FlashSim: A novel particle-in-cell numerical model for vacuum surface flashover simulation based on finite element method. - Liu, Hao-Yan; Sun, Guang-Yu; Liu, Yue-Lin; Zhang, Shu; Qi, Chang-Chun; Zhou, Sheng; Li, Wen-Rui; Zhang, Guan-Jun (Computer Physics Communications, 2025)