Corona discharge configurations

With the help of complementary surface analysis techniques such as XPS, Static SIMS and AES, we have been able to show how a short (23 msfilms leads to a slight oxidation of the surface as well as to the formation of N2 containing species. These modifications are necessary for the improvement of the adhesion observed with a scotch-tape test. However, the presence of oxygen is not the only factor responsible for a good adhesion, since the AES profiles of die deposited aluminium, show the same oxidized interface in the case of the non treated metallized polymeric film. The films are pretreated in a corona discharge configuration (hollow electrode-grounded cylinder) and the aluminium is deposited onto the film in situ. 

Metallized polypropylene (PP) is used today in many different fields such as automotive, decoration, electrical. In order to obtain a good adhesion between the aluminium and the polymer a pretreatment of the film prior to the metallization is necessary. Indeed, the very extreme surface of the polymer has to be modified in order to prepare it to a good adhesion with the metal. Thus the polymer is placed in a low pressure plasma of nitrogen with a corona discharge configuration of electrodes, and the metallization is carried out in situ after the pretreatment in nitrogen. This process, which simulates an industrial polymer film treatment has proven a great efficiency for very short treatment times (23 ms) (1).However, the mechanisms responsible for the improvement of adhesion are not totally explained yet. 

Corona discharges have been investigated extensively for NO removal [38-54], The effect of electrodes configuration, electrical circuit, gas composition and flow rate were studied. When the discharge was operated in pulsed mode, the influence of pulse rise time, duration, and repetition frequency, as well as the effect of the voltage polarity on NO conversion, were considered by numerous authors. 

Various mass spectrometer configurations have been used for the detection of explosives, such as ion traps, quadrupoles and time-of flight mass analyzers and combinations as MS/MS systems. The ionization method is usually APCI with corona discharge [24, 25]. An example is given in Figure 20, which shows the schematic diagram of an explosive mass spectrometer detector [25]. It is based on an ion trap mass analyzer, an APCI source with corona discharge and a counter-flow introduction (CFI) system. The direction of the sample gas flow introduced into the ion source is opposite to that of the ion flow produced by the ion source. 

In an attempt to find most efficient corona discharge device for xerographic-spectroscopic purposes, it seems necessary (as the author [4] did) to try various device configurations utilizing sharp pin(s) and wire(s) as the corona emitter. The schematic sketches of three corona devices are shown in Fig. 5.2. 

Figure 4-93. General schematie of a pulsed corona discharge in the wire-cylinder configuration with preheating.

Figure 4-94. Configuration of a pin-to-plate pulsed corona discharge (a) schematie of the electrodes and mounting blocks and (b) cross-sectional view of the assembled plasma reactor and gas streams. In the figures, a, anode plates b, cathode plates c, mounting block d, holes for the gas flow e, holes for a connecting post f connection wings.

Figure 4-95. Schematics of (a) wet and (b) spray configurations of the pulsed corona discharges.

Figure 11-69. Photo of the 10-kW pulsed corona discharge (organized in the water-spray configuration) through a window of the Mobile Environmental Laboratory.

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