ABSTRACT
The importance of the glow zone (luminous gas phase) for polymer formation can be seen in the polymer distribution pattern obtained by a small straight-tube reactor (o.d. 11mm) with a radio frequency coil placed in the middle of the tube [3]. In Figure 20.18 deposition rates of plasma polymers of tetrafluoroethylene, given by values of deposition rate divided by monomer flow rate, are plotted against the location. The location is measured from the center of the radio frequency coil in the direction of gas flow. The shaded band shows the extent of glow. The solid line represents the polymer distribution curve for F¼ 5.6 sccm, W¼ 8W (W/FM¼ 1.9 107 J/kg), and the dashed line represents that for F¼ 0.56 sccm,
W¼ 32W (W/FM¼ 7.7 108 J/kg). Thus, the deposition occurs mainly in the glow zone, and any factor that diminishes the glow zone would cause a sharp decrease in the polymer deposition rate.
