onto a rewind reel 25 drive for the reels 24 and 25 is controlled to provide a predetermined residence time between the plates 10 and within the plasma for any given web element the fig7 embodiment of the invention provides an electrically grounded screen 30 to support the web w as it is drawn between the opposite material flow slits 23 this configuration attenuates an accumulated electrical charge on the web and also structurally supports the traveling web as a pressure differential membrane between an upper gas inlet chamber and a lower vent chamber this swept flow differential assures an internal saturation of the web w by the gas supported plasma in a first operational example of the invention the fig1 described physical apparatus sustained a glow discharge plasma in one atmosphere of helium at standard temperature with a separation distance d of 3 0 cm between plates 10 the plates were energized with a 4 4 kv rms working potential holding these parameters constant r f frequency was increased as an independent variable as the dependent variable fig2 charts the corresponding breakdown current phase angle similarly fig3 charts the power required to sustain the plasma at the respective r f frequencies in a second operational example of the.