部分：作動実験、取りまとめ)

中空陰極を備えた宇宙飛翔体プラズマ接触器の研究開発。(担当部分：作動実験、取りまとめ)

宇宙プラズマ環境下における宇宙飛翔体アーキング現象の研究。(担当部分：作動実験、取りまとめ)

周辺プラズマ環境下における宇宙飛翔体アーキング現象の研究。(担当部分：作動実験、取りまとめ)

超音速アンモニア・窒素水素混合ガスプラズマジェットの速度測定。(担当部分：作動実験、取りまとめ)

Spectroscopic and electrostatic probe measurements were made to examine plasma exhaust plume characteristics with or without a titanium plate under nitriding for a 10-kW-class direct-current arc plasma jet generator with a supersonic expansion nozzle under a low-pressure environment. Ammonia and a mixture of nitrogen and hydrogen were used as the working gas. The NH3 and N2+3H2 plasmas in the nozzle and in the downstream plume without substrate plates were in thermodynamic nonequilibrium states. As a result, the H-atom electronic excitation temperature and the N2 molecule-rotational excitation temperature intensively decreased downstream in the nozzle although the NH molecule-rotational excitation temperature did not show an axial decrease. On the other hand, each temperature was kept in a small range in the plume without a substrate plate under 130 Pa except for the NH rotational temperature for NH3 working gas, although with a titanium plate the nonequilibrium plasma tended to have an equilibrium temperature as it approached the plate. © 2002 Elsevier Science Ltd. All rights reserved.

The closed-electron-drift Hall-effect accelerator is a promising thruster in space. The effects of magnetic field shape and strength on Hall thruster performance were studied using 1-kW-class THT-series Hall thrusters. The discharge current characteristics were sensitive to magnetic field shape and strength. The thrust for the THT-IIIA thruster with more intensive concentration of magnetic field near the acceleration channel exit, i.e., with a smaller magnetic field at the anode was slightly higher than that for the THT-III thruster. The THT-IIIA thruster could be stably operated at a higher magnetic field strength than that for the THT-III thruster. As a result, for the THT-IIIA thruster, a higher thrust efficiency was achieved with a lower discharge current and a higher thrust. Furthermore, Hall thruster flowfield analysis was made to understand inner physical phenomena. Both ionization and acceleration were found to efficiently occur in a thin region with a few mm thick near the acceleration channel exit. The calculated thruster performance roughly agreed with the experimental ones. © 2002 Elsevier Science Ltd. All rights reserved.

For the purpose of developing a rapid direct nitriding process to produce aluminum nitride layer without melting or vaporizing of aluminum during operation, nitridings of aluminum and aluminum alloy by using supersonic expanding nitrogen plasma jets were carried out. Nitride layer could not be formed on the substrate in the case of nitrogen gas, though the supersonic expanding plasma jets had enough reactivity to form rapidly titanium nitride layer on the surface of the substrate. Many fibers were formed on the substrate in the case of hydrogen/nitrogen mixture gas. However, the fibers could not be confirmed as aluminum nitride and the surface of the substrate came to be rough during operation in this case. Since the same phenomenon occurred in the case of hydrogen/argon mixture working gas, it was thought that the roughness of the substrate during operation was due to hydrogen infiltration into the substrate. In the case of nitriding of aluminum-magnesium alloy, unlike the case of aluminum substrate use, nitride layer was formed on the substrate even on the condition that pure nitrogen was used as working gas. From these results, this process was found to have a high potential for nitriding to produce aluminum nitride. © 2002 Elsevier Science Ltd. All rights reserved.

プラズマジェットの基板近傍プラズマ特性と熱流束特性の関係研究。(担当部分：作動実験、取りまとめ)

宇宙プラズマの中を飛翔する宇宙飛翔体から強制的に電子を放出する機器として、ホローカソードの基礎作動特性が取得された。電子サイクロトロン共鳴プラズマを用いた宇宙プラズマシミュレータの中で、ホローカソードが運転された。ホローカソード単体で作動する場合（ホローカソード周りに模擬宇宙プラズマ無し）に比べて、模擬宇宙プラズマ中で作動させると、放出電子電流が大きく増加し周辺プラズマの寄与が非常に大きいことがわかった。（担当部分：主な実験研究）

宇宙プラズマの中を飛翔する宇宙飛翔体から強制的に電子を収集する機器として、導電性の「ひも」（テザー）が有望視されている。本研究では、電子サイクロトロン共鳴プラズマを用いた宇宙プラズマシミュレータの中で、導電性テザーの作動特性が調べられた。導電性テザーの長さ・直径、さらに印加電圧を広範に変化させ、収集される電流を測定した。その結果、テザーのサイズに収集電流は大きく依存したが、無衝突プラズマ理論から導き出される理論最大電流を越えることはなかった。（担当部分：主な実験研究）

Mo溶射皮膜の耐摩耗性を向上させるために、燃焼火炎ＣＶＤ法による合成ダイヤモンドとの複合化が研究された。複合化条件を変え成形後、摩耗特性試験を行った結果、ダイヤモンド粒子の混入により耐摩耗性が著しく向上することがわかった。（担当部分：主な実験研究）

電磁プラズマエンジンにおける電力配分特性の外部磁場の影響調査。(担当部分：作動実験、取りまとめ)

低電力ホール型イオンエンジンシステムの開発研究。(担当部分：作動実験、取りまとめ)

プラズマ放出による宇宙飛翔体帯電の緩和現象の地上模擬実験。(担当部分：作動実験、取りまとめ)

ホール型イオンエンジンの１次元流れ場の数値計算。(担当部分：数値計算、取りまとめ)

10kW級直流アークジェットエンジンのプラズマ特性の取得。(担当部分：作動実験、取りまとめ)