Ultrafast heating and oxygen dissociation in atmospheric pressure air by nanosecond repetitively pulsed discharges
Ultrafast heating and oxygen dissociation in atmospheric pressure air by nanosecond repetitively pulsed discharges
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DOI：
10.1088/0022-3727/46/46/464010
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发表时间：
2013-11
期刊：
影响因子：
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通讯作者：
D. Rusterholtz;D. Lacoste;G. Stancu;D. Pai;C. Laux
中科院分区：
文献类型：
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作者：
D. Rusterholtz;D. Lacoste;G. Stancu;D. Pai;C. Laux
本文对纳秒重复脉冲放电在1000 K预热的大气压空气中产生的超快加热和氧离解机理进行了详细的实验研究。超快机制产生氮的激发电子态，然后通过淬灭反应分解分子氧，剩余的能量作为热量耗散。光学和电气诊断技术已被应用于提供一个自洽的一组实验数据的参考测试情况下，定义良好的放电和气体条件。脉冲的持续时间为10 ns，幅度为5.7 kV，重复频率为10 kHz，针到针电极间隔为4 mm。我们使用第二正氮系统的光发射光谱测量放电期间和之后的气体温度，激发电子态的绝对密度的空间分辨分布，使用氮的第一和第二正系统的阿贝尔反演光谱以及N2（A）、N2（B）、N2（C）、电子和原子氧的绝对密度的时间演化来确定。这些测量与脉冲电流、电压和能量的电气测量同步。发现放电分解了约50%的分子氧，并在20 ns内产生约900 K的温度升高，对应于约5 × 1010 K s−1的超快加热速率。与数值模拟的比较显示出良好的协议与测量和验证的超快机制。约35%的电能沉积到气体中，用于O2分解，约21%用于气体加热。最后，测量了2200 K下N2（B）和N2（C）与O2的解离猝灭速率，分别为2.8（±0.6）× 10−10 cm 3 s−1和5.8（±0.9）× 10−10 cm 3 s−1。结合这些测量和文献中300 K时的数值，我们提出在300-2200 K范围内，C态的函数温度依赖性为3.0 × 10−10（T/300）0.3 cm 3 s−1，B态的函数温度依赖性为3.0 × 10−10 cm 3 s−1。
A detailed experimental investigation of the mechanism of ultrafast heating and oxygen dissociation produced by nanosecond repetitively pulsed discharges in atmospheric pressure air preheated at 1000 K is presented. The ultrafast mechanism creates excited electronic states of nitrogen, which then dissociate molecular oxygen through quenching reactions, with the remaining energy dissipated as heat. Optical and electrical diagnostic techniques have been applied to provide a self-consistent set of experimental data for a reference test-case with well-defined discharge and gas conditions. The pulses have a duration of 10 ns, an amplitude of 5.7 kV, a repetition frequency of 10 kHz and the pin-to-pin electrodes are separated by 4 mm. We present measurements of the gas temperature during and after the discharge using optical emission spectroscopy of the second positive system of nitrogen, spatially resolved profiles of the absolute densities of excited electronic states, determined using Abel-inverted spectra of the first and second positive systems of nitrogen, as well as the temporal evolution of the absolute densities of N2(A), N2(B), N2(C), electrons and atomic oxygen. These measurements are synchronized with electrical measurements of pulse current, voltage, and energy. The discharge is found to dissociate about 50% of molecular oxygen and to produce a temperature increase of about 900 K within 20 ns, corresponding to an ultrafast heating rate of about 5 × 1010 K s−1. Comparisons with numerical simulations show good agreement with the measurements and validate the ultrafast mechanism. About 35% of the electric energy deposited into the gas goes into O2 dissociation, and about 21% into gas heating. Finally, the dissociative quenching rates of N2(B) and N2(C) with O2 at 2200 K were measured and found to be 2.8(±0.6) × 10−10 cm3 s−1 and 5.8(±0.9) × 10−10 cm3 s−1, respectively. Combining these measurements with the literature values at 300 K, we propose a functional temperature dependence in the range 300–2200 K of 3.0 × 10−10(T/300)0.3 cm3 s−1 for the C state, and a constant value of 3.0 × 10−10 cm3 s−1 for the B state.