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The electric fields under high-voltage direct current (HVdc) transmission lines and the ions produced by corona affect each other greatly. This paper presents an iterative method to calculate ion flow fields under HVdc bipolar transmission lines in the presence of wind. Both the electric fields and the ion densities are calculated by integral equation method. The method is fast and stable. The results are in good agreement with the experimental data. The ion flow fields under a ± 800-kV bipolar direct current (dc) transmission line are analyzed. [ABSTRACT FROM AUTHOR]

A model of deicing with Nd:YAG and CO2lasers for simulation using ANSYS software is presented. Experiments with a 300-W, 1-ms, 60-Hz Nd:YAG laser and a 500- to 2000-W cw CO2laser are reported. The Nd:YAG laser is considered as a volume thermal source, and the CO2laser as a plane thermal source. The model and the simulation results can describe both Nd:YAG and CO2laser deicing well. The results of the simulation and experiments suggest that the melting rates for the two lasers are almost equal at the same laser power density. So are the melting efficiencies. The hard and transparent ice irradiated by the Nd:YAG laser becomes opaque and loose, because the thermal stress is distributed in the body of the ice, while the ice irradiated by the CO2laser is still transparent and hard, because thermal stress hardly occurs. So the laser with characteristics of high output power and large ice absorbing length can be selected for the power line laser deicing system, and Nd:YAG laser is more appropriate for power-line deicing than CO2laser. [ABSTRACT FROM AUTHOR]