October 1, 2017.
Although one thinks of a thruster as utilizing both a fuel and an oxidizer, as well as an ignition source to release molecular energy, thrusters exist that combine the fuel and oxidizer in a single fluid. These monopropellant thrusters can utilize either an ignition source or a catalyst to release the molecular energy stored within the propellant. Monopropellant thrusters are especially attractive for space flight systems because they only require a single propellant line which reduces systems weight and complexity. Some monopropellant thrusters, including legacy hydrazine thrusters, and newer thrusters using hydrazine replacements, that utilize a heterogeneous catalyst have experienced performance anomalies due to the degradation of the catalyst bed. At the Air Force Research Laboratory, current state-of-health diagnostic techniques ate being developed to better understand this catalyst bed degradation for the new hydrazine replacement monopropellant, AF-M315E. Laser-induced Breakdown Spectroscopy (LIBS) is being used to detect and quantify active catalyst materials in the exhaust plume, such as iridium. Previous work has been unsuccessful in detecting iridium. However, by shortening the delay settings on the camera detector, the spectrometer used in LIBS will be able to pick up more of the emissions from the laser-ablated sample, leading to the detection of iridium.
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Air Force Research Laboratory (AFRL)
This material is based upon work supported by the National Science Foundation through the Robert Noyce Teacher Scholarship Program under Grant # 1418852. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. The research was also made possible by the California State University STEM Teacher and Researcher Program, in partnership with Chevron (www.chevron.com), the National Marine Sanctuary Foundation (www.marinesanctuary.org) and Air Force Research Laboratory.