Charge neutrality of fine particle (dusty) plasmas and fine particle cloud under gravity

•In fine particle (dusty) plasmas, the charge neutrality is much enhanced by the existence of fine particles.•The enhancement of charge neutrality generally occurs under microgravity and gravity.•Structure of fine particle clouds under gravity is determined by applying the enhanced charge neutrality.

The enhancement of the charge neutrality due to the existence of fine particles is shown to occur generally under microgravity and in one-dimensional structures under gravity. As an application of the latter, the size and position of fine particle clouds relative to surrounding plasmas are determined under gravity.