Characterization and electrical ignition of ADN-based liquid monopropellants

Monopropellant hydrazine rockets are today widely used in missiles and spacecrafts. Hydrazine is however highly toxic, volatile and carcinogenic, and thus costly safety measures are required. During the last years there has been an increasing interest in Europe and in the USA to find a possible substitute, since a non-toxic monopropellant will offer substantial cost savings. ADN based liquid monopropellants seems to be a promising alternative to hydrazine, being substantially easier to handle and having a 10 % higher specific impulse, and up to 60 % higher density-impulse, compared to hydrazine. To be able to replace hydrazine, ADN-based monopropellants must be as easy to ignite. Hydrazine and ADN-based liquid propellants are very different, and thus new ignition methods must be developed. This report presents the results from electrical ignition experiments of liquid ADN-propellants were the propellant is resistively heated by conducting an electric current through the propellant. It was found that substantially less electric energy was needed than expected. This is due to local phenomena close, or on the surface, of the electrodes. Very fast ignition was obtained, in most cases below 2 ms, and the lowest amount of electric energy needed was approximately 20 J. The pulsed-power supply required is estimated to weight of the order of one kilogram if getting the electric energy from the on-board electric power supply. These promising results show that this type of ignition method is feasible.