In various embodiments, an end block assembly for rotatably mounting a tubular electrode in a processing chamber is provided. The end block assembly includes a receptacle region for receiving a bearing assembly which has a coupling region for coupling the tubular electrode thereto, the bearing assembly of which the coupling region is supported by a sleeve of the bearing assembly. The sleeve is plug-fitted into the receptacle region. The sleeve is joined together from a plurality of segments, the external faces thereof forming a lateral surface of the bearing assembly and at least two segments thereof being formed from dissimilar materials. The external faces of the two segments are mutually aligned such that they are flush with one another.