采用高速摄影对姿控级小推力气氧气甲烷火箭发动机开展了点火过程观测研究，研究了火花塞类型、高压火花塞缩进及混合比对点火过程的影响。结果表明：发动机启动过程可分为点火过程与过渡过程2个阶段，其中点火过程则可进一步细分为火花产生、火核生成、火核生长、充满燃烧室、火焰往复波动、火焰稳定6个步骤；而过渡过程可细分为燃料流量增加、燃烧混合比下降、向稳态过渡。试验结果表明，在点火能量充足的条件下，起火熄火主要由混合比控制，试验验证的可靠混合比范围为2.01~18.3，此外点火的瞬时混合比还影响火花到火焰稳定的时间，通常低混合比对应该时间更长。总地来说，火花塞类型对点火特性影响不大；而长缩进通常意味着更长的火核传播时间和较短的生长时间。

Ignition process in the reaction control thruster fueled by gaseous oxygen and gaseous methane is experimentally observed with high-speed photography. The effects of the spark plug type， recess of the high-voltage plug， and mixture ratio on the ignition process are studied. The results show that the start-up process of the engine includes two sections， ignition process and transition process. The ignition process involves six phases in turn： spark formation， fire core formation， fire core grow-up， filling， fluctuation， and stable flame. However， during the transition process， with the increase of the fuel flow rate， the mixture ratio decreases to the stable condition. Experimental studies show that with enough spark energy， the flame is primarily controlled by the mixture ratio， and the range of the mixed ratio 2.01-18.3 has been validated. On the other hand， the duration from spark to stable flame is determined by the instantaneous mixture ratio at the spark time. In conclusion， the effect of the spark plug type does not play a significant role， while long recess of the spark plug always produces long duration of fire core propagation and short grow-up duration.