论文标题
碰撞低温等离子体的隐式和耦合多流体求解器
Implicit and Coupled Multi-Fluid Solver for Collisional Low-Temperature Plasma
论文作者
论文摘要
我们基于碰撞低温等离子体的全牛顿(非线性,隐性)方案,提出了一种具有自适应笛卡尔网格(ACM)的新的多流体,多温血浆求解器。使用电子和离子与电场泊松方程耦合的电子和离子的漂移扩散近似描述。此外,在与中性物种碰撞中,电子能量传输方程可解决电子导热率,焦耳加热和电子损失。电子诱导的电离速率是电子温度的函数,也可能取决于电子密度(对于等离子体分层很重要)。离子和气体温度保持恒定。传输方程的空间离散化使用适用于多维ACM框架的半导体物理学的非等温scharfetter-gummel方案。我们演示了新的求解器,以模拟直流电流(DC)和射频(RF)放电。耦合方程式的隐式处理允许使用大的时间步骤,而全牛顿方法可以在每个时间步骤中实现快速的非线性收敛性,从而极大地提高了流体等离子体模拟的效率。我们讨论解决不同血浆问题的时间步骤的选择。新求解器使我们能够解决现有软件之前无法解决的几个问题:整个DC放电的二维结构和三维结构,包括阴极和阳极区域,具有电场逆转,正常阴极点和阳极环,弥漫性和收缩的DC排放中的质量分层,以及RF放电中的静止条件。
We present a new multi-fluid, multi-temperature plasma solver with adaptive Cartesian mesh (ACM) based on a full-Newton (non-linear, implicit) scheme for collisional low-temperature plasma. The particle transport is described using the drift-diffusion approximation for electrons and ions coupled to Poisson equation for electric field. In addition, the electron-energy transport equation is solved to account for electron thermal conductivity, Joule heating, and energy loss of electrons in collisions with neutral species. The rate of electron-induced ionization is a function of electron temperature and could also depend on electron density (important for plasma stratification). The ion and gas temperature are kept constant. The spatial discretization of the transport equations uses non-isothermal Scharfetter-Gummel scheme from semiconductor physics adapted for multi-dimensional ACM framework. We demonstrate the new solver for simulations of direct current (DC) and radio frequency (RF) discharges. The implicit treatment of the coupled equations allows using large time steps, and the full-Newton method enables fast non-linear convergence at each time step, offering greatly improved efficiency of fluid plasma simulations. We discuss the selection of time steps for solving different plasma problems. The new solver enables us to solve several problems we could not solve before with existing software: two- and three-dimensional structures of the entire DC discharges including cathode and anode regions with electric field reversals, normal cathode spot and anode ring, plasma stratification in diffuse and constricted DC discharges, and standing striations in RF discharges.