对强流相对论电子束抽运氩产生的氩的第三谱带进行了研究。利用反射镜法对其小信号增益系数进行了测量。根据测量的实验装置和方法,建立了近距离探测的精确数学模型。综合运用数值分析方法对该模型进行了求解,得到了小信号增益系数。 The third band of argon produced by the intense relativistic electron beam pumping argon was studied. The small signal gain coefficient was measured by the mirror method. According to the experimental setup and method of measurement, an accurate mathematical model of close-range detection is established. The model is solved by numerical analysis and the gain coefficient of small signal is obtained.