Xie Hui-Qiao, Tan Yi, Liu Yang-Qing, Wang Wen-Hao, Gao Zhe. A collisional-radiative model for the helium plasma in the sino-united spherical tokamak and its application to the line intensity ratio diagnosticJ. Acta Physica Sinica, 2014, 63(12): 125203. DOI: 10.7498/aps.63.125203