Ionic Liquids

Ionic Liquids for Electric Propulsion

Funded by the Air Force Office of Scientific Research's Space Power and Propulsion Directorate and the Air Force Research Laboratory's Electric Propulsion Group, this research is a combined experimental and numerical modeling effort to understand how ionic liquids such as hydroxylammonium nitrate (HAN) and Han-based propellants decompose and ionize. The goals of this research are to:

Determine the decomposition products of HAN and HAN-based propellants when exposed to vacuum pressures, elevated temperatures, and strong electric fields
Use residual gas analysis (RGA) to experimentally measure the steady state decomposition products of HAN and HAN-based propellants
Use optical emission spectroscopy to measure the steady state ionization products of HAN and HAN-based propellants
Use laser induced fluorescence, Raman spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy to determine the decomposed products of HAN and HAN-based propellants
Determine the reaction pathways for decomposition of HAN and HEHN using quantum chemistry

Illustration of optical excitation and detection system used for LIF on HAN decomposition. An image of the fluorescence chamber with the laser beam is shown.

Plasma tube with a white solid deposited on the inner surface due to HAN decomposition.

Preliminary results:

Previously accepted pathways for HAN decomposition do not hold for decomposition at vacuum pressures and elevated temperatures.
Several methods have been designed to decompose HAN in vacuum with heat addition. Resultant decomposition products have been measured using RGA, Ramen spectroscopy, FTIR spectroscopy, and NMR spectroscopy.
Decomposition products of HAN were measured as N2O, NO, NO2, N2 and H2O with RGA and quantum chemistry.
Also evidence of HNO, OH, NH3NO4, NH3, and HNO3

Papers and Conference Proceedings

Kidd, F.G., Taylor, N.R., and Lemmer, K.M., “Decomposition of hydroxylammonium nitrate in a low pressure flowing thermal capillary system,” Journal of Molecular Liquids (2018). DOI: 10.1016/J.MOLLIQ.2018.04.065.

Taylor, N. and Lemmer, K., “Laser-induced Fluorescence Analysis of HNO Generated from the Thermal Decomposition of Hydroxylammonium Nitrate,” 10th Spacecraft Propulsion Joint Army, Navy, NASA, Air Force Conference, Tampa, FL, December 2019.

Taylor, N. and Lemmer, K. “On the Formation of Ammonium Nitrate from the Thermal Decomposition of Hydroxylammonium Nitrate: Quantification of NH3 and HNO3,” 10th Spacecraft Propulsion Joint Army, Navy, NASA, Air Force Conference, Tampa, FL, December 2019.

Kidd, F. and Lemmer, K., “Plasma Chemistry of Partially Ionized Hydroxylammonium Nitrate: Interactions with H2O, NO, and NO2 Ions,” 23rd International Symposium on Plasma Chemistry, Montreal, Canada, July 30-August 4, 2017.

Kidd, F.G., Baird, M.J., Neff, G.A., Lemmer, K.M., “Experimental Vaporization and Computational Modeling of Ionization of Hydroxylammonium Nitrate in Vacuum Conditions,” IEPC 2015-237, 34th International Electric Propulsion Conference, Kobe, Japan, July 6-10, 2015.

Lemmer, K.M., Kidd, F.G., Neff, G.A., “Preliminary Setup and Simulation for the Vaporization and Ionization of Ionic Liquids,” 62nd Joint Army Navy NASA Air Force (JANNAF) Propulsion Meeting/10th MSS/8th LPS/7th SPS Joint Subcommittee Meeting, Nashville, TN, June 1-5, 2015.