Design and Property Analysis of an Ultra-Low Range Pirani Vacuum Gauge for Rocket-sounding

Near-space atmospheric models play a crucial role in the advancement of hypersonic weapons. Current atmospheric models calculate air pressure using altitude back-calculation, but this method often falls short of providing the accuracy required for enhancing aircraft performance. This paper introduces an ultra-low pressure sensor based on Pirani's principle for in-situ sounding rockets. The sensor is constructed on a silicon substrate and employs gold wires as the sensing element, featuring an initial resistance of 1100 Ω. It uses a photosensitive polyimide (PSPI) as the micro-hot plate material, which has an area of 1 mm x 1 mm. To meet the environmental requirements under high overload conditions, an aluminum film is integrated into the structure to improve its resistance to such overloads. Additionally, this paper conducts an analysis of the thermal conductivity model to enhance the structural integrity and performance of the Pirani vacuum sensor. Finally, This paper presents a comprehensive model correlating physical dimensions with detection performance and performs an analysis of thermal stress utilizing simulation software. Additionally, it includes an examination of electromagnetic coupling and thermal field effects on the designed Pirani vacuum sensor. During the rocket launch for deploying a probe sensor for sounding, the sensor experiences a longitudinal overload of 200g. Finite element analysis indicates that the stress exerted on the sensor is 3.2 MPa, significantly lower than the PSPI/Al composite film's Young's modulus. The simulation results indicate that the sensor measurement range can reach 0.037-3634Pa. When the measuring range is 0.1 to 100 Pa, the sensitivity reaches 136.7/log(P). And for a measuring range of 100 to 1000 Pa, the sensitivity is 24.9/log(P). The sensor’s sensitivity, range, and stress characteristics are adequate to meet the requirements for rocket sounding. This sensor offers a valuable approach for full-altitude in-situ detection of atmospheric pressure during rocket sounding, contributing to the establishment of accurate near-space atmospheric models in our country.