is schematically illustrated in the accompanying figure the drum wise plasma chamber 1 is made of a stainless steel and can be evacuated by means of the vacuum pump 2 connected thereto to a vacuum of 0 001 torr or below of the pressure the plasma chamber 1 is also connected to a gas inlet 3 opening inside the chamber 1 it is optional according to need that the end of the gas inlet 3 is divided in manifold in three branches in the figure with an object to ensure uniformity of the atmospheric conditions inside the plasma chamber 1 inside the plasma chamber 1 a rotatable cylindrical electrode 4 made also of a stainless steel is provided as supported vacuum tightly in a cantilever manner by a shaft penetrating the face plate of the plasma chamber 1 in such a manner that this cylindrical electrode can be rotated by means of the electric motor 5 approximately coaxially with the drum wise plasma chamber 1 at a controllable velocity of rotation this cylindrical electrode 4 is electrically grounded through the wall of the plasma chamber 1 in order to facilitate control of the temperature of the plasma treatment a heating or cooling medium can be passed through inside of this rotatable cylindrical electrode 4 further a rod like electrode 6 which serves as the power electrode is provided inside the plasma chamber 1 in parallel with the axis of rotation of the.