A novel system for containerless electrostatic levitation (ESL) in μg environment (µg-ESL)

abstract

Containerless measurements of thermophysical properties on liquids allow high accuracy measurements over a wide temperature range with unmatched precision. Nevertheless, the experimental data suffer from gravitational effects, like a non-spherical shape or buoyancy convection on the levitating liquid. This can be overcome by using electrostatic levitation technique in μg, as it has been done earlier with electromagnetic levitation (EML) in the TEMPUS facility.

In this study the advantages of ESL shall be combined with those from μg condition. In state-of-the-art, ground based ESL systems gravity is compulsory for levitation. However, these ground based experiments face several problems due to heavy unidirectional disturbance by earths’ gravitational field. In contrast to this, the absence of a continuous unidirectional force in μg is a benefit for scientific output as well as a new challenge in technical issues.

Our newly designed electrode system is carefully optimized for handling disturbances in three-dimensions so as to perform under μg conditions. Our last step in the process of building up the μg ESL is to complete the position control algorithm, which is strictly necessary in outlook of the planed rocket flight. We therefore ask for an opportunity to carry out these calibrations in the drop tower. Although the available μg-time is not sufficient for measurement of the samples physical properties, it is absolutely sufficient to (1) start the levitation, (2) check whether the control algorithm is able to stabilize the sample in the field and (3) repetitively adjust the controlling parameters in-between drops. If tests are successful the μg ESL is ready for thermophysical measurements with extended μg-time on sounding rockets or orbital platforms.

experiment year: 2015
number of drops: 12

experiment year: 2014
number of drops: 6