We present a spatio-temporally resolved analysis of electron power absorption in capacitively coupled argon plasmas at low pressures (1–10 Pa), based on the 1D momentum balance equation embedded into 1d3v particle-in-cell/Monte Carlo collisions simulations. In contrast to the predictions of theoretical models we find ‘Ohmic heating’ to be the dominant electron power absorption mechanism on time average at the lowest pressures, and not ‘stochastic’ or ‘Pressure heating’. The cause for this is identified to be the attenuation of electron power absorption due to electron acceleration by the ‘ambipolar’ electric field on time average at low pressure, which is a consequence of the collisionless transit of energetic beam electrons generated during sheath expansion at one electrode to the opposite electrode. At such conditions, these energetic electrons arrive during the local sheath collapse and can be lost to the surface, thereby reducing the plasma density and creating a temporally more symmetric electron temperature within the radio frequency (RF) period compared to that in discharges operated at higher pressures. The more symmetric temperature profile causes a reduction of ‘Pressure heating’ on time average. The latter is reduced further, even to negative values, by the attenuation of the ‘ambipolar’ electric field at each electrode during the local sheath collapse, which is a consequence of the temporal modulation of the electron density profile within the RF period, observed at the lowest pressures studied.

我们基于嵌入到 1d3v 细胞内粒子/蒙特卡罗碰撞模拟中的一维动量平衡方程，对低压 (1-10 Pa) 下电容耦合氩等离子体中的电子功率吸收进行了时空解析分析。与理论模型的预测相反，我们发现“欧姆加热”是最低压力下时间平均的主要电子功率吸收机制，而不是“随机”或“压力加热”。造成这种情况的原因被认为是由于“双极”电场在低压下按时间平均进行电子加速导致电子功率吸收衰减，这是鞘层膨胀期间产生的高能束电子无碰撞传输的结果。电极到相反的电极。在这样的条件下，这些高能电子在局部鞘层塌陷期间到达并可能丢失到表面，从而降低等离子体密度并在射频 (RF) 周期内产生与在更高压力下操作的放电相比在时间上更对称的电子温度。更对称的温度曲线导致“压力加热”的时间平均减少。通过在局部鞘层塌陷期间每个电极处的“双极”电场的衰减，后者进一步降低，甚至降低到负值，这是 RF 周期内电子密度分布的时间调制的结果，观察到研究的最低压力。从而降低等离子体密度并在射频 (RF) 周期内产生与在更高压力下操作的放电相比在时间上更对称的电子温度。更对称的温度曲线导致“压力加热”的时间平均减少。通过在局部鞘层塌陷期间每个电极处的“双极”电场的衰减，后者进一步降低，甚至降低到负值，这是 RF 周期内电子密度分布的时间调制的结果，观察到研究的最低压力。从而降低等离子体密度并在射频 (RF) 周期内产生与在更高压力下操作的放电相比在时间上更对称的电子温度。更对称的温度曲线导致“压力加热”的时间平均减少。通过在局部鞘层塌陷期间每个电极处的“双极”电场的衰减，后者进一步降低，甚至降低到负值，这是 RF 周期内电子密度分布的时间调制的结果，观察到研究的最低压力。