等离子体针放电的振动温度和气体温度研究

Investigation of the Vibrational Temperature and Gas Temperature in Gas Discharge Generated by Plasma Needle

大气压等离子体针空气放电产生的低温等离子体由于脱离了真空装置,在工业上具有广泛的应用前景。本文采用等离子体针装置在空气中产生了稳定的大气压等离子体羽,并利用光谱法对等离子体羽的振动温度和气体温度进行了研究。结果发现大气压空气等离子体羽的放电区域分为强光区和弱光区。放电发光信号是宽度为几个微秒的脉冲。研究结果表明等离子体振动温度随空间位置不同在2 500～3 000K范围变化。振动温度在强光区随着远离针尖距离的增大振动温度呈上升趋势,在5mm左右存在极大值,在弱光区随着远离针尖距离的增大振动温度呈下降趋势。与其相似,弱光区放电的气体温度随着远离针尖距离增大,从640K降低到540K。这些结果对大气压空气放电的工业应用具有重要意义。

Low temperature plasma generated by plasma needle in atmospheric pressure air has extensive application prospects in industry because the vacuum device can be dispensable.In the present paper a stable plasma plume was generated in air by using a plasma needle device.The vibrational temperature and gas temperature were investigated for the plasma plume by optical spectroscopic method.Research results show that the plasma plume generated in atmospheric pressure air can be distinguished as a strong emission area near the needle followed by a weak emission area.The light emission signal from the discharge is a pulse per half cycle of the applied voltage with a time width of several microseconds.Results also indicate that the vabrational temperature varies from 2 500 to 3 000 K for different emission locations.The vibrational temperature increases with increasing the distance from the needle point in the strong emission area and it reaches a peak value at a distance of about 5mm from the needle point.The vibrational temperature decreases with increasing the distance from the needle.Similarly,the gas temperature decreases from 640K to 540K with increasing the distance from the needle point.These results are of great importance for the industrial applications of air discharge at atmospheric pressure.