Experimental study of a laser ignited thruster with a porous injector head

This paper reports the investigation of the laser ignition of a breadboard thruster with a porous injector head. Ignition tests were performed for 80 and 980 mbar combustion chamber pressure before injection of propellants, for the two combinations LOX/H₂ and LOX/CH₄ and for two ignition locations. The propellant injection, the resulting flow field, the ignition, and the flame development were monitored by a combined Schlieren-and OH*-diagnostics setup for each of the eight test configurations. The minimum laser pulse energies for successful ignition of 0.8 mJ up to 17.9 mJ were determined and depend strongly on the fuel used and the location of ignition. The tests proved the compatibility of the laser ignition technology and the porous injector concept which widens the applicability of laser ignition to this injector design for LOX/H₂ and LOX/CH₄ for sea level and in space pressure conditions.