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Silica nanoparticles were made via the gas-to-particle conversion of tetraethylorthosilicate (TEOS) in co-flowing turbulent methane-oxygen-enriched non-premixed flames. The effects of fuel velocity, oxygen concentration, flame residence time, and temperature distribution on the characteristics of the silica nanoparticles were investigated. The flame length was measured by OH chemiluminescence, using an intensified charge-coupled device (ICCD) camera. The primary particle diameter of the silica nanoparticles was quantitatively measured by transmission electron microscopy (TEM). Particle number concentration, as well as the geometric mean diameter and standard deviation, were measured by a scanning mobility particle sizer (SMPS) spectrometer. Adiabatic temperatures according to oxygen concentration and mixture fraction were calculated from thermodynamic equilibrium calculations, considering chemical species using CHEMKIN EQUIL code. Flame temperature, velocity, and turbulent intensity distributions were calculated using Fluent software adapted to the presumed probability density function (PDF) model, considering chemical species in the turbulent non-premixed methane-oxygen-enriched flame burner without including the particles. For each oxygen concentration condition, the flame residence time, average primary particle diameter, and geometric mean diameter decreased as the fuel velocity increased. Typically, agglomerates of silica nanoparticles were made on averaged primary particle diameters of 9-15 nm and geometric mean diameters of 60-100 nm, according to the oxygen concentration, which varied from 50% to 100% for first jet velocities of 40 and 70 m/s.

Several junction formation methods are known to make HgCdTe photovoltaic devices. Ion implantation is the most popular process, but it needs additional thermal annealing process. In-situ junction formation by several epitaxy techniques is the advanced process, but is still hard to fabricate. In this paper, for the first time, hydrogenation technique for p-to-n type conversion in HgCdTe has been studied to fabricate HgCdTe photovoltaic infrared detector. H 2 plasma generated in an inductively coupled plasma (ICP) system was used to hydrogenate p-type HgCdTe wafer. Using the ICP system, damages given to the HgCdTe wafer could be minimized. Junction depth measured by differential Hall measurement was able to be adjusted from 2µm to 20µm. Hydrogen atom profile was measured by secondary ion mass spectroscopy (SIMS) and doping profile was measured by differential Hall measurement. Similar depth profile was found between the hydrogen profile and doping profile. It suggests the diffused hydrogen atom is the source of the type conversion. Several experiments were also taken with vacancy-doped and gold-doped p-type HgCdTe wafers. Type conversion was observed only in vacancy-doped HgCdTe wafer, not in golddoped HgCdTe wafer. This means that junction formation by hydrogenation is not due to the damage by the hydrogen plasma, but due to the diffusion of the hydrogen atoms. By applying the hydrogenation process to vacancy-doped wafers, LWIR diodes were successfully fabricated. Currentvoltage (I-V) characteristics of hydrogenated Hg 0.79 Cd 0.21 Te diodes were also measured. Average RoA products of these diodes were about 50 Ωcm 2 . Device uniformity and stability were also tested. The characteristics of the hydrogenated devices did not changed under the baking condition of 80°C over 10 days.

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In this study, a multi-jet burner with an extremely intense flame was designed for oxy-fuel combustion. The flame characteristics were experimentally and numerically investigated at a fixed overall flow rate of fuel and oxygen and at oxygen feeding ratios (OFRs) of 0.25, 0.5, and 0.75, which gives an overall equivalence ratio of 0.909. The measured temperature profiles were compared to values predicted by numerical simulations, and good agreement was observed. To determine the cause of differing flame height at various OFRs, the iso-surfaces of the fuel, oxygen mole fraction, and the mixture fraction in the physical space were investigated using the numerical data. These results can be understood through an analysis of the scalar dissipation rate, which signifies the mixing characteristics of the fuel with the oxygen and the destruction of scalar fluctuations by turbulent mixing. The flame height seen at an OFR of 0.25 was the lowest because the peak scalar dissipation rate was higher than at other flow conditions. This information is important to reduce the flame height for the control of an intense flame.