乙炔笼网形空心阴极放电特性研究

Discharge Behavior of C_2H_2 in Mesh-Cage Shaped Hollow Cathode

为解决常规直流脉冲等离子体增强化学气相沉积工艺制备类金刚石膜沉积速率低问题,美国西南研究院开发了"笼网等离子体浸没离子沉积技术"。采用这种技术,本次实验研究了乙炔气压、流量、脉冲电压及氩气分压等工艺参数对笼形空心阴极放电动力学的影响。结果表明:在单个脉冲辉光放电过程中存在自辉光和空心阴极两种放电模式。工艺参数的影响表现为,乙炔气压由2.5升高到8 Pa,笼网放电击穿电压由1100降为620 V;当脉冲电压从900升高到1400 V,对应乙炔流量为200和100 m L/min时,工作气压分别下降1.4和3.9 Pa;提高脉冲电压或氩气分压,笼形空心阴极辉光增强,笼网电流增大,在p(C2H2):p(Ar)为1∶4时有最高值32 A。

The hydrogenated diamond-like carbon（ DLC） coatings were synthesized by meshed plasma immersion ion deposition（ MPIID） with acetylene（ C2H2） as the carbon source. The impact of the growth conditions,including the ratios of C2H2 and Ar partial pressures and flow rates,pulsed voltage and working pressure,on the discharge behavior was investigated. The results show that the pulsed voltage,flow-rate and partial-pressure of C2H2 strongly affect the modes of pre-discharge and hollow cathode discharge. For example,as the C2H2 partial-pressure increased from 2. 5 to 8 Pa,the breakdown voltage decreased from 1100 to 620 V; as the pulsed voltage of 900 V（ at200 mL / min of C2H2 flow-rate） increased to 1400 V（ at 100 m L / min） the working pressure decreased by 1. 4 and3. 9 Pa,respectively. An increase of the pulsed voltage and / or Ar partial-pressure increased the peak current,because of an increased hollow cathode discharge intensity. At a C2H2 and Ar partial-pressure ratio of 1∶ 4,the highest current reached 32 A.