Abstract Plasma decay after a high-voltage nanosecond discharge was experimentally and numerically studied in pure hydrocarbons (C2H6 and C3H8), and H2O:N2 and C3H8:O2 mixtures for pressures in the range 2–4 Torr and gas temperatures from 300 to 600 K. In a stoichiometric C3H8:O2 mixture, plasma decay was also studied in a repetitively pulsed discharge for varing numbers of discharge pulses (varying degrees of fuel oxidation). The rate of plasma decay was determined from the temporal evolution of electron density measured using the microwave interferometer. It was observed that gas heating to 600 K leads to a decrease in the rate of plasma decay in all cases. The effect of heating on plasma decay was most profound in the H2O:N2 mixture (after a single discharge pulse) and in the C3H8:O2 mixture for high degrees of fuel oxidation. A kinetic scheme was developed to numerically simulate the plasma decay in hydrocarbons and combustible mixtures. Numerical analysis showed that, under the conditions studied, plasma decay was controlled by dissociative electron recombination with simple molecular and cluster ions. Gas heating led to a decrease in the rate of the electron-ion recombination and the rate of conversion of molecular ions to cluster ions. As a result, the gas temperature increase caused a decrease in the fraction of cluster ions for which the recombination coefficients are an order of magnitude higher than the recombination coefficients for molecular ions. The influence of gas heating on the decrease of the amount of cluster ions was more important when the ion composition was dominated by hydrated H3O+(H2O)k ions. The rates of the formation of these ions are extremely sensitive to any variations in gas temperature. As a result, in agreement with our observations, gas heating led to an anomalous decrease in the rates of plasma decay in the H2O:N2 mixture, as well as in the C3H8:O2 mixture when H2O molecules were produced due to fuel oxidation.

中文翻译：

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在升高的气体温度下由高压纳秒放电激发的碳氢化合物和含碳氢化合物和 H2O 的混合物中的等离子体衰变

摘要 在纯碳氢化合物（C2H6 和 C3H8）以及 H2O:N2 和 C3H8:O2 混合物中，在 2-4 Torr 的压力和 300 到 600 K 的气体温度下，对高压纳秒放电后的等离子体衰变进行了实验和数值研究。 . 在化学计量的 C3H8:O2 混合物中，还研究了在重复脉冲放电中针对不同数量的放电脉冲（不同程度的燃料氧化）的等离子体衰减。等离子体衰变率由使用微波干涉仪测量的电子密度的时间演变确定。据观察，在所有情况下，将气体加热到 600 K 会导致等离子体衰变率降低。加热对等离子体衰变的影响在 H2O:N2 混合物（单次放电脉冲后）和 C3H8:O2 混合物中对高度燃料氧化的影响最为显着。开发了一种动力学方案来数值模拟碳氢化合物和可燃混合物中的等离子体衰变。数值分析表明，在所研究的条件下，等离子体衰变由与简单分子和簇离子的解离电子重组控制。气体加热导致电子-离子复合率和分子离子向团簇离子转化率的降低。结果，气体温度升高导致团簇离子的比例减少，其中团簇离子的复合系数比分子离子的复合系数高一个数量级。当离子组成以水合 H3O+(H2O)k 离子为主时，气体加热对团簇离子数量减少的影响更为重要。这些离子的形成速率对气体温度的任何变化都极为敏感。因此，与我们的观察结果一致，当燃料氧化产生 H2O 分子时，气体加热导致 H2O:N2 混合物以及 C3H8:O2 混合物中等离子体衰变速率的异常降低。