研究者詳細 - 杵淵　紀世志

Additive-manufactured single-piece thin multi-layer tungsten heater for an electrothermal thruster 査読有り

Kinefuchi K., Nakata D., Coral G., Suyalatu , Sakai H., Tsukizaki R., Nishiyama K.

Review of Scientific Instruments 92 巻 ( 11 ) 頁： 114501 2021年11月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Review of Scientific Instruments

In this study, a novel single-piece thin multi-layer tungsten resistive heater was successfully fabricated using additive manufacturing and tested as an electrothermal thruster. The heater has 12 resistive layers, with each layer having a thickness and height of 0.15 and 81 mm, respectively, and can provide high heating efficiency. A single-piece or monolithic heater was manufactured via additive manufacturing technique, which drastically improved its reliability and decreased its manufacturing cost. In the heating and thrust measurement tests that used nitrogen gas as a propellant, the heater reached a gas temperature of ∼2000 K at a 140-A heater current without experiencing any failure. The tungsten-heater resistance linearly increased with an increase in temperature due to the temperature dependence of tungsten's resistivity. The specific impulse and thrust increased with the heater temperature in accordance with the theoretical prediction. Even including a voltage drop due to a contact resistance, the achieved heater efficiency reached 63% at a 100-A heater current even without a thermal insulation around the thruster. The heater efficiency decreased with an increase in the heater temperature due to heat loss to the surroundings. The heat-loss analysis indicated that both thermal conduction and radiation heat losses were crucial for improving the heater performance at a high-temperature operation of over 2000 K.

DOI： 10.1063/5.0068926

Thrust density enhancement in an electrostatic–magnetic hybrid thruster 査読有り

Ichihara D., Oka K., Higo A., Nakamura Y., Kinefuchi K., Sasoh A.

Journal of Propulsion and Power 37 巻 ( 6 ) 頁： 973 - 976 2021年11月

Thermal Design and Experimental Verification of a Three-Dimensional-Printed Resistojet 査読有り

Nakata Daisuke, Kinefuchi Kiyoshi, Sakai Hitoshi, Suyalatu

JOURNAL OF PROPULSION AND POWER 38 巻 ( 1 ) 頁： 1 - 9 2021年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Propulsion and Power

A high-efficiency concentric tubular-type resistojet with potential application to short-term orbit-raising maneuvers has been fabricated by 3-D printing and demonstrated. The propellant flows through multiple layers of cylindrical shells, with this structure also functioning as a single-piece heater. A 6-cm-high cylinder was realized with a wall thickness of 0.2 mm, using Inconel 718. A nodal thermal analysis was performed to identify the upper-limit current at a temperature limit of the wall material, and it was revealed that an outlet gas temperature of 871 K can be achieved with 77 A of current at 0.2 g/s of mass flow rate. The designed heater was combined with a boron nitride insulator and a stainless-steel housing, and thrust was measured in a vacuum chamber with nitrogen as the propellant. At a mass flow rate of 0.2 g∕s and 75 A of current, an outlet temperature of 747 K, a specific impulse of 108 s, and a heater efficiency of 72% were achieved. These results with nitrogen propellant were used to predict the performance of a tungsten-made resistojet with a hydrogen propellant, and a specific impulse of over 700 s can be expected at a heater temperature of 2000 K.

DOI： 10.2514/1.b38187

Conceptual design study of a vertical takeoff and landing airbreather 査読有り

Kobayashi H., Maru Y., Richardson M.P., Kinefuchi K., Sato T.

Journal of Spacecraft and Rockets 58 巻 ( 5 ) 頁： 1279 - 1292 2021年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Spacecraft and Rockets

In this paper, the authors investigate whether airbreathing engines have useful application to vertical takeoff and vertical landing systems, which currently represent the mainstream for reusable launch vehicles. A theoretical analysis has been performed to determine the net impact of the specific impulse benefits and weight penalties of a vertical takeoff reusable launch vehicle fitted with an airbreathing propulsion system. To maximize the thrust-to-weight ratio of an airbreathing engine, the authors propose using a conventional fan driven by a separate gas generator in lieu of a conventional core airbreathing combustor, as well as combined rocket–airbreathing operation to reduce engine size. The proposed engine system and its propulsive performance are described herein. Furthermore, a new sounding rocket is described as a practical application for the proposed vertical takeoff and vertical landing airbreathing engine. Conventional horizontal takeoff and horizontal landing airbreathing engine concepts tend to focus on maximizing specific impulse and airspeed, which necessitates further development, specifically in the areas of heat-resistant materials and structural technology. By proposing a vertical takeoff and vertical landing airbreather in this study, a different approach is taken and the potential to significantly improve launch capability and reliability is demonstrated in comparison to the current technology level for reusable launch vehicles.

DOI： 10.2514/1.A34988

Neutral atom density measurements of xenon plasma inside a μ10 microwave ion thruster using two-photon laser-induced fluorescence spectroscopy 査読有り

Tsukizaki R., Yamashita Y., Kinefuchi K., Nishiyama K.

Vacuum 190 巻 2021年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Vacuum

This paper reports measurements of the xenon ground state and excited state densities inside a μ10 microwave ion thruster. This thruster exhibits a 40% thrust enhancement upon changing from the waveguide to the discharge chamber propellant injection mode. In the present work, the associated mechanism was quantitatively evaluated using two-photon laser induced fluorescence (TALIF) spectroscopy to monitor the thruster waveguide. The 834.7 nm emission from excited state xenon was investigated with a 224.3 nm dye laser to excite the Xe I 5p61 S0 6pʹ [3/2]2 state, compared with the emission without the laser. The resulting data confirm that the neutral density exhibits a linear relationship with the propellant flow rate in the cold gas and ionized state, while the ion acceleration decreases the neutral density by the same order of magnitude as the propellant utilization efficiency is changed. As the propellant flow rate increases, the collisions of neutrals that generate excited states occur in the waveguide and, when this process plateaus, the ground state emission suddenly increases. Propellant injection from the discharge chamber is evidently effective at suppressing collisions with electrons in the waveguide that generate excited states and that potentially interfere with microwave propagation.

DOI： 10.1016/j.vacuum.2021.110269

Performance of a miniature Hall thruster and an in-house PPU 査読有り

Naoji Yamamoto, Masatoshi CHONO, Ryudo TSUKIZAKI, Takato MORISHITA, Kenichi KUBOTA, Shinatra CHO, Kiyoshi KINEFUCHI, Toru TAKAHASHI

Transactions of the Japan Society for Aeronautical and Space Sciences 64 巻 ( 3 ) 2021年5月

Design and testing of additively manufactured high-efficiency resistojet on hydrogen propellant 査読有り

Coral Giulio, Kinefuchi Kiyoshi, Nakata Daisuke, Tsukizaki Ryudo, Nishiyama Kazutaka, Kuninaka Hitoshi

ACTA ASTRONAUTICA 181 巻頁： 14 - 27 2021年4月

Speckle beam-oriented schlieren technique 査読有り

Nakamura Y., Suzuki T., Kinefuchi K., Sasoh A.

Experiments in Fluids 62 巻 ( 1 ) 2021年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Experiments in Fluids

Abstract: An advanced background-oriented schlieren (BOS) method, named as the speckle beam-oriented schlieren technique, was newly developed to measure the distribution of refraction angles in transparent media. A speckle pattern is generated by passing a coherent laser beam through a holographic diffuser, a pinhole, and a lens, generating a collimated background image that is projected directly onto the image sensors. Since the intensity of the background image is maintained at a high level, this method is, in principle, useful for diagnosing fast and/or low signal-to-noise phenomena, such as high-temperature gasses with radiation emission. Moreover, by splitting the background beam into two imaging paths with different focal lengths, the refraction angles can be measured for a schlieren object with uncertain location, and the depth position of the refraction angles can be resolved. This technique was demonstrated by measuring the refraction angle and the depth position distribution in a sonic jet with different injected locations. Graphic abstract: [Figure not available: see fulltext.]

DOI： 10.1007/s00348-020-03113-3

Keeper ignition and discharge characteristics of hollow cathode center-mounted on hall Thruster 査読有り

Kinefuchi K., Cho S., Fukatsu T., Tsukizaki R., Funaki I., Hirano Y., Tashiro Y., Shiiki T.

Journal of Propulsion and Power 37 巻 ( 2 ) 頁： 223 - 230 2021年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Propulsion and Power

This Paper explores keeper ignition and discharge characteristic of a hollow cathode center mounted on a Hall thruster to discuss the optimum startup sequence. A strong magnetic field along the hollow cathode in the centermount configuration is considered to play an important role in the ignition and discharge; however, the characteristics in this configuration has never been reported. The effect of cathode mass flow rate on the ignition and discharge with 3Akeeperignitionis examined both with and without magnetic field. The influence of cathodeheater power and flow from the anode is also investigated. The lower flow rate causes strong ionization instability, while the higher flow rate seems to induce ion acoustic turbulence. Applied magnetic field improves the ionization instability due to the decrease in electron temperature through plasma production. These results indicate ignition sequences over 1.5 mg=s flow rate with magnetic field appear promising. On the other hand, the confined electrons around the magnetic field line prevent the initiation of the discharge. The ignition and instability are improved with high heat-up power because more thermionic emission is obtained. The anode flow provides slight improvement to the characteristics. The Fourier transform also demonstrates the presence of ionization instability and ion acoustic turbulence. The behavior of peak frequencies of ionization instability can be explained based on the predator-prey theory.

DOI： 10.2514/1.B37814

Performance of a miniature hall thruster and an in-house PPU 査読有り

Chono M., Yamamoto N., Tsukizaki R., Morishita T., Kubota K., Cho S., Kinefuchi K., Takahashi T.

Transactions of the Japan Society for Aeronautical and Space Sciences 64 巻 ( 3 ) 頁： 189 - 192 2021年

Experimental analysis of thermal behavior in cryogenic propellant tank with different pressurants 査読有り

Kinefuchi K., Kawashima H., Sugimori D., Umemura Y., Okita K., Kobayashi H., Himeno T.

Cryogenics 112 巻 2020年12月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Cryogenics

The thermal behavior of cryogenic propellant tanks is crucial issue in the operation of cryogenic propulsion systems. Herein, ground experiments were conducted in a 600-mm-diameter cryogenic tank filled with liquid nitrogen. As pre-pressurants, gaseous helium and gaseous nitrogen (of the same species as the liquid), were used to investigate its effect in accordance with actual propulsion systems. The tank was sealed after pre-pressurization to observe the self-pressurization. The evaporation rate and heat flow in the tank were estimated based on pressure and temperature measurements. In addition, the axial liquid temperature distribution was obtained through the liquid draining from the tank bottom, and a thermal stratification model was developed. These results demonstrated that the type of pre-pressurant significantly affected the thermal behavior in the tank. A higher evaporation rate and higher liquid internal energy rise rate with a thicker thermal layer were observed in the helium pre-pressurization case. The lower nitrogen partial pressure in the helium case enhanced the vaporization and growth of the thermal layer. Estimation of the power balance in the tank demonstrated that not only the ullage but also the heat mass of the tank provided heat for the evaporation and thermal layer. The evaporation occurs mainly at the contact point between the tank skin and liquid surface. The nitrogen vapor rises in a thin layer along the tank skin because of buoyancy under nitrogen pre-pressurization; however, buoyancy is lower under helium pre-pressurization, and a radial vapor flow is probably produced from the contact point instead, leading to a higher heat flux to the liquid.

DOI： 10.1016/j.cryogenics.2020.103196

Application of a microwave cathode to a 200-W Hall thruster with comparison to a hollow cathode 査読有り

Morishita T., Tsukizaki R., Yamamoto N., Kinefuchi K., Nishiyama K.

Acta Astronautica 176 巻頁： 413 - 423 2020年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Acta Astronautica

A hollow cathode is an efficient electron source in the self-heating mode utilizing the discharge power. However, in sub-ampere currents, it needs keeper power to maintain the thermionic electron discharge, which could decrease the thrust efficiency. To address this problem, we propose using a microwave cathode, which is based on the flight model of a microwave ion thruster neutralizer cathode, as an alternative to a hollow cathode. First, we redesigned the magnetic field of a microwave cathode discharge chamber and tested it in the diode mode configuration. The electron emission current is doubled compared to the original performance. Next, we coupled the improved microwave cathode with a 200-W class Hall thruster and compared the characteristics and performance with a hollow cathode. We confirmed that the magnetic field polarity affects the ignition characteristics. We measured the thrust by an inverted thrust stand, the ion energy distribution functions by a retarding potential analyzer, and the beam profiles by an ion collector. The thrust and thrust efficiency are equivalent for both types of cathode. The specific impulse is 10% higher in the case of the microwave cathode. Since the potential difference between the microwave cathode and ground rapidly increased at currents above 600 mA, this could be taken to be the trade-off point against the hollow cathode.

DOI： 10.1016/j.actaastro.2020.06.049

Cryogenic propellant recirculation for orbital propulsion systems 査読有り

Kinefuchi Kiyoshi, Kawashima Hideto, Sugimori Daizo, Okita Koichi, Kobayashi Hiroaki

CRYOGENICS 105 巻 2020年1月

Characterization of a capillary flow controller for electric propulsion 査読有り

Kinefuchi K., Cho S., Tsukizaki R.

Journal of Propulsion and Power 36 巻 ( 4 ) 頁： 586 - 592 2020年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Propulsion and Power

A low-cost and reliable propellant flow controller is necessary to offer competitive electric propulsion systems. This paper first reviews xenon flow control methods for Hall thrusters and ion engines. Through a trade study, a simple and low-cost xenon flow controller applying a heated capillary is proposed. The test article is fabricated based on a developed theory and tested with xenon. The estimation based on laminar flow shows slightly different characteristics from those of the experiment, although the Reynolds number indicates a laminar condition. The turbulent flow assumption is in good agreement with the experiment at a high mass flow rate while the flow characteristics are between laminar and turbulent at a low mass flow rate. That implies that the surface roughness and tube curvature induce the laminar–turbulent transition even in the low mass flow rate case. To obtain a wider flow rate range, maintaining laminar flow in the capillary is desirable because of the high sensitivity of the friction coefficient with temperature in the laminar flow. Component improvements achievable through miniaturization and reduction of the inner wall surface roughness and capillary curvature are considered to be necessary to prevent the turbulent transition.

DOI： 10.2514/1.B37726

Neutral ground state particle density measurement of xenon plasma in microwave cathode by two-photon laser-induced fluorescence spectroscopy 査読有り

Application of two-photon laser-induced fluorescence spectroscopy to microwave cathode 査読有り Open Access

Tsukizaki R., Yamashita Y., Kinefuchi K., Nishiyama K.

Transactions of the Japan Society for Aeronautical and Space Sciences 63 巻 ( 6 ) 頁： 281 - 283 2020年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Transactions of the Japan Society for Aeronautical and Space Sciences

To investigate the neutral xenon density distribution of electric thrusters such as ion and Hall thrusters, two-photon absorption laser-induced fluorescence (TALIF) spectroscopy was applied to a microwave cathode. First, the background pressure of the vacuum chamber was measured by TALIF. In the present measurements, the ground state was excited by a 224.29 nm laser, and 834.68 nm fluorescence was detected. The first measurement confirmed that the fluorescence intensity linearly increases with respect to the ground state number density. Based on this result, the density of neutral ground-state xenon was measured at the exit of the nozzle of the microwave cathode. The variation in the density with the microwave power was successfully measured at xenon flow rates of 0.029 and 0.098 mg/s. The measured densities varied from 2.3 © 1019 to 8.4 © 1019 m3 with a maximum error of «20% due to the plasma fluorescence.

DOI： 10.2322/tjsass.63.281

In-flight S-band telemetry attenuation by ionized solid rocket motor plumes at high altitude 査読有り

Kinefuchi Kiyoshi, Yamaguchi Hiroyuki, Minami Mineko, Okita Koichi, Abe Takashi

ACTA ASTRONAUTICA 165 巻頁： 373-381 2019年12月

Yamashita Y., Tsukizaki R., Kinefuchi K., Koda D., Tani Y., Nishiyama K.

Vacuum 168 巻 2019年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Vacuum

This paper reports the first study to measure xenon neutral ground state particle density of microwave cathode by two-photon laser induced fluorescence spectroscopy (TALIF). Xenon is commonly used as a propellant in electric propulsion like Hall thrusters, ion thrusters, and their cathodes. For electric propulsion, information about neutral particles is important such as the ionization degree and the charged exchange collisions (CEX). The measurement target is XeI 5p61S06p[3/2]2, which absorbs at a wavelength of 224.29 nm and emits fluorescence of 834.7 nm. The measurement system was demonstrated for three cases: cold gas, without electron extraction, with electron extraction. From three cases, the measurement system can detect a neutral ground state particle density of 1019m−3 order without and with a plasma. In a cold gas, the neutral ground state particle density is (8.4±0.4)×1019m−3 at 0.098 mg/s. Without electron extraction, the neutral ground density decreases by ionization and excitation With electron extraction, the density varied from 0.6 to 2.3 times compared to without electron extraction depending on anode voltage.

DOI： 10.1016/j.vacuum.2019.108846