计算了放电等离子体极紫外光刻光源中，不同等离子体长度条件下的收集效率，实验上研究了等离子体长度对Xe气放电极紫外辐射的影响。结合本系统光学收集系统设计参数和理论计算结果，给出了不同等离子体长度条件下中间焦点处13.5 nm(2%带宽)光功率。结果表明等离子体长度为3~6 mm时毛细管光源中间焦点光功率和尺寸最优。

The plasma size has important influence on the power of the extreme ultraviolet source at the intermediate focus (IF point) and the design of the illumination system for a capillary discharge extreme ultraviolet source. The collection efficiency was calculated under different lengths of the plasma theoretically. Moreover, the spectra of the Xe plasma under different lengths of the plasma were obtained by a Rowland spectrometer. By combining the theoretical and experimental results with the design of the collectors in this system, the 13.5 nm (2% bandwidth) emissions at the IF point were calculated under different lengths of the plasma. The results show that the optimal power at the IF point and the optimal size of the plasma can be obtained when the length of the plasma is 3-6 mm.