Laser Ignition of a Research 200N RCS LOx/GH2 and LOx/GCH4 Engine

An extensive test campaign has been conducted to assess the feasibility of the implementation of laser ignition in cryogenic RCS and OMS engines. The 200N research thruster used for this purpose is a single-coaxial injector element combustion chamber. A table-top laser with a system of mirrors and a lens was used as ignition system. This paper reports location of energy deposition, levels of energy deposited and associated ignition probabilities for the propellant combinations LOx/GH2 and LOx/GCH4. Gas-breakdown (plasma) ignition and ablation ignition were both tested. Minimum energies were lower for LOx/GH2 (72 mJ) than for LOx/GCH4 (92 mJ) and lower for ablation (14.5 mJ for LOx/GH2 and 61.7 mJ for LOx/GCH4) than plasma ignition. Regions for successful energy deposition for 100% ignition success were also identifed. Finally it has been established that the dynamic of flame growth determines ignition overpressure in a laser ignited chamber. A separate paper has been dedicated to the discussion of the influence of pre-ignition conditions and flow fields on altitude ignition.