Improved Electrodynamic Particle-Size Sorting System for Lunar Regolith

AbstractIn situ resource utilization (ISRU) of lunar regolith is indispensable for the success of large-scale and long-term human lunar explosions at lower costs. Many new technologies must be developed to realize efficient ISRU. Because particle sorting is one of the essential processes of ISRU, a unique technology has been developed using the balance between electrodynamic and gravitational forces. First, a sorting system using an electrodynamic standing wave was developed. The particles on the parallel-line electrodes were agitated by the electrodynamic force created by the application of a standing wave, and floated small particles at a high altitude were collected in a box located above the electrodes. The experiment and numerical calculation indicated that although a high collecting position was preferable for sorting small particles, a large number of small particles hardly reached a high position and a high yield was not attained. Next, an improved sorting system that uses a traveling wave instead of a standing wave was developed to mitigate the incompatibility. When a four-phase high voltage is applied to the vertically supported parallel-line electrodes, an electrodynamic traveling wave is formed above the electrodes, forcing small regolith particles to move upward at a high position, while large particles are apt to fall. Additionally, particles were fed through a vibrating sieve to break off the aggregated particles. Finally, an averaged particle size of 12 μm and 30% in a yield of particles less than 10 μm particles was attained. The system would be suitable for space applications because it is simple, lightweight, has low power consumption, and does not require any mechanical drive or consumables.