Yasumasa Ashida
(Kyoto University, Japan)

The magnetic sail is a spacecraft propulsion system using the interaction between the magnetic field and the solar wind. New numerical analysis model with the finite Larmor-radius effect for the propulsive force generated by a Pure Magnetic Sail spacecraft is proposed. In this analysis model, the kinetic equations of particles are solved in the static electromagnetic field assumed by Flux-Tube method to reduce the computational effort. The Flux-Tube method has been developed originally for the ion engine and the only static electric field is concerned. Our new model can consider the induced magnetic field for the magnetic sail. When we assumed a 500km magnetosphere around the magnetic sail, the propulsive force was estimated as 1500 N by the new model. This force agrees with the force computed by MHD simulation 1600 N and Hybrid-PIC simulation 1560 N. Also, the computational cost of the Flux-Tube method is reduced to about 1/10 of that of Hybrid-PIC simulation.

Masaharu Matsumoto
(JAXA, Japan)

The solar wind plasma behavior and thrust of a magnetic sail under the condition with an interplanetary magnetic field (IMF) are examined by time-dependent, two-dimensional, hybrid Particle-In-Cell (PIC) simulations. Magnetic sail is a propellant less propulsion system proposed for an interplanetary space flight. The propulsive force is produced by the interaction between the magnetic field artificially generated by a superconducting magnet in the spacecraft and solar wind plasma radiated by the Sun. The thrust performance of magnetic sail depends on the ratio of ion Larmar radius of solar wind to the characteristic length of magnetopause. The numerical simulations show that the solar wind behavior and thrust performance under the conditions existing interplanetary magnetic fields are clarified. Although there still exist many phenomena to be clarified and many problems to be overcome in order to realize the system, the magnetic sail is surely worth examining in more detail.

Yoshihiro Kajimura
(ISAS/JAXA, Japan)

Magnetic Sail is a propellantless propulsion system used in space, which is capable of generating a propulsive force by the interaction between the magnetic field generated by a hoop coil and the solar wind. 3D hybrid simulations and scale-model experiments are performed to investigate the plasma flow structure in a magnetosphere with a size of 10 km (ion inertial scale) with various attack angles between the magnetic moment and solar wind plasma flow. We report the characteristics of the magnetosphere, such as the profile of magnetic field, induced current structure and the predicted thrust value obtained by the hybrid simulation, which are compared with the experimental results, when simulations are carried out by considering the ion-neutral collision effect. The hybrid simulation carried out without considering its collision effect gives a thrust value, which can be applied to the thrust evaluation of the magnetic sail in a collisionless interplanetary space.

Kazuma Ueno
(The Graduate University for Advanced Studies, Japan)

Magnetic sail (magsail) is a deep space propulsion system that uses the energy of the solar wind. Magsail spacecraft with a hoop coil could produce an artificial magnetosphere to reflect the solar wind particles approaching the coil. Because of this interaction, the solar wind flow will lose its momentum, and the corresponding repulsive force would exert on the coil to accelerate magsail spacecraft in the solar wind direction. Thrust characteristics of magsail were numerically obtained by Nishida, Kajimura. In this study, the magsail scale model experiment was conducted under 2 conditions of the simulated solar wind and thrust of magsail was measured directly for various tilt angles with a parallelo-pendulum thrust stand in order to check the characteristics of thrust coefficient of magsail for various tilt angle experimentally. The experiment found thrust coefficient is related to the tilt angle of magsail coil and the magnetospheric size. This result agrees well with the previous reports conducted by the numerical simulations.

Takuya Matsumoto
(Shizuoka University, Japan)

Increasing space debris are becoming obstacles for space activities on earth orbits.An Electrodynamic tether (EDT) system is one of the most useful method for removing space debris.The EDT system is a Non-chemical propulsion system that uses Lorentz force produced by the interaction between the tether current and the geomagnetic field as propulsive force.The performance of EDT depends on the performance of electron emitters and electron emitter's potential.Research and development of Field Emission Cathode (FEC) are progressed as an electron source of the EDT system in JAXA.FEC can reduce size and weight of cathode system because working gas which is necessary in hollow cathodes becomes unnecessary in FEC. In this study, we examined the current-voltage characteristic of the FEC and evaluated the relationship between the emitter current-voltage characteristic and the emitter potential.The FEC consists of four parts; an emitter, a mask, a gate and a shield, and the experiment was performed that their potentials were changed at the condition of the same potential difference between the emitter and the gate.In addition, we performed the two dimensional numerical analysis of electron emission from FEC and compared its results with the experimental results.

Bin Wang
(The University of Tokyo, Japan)

The thrust performance of air breathing mode laser propulsion using high power solid laser was experimentally studied on a pendulum impulse measuring system. The momentum coupling coefficient, Cm, is influenced by factors like laser characteristics, focusing condition and thruster nozzle geometry in the propulsion process. For impulse optimization, the Cm of thrusters with various half-cone angles was tested and the obtained result was compared with that of using CO2 laser. Besides, the dependency of Cm on laser focusing number f was also studied, since former investigation shows that f has significantly influence on the initial blast wave forming and evolution history as well as the energy conversion efficiency from laser to that of the blast wave.