采用精密的侧吹辅助气体调节和控制装置，实验研究了等离子体控制的各种工艺参数；采用光电晶体管检测熔池表面及小孔内等离子体光强变化；从理论上分析了等离子体控制的机理．结果表明：当辅助气体流量变化时，等离子体控制效果呈现三个区间．无论采用何种气体，只要辅助气体的操作压力稍大于金属蒸气压力，等离子体即被最佳控制 A precise side-blown auxiliary gas regulating and controlling device was used to study the various process parameters of plasma control. The phototransistor was used to detect the change of light intensity in the surface of the molten pool and in the small holes. The plasma-controlled mechanism. The results show that when the auxiliary gas flow rate changes, the plasma control effect presents three intervals. Regardless of the gas used, the plasma is optimally controlled as long as the operating pressure of the auxiliary gas is slightly greater than the metal vapor pressure