Status Of The Electrostatic Levitation Furnace In The Iss - Evaluation Of Sample Position Control

An electrostatic levitation furnace for microgravity experiments has been developed and transferred to the International Space Station (ISS). This electrostatic levitation method utilizes Coulomb force between a charged sample and surrounding electrodes for sample position control. On the ground experiment, amount of charge accumulated on the sample surface has to be 10(-9) to 10(-10) C to levitate it against gravity. In microgravity, it was found that a sample can be stably handled even though the amount of surface charge is 10(-13) C. When the control parameters are properly chosen, the position stability of the sample during heating can be maintained better than +/- 100 mu m. This stability is good enough to precisely measure the sample temperature by a pyrometer as well as to measure the sample volume by an image analysis.