The dynamics of the plasma-erosion-opening switch is characterized with the aid of 2D three-fluid simulation using the anthem implicit simulation code, for plasma fill densities ranging from 1012 to 6×1013 cm−3 with 45-ns pulse rise times. The switch behavior is found to depend sensitively on the threshold for electron emission at the cathode, on the detailed structure of the anode with its injection holes, and on the possible action of anomalous resistivity in the fill plasma. Closest agreement with NRL GAMBLE I experimental results is obtained with the combination of zero electric field threshold emission at the cathode, an ‘‘open’’ anode, and modest anomalous resistivity.