High Reliability Cryogenic Piezoelectric Valve Actuator

Piezoelectric actuators constructed with the "smart material" PZT offer many potential advantages for use in NASA cryo-valve missions relative to conventional electromagnetic-driven mechanical actuators. In addition to their very high resolution (a benefit to nanopositioning applications for many years), they offer potential advantages for miniaturization and reduction of heat load as compared to electromagnetic actuators. While some notable successes have been achieved in adapting piezoelectric actuators to cryogenic applications, the technology needs further innovation, development, and validation in order to reach a readiness level that can realistically be considered for use in future missions. Variation in strain rate with temperature, CTE mismatch relative to structural materials, and problems with protective coatings make use of PZT in cryogenic environment difficult. Thorough characterization of existing PZT material and proposed improvements to coatings and structural materials used with PZT transducers offer the potential for higher performance and reliability. With these improvements, it will be practical to use piezoelectric actuators in applications such as high force cryo-valves that can not presently be considered.