Real-Time Fuel Chemistry Analysis for Hypersonic Propulsion System Ground T&E Using Miniature Mass Spectrometry

We propose a novel two-dimensional mass spectrometry (2D-MS) technique based on ion trap arrays for in situ chemical analysis of supercritical fuels (1300 °F, 1200 psia) in scramjet heat exchangers (HEX). This approach will provide real-time information on the state of the conditioned fuel supplied by the facility because of the rapid sampling (<100 ms per sample) and the marked multiplex advantage of 2D-MS. By performing collision-induced dissociation (CID) experiments on different ions simultaneously throughout the trap array, we will rapidly identify and quantify light hydrocarbon cracking products in the HEX without relying on off-line chromatographic techniques (LC- or GC-MS) that require a temperature or pressure drop before analysis. Our technique will also have much greater specificity than low-resolution condensed-phase optical spectroscopy (e.g., FTIR, Raman, and UV/Vis) because the analytes can be easily identified by their mass-to-charge ratios (m/z). In Phase I, we will (1) construct a 2D-MS instrument with a supercritical pyrolysis source, (2) perform quantitative analysis with NIST-traceable standards using mini MS, and (3) demonstrate the capabilities of ion isolation and activation. These proof-of-concept experiments will lead to the construction of a rugged Phase II prototype for in situ quantification of cracking products to <1% error.