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1: Final installation and layout of Uni-Solar Ovonic´sOvonic´s Thin Film Flexible Solar PV panels. Photographer: Ken Fields.
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This thesis presents an investigation into arcing and parasitic plasmas in large area plasma enhanced chemical vapour deposition reactors. Two types were investigated: RF breakdown in millimetric gaps in absence of plasma (e.g. dark space shielding), in a millibar pressure range, and RF hollow cathodes in glow discharges. RF breakdown curves (volta...
Contexts in source publication
Context 1
... properties of the generated plasma depend on the density and type of the neutral gas, the material and shape of the boundaries and the amount and method of energy input. Plasmas exist over an enormous range of parameters, as shown in figure 1.2, which shows laboratory and space plasmas over a range of 7 orders of magnitude for the electron temperature T e , and 21 orders of magnitude for the plasma density n. In this work we will mainly deal with weakly ionised, electro-positive plasmas, (hatched area in figure 1.2), where we can use equation 1.3 with only one or two species. ...
Context 2
... exist over an enormous range of parameters, as shown in figure 1.2, which shows laboratory and space plasmas over a range of 7 orders of magnitude for the electron temperature T e , and 21 orders of magnitude for the plasma density n. In this work we will mainly deal with weakly ionised, electro-positive plasmas, (hatched area in figure 1.2), where we can use equation 1.3 with only one or two species. ...
Context 3
... coupled plasmas use an an- tenna emitting high-frequency RF radiation to induce electric currents in the plasma, thereby supplying it with energy. Figure 1.3 shows a schematic of an inductively coupled reactor: the antenna is wound around the top of the vacuum chamber, producing a plasma that reaches down to the substrate. ...
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... avoid this, it is necessary to use an RF matching network or matchbox to bring the impedance of reactor plus matching network to match the 50 Ω output impedance of the generator. There are various types of matching networks available -in this case a high-pass "T" matching net- work was used (see figure 3.19) [29]. The network, a modified Advanced Energy matchbox, consisted of a water-cooled 128 pH inductance, a Comet 50-500 pF variable vacuum capacitor at the source side and a Comet 5-170 pF variable vacuum capacitor at the load side. ...
Context 5
... results in Figures 4.13, 4.15 and 4.16 can be understood by visualising the way breakdown happens for parallel plates on the right and left sides of the minimum of the breakdown curve (which depends on pressure times gap-width). In both cases, initial free electrons (from cosmic rays or other external sources) are accelerated by the RF electric field. ...
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... hydrogen, the simulation is somewhat less accurate, consistently pre- dicting somewhat higher breakdown voltages at the right-hand side of the breakdown curve (see figure 5.17). Furthermore, the left-hand branch of the 4 mm parallel breakdown simulation shows lower pressures at high voltages than the experiment. ...
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Next to the sound velocity, the absorption coefficient of acoustic waves in fluids is an important thermodynamic property. Although measurements of acoustic absorption have been conducted in the past, most of them negate the influence of parasitic dissipative effects or rely on either analytical or empirical compensation. A typical method for measu...
Citations
... The electrons are lost by two dierent channels: they recombine on the walls; volumetric collisions becomes a possible non-negligible source of recombination for electrons in certain gases at pressures above a few hundreds Pa. If the production rate exceeds the loss rate, then distance between the electrodes, electric eld, gas composition, gas pressure) [53]. ...
... This is due to the fact that, as the pressure goes down, the electrons lose less energy by collisions. They can travel a greater distance in the electric eld and have a greater chance of ionizing the gas [53]. In region II, the breakdown voltage is relatively at. ...
... In region II, the breakdown voltage is relatively at. In this region the electron loss to the walls increases due to their higher oscillation amplitude in the electric eld [53]. Here the exact range of region II is only approximative since there is only two measurement points in the vicinity of this region. ...
