TY - JOUR ID - TI - Solving Laplace Equation for Numerical Treatment of Surface Potential Generated by Laser-Solid Interaction حل معادلة لابلاس لمعالجة عددية للجهد السطحي المتولد عن تفاعل الليزر والمادة الصلبة AU - Noor E. Naji PY - 2020 VL - 16 IS - 4 SP - 3 EP - 11 JO - Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية SN - 18132065 23091673 AB - In this work, a numerical treatment to solve Laplace equation was presented in order to determine the electric potential generated at the surface of a solid irradiated by laser pulses. This treatment was based on the finite-difference method (FDM) to give the governing partial differential equation for a particular electromagnetic problem. The experimental data required for the numerical treatment were taken from a solid stainless-steel 304 sample irradiated by 1.069 μm Nd:YAG laser pulses with intensity of 12.4 MW/cm2. The collected results were interpolated as temporal and spatial voltages and they represent the potential over a lateral distance of 9 mm. The treatment has considered two main considerations; charge and hole size. A large change in the potential values appears the interaction zone. This will cause a large electric field. This means that there is a large force acts on the charges leading to a large acceleration and collision and therefore provides good ionization and absorption conditions, which was not considered before. The most important advantage of this method is it can clearly define for the first time the position of the Knudsen layer, which defines the region where the density, velocity and pressure changes dramatically.

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