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The aim of this paper is to determine electric and physical properties by 2D modelling of glow discharge low pressure in continuous regime maintained by term constant source. This electric discharge is confined in reactor plan-parallel geometry. This reactor is filled by Argon monatomic gas. Our continuum model the order two is composed the first three moments the Boltzmann’s equations coupled with Poisson’s equation by self consistent method. These transport equations are discretized by the finite volumes method. The equations system is resolved by a new technique, it is about the N-BEE explicit scheme using the time splitting method. [ABSTRACT FROM AUTHOR]

In this paper, we present the design of a low cost Q-switched Nd: YAG laser micro-machining system for photo masks fabrication. It consists of: Nd:YAG laser source, beam delivery system, X-Y table, PC, The CCD camera and TV monitor. The synchronization between the laser source and the X-Y table is realised by NI PCI-7342, the two axis MID-7602 and LabVIEW based program. The first step of this work consists of engraving continuous and discontinuous lines on a thin film metal with a 100 μm resolution by using the YG 980 Quantel Q-switched Nd:YAG laser. [ABSTRACT FROM AUTHOR]

In this paper, we present a 1D Particle in Cell with Monte Carlo Collisions model, developed in order to calculate the energy balance in a micro-discharge, under conditions similar to those of a Plasma Display Panel (PDP) cell. The discharge takes place in a xenon-neon (10%–;90%) mixture at 560 torr and for a gap length of 100 μm. The model is used to analyze in details the energy deposition during the discharge pulse. The results show the amount of energy dissipated by ions (collisions in the gas and on the cathode), by electrons (excitation of the different electronic states, ionization), and their variations with the applied voltage. This model will be used in the future to test the approximations of the fluid models which are generally used to optimize PDP operating conditions, and to check whether or not fluid models can correctly predict the trends in the variations of the energy balance with parameters such as voltage, pressure, gas mixture. [ABSTRACT FROM AUTHOR]

Any physical modelling of a circuit-breaker arc therefore requires an understanding of the radiated energy which is taken into account in the form of a net coefficient. The evaluation of the net emission coefficient is performed by the knowledge of the chemical plasma composition and the resolution of the radiative transfer equation. In this paper, the total radiation which escapes from a CH4-N2 plasma is calculated in the temperature range between 5000 and 30000K on the assumption of a local thermodynamic equilibrium and we have studied the nitrogen effect in the hydrocarbon plasmas. [ABSTRACT FROM AUTHOR]

This paper contains our last results concerning the understanding of fundamental processes occurring inside metallic melt pool produced during deep penetration CW Nd-Yag laser welding. When the welding speed varies from a few m/min to a few tens of m/min, one can observe that melt pool behavior has very different and complex hydrodynamics. At low welding speed, the keyhole appears to be quite vertical, embedded inside a large pool that fluctuates due to friction effects induced by the quite vertical ejected plume. At high welding speeds, laser interaction is only localized on the keyhole front whose inclination increases with the welding speed. Induced melt flow then dominates and can generate the humping regime, with severe undercuts. For intermediate welding speeds, it is the interaction of the vapor plume with the melt pool that controls its stability and the final quality of the weld seam. The vapor plume behavior that is ejected from the keyhole, such as its fluctuations or its dynamic pressure, has been also studied as a function of these different operating parameters. Also the behavior of the keyhole and more precisely its front wall is analyzed by using a simple modeling approach that allows us to reproduce its main characteristics such as the penetration depth or the keyhole front wall inclination dependences with operating parameters. The interpretation of these different experiments allows us to confirm that the dynamic pressure of the vapor plume, which is emitted with a variable intensity and direction perpendicularly from the inclined keyhole front, has an essential role for the melt pool stability and its dynamics in deep penetration laser welding. [ABSTRACT FROM AUTHOR]

The power supply of flash lamp-pumped solid-state lasers (such as ND: YAG Laser) basically consists of a trigger circuit, a simmer circuit and the main discharge circuit. All of which are synchronized by a command circuit. To reduce both size and weight of this power supply, we have modelled and designed it by using the concept of the switch mode power supplies. In this paper we will present the modelling of the main discharge transformer and the experimental characterization of the THT used in the trigger circuit. The results of modelling have been validated by an experimental development. [ABSTRACT FROM AUTHOR]

We use in this paper the semi-implicit finite difference operator splitting Padé (OSPD) method for solving the coupled higher-order nonlinear Schrödinger equation which describes the propagation of vector solitons in optical fibers. This method having a fourth order accuracy in space shows good stability and efficiency for the coupled HNLS equations describing vector solitons. We have tested this method for analyzing the behavior of optical pulses in birefringent fibers verifying that the third order dispersion TOD has different effects on the two polarizations and the asymmetric oscillation is significant only in one polarization. [ABSTRACT FROM AUTHOR]

In this paper, we define plasma etch process and we describe two etch equipments used in our clean room: Lam 4500 and Lam 4400. [ABSTRACT FROM AUTHOR]

In this paper a new method using the combination of Neural Networks and the Newton-Raphson algorithm is developped. The technique consists of the use of the solution obtained by Newton-Raphson algorithm between 0.5 and 2.1eV for pure manganese (Mn) and for the amorphous metallic alloy Al88Mn12, to construct two parts of datasets; the first one is used for training the neural network and the second one for the validation tests. The validated neural network model is applied to the determination of optical constants of the two materials Mn and Al88Mn12 in the range of 0.5 and 6.2eV (IR-VIS-UV). The results obtained over all the studied energy range are used to trace back to dielectric function, optical absorption and electronic structure of the same material. By using the partial solution obtained by Newton-Raphson as a database of the neural network prediction model, it is shown that the obtained results are in accordance with those of the literature which consolidate the efficiency of the suggested approach. [ABSTRACT FROM AUTHOR]

There are a number of key technologies involved in the successful design and construction of high power, Carbon Dioxide TEA lasers (Transverse Excitation Atmospheric). These include uniform field electrodes, excitation circuit design including high voltage switching, discharge preionisation and for high repetition, high power applications fast transverse gas flow and the management of acoustic waves. This paper provides a summary of the design aspects of high repetition rate, high average power CO2 TEA lasers. Experimental data measured on high power CO2 TEA laser systems delivering average outputs of several kW and kHz repetition rates will be reported showing the detrimental effect of acoustic waves on laser performance and the improvement that can be achieved through effective acoustic damping measures. [ABSTRACT FROM AUTHOR]