An annular apparatus is provided for generating accelerated electrons, wherein ions from a glow discharge plasma may be accelerated onto the surface of an annular second cathode and electrons emitted by the annular second cathode may be accelerated towards an annular electron exit window by a second electrical voltage applied between the annular second cathode and an annular second anode, wherein a housing is designed as a first cathode; a first anode comprises a number of wire-like electrodes which extend completely or partially through an annular evacuable space, and wherein a second reservoir contains a hydrocarbon-containing compound which may be admitted into the evacuable space through the at least one first inlet.

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