Miniaturized Low-Power Piezo Microvalve for NanoSat and CubeSat Propulsion

In space propulsion applications, an increasingly unmet need is compact, low-power, precision flow regulating valves. Propulsion for increasingly small spacecraft is limited by the availability of such valves. Although much work on miniaturizing valves has been performed using microfabrication approaches, few of these efforts have resulted in technologies suitable for propulsion. Busek proposes a piezo-actuated microvalve suitable for continuous regulation of gas, resolved to flowrates of better than 10^-3 sccm, enabling precision control of cold gas thrusters, resistojets, and low-power ion and Hall thrusters. Busek's fluid microvalve, developed for colloid thruster operation on NASA's ST7 project, has demonstrated resolving fluid flow to 2.5 picoliters/s over the 0-60 microliter/s regime for 1 atm source pressure (delta p); preliminary microvalve gas tests indicate the ability to resolve gas flows to 10^-2 sccm over the 0-.25 sccm regime for similar delta p. The valve architecture, when used with smaller available orifice diameters, provides 1-2 orders of magnitude lower flowrates. The focus of the effort shall be improvement of several design aspects in Busek's existing valve design, upgrading the design for high pressure gas service, and novel repackaging into a volume of approximately 4cm^3.