Mechanism of mass expulsion from the surface of a pure tungsten cathode during dc arc initiationM. A. Sargsyan, D. V. Tereshonok, M. Kh. Gadzhiev and A. S. TyuftyaevEPL, 131 4 (2020) 45002DOI: https://doi.org/10.1209/0295-5075/131/45002