A 2D two-temperature chemical non-equilibrium model considering both cathode and anode space-charge sheath is applied to investigate the plasma–electrode interaction in a laminar argon DC plasma torch working at atmospheric pressure. In order to validate the model, the predicted arc voltage is compared with experimental values under different working conditions, and a reasonable agreement is obtained. The distributions of arc characteristics in the plasma column and electrode regions of a DC arc plasma torch are analyzed in detail. Moreover, the effects of thoriated tungsten, pure tungsten and non-uniform thoriated tungsten cathodes on the plasma characteristics inside the DC plasma torch are investigated. It is found that a constricted arc attachment with the highest current density is obtained at the non-uniform cathode, leading to the largest velocity and electric potential drop in the plasma column. The pure tungsten cathode produces the highest temperatures and heat flux along the cathode surface, which is caused by the largest arc voltage and intense space-charge sheath heating. The temperature and heat flux density on the thoriated tungsten cathode are the lowest, leading to a diffuse distribution of current density. The results indicate that the different cathodes can exert an important influence upon the plasma behavior near the cathode. Furthermore, the torch exit parameters are also slightly different due to their different arc voltages and overall input power.

应用考虑阴极和阳极空间电荷鞘的二维双温度化学非平衡模型来研究在大气压下工作的层流氩直流等离子体炬中的等离子体 - 电极相互作用。为了验证模型，将预测的电弧电压与不同工况下的实验值进行比较，得出合理的一致性。详细分析了直流电弧等离子炬的等离子柱和电极区域的电弧特性分布。此外，研究了钍钨、纯钨和非均匀钍钨阴极对直流等离子体炬内等离子体特性的影响。发现在非均匀阴极处获得具有最高电流密度的收缩电弧附件，导致等离子体柱中的最大速度和电势降。纯钨阴极沿阴极表面产生最高的温度和热通量，这是由最大的电弧电压和强烈的空间电荷鞘加热引起的。钍钨阴极上的温度和热流密度最低，导致电流密度的扩散分布。结果表明，不同的阴极可以对阴极附近的等离子体行为产生重要影响。此外，由于电弧电压和总输入功率不同，割炬出口参数也略有不同。这是由最大的电弧电压和强烈的空间电荷护套加热引起的。钍钨阴极上的温度和热流密度最低，导致电流密度的扩散分布。结果表明，不同的阴极可以对阴极附近的等离子体行为产生重要影响。此外，由于电弧电压和总输入功率不同，割炬出口参数也略有不同。这是由最大的电弧电压和强烈的空间电荷护套加热引起的。钍钨阴极上的温度和热流密度最低，导致电流密度的扩散分布。结果表明，不同的阴极可以对阴极附近的等离子体行为产生重要影响。此外，由于电弧电压和总输入功率不同，割炬出口参数也略有不同。