Acoustic levitation at high temperatures in the microgravity of space

Abstract

Acoustic levitation of a small specimen is obtained in the energy well produced by a single axis arrangement consisting of a sound source and a small acoustic reflector. At high temperatures, the acoustic forces are generally insufficient to levitate a specimen except in the microgravity environment available in space. A single axis acoustic levitator (SAAL) has been built to levitate a specimen inside a high-temperature furnace where it may be heated, melted, cooled, and solidified while being positioned without physical contact. The acoustic field configuration in such a containerless processing device has been analyzed and the expected levitation or positioning forces are calculated for the specific case of the NASA-SAAL experimental hardware as flown on the Space Shuttle on the STS-61A mission. This experiment successfully levitated and processed three samples at temperatures from 600 °C to 1550 °C. Experimental data are presented and the results compared with those predicted. [Work supported by NASA.]

Ultrasound Noncontact Particle Manipulation of Three-dimensional Dynamic User-specified Patterns of Particles in Air

“…Noncontact particle manipulation (NPM) techniques are of critical importance in many engineering applications such as lab-on-chip [1], container-less processing [2], measurement [3], transport [4], chemical analysis [5], and manufacturing engineered materials [6]. Commonly, NPM techniques involve manipulating particles dispersed in a liquid or gas host medium into a userspecified pattern, or along a user-specified trajectory, by means of an electric [7,8], magnetic [9,10], or ultrasound field [11][12][13][14][15][16] created by a set of transducers.…”

Acoustic levitation with self-adaptive flexible reflectors

“…[1][2][3][4] So far, acoustic levitation has found more and more applications in the fields of drop and bubble dynamics, [5][6][7][8] chemical analysis, 9,10 materials science, 11,12 noncontact measurements, [13][14][15] life science, 16,17 and space science. 18 Generally, a single-axis acoustic levitator is mainly made up of a couple of emitter and reflector, both of which are rigid and fixed during levitation process. In the previous works, rigid reflector has been carefully studied by optimizing its reflecting surface, and as a result, the acoustic levitation force is enhanced greatly.…”