Design and Experimental Validation of a High-Precision Pressure Regulation Unit for Cold-Gas Micro-Propulsion

The next generation of space-based gravitational wave observatories, such as LISA, TianQin, and Taiji, requires ultra-precise drag-free control and therefore micro-propulsion systems with thrust noise below 0.1μN/Hz. This paper presents the design and experimental validation of a high-precision pressure regulation unit (PRU) for cold-gas micro-propulsion, guided by a requirement-driven analysis of pressure-induced thrust-noise sensitivity. A first-order mapping translates the mission-level thrust-noise constraint into a subsystem-level pressure-stability target, yielding an upper bound of about 50Pa/Hz and an adopted design budget of about 40Pa/Hz. On this basis, a dual-stage architecture integrating solenoid pre-conditioning and piezoelectric fine regulation is developed. Stochastic simulations indicate that thermal drift dominates at very low frequency, whereas pressure fluctuation is the dominant contributor in the main 0.01–1Hz control band under the adopted budget. Experimental validation under three operating modes shows that solenoid-only regulation provides the smallest performance margin, that the piezoelectric stage significantly improves outlet stability, and that the integrated dual-stage configuration achieves the strongest pressure-noise suppression in the mission-relevant sensitive band. These results provide a subsystem-level pressure-conditioning basis for the further development of high-precision cold-gas micro-propulsion systems for future drag-free missions.