Iridium catalyst detection by laser induced breakdown spectroscopy

Monopropellant catalytic thrusters have been used for decades in space systems due to their simplicity and reliability. However, the degradation or loss of the catalyst is a major lifetime limiting effect, both for hydrazine fueled systems as well as for newer hydrazine-replacement fueled systems. C...

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Bibliographic Details
Published in:Spectrochimica acta. Part B: Atomic spectroscopy 2022-01, Vol.187, p.106327, Article 106327
Main Authors: Burnette, Matthew, Chambreau, Steven D., Vaghjiani, Ghanshyam L.
Format: Article
Language:English
Subjects:
Analytical methods
Catalysts
Detection
Diagnostic systems
Emission analysis
Gas-phase
Hydrazine
Hydrazines
Ir-supported catalyst
Iridium
Iridium compounds
Laser induced breakdown spectroscopy
Lasers
Monopropellant thruster
Nanosecond pulsed-laser
Spectroscopy
Spectrum analysis
Thrusters
Vapor phases
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Summary:Monopropellant catalytic thrusters have been used for decades in space systems due to their simplicity and reliability. However, the degradation or loss of the catalyst is a major lifetime limiting effect, both for hydrazine fueled systems as well as for newer hydrazine-replacement fueled systems. Currently there is no in-situ diagnostic technique to measure the health status of the catalyst in such devices. Herein, we report a gas-phase diagnostic technique for measuring iridium, a common catalyst material for monopropellant thrusters. Laser induced breakdown spectroscopy was employed to quantify iridium in the gas phase by thermally vaporizing various organometallic iridium compounds to known concentrations within a test cell and observing the resulting iridium optical emission lines that had no interfering lines in the region from other possible emitting species (such as nitrogen, oxygen, and carbon). A limit of detection for the iridium was determined to be 6.21 μmol/L (197 ppm by volume), and this, to our knowledge, is the first report on the quantitative analysis of gas-phase iridium by laser induced breakdown spectroscopy. [Display omitted] •Ir-organometallic compounds were vaporized into the gas phase to known quantities.•LIBS was used to measure the gas-phase iridium LOD as low as 197 ppm (by volume).•LIBS provides for real-time iridium catalyst loss monitoring in thruster plumes.
ISSN:0584-8547
1873-3565
DOI:10.1016/j.sab.2021.106327