Patent ID: 8664861

Claim:
A plasma generator that ionizes a gas using high-frequency discharge within a plasma generating chamber to generate plasma and discharges electrons externally using that plasma through an electron discharge hole, wherein the plasma generator is equipped with an antenna installed in the plasma generating chamber that radiates high-frequency waves and an antenna cover that covers the entire antenna and is comprised of an insulating material, in a plasma generator in which the plasma electrode material that has the electron discharge hole is comprised of conductive material, between the plasma electrode and the antenna, in the cylindrical frame region, a frame cover is provided that has protrusions of different thicknesses that are on the inner side or the inner and outer sides of the frame, the material of the frame cover being an insulating material, the ones of the protrusions near a top surface of the plasma electrode and near the frame cover forming shadows near the top surface of the plasma electrode, the formed shadows configured to prevent accumulation of the insulating material on the plasma electrode, the accumulation being associated with sputtering by the plasma.