【摘要】 运用电磁学和热流体学的方法研究了直流大阳极喷嘴长电弧通道等离子体炬中电弧的行为，并通过实验证明了温度梯度与电场梯度作用于流体时所产生的特殊现象；结果表明：电弧弧柱的高温效应剧烈排斥冷气流的混入，使ＣＶＤ过程受到抑制。新产生的胶体粒子在热泳现象作用下逐渐沉积于通道内壁上。改变不同气体的进气位置以及减小温度与电场梯度并增设径向旋转磁场，可有效地解决上述问题更多还原

【Abstract】 Arc action in plasma torch with large anode nozzle and long arc passage has been researched by means of electromagnetism and hot fluid mechanics.It has been showed that the special phenomenon will emerg when temperature gradient and electric field gradient act on fluid.The results indicate that high temperature effect of arc column strongly prevents cold gas current from getting in,so as to restrain CVD process.Newly emerging colloidal particles deposit progressively on passage wall under the action of heatphoresis.Above mentioned problems can be solved effectively by changing entrance positions of different gases,reducing gradients of temperature and electric field as well as adding radial circular magnetic field.更多还原