Abstract: A triode apparatus with magnetic enhancement for dry processing semiconductor wafers and the like. A conductive substantially cylindrical chamber contains a cathode that is connected to a first source of AC power. A wafer stage mounted on the inside of the chamber wall is connected to a second source of AC power. The chamber has means for connection to a reference voltage potential. Means for generating a magnetic field perpendicular to the electric field generated between the chamber walls and the cathode is also provided.