Properties of atmospheric pressure plasmas sustained by a 5 kHz pulse power are investigated by adjusting the duty cycle from 10% to 80%. As a result of the decrease of the duty cycle, the upward trends are observed in the electron density and excitation temperature, however, the downward trend appears in the gas temperature. The spatially averaged model is applied to simulate the temporal evolutions of the electron density and temperature, further validated by the time-resolved experimental measurements. Since the discharge volume in the open-air conditions increases at higher duty cycles, the time-averaged electron density within the pulse-on period consequently declines. For shorter duty cycles, fewer charges remain for the next discharge, and a higher initial peak of the electron temperature appears. As a result, the time-averaged electron temperature within the pulse-on period increases. Both the experimental and simulation results suggest that the discharge volume of the atmospheric pressure plasma in the open air has a strong effect on the time-averaged electron density during the pulse-on period whereas the remnant electron density determines the time-averaged electron temperature within the pulse-on period. This work reveals the effective mechanisms for controlling the electron temperature and electron density of atmospheric pressure plasmas in open air by using short pulse driven discharges.

中文翻译：

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占空比对脉冲放电大气压等离子体的影响：放电体积和残余电子密度

通过将占空比从 10% 调整到 80% 来研究由 5 kHz 脉冲功率维持的大气压等离子体的特性。由于占空比降低，电子密度和激发温度呈上升趋势，而气体温度则呈下降趋势。空间平均模型用于模拟电子密度和温度的时间演变，并通过时间分辨实验测量进一步验证。由于露天条件下的放电量在更高的占空比下增加，脉冲开启期间的时间平均电子密度因此下降。对于较短的占空比，下一次放电剩余的电荷较少，并且出现较高的电子温度初始峰值。因此，脉冲开启期间的时间平均电子温度增加。实验和模拟结果都表明，大气中大气压等离子体的放电体积对脉冲开启期间的时均电子密度有很大影响，而剩余电子密度决定了脉冲开启期间的时均电子温度。脉冲开启周期。这项工作揭示了通过使用短脉冲驱动放电来控制露天大气中大气压等离子体的电子温度和电子密度的有效机制。实验和模拟结果都表明，大气中大气压等离子体的放电体积对脉冲开启期间的时均电子密度有很大影响，而剩余电子密度决定了脉冲开启期间的时均电子温度。脉冲开启周期。这项工作揭示了通过使用短脉冲驱动放电来控制露天大气中大气压等离子体的电子温度和电子密度的有效机制。实验和模拟结果都表明，大气中大气压等离子体的放电体积对脉冲开启期间的时均电子密度有很大影响，而剩余电子密度决定了脉冲开启期间的时均电子温度。脉冲开启周期。这项工作揭示了通过使用短脉冲驱动放电来控制露天大气中大气压等离子体的电子温度和电子密度的有效机制。