Hiroyuki Kawamoto

Numerical and experimental investigations have been carried out on transport of particles in an electrostatic travelling field. A three-dimensional hard-sphere model of the distinct element method was developed to simulate the dynamics of particles. Forces applied to particles in the model were the Coulomb force, the dielectrophoresis force on polarized dipole particles in a non-uniform field, the image force, gravity and the air drag. Friction and repulsion between particle–particle and particl

Electrohydrodynamic deformation of water surface was investigated in a pin-to-plate gas discharge system that consisted of a pin electrode made of metal and an ion-conductive water electrode. In the condition of a lower applied voltage than the corona threshold, because an extremely small electrostatic attractive force, a Coulomb force in the order of 10 µN, was induced, water lifted up in the order of several tens of micrometres at the centre. Over the threshold voltage corona discharge took pl

Basic research has been carried out on the transport of a liquid drop and a soft body in an electrostatic travelling field. A conveyer consisting of parallel electrodes was constructed and a four-phase electrostatic travelling wave was applied to the electrodes to transport the drop on the conveyer. The following were clarified by the experiment. (1) Drops and soft bodies can be transported by virtue of the travelling wave in an insulative liquid that is insoluble to the drop, because the drop w

Experimental research was carried out on transport of particles and particle size classification in a traveling electrostatic field. Particle conveyors which consisted of parallel electrodes were constructed and a four phase traveling electrostatic wave was applied to the electrodes to transport particles on the conveyor. The following points were clarified by the experiment: (1) Particles were transported almost linearly with time. Transport rate was also linear with applied voltage but a thres

Removing lunar dust adhering to astronaut space suits is critically important for long-term lunar exploration. We are developing an automatic cleaning system that uses electrostatic force. It employs an alternating electrostatic field that forms a barrier on the surface of fabrics. In this study, we applied single-phase rectangular voltage to parallel wire electrodes stitched into the insulating fabric of space suits. By applying mechanical vibration and operating the system in a vacuum, we real

To realize a long-term lunar exploration, it is essential to develop a technology for transporting lunar soil for in situ resource utilization. We are developing a particle transport system that utilizes electrostatic traveling waves. The conveyer consists of parallel electrodes printed on a plastic substrate. Four-phase rectangular voltage is applied to the electrodes to transport particles on the conveyer. Mechanical vibration was applied to the conveyer to transport particles more efficiently

A fundamental investigation was conducted on electrostatic ink jet phenomena. High voltage was applied between an insulative capillary tube filled with ion conductive water and a metal plate electrode. A large water drop was formed and dropped from the tube at the dark discharge under conditions of appropriate voltage application and water level. The diameter of the drop was about one millimeter. At the beginning of corona discharge, however, a Taylor cone of water was formed at the tip of the t

The removal of lunar dust adhered to an astronaut’s spacesuit is critical for long-term lunar exploration. The author is developing a cleaning device that utilizes electrostatic force; this system employs a combination of electrostatic capture and electrostatic transport of dust. High voltage is applied between a screen electrode and an aluminum film deposited on a Mylar sheet positioned under the surface fabric of the spacesuit. By means of electrostatic force, dust adhered to the fabric is cap

To realize reliable and autonomous regolith sampling from asteroids in space, the author has developed a new sampling system that uses electrostatic force. This system uses a combination of electrostatic capture and transport of particles. High voltage is applied between parallel screen electrodes of the sampling device. As a result of the electrostatic force, particles are captured by the screen electrodes. The captured particles are then transported by an electrostatic traveling wave and trans