Triple-sheath structures and temporal evolution of the dust grain-charge in
a dusty plasma with the trapped dust grains are investigated by numerical
calculation. Trapped dust grains modify the shape of the sheath and give ri
se to the triple-electric field structures. The sheath width becomes narrow
er than that of the Boltzmann distributed dust grains due to the existence
of trapped dust grains. It is found that trapped dust grains play an import
ant role in the formation of the new sheath structure and shorten the charg
ing time. (C) 2001 American Institute of Physics.