In this study, a plasma torch is used as an igniter for hybrid rockets. This igniter contains no explosive and can be used multiple times to restart a rocket. This plasma torch is not cooled with water or other fluids for easy use in space. Ignition experiments were conducted using a small lab-scale unchoked hybrid rocket. FT-0070 wax, FT-105 wax, polymethylmethacrylate, and polyethylene were used as fuels, and gaseous oxygen was used as the oxidizer. These fuels were ignited successfully by using the plasma torch with an ignition assistant wax fuel, which was mounted at the igniter exit. Subsequently, the rocket was ignited twice in succession by using the plasma torch. Finally, the plasma torch was used to ignite a lab-scale choked hybrid rocket with a rated chamber pressure of 3 MPa during firing tests. The ignitions were achieved by combustion of the ignition-assistant fuel vapor or melted droplets produced by the plasma torch. Thus, we demonstrated that a plasma torch igniter is suitable for use in space flights.
plasma torch, igniter, hybrid rocket