Resonant Laser Ignition Study of HAN-HEHN Propellant Mixture

Abstract

Resonant laser ignition at wavelengths in the UV and IR was demonstrated for hydroxyl ammonium nitrate (HAN)–hydroxyethylhydrazinium nitrate (HEHN) mixtures. This prototypical ionic liquid propellant was successfully and reliably ignited under confinement with single laser pulses in the mid IR at 2.94 and 10.6 µm. UV wavelengths at 193 and 248 nm were also resonant with sample absorption, but they did not lead to ignition with the available excimer laser pulse energies. The results are consistent with absorption of the IR laser pulse within a short path length, efficient V→T relaxation, and thermal decomposition of HAN that leads to additional chemical reaction and ignition of milligram samples within tens of microseconds.

Keywords:

• Ionic liquid propellant
• Laser ignition

This work was performed at Edwards AFB under a Cooperative Research and Development Agreement (USAF CRADA 07–283-PR-01) between the Air Force Research Laboratory and Northrop Grumman Aerospace Systems (NGAS). Financial and facilities support from AFOSR, EAFB, and the Technology and Emerging Systems Division of NGAS is gratefully acknowledged.