The mechanisms for population inversion among the excited states of He I and Ne I in regenerative sooting discharges have been investigated as a function of the geometry and the physical parameters of the graphite hollow cathode sources. The effect of the state of sooting of the hollow cathode, the gas pressure and the role of the cycling of i dis on the population inversion of the excited He I and Ne I levels have been investigated.
The photo-electrical behavior of n-Si/orange dye/conductive glass and p-Si/orange dye/conductive glass sandwich type cells were investigated. In these cells crystal silicon of n-type and p-type and conductive glass (CG) electrodes were employed and the aqueous solution of organic dye (OD) was used as an electrolyte in the distilled water. Under filament lamp illumination, photo-induced open-circuit voltage and shortcircuit current exponentially dropped with time for the n-Si/orange dye/CG cell. In the p-Si/orange dye/CG cell, the photovoltaic effect was not observed. The n-Si/OD/CG cell showed high photo-electrical response under illumination. In the light-voltage/current conversion, these cells behaved as a differentiator and exhibited charge-storage properties.
Carbonaceous vapour created by nitrogen and helium discharges in graphite hollow cathodes has been investigated to identify the mechanisms for CN formation. The characteristics of hollow cathode discharge have been exploited to provide the two-energy-regime electrons that initiate a complex process for the production of ions and metastable atoms and molecules of He and N2. These introduce the sputtered carbon species Cx (x ≥ 1) from the graphite cathode. Dominant among the Cx species are C1 and C2 that are excited and participate in inter- and intra-species collisions. CN, therefore, is the direct by-product of reactions between sputtered C and N2. From the optical emission spectra the level densities of nitrogen and helium were recorded during the cycling of discharge current idis of the graphite hollow cathode. The emission spectra are dominated by strong emission bands of CN (violet system Δν = −1, 0, +1) and N2 (2nd positive system), along with the atomic lines of He and C. We have identified and suggested a mechanism for the formation of CN in nitrogen plasmas in graphite hollow cathodes.
A method of adding RAM directly in silica phenolic composite was tested. Due to direct incorporation of RAM, the resultant composite not only can show microwave absorption at normal conditions but can sustain this capability at high heat fluxes. Such RAM added composite becomes more applicable for materials which are exposed to high temperatures. Two different RAM added silica fibre phenolic composites were developed and their RF-absorptions were compared with pure silica fibre phenolic sample. It was found that depending on the type of RAM their RF-absorption can be enhanced. Strength and ablation properties of the resultant composites were also found to alter with the addition of RAM in the composite.
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