Dominant heating mechanisms in a surface barrier discharge
Dominant heating mechanisms in a surface barrier discharge
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DOI：
10.1088/1361-6463/abdff4
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发表时间：
2021-04-29
影响因子：
3.4
通讯作者：
Hasan, M., I
中科院分区：
文献类型：
--
作者：
Gilbart, B.;Dickenson, A.;Hasan, M., I
在大气压表面阻挡放电（SBD）的计算模型中，电介质材料和静止气体受热的作用常常被忽略，这影响了所计算化学动力学的准确性。在本文中，开发了一个SBD的二维流体模型，并通过实验进行了验证，以确定主要热传递机制的相对贡献，并量化放电加热对产生的化学过程的影响。研究了三种加热机制，包括由于非弹性碰撞导致的背景气体的电子加热、电介质表面的离子轰击以及随时间变化的电场对电介质的加热。结果表明，尽管电子加热是靠近电极的气体的主要加热机制，但背景气体的电子加热并不足以解释实验中观察到的电介质材料的温度升高。由于SBD装置中使用的典型电介质材料的频率响应与在千赫兹频率下激发的SBD的实验观测功率谱不重叠，所以排除了电介质加热。发现离子通量加热是电介质材料和SBD驱动的下游气流的主要加热机制。发现等离子体加热对放电化学过程的最大影响在于活性氮物质（RNS）的产生，当采用适当的加热处理时，RNS的密度会增加。这对放电化学过程有显著影响，与理想化的恒温情况相比，NO₂的浓度增加了近50%。
In computational models of atmospheric pressure surface barrier discharges (SBDs) the role of heating of the dielectric material and the quiescent gas is often neglected, impacting the accuracy of the calculated chemical kinetics. In this contribution, a two-dimensional fluid model of an SBD was developed and experimentally validated to determine the relative contribution of the dominant heat transfer mechanisms and to quantify the impact of discharge heating on the resultant chemistry. Three heating mechanisms were examined, including electron heating of the background gas due to inelastic collisions, ion bombardment of the dielectric surface and dielectric heating by the time-varying electric field. It was shown that electron heating of the background gas was not significant enough to account for the experimentally observed increase in temperature of the dielectric material, despite being the dominant heating mechanism of the gas close to the electrode. Dielectric heating was ruled out as the frequency response of typical dielectric materials used in SBD devices does not overlap with the experimentally observed power spectrum of an SBD excited at kHz frequencies. The ionic flux heating was found to be the dominant heating mechanism of the dielectric material and the downstream flow driven by the SBD. The largest impact of plasma heating on discharge chemistry was found in reactive nitrogen species (RNS) production, where the densities of RNSs increased when an appropriate treatment of heating was adopted. This had a marked effect on the discharge chemistry, with the concentration of NO2 increasing by almost 50% compared to the idealized constant temperature case.