Abstract:
A novel approach to crystal growth from a solution has been introduced by combining the electrostatic levitation technology with the sample rotation capabilities of a single-axis ultrasonic levitator. In the current implementation, a 22-kHz standing wave is used to position and to rotate an electrostatically levitated 0.4-cm-diam droplet along a horizontal axis. Current studies are investigating the specific capabilities for rotation control (rotation rate and rotation axis orientation) as well as the trajectory of an immersed liquid and solid sample within the levitated solution droplet. The physical mechanism for torque generation is currently believed to be the aerodynamic drag from acoustic streaming flows external to the levitated droplet. The results of internal and external flow visualization studies are presented. [Work funded by NASA.]