Laser-Induced Particle Jet And Its Ignition Application In Premixed Combustible Gases

A hot particle jet is induced as a laser pulse from a free oscillated Nd:YAG laser focused on a coal target. The particle jet successfully initiates combustion in a premixed combustible gas consisting of hydrogen, oxygen, and air. The experiment reveals that the ionization of the particle jet is enhanced during the laser pulse. This characteristic is attributed to the electron cascade process and the ionization of the particles or molecules of the target. The initial free electrons, which are ablated from the coal target, are accelerated by the laser pulse through the inverse Bremsstrahlung process and then collide with the neutrals in the jet, causing the latter to be ionized.

Using different carrier gases to control AlN film stress and the effect on morphology, structural properties and optical properties

On the metalorganic chemical vapour deposition growth of AlN, by adjusting H-2+N-2 mixture gas components, we can gradually control island dimension. During the Volmer - Weber growth, the 2-dimensional coalescence of the islands induces an intrinsic tensile stress. Then, this process can control the in-plane stress: with the N-2 content increasing from 0 to 3 slm, the in-plane stress gradually changes from 1.5 GPa tensile stress to - 1.2GPa compressive stress. Especially, with the 0.5 slm N-2 + 2.5 slm H-2 mixture gas, the in-plane stress is only 0.1 GPa, which is close to the complete relaxation state. Under this condition, this sample has good crystal and optical qualities.

Abatement of waste gases and water during the processes of semiconductor fabrication

The purpose of this article is to examine the methods and equipment for abating waste gases and water produced during the manufacture of semiconductor materials and devices. Three separating methods and equipment are used to control three different groups of electronic wastes. The first group includes arsine and phosphine emitted during the processes of semiconductor materials manufacture. The abatement procedure for this group of pollutants consists of adding iodates, cupric and manganese salts to a multiple shower tower (MST) structure. The second group includes pollutants containing arsenic, phosphorus, HF, HCl, NO2, and SO3 emitted during the manufacture of semiconductor materials and devices. The abatement procedure involves mixing oxidants and bases in an oval column with a separator in the middle. The third group consists of the ions of As, P and heavy metals contained in the waste water. The abatement procedure includes adding CaCO3 and ferric salts in a flocculation-sedimentation compact device equipment. Test results showed that all waste gases and water after the abatement procedures presented in this article passed the discharge standards set by the State Environmental Protection Administration of China.

Carbonaceous aerosols in PM10 and pollution gases in winter in Beijing

IEECAS SKLLQG

Retrieval of Electron Return Time from High-order Harmonics Generated in a Mixture of He and Ne Gases

In terms of single-atom induced dipole moment by Lewenstein model, we present the macroscopic high-order harmonic generation from mixed He and Ne gases with different mixture ratios by solving three-dimensional Maxwell's equation of harmonic field. And then we show the validity of mixture formulation by Wagner et al. [Phys. Rev. A 76 (2007) 061403(R)] in macroscopic response level. Finally, using least squares fitting we retrieve the electron return time of short trajectory by formulation in Kanai et al. [Phys. Rev. Lett. 98 (2007) 153904] when the gas jet is put after the laser focus.

Application of acetone and dimethyl ether chemical ionization reagent gases to structural analysis

Acetone and dimethyl ether( DME) have been shown to be reagent gases of exceptional utitlity and versatility for the characterization of a variety of class of organic compounds. The fragmentation mechanisms of the adduct product ions, formed by ion/molceule reaction of the substrate with the ionized gases, have been studied and substantiated by experiments with acetone-d(6) and DME-d(6).

STUDIES ON THE SULFONATION OF POLY(PHENYLENE OXIDE) (PPO) AND PERMEATION BEHAVIOR OF GASES AND WATER-VAPOR THROUGH SULFONATED PPO MEMBRANES .3. SORPTION BEHAVIOR OF WATER-VAPOR IN PPO AND SULFONATED PPO MEMBRANES

Water vapor absorption and desorption by poly (phenylene oxide) (PPO) and sulfonated PPO (SPPO) membranes were studied at a constant temperature of 30-degrees-C and over a broad range of water activity (0.05 less-than-or-equal-to a < 0.8) by the weighing

Coflow jets with large velocity difference - a new aerodynamic principle of flame stabilization and combustion intensification

A new aerodynamic principle of flame stabilization and combustion intensification, the coflow jets with large velocity difference, is described. One or more small high-velocity jets of air or steam, injected off the axis and in the same direction as the low-velocity main fuel-air flow into the combustor, create a large recirculation zone of high turbulence intensity in which the combustibles and high temperature gases are effectively mixed, so that stable and intensive combustion can be maintained even for fuels with poor ignition. A pulverized coal combustor based on the principle mentioned above is shown to be characteristic of excellent combustoom and a simple structure. A number of precombustors of this type are in operation at some power stations and industrial boilers of China. Using such precombustor, successtul startups and part-load operation of the boilers have become available under conditions of unpreheated air and low-grade coal with volatiles as low as 15% and ash content as high as 30%. This principle shows good promise as an attractive new technology of combustion.

Ab Initio Study Of Zno-Based Gas-Sensing Mechanisms: Surface Reconstruction And Charge Transfer

Density functional theory (DFT) calculations were employed to explore the gas-sensing mechanisms of zinc oxide (ZnO) with surface reconstruction taken into consideration. Mix-terminated (10 (1) over bar0) ZnO surfaces were examined. By simulating the adsorption process of various gases, i.e., H-2, NH3, CO, and ethanol (C2H5OH) gases, on the ZnO (10 (1) over bar0) surface, the changes of configuration and electronic structure were compared. Based on these calculations, two gas-sensing mechanisms were proposed and revealed that both surface reconstruction and charge transfer result in a change of electronic conductance of ZnO. Also, the calculations were compared with existing experiments.

Numerical and Experimental Investigation On The Prevention of Co Deflagration

The exhaust gases from industrial furnaces contain a huge amount of heat and chemical enthalpy. However, it is hard to recover this energy since exhaust gases invariably contain combustible components such as carbon monoxide (CC). If the CO is unexpectedly ignited during the heat recovery process, deflagration or even detonation could occur, with serious consequences such as complete destruction of the equipment. In order to safely utilize the heat energy contained in exhaust gas, danger of its explosion must be fully avoided. The mechanism of gas deflagration and its prevention must therefore be studied. In this paper, we describe a numerical and experimental investigation of the deflagration process in a semi-opened tube. The results show that, upon ignition, a low-pressure wave initially spreads within the tube and then deflagration begins. For the purpose of preventing deflagration, an appropriate amount of nitrogen was injected into the tube at a fixed position. Both simulation and experimental results have shown that the injection of inert gas can successfully interrupt the deflagration process. The peak value of the deflagration pressure can thereby be reduced by around 50%. (C) 2008 Elsevier Ltd. All rights reserved.

Space-frequency coupling, conical waves, and small-scale filamentation in water

Numerical simulations of fs laser propagation in water have been made to explain the small-scale filaments in water we have observed by a nonlinear fluorescence technique. Some analytical descriptions combined with numerical simulations show that a space-frequency coupling mainly from the interplay among self-phase modulation, dispersion and phase mismatching will reshape the laser beam into a conical wave which plays a major role of energy redistribution and can prevent laser beam from self-guiding over a long distance. An effective group velocity dispersion is introduced to explain the pulse broadening and compression in the filamentation. (c) 2005 American Institute of Physics.