High-power electrostatic levitation linear motor for ultra-clean and vacuum environment

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In this research, we have developed high-power electrostatic linear levitation motor for vacuum condition. Since electrostatic motor does not emit magnetic field it is suitable for EB applications, such as electron microscope and EB lithography system, which are some of the most important applications using vacuum condition.In the first step of the research, we have developed electrostatic linear motor stage specialized for vacuum use, with which characteristics of non-levitation electrostatic motor in vacuum condition was investigated. The developed stage generates almost the same thrust force in vacuum as in the normal condition. We have developed new electrostatic linear encoder which is embedded into the electrostatic motor. Using the developed linear encoder, we perform positioning control in vacuum condition.Next, we have studied electrostatic levitation motor, in which high-power electrostatic motor technology and electrostatic levitation technology are combined. We proposed several principles for levitation motor and revealed their characteristics theoretically. To verify the proposed principles, we have developed two-DOF prototype, which has one degree of freedom for thrust direction and one for levitating direction. The developed prototype demonstrated levitated driving motion in vacuum condition. The slider was levitated under the stator with a gap of 200μm and moved with a speed of 20mm/s in the thrust direction. Also, we performed positioning control with keeping levitated state. These results verify the proposed principles of electrostatic levitation motor.