Publications (2)4.71 Total impact
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Article: Modeling and application of plasma charge current in deep penetration laser welding
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ABSTRACT: Plasma charge current distribution during deep penetration CO <sub>2</sub> laser welding was analyzed theoretically and experimentally. The laser-induced plasma above the workpiece surface expands up to the nozzle, driven by the particle concentration gradient, forming an electric potential between the workpiece and the nozzle due to the large difference between the diffusion velocities of the ions and the electrons. The plasma-induced current obtained by electrically connecting the nozzle and the workpiece can be increased by adding a negative external voltage. For a fixed set of welding conditions, the plasma charge current increases with the external voltage to a saturation value. The plasma charge current decreases as the nozzle-to-workpiece distance increases. Therefore, closed-loop control of the nozzle-to-workpiece distance for laser welding can be based on the linear relationship between the plasma charge current and the distance. In addition, the amount of plasma above the keyhole can be reduced by a transverse magnetic field, which reduces the attenuation of the incident laser power by the plasma so as to increase the laser welding thermal efficiency. © 2003 American Institute of Physics.Journal of Applied Physics 07/2003; · 2.17 Impact Factor -
Article: Controlling the plasma of deep penetration laser welding to increase power efficiency
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ABSTRACT: During deep penetration laser welding, the plasma over the keyhole absorbs beam energy and reduces the power efficiency. The thermal movement of laser produced plasma is analysed theoretically and experimentally. A method to increase the electric current in the plasma is put forward. The principle and feasibility of controlling the plasma by electric and magnetic fields are discussed. An experimental procedure involving elevating the nozzle during laser welding is used to evaluate the effect of increasing the power efficiency by driving away the charged particles. The power efficiency increases with increasing magnetic field intensity. There is an optimal electric field intensity at which the power efficiency reaches its highest value. It is indicated that by applying proper electric and magnetic fields the charged plasma particles can be driven away and the power efficiency is increased.Journal of Physics D Applied Physics 10/2001; 34(21):3145. · 2.54 Impact Factor
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2001
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Tsinghua University
- Department of Mechanical Engineering
Beijing, Beijing Shi, China
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