Papers by Keyword: Plasma Plume

Abstract: The performing features of workpiece cathode (W electrode) and the orificed hollow cathode (P electrode) in the triple-cathode plasma surface alloying system are studied. Current densities of the W cathode and the P cathode are obtained under the conditions of the different voltages and the different chamber pressures, based on which current transmitting densities of the orifice of the P cathode are obtained and the conditions of plasma plume flow occurrences are, combined with the observe records of experiments, discussed and analyzed.

Abstract: Appling a high voltage to the dielectric barrier discharge device in a coaxial geometry in flowing argon, a uniform plasma plume is generated at one atmospheric pressure. The waveforms of discharge current and the applied voltage are investigated and results indicate that both the intensity and duration width of the discharge current pulse increase with increasing the applied voltage. The gas temperature of the plasma plume is investigated by using an infrared thermometer. The gas temperature of the plasma plume are functions of gas flow rate, peak value and the frequency of the applied voltage. Results show that the gas temperature increases with increasing the applied voltage or its frequency, while it decreases with increasing the gas flow rate. A qualitative explanation is given for the variance of gas temperature as functions of the experimental parameters by analyzing the waveforms of the discharge current and the applied voltage.

Abstract: This paper mostly summarizes experimental device of laser-induced plasma and taking pictures of plasma plume. The progress in the experimental study on laser-induced plasma was discussed. The experimental apparatus include the laser、delay device; The system of the plasma radiation gathered and radiation received were reviewed. In addition, photos of plasma plume were discussed; at last, dynamic process of laser-induced plasma plume explosion was discussed.

Abstract: Chemical cleaning has been used for several decades as a surface preparation technique for diffusion bonding. Here we present a theoretical investigation that examines the effect of changes in the process parameters when a laser is used as an alternative to chemical cleaning for surface contaminant removal. Here a theoretical model is described that includes laser beam attenuation in the plasma plume and its effect on evaporation of the material. Using the model, a comprehensive analysis of the effect of different fluences and other parameters for a KrF Excimer laser is presented. Calculations were carried out for a range of peak fluxes from below the ablation threshold to fluxes of the order of 9 x 1012 W/m2. The predicted effects on evaporation, melt depth and surface temperature are reported, illustrated by a number of surface topographic images from preliminary experiments. Finally, optimal parameters for cleaning according to the theoretical investigation are proposed.