Microwave Ignition of Green Monopropellants

Open Access
Lani, Brian Phillip
Graduate Program:
Aerospace Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
April 22, 2014
Committee Members:
  • Michael Matthew Micci, Thesis Advisor
  • Sven G Bilen, Thesis Advisor
  • George A Lesieutre, Thesis Advisor
  • microwave ignition
  • monopropellant
  • HAN
  • ADN
  • plasma torch
  • ionic liquid
  • microwave igniter
  • ohmic heating
  • green fuels
Research on a microwave ignition system was conducted at The Pennsylvania State University to investigate the possibility of replacing traditional catalyst beds with an alternative ignition scheme for green monopropellants. These highly energetic ionic liquids promise to offer higher performance, safety, energy density, and system simplification if an igniter could be developed to withstand the elevated combustion temperatures. The microwave igniter was built upon previous high-temperature microwave plasma torch research, using an optimized experimental setup to maximize the probability for monopropellant ignition under ambient atmospheric conditions. The ignition system propagates microwave energy at 2.45 GHz through rectangular waveguides in the TE10 mode where it encounters a tunable sliding short and establishes a standing wave. A conducting monopropellant feed line protrudes through the wide walls of the waveguide at an antinode location, amplifies the local electric field, and delivers the required breakdown energy into the propellant at 99% efficiency. Prior research indicates that the microwave energy deposited into the ionic liquid causes it to ignite due to a combination of ohmic heating and ion migration. The primary areas of interest during experimentation focused on: verification of ignition without a catalyst, demonstration of sustained combustion, optimization of propellant flow rate, and extension of torch lifetime expectancy.