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采用一维流体模型研究了非广延分布电子对等离子体鞘层中二次电子发射的影响. 通过数值模拟, 研究了非广延分布电子对考虑二次电子发射的等离子体鞘层玻姆判据、器壁电势、器壁二次电子临界发射系数以及等离子体鞘层中二次电子密度分布的影响. 研究结果发现, 当电子分布偏离麦克斯韦分布( q= 1, 广延分布)时, 非广延参量 q的改变对器壁二次电子发射有着重要的影响. 不论电子分布处于超广延( q< 1), 还是处于亚广延状态( q> 1), 随着非广延参量 q的增加, 都会出现鞘边临界马赫数跟着减小, 同时对于随着二次电子发射系数的增加, 临界马赫数跟着增加. 器壁电势随着参量 q的增加而增加. 器壁二次电子临界发射系数则随着非广延参量的增加而减小, 并且等离子体中所含的离子种类质量数越大, 非广延参量的变化对器壁二次电子临界发射系数的值影响越小. 此外, 随着非广延参量的增加, 鞘层厚度减小, 鞘层中二次电子数密度增加. 通过对数值模拟结果分析, 发现电子分布处于超广延分布状态对等离子体鞘层中二次电子发射特性的影响要比电子处于亚广延分布状态要更明显.A one-dimensional fluid model is used to investigate the characteristics of secondary electron emitted by the interaction between electrons and the wall in plasma sheath with nonextensive electrons. The study focuses on the effects of electron nonextensive parameter on Bohm criterion, the wall potential, the critical emission coefficient of secondary electrons and the density of seconday electrons in plasma sheath through numerical simulation. Some conclusions are obtained. It is shown that secondary electron is significantly affected by electron nonextensive parameter. Whether the electron distribution is superextensive or subextensive, the critical Mach number at the sheath edge increases with the secondary electron emission coefficient increasing, but decreases with q-parameter increasing. The increase of q-parameter can cause the wall potential to increase and the critical emission coefficient of secondary electron at the wall to decrease. And for different types of plasmas, the effects of nonextensive parameter on the critical emission coefficient of secondary electron are different. The larger the mass number of ion in plasma, the smaller the influence of nonextensive parameter on the critical secondary electron emission coefficient will be. In addition, the increase of nonextensive parameter can result in the decrease of the sheath thickness and the increase of the number density of secondary electrons. It is found that the superextensive electron distribution has greater influence on the characteristics of secondary electron emission in plasma sheath than the subextensive electron distribution.
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Keywords:
- secondary electron emission/
- nonextensive/
- plasma/
- sheath
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