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arXiv 1203.5035physics.plasm-phphysics.comp-ph
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负拖缆的三维粒子、流体和混合模拟的比较

A comparison of 3D particle, fluid and hybrid simulations for negative streamers

Chao Li, Jannis Teunissen, Margreet Nool, Willem Hundsdorfer, Ute Ebert

摘要:

在放电流注头部的高场区,电子能量分布发展出一个长的拖尾。在负流光中,这些电子可以逃逸并有助于高能过程,如地球伽马射线和电子闪光。此外,电子密度波动可以加速流光分支。为了跟踪相关区域中单个电子的能量和位置,我们开发了一个3D混合模型,该模型将高场和低电子密度区域中的粒子模型与其余区域中的流体模型耦合。在这里,我们验证了我们的3D混合模型的3D(超)粒子模型的负流光在overvolted间隙,我们表明,它几乎达到了3D流体模型的计算效率。我们还表明,扩展的流体模型近似的粒子和混合模型,直到随机波动变得重要,而经典的流体模型低估了速度和电离密度。我们比较密度波动和发病的模型之间的分支,我们比较了前速度与分析近似。

英文摘要:

In the high field region at the head of a discharge streamer, the electron energy distribution develops a long tail. In negative streamers, these electrons can run away and contribute to energetic processes such as terrestrial gamma-ray and electron flashes. Moreover, electron density fluctuations can accelerate streamer branching. To track energies and locations of single electrons in relevant regions, we have developed a 3D hybrid model that couples a particle model in the region of high fields and low electron densities with a fluid model in the rest of the domain. Here we validate our 3D hybrid model on a 3D (super-)particle model for negative streamers in overvolted gaps, and we show that it almost reaches the computational efficiency of a 3D fluid model. We also show that the extended fluid model approximates the particle and the hybrid model well until stochastic fluctuations become important, while the classical fluid model underestimates velocities and ionization densities. We compare density fluctuations and the onset of branching between the models, and we compare the front velocities with an analytical approximation.

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