In a distributed antenna array reactor, microwave H2-CH4-CO2 plasmas with admixture of N2 used for the low-temperature deposition of nanocrystalline diamond (NCD) films are studied by in situ infrared laser absorption spectroscopy (LAS) and optical emission spectroscopy techniques. The experiments are carried out in order to analyze the dependence of temperatures and species densities as a function of the admixture of nitrogen. The evolution of the concentrations of the methyl radical (CH3), and of five stable molecules (NH3, HCN, CH4, C2H2, and CO), are monitored in the plasma processes by LAS using tunable lead salt diode lasers and external-cavity quantum cascade lasers (EC-QCL) as radiation sources. OES is performed simultaneously to obtain complementary information about (i) the degree of dissociation of H2 precursor gas, (ii) the gas temperature and therefore (iii) the density of atomic hydrogen, a key species in the chemistry of NCD deposition plasmas. The species temperatures are not significantly affected by the nitrogen addition. The concentrations of the various species are in the range between 1011 to 1015 molecules cm−3. HCN and CO are the major products in the plasma besides atomic hydrogen. The analysis of the nitrogen and carbon mass balances of the measured species shows that in addition to NH3 and HCN other nitrogen containing species are produced in the plasma which were not probed. It is shown that the formation of HCN consumes C atoms that can be provided from hydrocarbon species and from the deposition of carbon-containing films on the reactor walls, which results in a decrease of the measured densities of hydrocarbon species.

This paper presents a general model to carry out a small signal stability analysis in electrical power systems (EPSs) that operate in unbalanced conditions. The classic traditional approach is based on a phase representation where it is supposed that the triphasic electric grid does not suffer any variations during its operation. With the presence of unbalances in transmission lines and loads, it is necessary to develop a general model that allows answering the needs and challenges with which modern electric systems must deal. The present work firstly intends to address the three-phase representation of an EPS, including the controllers. The proposed model is applied to a classical test system, a three machine-nine bus system, considering all the dynamic and algebraic variations associated with angular stability analysis. The proposed approach to small signal stability analysis shows results that differ from the classical analysis. The results are backed up with time domain simulations, and therefore, these results could be used in the calculation of the controllers that operate in unbalanced multimachine systems.

Plasma polymer thin films are pinhole-free and have also a high cross-linked structure. These kinds of films are insoluble in mild acids and bases and present good adhesion on different materials. These features make the films relevant for industrial applications and are used in different fields such as electronics, mechanics, biomedics, electrics, protective coatings and others. The plasma polymer hexamethyldisilazane/argon films (ppHMDSN/Ar) were deposited on substrates which were placed between two stainless steel parallel plate electrodes fed by a radio-frequency source operated at 13.56 MHz and 50 W at a total pressure (HMDSN and argon) of 80 mTorr. The negative bias of 10 kV and 10 Hz pulse were used for ion implantation. The structural characterization of the films was done by FTIR spectroscopy. The contact angle for water was of approximately 98°and the surface energy of 30 mJ/m 2 which represents a hydrophobic surface, measured by goniometric method. The refractive index of these materials presents values from 1.56 to 1.64 measured by ultraviolet-visible technique. The thickness of the samples was measured by profilometry and showed values from 96 to 210 nm for different deposition conditions resulting in deposition rates from 4.8 to 10.5 nm/min. Hardness values ranging from 0.9 to 2.6 GPa were found for the films measured by nanoindentation technique.

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