There is provided a compound electrode assembly for generating a plasma in a plasma chamber of a plasma discharge device. The compound electrode assembly includes a casing, a discharge electrode and a sealing compound. The casing is made of a dielectric material and includes at least one side wall and an end wall defining a closed end. The discharge electrode is mounted in the casing and is bonded to the end wall. The sealing compound surrounds the discharge electrode and extends within the casing.