实验研究了放电频率、电脉冲能量、碎屑缓冲气体流量等极紫外光源参数对极紫外辐照损伤测试系统聚焦光束性能的影响。测试结果表明:极紫外辐照损伤测试系统焦深为±1.5 mm;聚焦光斑尺寸及单脉冲能量随光源电脉冲能量的增大而明显增大,受光源放电频率影响较小;典型工作条件下,光斑尺寸在0.79~1.44 mm之间,聚焦光束单脉冲能量在112.09~436.06 μJ范围内;在200 Hz、5.0 J时聚焦光束单脉冲能量最高为436.06 μJ,聚焦光束单脉冲能量密度最高达到31.53 mJ/cm 2,在1500 Hz、4.6 J时聚焦功率密度达32.87 W/cm 2;最优缓冲气体Ar气工作气压为1~2 Pa,此时聚焦光束单脉冲能量最优。该测试研究可为极紫外辐照损伤测试研究中系统参数优化及设置提供指导参考。

Herein, the effect of extreme ultraviolet (EUV) source parameters, such as discharge frequency, electric pulse energy, and buffer gas pressure, on the focused beam performance of the EUV radiation-damage-test system was studied. Results show that the focal depth of the EUV radiation-damage-test system was approximately ±1.5 mm. Although the discharge frequency has no significant effect on them, the focal spot size and single pulse energy increased with increasing electric pulse energy. Under typical working conditions, the range of focal spot size was 0.79-1.44 mm and that of single pulse energy was 112.09-436.06 μJ. The highest single pulse energy and single pulse energy density were 436.06 μJ and 31.53 mJ/cm 2, respectively, with 200-Hz source discharge frequency and 5.0-J electric pulse energy. Moreover, the highest power density of 32.87 W/cm 2 can be achieved with 1500-Hz source discharge frequency and 4.6-J electric pulse energy. The optimal buffer gas pressure (Ar) was 1-2 Pa, and the corresponding single pulse energy of focused beam is the best. This study can provide guidance for the optimization and setting of the system parameters for the study of EUV radiation damage.