大气压介质阻挡放电的光谱研究

Study on the Characteristics of Dielectric Barrier Discharge at Atmospheric Pressure by Spectroscopic Method

使用水电极介质阻挡放电装置,分别在大气压空气和氦气中实现了稳定的高气压放电。通过水电极观察两种气体的放电,发现大气压空气中放电为空间随机分布的微放电丝,等离子体是不均匀的,而在氦气中放电没有微放电丝,空间分布比较均匀。比较而言,这种均匀放电产生的等离子体具有更广泛的工业应用前景。对两种气体中放电的电流波形进行了比较,发现空气中放电的电流脉冲在时间上是随机出现的而氦气中放电的电流脉冲在时间上具有周期性,并且空气中放电脉冲宽度约为几十ns而氦气中放电的电流持续时间较长,脉冲宽度大约为1μs。文章还对两种气体中介质阻挡放电发射光谱进行了研究,结果表明大气压氦气中均匀放电的N2+(B2Σu+→X2Σg+)谱线391.4nm很强而在大气压空气放电中此光谱线很弱。这些研究结果对高气压条件下均匀放电的实现和大气压辉光放电的工业应用具有重要意义。

In the present paper, stable discharges were respectively obtained in air and helium at atmospheric pressure with a dielectric barrier discharge device consisting of water electrodes. By comparing the discharges in the two gases, it was found that the discharge in air at atmospheric pressure is not uniform and micro-discharges can be discerned which are distributed on the electrode stochastically, while the discharge in helium at atmospheric pressure is quite uniform and no discharge filament can be discerned. Comparing the two kinds of discharges, the plasma generated in helium discharge at atmospheric pressure has better prospect for application in industry because of its uniformity. The discharge current waveforms in air and helium at atmospheric pressure were compared, and the results show that the discharge current pulses in air are stochastically distributed in time, while the current pulses in helium discharge appear periodically. The discharge duration in helium is much longer than that in air at atmospheric pressure. The discharge pulse length is about tens of nanoseconds in air and is about one microsecond in helium. Meanwhile the spectra emitted from the two kinds of discharges were studied, and the results show that the spectral line of 391.4 nm emitted from N2^＋（B^2∑s^＋→ X^2∑g^＋ ） is quite strong in helium discharge. On the contrary, the strength of 391.4 nm spectral line is very weak in air discharge. These experimental results are significant for the realization of uniform discharge at atmospheric pressure and industrial application of dielectric barrier discharge.