Inlet Pressure Effects on the Catalytic Ignition Behavior of N 2 O Monopropellant Thruster

Nitrous oxide ([Formula: see text]), a green and nontoxic monopropellant, shows significant potential for micro- and nanosatellite propulsion. The catalytic ignition behavior of [Formula: see text] decomposition is critical to achieving reliable thruster operation. This study experimentally investigates how inlet pressure affects the catalytic ignition characteristics of a 100-mN-class thruster equipped with a [Formula: see text] catalyst bed. Results show that, within the experimental temperature resolution of 50°C, the minimum preheating temperature required for reliable catalytic ignition was approximately 450°C across the tested inlet-pressure range. However, inlet pressure significantly affects the subsequent ignition-establishment process and steady-state decomposition behavior. Higher inlet pressures accelerate the propagation of the high-temperature reaction zone and promote more rapid establishment of self-sustained decomposition, which subsequently improves apparent decomposition efficiency and characteristic velocity. At an inlet pressure of 0.8 MPa, the decomposition efficiency reaches 82.78%. These findings clarify the distinct roles of inlet pressure during ignition triggering, ignition establishment, and steady-state operation, providing insights for optimizing operating conditions and catalyst-bed design of [Formula: see text] monopropellant thrusters.