The expansion of the pulsed plasma sheath away from a segmented planar
electrode is studied using a collisionless particle-in-cell simulatio
n. One segment of the electrode is biased negatively, while the other
is fixed at ground potential. Cases where the grounded and biased segm
ents are semi-infinite and where the width of the grounded segment is
equal to the ion-matrix sheath width are considered. For the case of t
wo half-planes, one grounded and one biased, it is found that the expa
nding sheath sweeps up ions from above the grounded segment and accele
rates them to the biased segment, forming an are of high ion density e
ncircling a void region at the junction between the segments. Further,
for this case sheath expansion is found to be self-similar as the pro
blem lacks any length scale excepting the sheath width. (C) 1996 Ameri
can Institute of Physics.