Fiber optic hydrogen sensor leak detection system for launch vehicle applications

Abstract

This paper describes the successful test of a multi-point fiber optic hydrogen sensor system during the static firing of an Evolved Expandable Launch Vehicle (EELV)/Delta IV common booster core (CBC) rocket engine at NASA's Stennis Flight Center. The system consisted of microsensors (optrodes) using a hydrogen gas sensitive indicator incorporated onto an optically transparent porous substrate. The modular optoelectronics and multiplexing network system was designed and assembled utilizing a multi-channel opto-electronic sensor readout unit that monitored the hydrogen and temperature response of the individual optrodes in real-time and communicated this information via a serial communication port to a remote laptop computer. The sensor packaging for hydrogen consisted of two optrodes --one doped with an indicator sensitive to hydrogen, and the other doped with an indicator sensitive to temperature. The multi-channel hydrogen sensor system is fully reversible. It has demonstrated a dynamic response to hydrogen gas in the range of 0% to 4% with 0.1% resolution and a response time of ≤15 seconds. The sensor package was attached to a custom fiber optic ribbon cable, which was then connected to a fiber optic trunk communications cable (standard telecommunications-grade fiber) that connected to the optoelectronics module. Each board in the expandable module included light sources, photo-detectors, and associated electronics required for detecting hydrogen and temperature. The presentation would discuss the sensor design and performance data under field deployment conditions.

Integrated optical hydrogen and temperature sensor on silicon-on-insulator platform

“…They are very compact, immune from electromagnetic interference, and also free from the risk of electrical sparking [3][4][5][6][7]. A distinct advantage of any integrated optics platform is its ability to integrate many different sensor channels on the same chip.…”

Review on hydrogen leak detection: comparison between fiber optic sensors based on different designs with palladium

“…19 The colorimetric material consisted of inserted Pd into a porous substrate. This micromirror sensor showed a very good reproducibility and reliability.…”