Research Institute for Sustainable Humanosphere

Uji, Japan

Research Institute for Sustainable Humanosphere

Uji, Japan

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Kajimura Y.,Kyoto University | Kajimura Y.,Research Institute for Sustainable Humanosphere | Kajimura Y.,Japan Science and Technology Agency | Usui H.,Kobe University | And 7 more authors.
Journal of Propulsion and Power | Year: 2010

Magnetic sail is a propellantless propulsion system proposed for an interplanetary space flight. The propulsive force is produced by the interaction between the magneticfield artificially generated by a hoop coil equipped with the magnetic sail and the solar wind. Three-dimensional hybrid particle-in-cell simulations are performed to elucidate the plasma flow structure around the magnetic sail and to measure the propulsive force of the magnetic sail. We report the characteristics of the magnetosphere, such as the profile of the magnetic field, the thickness of the magnetopause current layer, and the predicted thrust value obtained by simulations, which agree well with laboratory experiment when simulations are carried out by considering the ion-neutral collision effect. The hybrid particle-in-cell simulation carried out without considering the collisional effect gave a thrust valueof3.5 N,which can be applied to the thrust evaluation of the magnetic sail in a magnetosphere with size of 300 km in a collisionless interplanetary space. © 2009 by the American Institute of Aeronautics and Astronautics, Inc.


Bando M.,Kyoto University | Bando M.,Research Institute for Sustainable Humanosphere | Ichikawa A.,Kyoto University
Journal of Guidance, Control, and Dynamics | Year: 2010

A new formulation of formation flying in an elliptic orbit with restricted control interval is discussed. The main performance index is the L1 norm of the control input generated by an employed feedback control, which is proportional to the fuel consumption. The null controllability with vanishing energy (NCVE) property enables to design feedback controllers through the linear quadratic regulator (LQR) theory, which generate control inputs with arbitrarily small L2 norms by imposing a large penalty on control. The L1 norm of the control input decreases monotonically as the penalty on control increases, and suboptimal controllers are designed. The velocity of the satellite near the apogee is smaller, a relatively small velocity change is required for orbit control and it is assumed that t = 0 is the perigee passage time of the leader, and restrict the control input to the interval.


Tsujii S.,Kyoto University | Bando M.,Kyoto University | Yamakawa H.,Kyoto University | Yamakawa H.,Research Institute for Sustainable Humanosphere
Journal of Guidance, Control, and Dynamics | Year: 2013

The motion of a charged satellite subjected to the Earth's magnetic field is considered. The Lorentz force, which acts on a charged particle when it is moving through a magnetic field, provides a new concept of propellantless electromagnetic propulsion. A dynamic model of a charged satellite, including the effect of the Lorentz force in the vicinity of a circular or an elliptic orbit, is derived and its application to formation flying is considered. Based on Hill-Clohessy-Wiltshire equations and Tschauner-Hempel equations, analytical approximations for the relative motion in Earth orbit are obtained. The analysis based on the linearized equations shows the controllability of the system by stepwise charge control. The sequential quadratic programming method is applied to solve the orbital transfer problem of the original nonlinear equations in which the analytical solutions cannot be obtained.Astrategy to reduce the charge amount using sequential quadratic programming is also developed. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.


Bando M.,Kyoto University | Bando M.,Research Institute for Sustainable Humanosphere | Yamakawa H.,Kyoto University | Yamakawa H.,Research Institute for Sustainable Humanosphere
Journal of Guidance, Control, and Dynamics | Year: 2010

A study was conducted to demonstrate the formulation of the new Lambert Algorithm using the Hamilton-Jacobi-Bellman Equation (HJB). The two-point boundary-value problem (TPBVP) of the Hamiltonian system was treated as an optimal control problem where the Lagrangian function played a role as a performance index. The approach demonstrated in the study was based on the expansion of the value function in the Chebyshev series with unknown coefficients, considering the computational advantages of the use of Chebyshev polynomials. The differential expressions that arose in the HJB equation were expanded in Chebyshev series with the unknown coefficients. The new algorithm had the potential to provide a solution to the TPVBP using the spectral information about the gravitation potential function and was applicable to the problem under a higher-order perturbed potential function without any modification.


Mitani S.,Japan Aerospace Exploration Agency | Yamakawa H.,Kyoto University | Yamakawa H.,Research Institute for Sustainable Humanosphere
Journal of Guidance, Control, and Dynamics | Year: 2014

A rendezvous problem under thrust magnitude and direction constraints is considered. A constraint-satisficing scheme has been newly proposed by introducing two barrier functions. The constraint-satisficing set smoothly establishes an intersection between the unconstrained satisficing set and the input constraint set as the perturbation parameters of two barrier functions tend toward zero. For a simple nonlinear controller, a controller generated by projecting a constraint-free linearized optimal controller onto the input constraint is proposed and its stability is investigated. Some numerical simulations treating nonlinear relative orbit systems show that various control sets, which guide the orbit to the origin, can be generated, whereas the convergence property of the closed-loop system is analyzed by the proposed parameter design with the assistance of a graphical plot. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.


Hoshi K.,Kyoto University | Muranaka T.,Chukyo University | Kojima H.,Kyoto University | Kojima H.,Research Institute for Sustainable Humanosphere | And 4 more authors.
Journal of Spacecraft and Rockets | Year: 2016

This paper treats the electric-potential characteristics of active spacecraft charging using a full particle-in-cell simulation. A new active spacecraft charging model that considers the velocity distribution of beam particles is proposed. The electric potential of active charging canbe calculated numerically and quickly using the new model; by contrast, the conventional model can only express active charging qualitatively, and particle-in-cell simulations require a very high load. The numerical solution of the new model shows very good agreement with the results of the full particle-in-cell simulation for a cubic spacecraft model with electron beam emission. © Copyright 2016 by the American Institute of Aeronautics and Astronautics, Inc.


Ashida Y.,Kyoto University | Ashida Y.,Research Institute for Sustainable Humanosphere | Yamakawa H.,Kyoto University | Yamakawa H.,Research Institute for Sustainable Humanosphere | And 5 more authors.
Journal of Propulsion and Power | Year: 2014

A magnetic sail is a spacecraft propulsion system that generates an artificial magnetosphere to block solar wind particles and uses the imparted momentum to accelerate a spacecraft. In the present study, three-dimensional particle-in-cell simulations were conducted on small-scale magnetospheres to investigate the thrust characteristics of small-scale magnetic sails. The results show that electron Larmor motion and charge separation become significant in small-scale magnetospheres, and that the thrust of the magnetic sail is affected by the cross-sectional area of the charge-separated plasma cavity. Empirical formulas for the thrust are obtained by changing spacecraft design and solar wind parameters. These equations show that the thrust of a small-scale magnetic sail is approximately proportional to magnetic moment, solar wind density, and solar wind velocity. The empirical formulas enable determination of the trajectory of the spacecraft and performance of a mission analysis. © 2012 AIAA.


Ashida Y.,Kyoto University | Ashida Y.,Research Institute for Sustainable Humanosphere | Funaki I.,Japan Aerospace Exploration Agency | Yamakawa H.,Kyoto University | And 5 more authors.
Journal of Propulsion and Power | Year: 2014

Amagnetic sail is spacecraft propulsion that produces an artificial magnetosphere to block solar wind particles and thus impart momentum to accelerate a spacecraft. In the present study, the authors conducted two-dimensional particle-in-cell simulations on small-scale magnetospheres to investigate thrust characteristics of a magnetic sail and its derivative, magnetoplasma sail, in which the magnetosphere is inflated by an additional plasma injection. As a result, the authors found that the electron Larmor motion and the charge separation become significant on such a small-scale magnetosphere and the thrust of the magnetic sail is affected by the cross-sectional size of the chargeseparated magnetosphere. The authors also reveal that the plasma injection, on the condition that the kinetic energy of plasma is smaller than the local magnetic field energy (β ~ 10 -3), can significantly inflate the magnetosphere by inducing diamagnetic current in the same direction as the onboard coil current. As a result, the magnetoplasma sail thrust is increased effectively by an additional plasma injection: the magnetoplasma sail thrust (15 μN/m) becomes up to 7.5 times larger than the original thrust of the magnetic sail (2.0 μN/m). In addition, they found that the thrust gain of the magnetoplasma sail, defined as "magnetoplasma sail thrust/ (magnetic sail thrust + plasma injection thrust)" becomes up to 2.2. © 2012 AIAA.


Sato M.,Japan National Institute for Fusion Science | Fukushima J.,Nagoya University | Kashimura K.,Research Institute for Sustainable Humanosphere | Tanaka M.,Chubu University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

The monochromatic and single phase electromagnetic fields generate ordered motions in the electrons and ions in the solid and liquid materials. The coherent motion stored kinetic energy. If the kinetic energy is large enough to destroy the crystal structures, the phase deformations happens at much under temperatures expected in the thermally equilibrium state. If it could couple to the optical light generated by thermal motions of the material, it would excite stimulated Brillouin emissions. The stimulated emission supply the energy under the thermally non-equilibrium state. © 2011 SPIE.


Nakamiya M.,Kyoto University | Nakamiya M.,Research Institute for Sustainable Humanosphere | Kawakatsu Y.,Japan Aerospace Exploration Agency
Journal of Guidance, Control, and Dynamics | Year: 2014

The transfer trajectories from the moon to a Halo orbit was studied. Assuming the usage of the stable manifold for the transfer, the connectivity of the stable manifold with the orbit of the moon was investigated. As a consequence, there were four connecting points even if the size of the Halo orbit is small. It allows sending spacecraft into the small Halo orbit using the stable manifold and to increase the opportunity of launch via the moon. Moreover, it was found that the relative velocity of the stable manifold at the connecting point with respect to the moon and the time of flight from the moon to the Halo orbit decrease with the decreasing size of the Halo orbit.

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