Flight engineering to conduct a quantitative measurement of the piston effect in CO2 critical fluid was developed based on the interface limitation of the TEXUS sounding rocket. The function of the flight facility was designed to observe the detailed dynamics of the piston effects as: 1) the emission of the piston wave from the heater boundary, 2) the propagation in the bulk critical fluid, 3) the reflection at the opposite boundary against the heater, and 4) the thermal relaxation due to side walls. The precise density measurement system was developed using the multi-mantle type temperature regulating system and the IR Mach-Zehnder interferometer. The piston wave was generated in the pulses of 5-200 μs by heating the Nichrome thin film heater. The newly developed flight apparatus showed the comparable precision with the on-ground experimental facility.
