Micro Thermal Ignition of High Performance Green Monopropellants

The future of monopropellant thrusters is moving towards energetic high performance green propellants based on hydroxyammonium nitrate (HAN) and ammonium dinitramide (ADN).  One of the impediments in switching from hydrazine to one of these higher performance propellants is the lifetime issue of the catalyst bed.  This class of propellants has high combustion temperatures that severely limit the lifetime of the catalyst material.  To date, the use of these otherwise attractive propellants has been inhibited by the necessity to utilize lower performance formulations in order to obtain reasonable catalyst life. We propose to bypass the catalyst bed all together and investigate thermal ignition techniques suitable for micro chemical monopropellant thrusters.  This component can be combined with Buseks micro-valve technology and a rocket chamber and nozzle. In Phase I we will demonstrate thermal ignition and combustion of one or more of these propellants and determine the feasibility of utilizing these techniques in space thrusters.  In particular, micro ignition will be investigated for future micro chemical rocket development. In Phase II we will integrate the thermal ignition device with a micro chemical combustor and rocket suitable for attitude and control functions.  The thrust goal will be in the range of 100mN and below. BENEFIT: Successful demonstration of the proposed technique should enable more vigorous introduction of high performance (energetic) green propellants space thrusters for integration onto spacecraft.  ACS micro thrusters will be able to utilize green monopropellant formulations with expected specific impulse of 250 seconds, or more, with the successful outcome of this program.  Further, should the thermal ignition concept prove scalable, larger scale thrusters should be able to utilize this ignition source, eliminating the catalyst bed altogether. In addition, non-spacecraft propulsion applications include ICBM post-boost, missile defense applications and chemical processing and injectors for combustion improvements.  )