We present a zero-dimensional plasma kinetics model, including both surface and gas phase kinetics, to determine the role of vibrationally excited states in plasma-catalytic ammonia synthesis. We defined a new method to systematically capture the conditions of dielectric barrier discharges (DBDs), including those found in packed bed DBDs. We included the spatial and temporal nature of such discharges by special consideration of the number of micro-discharges in the model. We introduce a parameter that assigns only a part of the plasma power to the micro-discharges, to scale the model conditions from filamentary to uniform plasma. Because of the spatial and temporal behaviour of the micro-discharges, not all micro-discharges occurring in the plasma reactor during a certain gas residence time are affecting the molecules. The fraction of power considered in the model ranges from 0.005 %, for filamentary plasma, to 100 %, for uniform plasma. If vibrational excitation is included in the plasma chemistry, these different conditions, however, yield an ammonia density that is only varying within one order of magnitude. At only 0.05 % of the power put into the uniform plasma component, a model neglecting vibrational excitation clearly does not result in adequate amounts of ammonia. Thus, our new model, which accounts for the concept in which not all the power is deposited by the micro-discharges, but some part may also be distributed in between them, suggests that vibrational kinetic processes are really important in (packed bed) DBDs. Indeed, vibrational excitation takes place in both the uniform plasma between the micro-discharges and in the strong micro-discharges, and is responsible for an increased N2 dissociation rate. This is shown here for plasma-catalytic ammonia synthesis, but might also be valid for other gas conversion applications.

中文翻译：

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非填充床和填充床介质阻挡放电的零维建模：振动动力学在氨合成中的作用

我们提出了一个零维等离子体动力学模型，包括表面和气相动力学，以确定振动激发态在等离子体催化氨合成中的作用。我们定义了一种新方法来系统地捕获介质阻挡放电 (DBD) 的条件，包括在填充床 DBD 中发现的那些条件。我们通过特别考虑模型中微放电的数量，包括了这种放电的空间和时间性质。我们引入了一个参数，该参数仅将一部分等离子体功率分配给微放电，以将模型条件从丝状等离子体扩展到均匀等离子体。由于微放电的空间和时间行为，在一定的气体停留时间内，并非所有发生在等离子体反应器中的微放电都会影响分子。模型中考虑的功率分数范围从 0.005%（对于丝状等离子体）到 100%（对于均匀等离子体）。但是，如果等离子体化学中包含振动激发，这些不同的条件会产生仅在一个数量级内变化的氨密度。在只有 0.05% 的功率输入到均匀等离子体组件中时，忽略振动激发的模型显然不会产生足够量的氨。因此，我们的新模型解释了并非所有能量都由微放电沉积，但某些部分也可能分布在微放电之间的概念，这表明振动动力学过程在（填充床）DBD 中非常重要. 事实上，振动激发发生在微放电和强微放电之间的均匀等离子体中，并且是 N2 解离率增加的原因。这在此处显示用于等离子体催化氨合成，但也可能适用于其他气体转化应用。