研究者業績
基本情報
- 所属
- 国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 宇宙飛翔工学研究系 教授総合研究大学院大学 物理科学研究科 宇宙科学専攻 教授
- 学位
- 博士（工学）(1995年3月 東京大学)
- J-GLOBAL ID
- 200901056190267532
- researchmap会員ID
- 1000253787
- 外部リンク
研究キーワード
4研究分野
3主要な経歴
18-
2020年 - 現在
-
2019年 - 現在
学歴
2-
- 1995年
-
- 1990年
委員歴
6-
2020年 - 現在
-
2014年 - 現在
-
2014年 - 2015年
-
2014年 - 2015年
-
2011年 - 2015年
受賞
3-
2014年
-
2012年
-
1999年
論文
272-
JOURNAL OF PROPULSION AND POWER 25(2) 536-539 2009年3月 査読有り
-
TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, SPACE TECHNOLOGY JAPAN 7(ists26) Pb_95-Pb_99 2009年 査読有り
-
Journal of Plasma and Fusion Research SERIES Vol.8, 25-30 2009年
-
Journal of Plasma and Fusion Research SERIES Vol.8 1616-1621 2009年 査読有り
-
Journal of Plasma and Fusion Research SERIES Vol.8 1580-1584 2009年 査読有り
-
Journal of Plasma and Fusion Research SERIES Vol.8 1585-1589 2009年 査読有り
-
Journal of Plasma and Fusion Research SERIES Vol.8 1569-1573 2009年 査読有り
-
Journal of Plasma and Fusion Research SERIES Vol.8 1574-1579 2009年 査読有り
-
RAREFIED GAS DYNAMICS 1084 784-+ 2009年 査読有りTo capture the kinetic energy of the solar wind by creating a large magnetosphere around the spacecraft, magneto-plasma sail injects a plasma jet into a strong magnetic field produced by an electromagnet onboard the spacecraft. The aim of this paper is to investigate the effect of the IMF (interplanetary magnetic field) on the magnetosphere of magneto-plasma sail. First, using an axi-symmetric two-dimensional MHD code, we numerically confirm the magnetic field inflation, and the formation of a magnetosphere by the interaction between the solar wind and the magnetic field. The expansion of an artificial magnetosphere by the plasma injection is then simulated, and we show that the magnetosphere is formed by the interaction between the solar wind and the magnetic field expanded by the plasma jet from the spacecraft. This simulation indicates the size of the artificial magnetosphere becomes smaller when applying the IMF.
-
AIP Conference Proceedings Vol. 1084, pp.784-792 2009年 査読有り
-
VACUUM 83(1) 52-56 2008年9月 査読有りPreliminary numerical simulation using a Direct Simulation Monte Carlo (DSMC) method was conducted to elucidate the internal flowfield and external plume characteristics of micro-single-nozzles and micro-nozzle-arrays, since these small-sized nozzles generally undergo a severe viscous loss due to the low Reynolds numbers. This study also contains the investigation on optimization of the geometry and configuration of the micro-nozzles and micro-nozzle-arrays to achieve the improved propulsive performance. Typical sizes of each rectangular nozzle element were 0.1 mm in throat height, 0.36 mm in exit height, and 0.35 mm in length of the divergent part. For the micro-single-nozzles, calculated specific impulses were fairly in good agreement with our previous experimental data, showing a poor nozzle efficiency due to the viscous loss of low Reynolds number. Also, mechanisms of exhaust jet interaction of multi-nozzle-array jets, bringing a significant improvement in thrust performance, were investigated. As a result, it was shown that pressure and temperature increased at the exit and jet boundaries, and then the exhaust multi-jets were not expanded after the exit, or rather being confined, showing possibilities to realize the higher propulsive performance due to the augmented effect of the pressure thrust. (c) 2008 Elsevier Ltd. All rights reserved.
-
VACUUM 83(1) 213-216 2008年9月 査読有りFor space propulsion applications, a fundamental study of a laser-electrostatic hybrid thruster was conducted. A new type of thruster, in which a laser-produced plasma was accelerated by an additional electrostatic field, was tested to optimize the ion acceleration process. A time-of-flight measurement by a Faraday cup showed that the average speed of ions was about 15 km/s when only 0.04 mJ of laser impulse was introduced to a copper target. When an accelerator electrode with a 6-mm-diameter hole was placed in front of the laser target, it was observed that the average speed of ions increased. The maximum velocity was 23 km/s, which corresponded to the case where the accelerator grid was biased to +100 V for the target-to-electrode gap of 2 mm. It was found that the positively biased electrode was more effective than the negatively biased electrode for ion acceleration in the thruster. (C) 2008 Elsevier Ltd. All rights reserved.
-
The 26th International Symposium on Space Technology and Science(CD-ROM) 2008-b-57p 2008年6月
-
JOURNAL OF THE ASTRONAUTICAL SCIENCES 56(1) 1-16 2008年1月 査読有りA semi-analytic method for determining the periodic trajectories of a spacecraft under the influence of a constant small thrust directed from a central station in a circular orbit is presented using the Clohessy-Wiltshire equations. The amplitude and frequency of the radially accelerated periodic trajectories are semi-analytically derived. A simple on-off orbital control scheme to change the amplitude of these radially accelerated trajectories is also proposed and numerically verified. These radially accelerated periodic orbits are applicable for a small thrust laser laser-propelled space vehicle mission in the vicinity of in Earth orbiting laser station.
-
BEAMED ENERGY PROPULSION 997 316-+ 2008年 査読有りTrajectories applicable to laser-propelled space vehicles with a laser station in low-Earth orbit are investigated. Laser vehicles are initially located in the vicinity of the Earth-orbiting laser station in low-earth orbit at an altitude of several hundreds kilometers, and are accelerated by. laser beaming from the laser station. The laser-propelled vehicles start from low-earth orbit and finally escape from the Earth gravity well, enabling interplanetary trajectories and planetary exploration.
-
TAUP2007: TENTH INTERNATIONAL CONFERENCE ON TOPICS IN ASTROPARTICLE AND UNDERGROUND PHYSICS 120 2008年 査読有り
-
BEAMED ENERGY PROPULSION 997 553-+ 2008年 査読有りWhen Magnetic sail (MagSail) spacecraft is Operated in space, the supersonic solar wind plasma flow is blocked by an artificially produced magnetic cavity to accelerate the spacecraft in the direction leaving the Sun. To evaluate the momentum transferring process from the solar wind to the coil onboard the MagSail spacecraft, we arranged a laboratory experiment of MagSail spacecraft. Based on scaling considerations, a solenoidal coil was immersed into the plasma flow from a magnetoplasmadynamic arcjet in a quasi-steady mode of about 1 ms duration. In this setup, it is confirmed that a magnetic cavity, which is similar to that of the geomagnetic field, was formed around the coil to produce thrust in the ion Larmor scale interaction. Also, the controllability of magnetic cavity size by a plasma jet from inside the coil of MagSail is demonstrated, although the thrust characteristic of the MagSail with plasma jet, which is so called plasma sail, is to be clarified in our next step.
-
STATISTICAL PHYSICS, HIGH ENERGY, CONDENSED MATTER AND MATHEMATICAL PHYSICS 539-539 2008年 査読有り
-
JOURNAL OF PROPULSION AND POWER 23(3) 544-551 2007年5月 査読有りThe electron cyclotron resonance ion engine has long life and high reliability because of electrodeless plasma generation in both the ion generator and the neutralizer. Four mu 10s, each generating a thrust of 8 mN, specific impulse of 3200 s, and consuming 350 W of electric power, propelled the Hayabusa asteroid explorer launched on May 2003. After vacuum exposure and several baking runs to reduce residual gas, the ion engine system established continuous acceleration. Electric propelled delta-V Earth gravity assist, a new orbit change scheme that uses electric propulsion with a high specific impulse was applied to change from a terrestrial orbit to an asteroid-based orbit. In 2005, Hayabusa, using solar electric propulsion, managed to successfully cover the solar distance between 0.86 and 1.7 AU. It rendezvoused with, landed on, and lifted off from the asteroid Itokawa. During the 2-year flight, the ion engine system generated a delta-V of 1400 m/s while consuming 22 kg of xenon propellant and operating for 25,800 h.
-
JOURNAL OF PROPULSION AND POWER 23(3) 513-521 2007年5月 査読有りRadiated electric field emissions from the prototype model of the ion engine system of the asteroid explorer Hayabusa (MUSES-C) were measured in approximate accordance to MIL-STD-461C. The typical noise level exceeded the narrowband specification at frequencies less than 5 MHz. The microwave discharge neutralizer generates broadband noise and narrowband oscillations that have a fundamental frequency of about 160 kHz and are accompanied by its harmonics up to the fifth. Leakage of 4.25 GHz microwaves for plasma production and its second harmonic were 65 dB and 35 dB above specifications, respectively. The X-band receiver onboard Hayabusa measured the noise from the ion engine system at the uplink frequency of 7.16 GHz through a horn antenna. This susceptibility test showed that the microwave discharge ion thruster is unlikely to interfere with deep space microwave communication.
-
JOURNAL OF PROPULSION AND POWER 23(2) 495-499 2007年3月 査読有りA miniaturized microwave ion source with a 1.6-cm beam diameter grid system was designed and then evaluated experimentally. based on the HAYABUSA mu 10 neutralizer, we fabricated a small 18-mm-diam discharge chamber, into which 4.2 GHz microwaves were launched through an L-shaped antenna that was located in a magnetic field created by permanent magnets and iron yokes. Ion beams were emitted from the small discharge chamber when operated with a grid system whose respective hole diameters of the screen grid and acceleration grid were 0.72 and 0.43 mm, and the total number of grid holes was 211. For a beam voltage of 1500 V and a microwave input power of 10 W, the typical thruster performance was thrust of 0.34 mN, a thrust/power ratio of 16 mN/kW, propellant utilization efficiency of 68%, and a specific impulse of 3200 s. If we were able to further reduce the ion production cost (circa 3000 W/A in the current experiment), this thruster would be a candidate for main propulsion of a small satellite or precise attitude control of various sizes of satellites.
-
FUSION SCIENCE AND TECHNOLOGY 51(2T) 220-222 2007年2月 査読有りThe influence of the Hall effect on the current distribution and the plasma flow was investigated using two-dimensional numerical simulation for a self-field MagnetoPlasmaDynamic (MPD) thruster consisting of a short cathode and a flared anode. When the Argon mass flow rate and the total discharge current were set to 0.8 g/s and 5 kA respectively, the result with the Hall effect showed that concentrations of current density on the root of the cathode and on the edge of the flared anode were found. Such a highly skewed current lines near the cathode are caused by large local Hall parameters, which also lead to a large potential drop near the cathode surface.
-
FUSION SCIENCE AND TECHNOLOGY 51(2T) 226-228 2007年2月 査読有りMagnetic sail (MagSail) is a next-generation deep space propulsion system, which uses the energy of the solar wind. The MagSail produces an artificial magnetic field and captures the energy of the solar wind plasma to propell a spacecraft in the direction of the solar wind In order to conduct a scale-model experiment of the plasma flow of a MagSail, we developed a solar wind simulator based on a magnetoplasmadynamic arcjet, which obtained a high density (similar to 10(18) m(-3)) and high velocity (similar to 60 km/s) plasma flow in a quasi-steady mode of about 1 ms duration. Based on scaling considerations, a solenoidal coil (18 mm in diameter and the magnetic flux density at the coil center similar to 1.9 T) was designed and was immersed into the plasma flow. A magnetic cavity, which is very similar to that of the geomagnetic field, was observed, although the magnetic cavity of MagSail is usually much smaller than the geomagnetic cavity of the Earth.
-
ASTROPHYSICS AND SPACE SCIENCE 307(1-3) 63-68 2007年1月 査読有りTo propel a spacecraft in the direction leaving the Sun, a magnetic sail (MagSail) blocks the hypersonic solar wind plasma flow by an artificial magnetic field. In order to simulate the interaction between the solar wind and the artificially deployed magnetic field produced around a magnetic sail spacecraft, a laboratory simulator was designed and constructed inside a space chamber. As a solar wind simulator, a high-power magnetoplasmadynamic arcjet is operated in a quasisteady mode of 0.8 ms duration. It can generate a simulated solar wind that is a high-speed (above 20 km/s), high-density (10(18) m(-3)) hydrogen plasma plume of similar to 0.7 m in diameter. A small coil (2 cm in diameter), which is to simulate a magnetic sail spacecraft and can obtain 1.9-T magnetic field strength at its center, was immersed inside the simulated solar wind. Using these devices, the formation of a magnetic cavity (similar to 8 cm in radius) was observed around the coil, which indicates successful simulation of the plasma flow of a MagSail in the laboratory.
-
2007/11/12-15, Kona, Hawaii, US, 553-560 2007年 査読有り
-
Advances in the Astronautical Sciences 127 PART 1 607-620 2007年 査読有りSince the first proposal in the early 1970s, laser-propelled launch vehicles have been considered as one of the candidates offering the potential of thousands of launches to low Earth orbit. Previous papers mainly investigate the ascent trajectory phase utilizing this laser propulsion system, while this paper proposes in-orbit laser propulsion system and investigates the dynamics of a laser-propelled space vehicle around an orbiting station with a laser propulsion capability. The linear rendezvous equations, Clohessy-Wiltshire equations, are used for the analysis. The objective is to investigate the orbital dynamics, orbital control method, and feasibility of laser-propelled system for application to space vehicle orbital transfer. The thrust given by laser system is assumed in the direction from the orbiting laser station to the space vehicle around it. First, a conservative function denoting total energy in the rotating frame is discussed. Then, periodic trajectories around the orbiting laser station are investigated and an approximate analytical solution is given, which provides sufficient description of the laser-propelled orbital dynamics in terms of amplitude and frequency variation. Finally a simple on-off control scheme is proposed to control the size of the orbit around the orbiting laser station.
-
IEEE TRANSACTIONS ON PLASMA SCIENCE 34(5) 2125-2132 2006年10月 査読有りMicrowave discharge ion engines "mu 10" are dedicated to the main propulsion on the HAYABUSA asteroid explorer. In a development program, various tests and assessments were conducted on the ion engines and the spacecraft. They include endurance tests, an electromagnetic interference susceptibility test, an interference test between the plasma and communication microwave, a beam exhaust test on the spacecraft, assessments on the plasma interference with a solar array, and so on. The spacecraft was launched in deep space by the M-V rocket in May 2003. After vacuum exposure and several runs of baking for reduction of residual gas, the ion engine system established continuous acceleration of the spacecraft toward the asteroid ITOKAWA. The spacecraft passed through a perihelion of 0.86 astronomical unit (AU) in February 2004 and an aphelion of 1.1 AU in February 2001, becoming the first solar electric propulsion system to travel this far toward and away from the Sun. The HAYABUSA succeeded in rendezvousing with the target asteroid in September 2005.
-
IEEE TRANSACTIONS ON PLASMA SCIENCE 34(5) 2031-2037 2006年10月 査読有りCharging of a small electrically floated body, equipped with an unneutralized microwave ion source, was experimentally studied in a vacuum chamber. When a xenon ion beam of 16 mm in diameter was released from a cubic floating body, 10 cm on each side, the body was negatively charged at a rate of I-b/C, where I-b is the ion-beam current and C is the capacitance between the floated body and the ground. For large I-b/C parameters, the body potential changes faster than the xenon ions can react. This simulation results in space-charge-induced potential oscillations, which are detected in experimental measurements and observed in numerical simulations. The time scale of the oscillation relaxation time was found to be at least several times, corresponding to the ion movements around the body. As expected, the steady-state potential of the floated body was relatively negative to the vacuum-facility ground at a value equal to the magnitude of the ion-beam voltage.
-
ACTA ASTRONAUTICA 59(8-11) 777-784 2006年10月 査読有りThe magneto-plasma sail (mini-magnetospheric plasma propulsion) produces the propulsive force due to the interaction between the artificial magnetic field around the spacecraft inflated by the plasma and the solar wind erupted from the Sun with a speed of 300-800 km/s. The principle of the magneto-plasma sail is based on the magnetic sail whose original concept requires a huge mechanical coil structure, which produces a large magnetic field to capture the energy of the solar wind. Meanwhile in the case of the magneto-plasma sail, the magnetic field will be expanded by the inertia of plasma flow to a few tens of kilometer in diameter, resulting in a thrust of a few Newton R. Winglee's group of the University of Washington originally proposed the idea of magnetic field inflation by the plasma. This paper investigates the characteristics of the magneto-plasma sail by comparing it with the other low-thrust propulsion systems (i.e., electric propulsion and solar sail), and the potential of its application to near future outer planet missions is studied.Furthermore, an engineering validation satellite concept is proposed in order to confirm the propulsion system specification and operation methodology. The main features are summarized as: (1) The satellite mass is around 180kg assuming the H-IIA piggyback launch. (2) Since the magnetopause of the Earth magnetosphere is about 10 Re at Sun side and the bow shock is located at about 13 Re from the Earth, the satellite is injected into an orbit with 250 km perigee altitude and 20 Re apogee distance where apogee is located at the Sun side. (3) The magneto-plasma sail is turned on only in the vicinity of apogee outside the Earth's magnetosphere. (4) The thrust is estimated by the orbit determination result, and the plasma wind monitor is installed on the satellite to establish the relationship between the solar wind and the thrust. (c) 2005 Elsevier Ltd. All rights reserved.
-
JOURNAL OF PROPULSION AND POWER 22(5) 1085-1090 2006年9月 査読有りExperimental velocimetry in the discharge chamber of a two-dimensional magnetoplasmadynamic (MPD) arejet, fabricated for experimental internal flow measurement, was conducted to investigate the acceleration process for hydrogen propellant. In the experiment, we evaluated the neutral atom velocity and the temperature from the laser absorption spectroscopy using a tunable diode laser. The results using two types of anode, a flared-type anode and a converging-diverging (C-D)-type anode, were compared for the case with a discharge current of 13 kA and a mass-flow rate of 0.65 g/s. It was found that a large velocity slip between the ions and the neutrals prevented the acceleration of the neutral particles. This velocity slip is expected to reduce thrust performance because the flow with ion-neutral slip requires additional electric power compared to the flow without velocity slip. The velocity slip was reduced in the case of the C-D anode compared to the flared anode because of strong ion-neutral momentum coupling in the throat region of the C-D anode.
-
TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 49(164) 87-93 2006年8月 査読有りIn the MUCES-C mission conducted by JAXA (Japan Acro Exploration Agency), a microwave neutralizer is mounted with a microwave ion engine on the HAYABUSA space probe. The neutralizer consists of an L-shaped antenna to inject microwaves and samarium cobalt magnets to provide ECR (electron cyclotron resonance). Plasma production of a higher density than the cutoff density is expected in the discharge chamber, but the neutralizer is so small that high-precision measurements using a probe are difficult. To clarify the plasma production mechanism in the microwave neutralizer, numerical analysis was conducted using a code coupling PIC (particle-in-cell) method, and a FDTD (finite-difference-time-domain) method. This paper describes effects caused by varying magnetic field configuration and antenna position in the neutralizer. The calculation results show that bringing the antenna closer to the ECR region is effective for plasma production.
-
THIN SOLID FILMS 506 609-612 2006年5月A simulation code has been developed for analyzing plasma behavior and microwave propagation in a microwave ion engine. The code consists of PIC (particle-in-cell) method and FDTD (finite-difference-time-domain) method. In the present study, 10-cm-class microwave ion engine developed by the Japan Aerospace Exploration Agency (JAXA) is adopted as a calculation model. The microwave propagations in the discharge chamber are compared under boundary conditions such as absorption and reflection. In the calculation with plasma, effect of boundary condition on electron energy is investigated. As a result, it is found that increase of electron energy is larger for reflection boundary condition than absorption one. (c) 2005 Elsevier B.V. All rights reserved.
-
JOURNAL OF SPACECRAFT AND ROCKETS 43(3) 667-672 2006年5月 査読有りA magnetic sail (Magsail) is a unique deep-space propulsion system that captures the momentum of the solar wind by a large artificial magnetic field produced around a spacecraft. To clarify the momentum transfer process from the solar wind to the spacecraft, we simulated the interaction between the solar wind and the artificial magnetic field of the Magsail using the magnetohydrodynamic model. The result showed the same plasma flow and magnetic field as those of the magnetic field of the Earth; when the solar wind passes a bow shock, the solar wind is decelerated and deflected because the solar wind cannot penetrate into the magnetic field, which is called the magnetosphere around the spacecraft. The change of the solar-wind momentum resulted in a pressure distribution along the magnetopause, which is the boundary between the solar-wind plasma and the magnetosphere. The pressure on the, magnetopause is then transferred to the spacecraft via the Lorentz force between the induced current along the magnetopause and the current along the coil of the spacecraft. The simulation successfully demonstrated that the change of the momentum of the solar wind is transferred to the spacecraft via the Lorentz force, and the drag coefficient of the Magsail was estimated to be 0.9 +/- 0.1 when the magnetic dipole is parallel to the solar wind.
-
Journal of Space Technology and Science Vol.22(No.1, ,) pp.1-10.-10 2006年 査読有り
-
Journal of Spacecraft and Rockets 43(1) 63-70 2006年1月 査読有りInfluences of the electrical conductivity of the wall of a space vehicle on the control of the aerodynamic heating in Earth-reentry flight by applying the magnetic field are numerically examined using an axisymmetric two-dimensional (r-z) thermochemical nonequilibrium magnetohydrodynamic computational fluid dynamics code. Numerical results show that when the wall of an axisymmetric blunt body is assumed to be an insulating wall, applying a dipole-type magnetic field with r and z components pushes the bow shock wave away from the blunt body and reduces the aerodynamic heating. On the other hand, when the wall is assumed to be a conducting wall, the aerodynamic heating cannot be reduced by applying the magnetic field. This is because the strong Hall electric field on the r-z plane cannot be obtained in the case of the conducting wall, so that the large electric current density in the azimuthal direction cannot be obtained and the shock wave cannot be pushed away from the blunt body. Copyright © 2005 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
-
Proceedings of 7th International School/Symosium for Space Simulations P-3-4 2005年1月 査読有り
-
15th International Conference on MHD Energy Conversion 2 621-629 2005年1月
-
JOURNAL OF PROPULSION AND POWER 20(4) 718-727 2004年7月 査読有りPlasma characterization was conducted for an electron-cyclotron-resonance (ECR) type ion thruster. For a 10-cm diameter microwave discharge ion source consisting of two samarium cobalt magnet rings surrounding a centered waveguide for launching microwaves, plasma profiles were found to have severely non-uniform distributions, with localized plasma found near the magnet rings. This localized plasma is mainly produced in the magnetic flux tubes between the two ring magnets, where electrons gain microwave energy as they pass the ECR line during the bouncing movement between magnetic mirrors. To obtain a low-cost microwave ion source, this type of ionization mechanism can be exploited. When introducing microwaves through a low magnetic field boundary, however, it is impossible to eliminate the accessibility difficulty related to the cutoff density, which results in a plasma below the cutoff density. Because of the accessibility difficulty, in this work, only a relatively small ion beam current density of 1.8 mA/cm(2) was achieved.
-
35th AIAA Plasmadynamics and Lasers Conference AIAA 2004-2561 2004年6月
MISC
206主要な書籍等出版物
6講演・口頭発表等
561-
第63回航空原動機・宇宙推進講演会／北部支部2024年講演会ならびに第5回再使用型宇宙輸送系シンポジウム 日本航空宇宙学会
共同研究・競争的資金等の研究課題
28-
日本学術振興会 科学研究費助成事業 基盤研究(S) 2020年8月 - 2025年3月
-
日本学術振興会 科学研究費助成事業 特別推進研究 2019年4月 - 2024年3月
-
日本学術振興会 科学研究費助成事業 基盤研究(B) 2018年4月 - 2021年3月
-
日本学術振興会 科学研究費助成事業 基盤研究(B) 2017年4月 - 2021年3月
-
日本学術振興会 科学研究費助成事業 挑戦的研究(萌芽) 2019年6月 - 2021年3月
