the same perforated stock as is used to form the cylinder s the sterilization chambers shown in fig4 and 6 may be connected to a microwave discharge source typically operating at 2540 mhz in lieu of an rf energy source in this case the concentric perforated metallic cylinder s may be replaced by a single perforated shield in accordance with the operational description given for fig3 fig7 illustrates a third preferred embodiment of the apparatus for practicing the process of the invention in this diagrammatic description the outer chamber wall 21 is again formed of metal such as aluminum or stainless steel and is of similar dimensions to that illustrated in fig4 mounted within the chamber are two planar metallic electrodes 50 and 51 preferably constructed of aluminum which may be coated with insulating aluminum oxide the gap 52 between electrodes 50 and 51 is adjustable by virtue of the movable bottom electrode 50 terminals a and b are connected to the electrodes via an insulating feedthrough 48 the outer end of these terminals may be connected to an rf source not shown in such a way that when terminal b is connected to a ground potential terminal a must be connected to the rf source or vice versa providing for an electrical symmetrical configuration the work load to be sterilized is placed on lower electrode 50 it is important to maintain the distance between the electrodes always smaller than the distance of the rf powered electrode 39 s edge to the grounded chamber 39 s wall this enables a well defined and intense plasma glow to be confined to space 52 between the electrodes and prevents deleterious sparking the electrode.