Pumping Capacity and Reliability Study on Silicon-Based Cryogenic Micro Pump

摘要

As part of a program to develop a cooling system for satellite instrumentation capable of working at cryogenic temperature, we present herein pumping capacity and material reliability study on a silicon-based cryogenic micro pump which will be applied into a future cooling system to satisfy both active and remote cooling requirements. A test rig for actuating silicon diaphragm, the main functional component of the micro pump, was built by using compressive gas actuation. A Dewar was utilized to cool the diaphragm down to cryogenic temperature. The deflection of silicon diaphragms was measured using both WYKO and ZYGO interferometer. As a result, pumping capacity was derived. The maximum deflection of the silicon diaphragm was found to vary linearly with differential pressure, and the pumping capacity decreased at the cryogenic temperature. Additionally, micro-Raman spectroscopy was employed for stress mapping. As expected, the diaphragm edge centers are most vulnerable to fracture. Finally, a cryogenic fatigue test was conducted. The diaphragm suffered no damage during 10~6 cycles for ～10 days, thereby demonstrating the viability of the silicon-based system for space applications.