基于FLUENT软件直流电弧等离子体喷射法等离子体放电特征二维数值模拟

Numerical Simulation of Plasma Discharge Properties in DC Arc Plasma Jet

直流电弧等离子体喷射法制备金刚石膜的过程中氩气主要起维持电弧放电作用,在一定程度上保证电弧放电的稳定性。本文利用自定义标量和自定义函数技术对FLUENT软件进行二次开发,在动量和能量守恒方程中添加相应电磁源项。对纯氩直流电弧等离子放电特征进行二维数值模拟,并经过实验验证后最终得到等离子体放电区域的温度、焦耳热、电流密度和速度等分布。模拟结果表明气压为1000 Pa工作电流为100 A条件下：氩等离子体最高温度和最大速度达到11000K和340 m/s,且均出现在阴极尖端位置附近;较强的外侧气流使阳极斑点稳定维持在阳极内侧下边缘位置,其附近等离子体温度在9000 K左右;基体表面附近等离子体温度受到焦耳热分布和阴极高温射流共同作用,维持在3000～4000 K。

The characteristics of the DC argon arc plasma discharge jet,used in diamond film deposition,were empirically approximated,mathematically formulated with 2-D model,numerically simulated with the self-developed program by adding an electromagnetic source to the conservation equations of software FLUENT,and experimentally evaluated. The influence of the Ar-pressure and discharge cuurent on the jet behavior,including the distributions of tempersature,electric current density,velocity and Joule heat of the arc plasma,was investigated. The simulated results show that at 1000 Pa and 100 A,the highest temperature（ 11000 K） and velocity（ 340 m / s） locate around the cathode tip,and that the strong outboard-flow focuses the anode spot at its bottom inner edge,where the plasma temperature is about 9000 K. The Joule heat distribution and plasma jet irradiation result in a stable plasma temperture in 3000 ~ 4000 K range above the graphite substrate surfaces. The simulated and measured results were in good greement.