Characterization of DC plasma torch voltage fluctuations
Characterization of DC plasma torch voltage fluctuations
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DOI：
10.1007/bf01512636
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发表时间：
1996-03-01
影响因子：
3.6
通讯作者：
Fauchais, P
中科院分区：
文献类型：
--
作者：
Coudert, JF;Planche, MP;Fauchais, P
直流阳极喷嘴的根部起伏。系统地研究了喷嘴直径为6~10 mm、具有特殊电极结构的等离子喷枪在相同气体流量下的工作特性。等离子体气体为Ar/H2(25Vol%H2)，电流在200~600A之间变化，等离子体气体流量在24~80SLM之间变化。在30-60mN工作后，喷嘴壁面开始被充分侵蚀，形成一个停滞的弧斑，一直持续到电弧产生另一个弧斑。结果表明，上游弧斑的寿命比下游弧斑的寿命长30-40%，这对电极的腐蚀起着重要的作用。量纲分析可以找到喷嘴直径D、电弧电流I和气体流量G以及平均光斑寿命之间的关系，而平均光斑寿命与D和弧柱的电直径之间的差密切相关。通过比较等离子体射流轴线上靠近喷嘴出口的点的电压信号和光发射，可以确定等离子体柱内的平均电场和弧根的平均位置。与明确条件下电极侵蚀面积的比较表明，与计算的弧根位置有很好的相关性。
The are root fluctuations at the anode-nozzle of a d.c. plasma spray torch with a special configuration of the electrodes allowing to work with the same gas flowrate with nozzle diameters ranging from 6 to 10 mm were systematically studied. The plasma gas was Ar/H2 (25 vol % H2), the current was varied between 200 and 600 A and the plasma gas flowrate between 24 and 80 slm. After 30-60 mn working the nozzle wall started to be sufficiently eroded to have a stagnant are spot which lived until arcing created another one. It was shown that the life time of the upstream are spots were 30-40 % longer than the downstream ones which could play an important role in the electrode erosion. Dimensional analysis allowed to find a relationship between the nozzle diameter D, the are current I and gas flow rate G and the mean spot lifetime which is closely connected with the difference between D and the electrical diameter of the are column. The comparison of voltage signal and light emission at a point of the plasma jet close to the nozzle exit on its axis allowed to determine the mean electrical field within the plasma column and the mean position of the are root. The comparison with the electrode erosion area for well defined conditions showed a good correlation with the calculated are root position.