讨论了He/K混合蒸汽中两步激励产生极紫外(XUV)相干辐射机制中存在的斯托克斯及反斯托克斯跃迁过程.计算了有关跃迁的振子强度、极紫外辐射过程及其竞争过程的受激拉曼散射增益系数和阈值.结果表明,其中64.3 nm极紫外相干辐射的产生过程与其竞争过程相比,具有最大的增益及最小的阈值；但到能级K[3p54ｓ22P1/2,3/2]的反斯托克斯跃迁及到能级K[3p53d(3P)4s22P1/2,3/2]的斯托克斯跃迁将对其中59.8 nm极紫外相干辐射的产生构成严重竞争.

Stokes and anti-Stokes competing processes of producing XUV coherent radiation by two-step excitation in He/K mixture vapour was discussed. The relative transition oscillator strengths, SRS gain coefficients and thresholds were calculated. The processes of producing 64.3 nm coherent radiation has the larger gain coefficient and less threshold compared with those competing processes. But the anti-Stokes processes to level K[3p54s22p1/2,3/2] and the stokes processes to levels K[3p53d(3P)4s2P1/2,3/2] will compet seriously with the producing process of 59.8 nm XUV coherent radiation.