*通讯联系人 e-mail: plasmalab@126.com

Spectral Investigation on the Direct-Current Uniform Discharge Ignited by a Dielectric Barrier Discharge at Atmospheric Pressure
LI Xue-chen, WU Kai-yue, JIA Peng-ying*, BAO Wen-ting, DI Cong
College of Physics Science and Technology, State Key Laboratory of Photo-Electronics Information Materials of Hebei Province, Hebei University, Baoding 071002, China
Abstract

Atmosphere pressure uniform plasma has the broad application prospect in the industrial field. In order to get a atmosphere pressure uniform plasma in large scale, a large gap uniform discharge (up to 5 cm) was initiated between a needle anode and a plate cathode, which was ignited under a low sustaining voltage by a coaxial dielectric barrier discharge in ambient air with argon used as working gas. The characteristics of the discharge were investigated. The coaxial dielectric barrier discharge can lower the voltage for gas breakdown effectively. The results showed that the atmospheric pressure uniform discharge included a plasma column near the anode, a plasma plume, a dark space and a cathode glow. The plasma column and the cathode glow were continuous discharges, while in the plasma plume region the discharges at different positions initiated at different time. In fact, the plasma plume behaved like a “plasma bullet” which traveled from the cathode to the plasma column. Through electrical method, the voltage-current characteristic was investigated. The voltage-current curve had a negative slope, whichwas similar with the normal glow discharge at low pressure. By analyzing the optical emission spectrum from the discharge, the optical emission spectrum was composed of the second positive system of nitrogen molecules, the spectral lines from argon atom and oxygen atom. By Boltzmann plot method, the spatially-resolved excited electron temperature was obtained. It was found that the excited electron temperature of the plasma column was lower than that of the plasma plume. These experimental phenomena were explained qualitatively. These results are of great importance to the development of atmospheric pressure uniform discharge plasma source and its application in industrial field.

Keyword: Atmospheric pressure uniform discharge; Plasma column; Plasma plume; Excited electron temperature

1 实验部分

 Figure Option 图1 实验装置示意图Fig.1 Schematic diagram of the experimental setup

2 结果与讨论

 Figure Option 图2 放电电流10 mA, 不同曝光时间下的放电照片(a): 1 ms; (b): 100 nsFig.2 Discharge images with a discharge current of 10 mAThe exposure time in (a) is 1 ms and in (b) is 100 ns

 Figure Option 图3 发光信号的空间分布测量Fig.3 The spatially resolved measurement of the light emission

 Figure Option 图4 大气压均匀放电电压与电流的关系Fig.4 The voltage and current characteristic for APUD

 Figure Option 图5 放电电流10 mA时, 300~800 nm大气压均匀放电的发射光谱Fig.5 The optical emission spectrum from the APUD in the range from 300 to 800 nm. The discharge current is 10 mA

$I1I2=A1g1λ2A2g2λ1exp-E1-E2Te(1)$

$-1Te=lnλ1I1/g1A1-lnλ2I2/g2A2E1-E2(2)$

 Figure Option 图6 放电电流10 mA, 气体流速1 L· min-1时, 利用Boltzmann分布计算等离子体柱的电子激发温度Fig.6 Boltzmann plot to calculate the excited electron temperature in the plasma column with a discharge current of 10mA and a gas flow rate of 1 L· min-1

 Figure Option 图7 放电电流10 mA, 气体流速1 L· min-1时, 电子激发温度的空间分布测量Fig.7 The spatially resolved measurement of the excited electron temperature with a discharge current of 10 mA and a gas flow rate of 1 L· min-1

$T=eλ̅E(3)$

3 结论

The authors have declared that no competing interests exist.

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