Gyergyek T, Kovačič J
Jožef Stefan Institute, Jamova 39, P.O. Box 100, 1000 Ljubljana, Slovenia.
Phys Plasmas. 2017 Jun;24(6):063505. doi: 10.1063/1.4984786. Epub 2017 Jun 6.
A one-dimensional, two-fluid, steady state model is used for the analysis of ion temperature effects to the plasma-wall transition. In this paper, the model is solved for a finite ratio between the Debye and the ionization length, while in Part II [T. Gyergyek and J. Kovačič, Phys Plasmas 24, 063506 (2017)], the solutions for [Formula: see text] are presented. Ion temperature is treated as a given, independent parameter and it is included in the model as a boundary condition. It is shown that when the ion temperature larger than zero is selected, the ion flow velocity and the electric field at the boundary must be consistent with the selected ion temperature. A numerical procedure, how to determine such "consistent boundary conditions," is proposed, and a simple relation between the ion temperature and ion velocity at the boundary of the system is found. The effects of the ion temperature to the pre-sheath length, potential, ion temperature, and ion density drops in the pre-sheath and in the sheath are investigated. It is concluded that larger ion temperature results in a better shielding of the plasma from the wall. An attempt is made to include the ion heat flux into the model in its simplest form [Formula: see text], where [Formula: see text] is a constant heat conduction coefficient. It is shown that inclusion of such a term into the energy transfer equation introduces an additional ion heating mechanism into the system and the ion flow then becomes isothermal instead of adiabatic even in the sheath.
采用一维双流体稳态模型分析离子温度对等离子体 - 壁面过渡的影响。本文针对德拜长度与电离长度的有限比值求解该模型，而在第二部分[T. 杰尔盖耶克和J. 科瓦契奇，《物理等离子体》24, 063506 (2017)]中给出了(\lambda_D / \lambda_i \to 0)时的解。离子温度被视为给定的独立参数，并作为边界条件包含在模型中。结果表明，当选择大于零的离子温度时，边界处的离子流速和电场必须与所选离子温度一致。提出了一种确定此类“一致边界条件”的数值方法，并找到了系统边界处离子温度与离子速度之间的简单关系。研究了离子温度对预鞘层长度、电势、离子温度以及预鞘层和鞘层中离子密度下降的影响。得出的结论是，较高的离子温度会使等离子体对壁面的屏蔽效果更好。尝试以最简单的形式(q_i = - \kappa_i \nabla T_i)（其中(\kappa_i)是恒定热传导系数）将离子热通量纳入模型。结果表明，将这样一项纳入能量传递方程会在系统中引入额外的离子加热机制，即使在鞘层中，离子流也会变为等温而非绝热。
