Engineering Physics Department, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Phys Rev Lett. 2013 Aug 16;111(7):075002. doi: 10.1103/PhysRevLett.111.075002.
A one-dimensional kinetic theory of sheaths surrounding planar, electron-emitting surfaces is presented which accounts for plasma electrons lost to the surface and the temperature of the emitted electrons. It is shown that ratio of plasma electron temperature to emitted electron temperature significantly affects the sheath potential when the plasma electron temperature is within an order of magnitude of the emitted electron temperature. The sheath potential goes to zero as the plasma electron temperature equals the emitted electron temperature, which can occur in the afterglow of an rf plasma and some low-temperature plasma sources. These results were validated by particle in cell simulations. The theory was tested by making measurements of the sheath surrounding a thermionically emitting cathode in the afterglow of an rf plasma. The measured sheath potential shrunk to zero as the plasma electron temperature cooled to the emitted electron temperature, as predicted by the theory.
提出了一种一维运动学理论，用于描述围绕平面电子发射表面的鞘层，该理论考虑了等离子体电子向表面的损失和发射电子的温度。结果表明，当等离子体电子温度在发射电子温度的一个数量级范围内时，等离子体电子温度与发射电子温度的比值对鞘层电势有显著影响。当等离子体电子温度等于发射电子温度时，鞘层电势趋于零，这种情况可能发生在射频等离子体的余晖和一些低温等离子体源中。这些结果通过粒子在细胞模拟得到了验证。该理论通过测量射频等离子体余晖中热电子发射阴极周围的鞘层得到了验证。正如理论所预测的那样，当等离子体电子温度冷却到发射电子温度时，测量到的鞘层电势趋于零。
