The temporal evolution of the collisionless, pulsed plasma sheath arou
nd a square bar is studied using a two-dimensional particle-in-cell co
de. It is found that the incident ion dose is peaked near to, but not
on, the corner. This effect is explained physically by considering ion
trajectories across the sheath, yielding an estimate for the dose in
good agreement with the simulation results. The present results are co
mpared to those from a fluid simulation [T. E. Sheridan and M. J. Alpo
rt, Appl. Phys. Lett. 64, 1783 (1994)], and it is found that the fluid
simulation erroneously underestimates the ion dose near the corner of
the bar. (C) 1996 American Institute of Physics.