The invention is directed to a corona charging device having a powder feed
with an outlet. The device has an internal charging cavity having an
inlet and a charged powder outlet. The powder feed outlet is positioned
at the internal charging cavity inlet. The device is adapted to guide a
powder stream downstream from the powder feed outlet to the charged
powder outlet. The device also includes a corona charger having one or
more needle projections (each having a tip) positioned and adapted to
facilitate a corona ion flow from the needle projections and intersecting
the powder stream. The device also includes a rotating ground electrode
adapted to be charged or grounded to attract the corona flow from the
needle projections, and to rotate segments of the ground electrode
between the internal charging cavity and a ground electrode cleaner.