We use numerical simulations to study the dynamics of surface discharges, which are common in high-voltage engineering. We simulate positive streamer discharges that propagate towards a dielectric surface, attach to it, and then propagate over the surface. The simulations are performed in air with a two-dimensional plasma fluid model, in which a flat dielectric is placed between two plate electrodes. Electrostatic attraction is the main mechanism that causes streamers to grow towards the dielectric. Due to the net charge in the streamer head, the dielectric gets polarized, and the electric field between the streamer and the dielectric is increased. Compared to streamers in bulk gas, surface streamers have a smaller radius, a higher electric field, a higher electron density, and higher propagation velocity. A higher applied voltage leads to faster inception and faster propagation of the surface discharge. A higher dielectric permittivity leads to more rapid attachment of the streamer to the surface and a thinner surface streamer. Secondary emission coefficients are shown to play a modest role, which is due to relatively strong photoionization in air. In the simulations, a high electric field is present between the positive streamers and the dielectric surface. We show that the magnitude and decay of this field are affected by the positive ion mobility.

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正流光与电介质相互作用的计算研究

我们使用数值模拟来研究表面放电的动力学，这在高压工程中很常见。我们模拟正流光放电，它向电介质表面传播，附着在它上面，然后在表面上传播。模拟是在空气中使用二维等离子体流体模型进行的，其中平面电介质放置在两个板电极之间。静电吸引是导致拖缆向电介质生长的主要机制。由于流注头中的净电荷，电介质被极化，流注和电介质之间的电场增加。与散装气体中的流注相比，表面流注具有更小的半径、更高的电场、更高的电子密度和更高的传播速度。更高的施加电压导致更快的表面放电开始和更快的传播。较高的介电常数导致拖缆更快速地附着到表面和更薄的表面拖缆。二次发射系数显示出适度的作用，这是由于空气中相对强的光电离。在模拟中，正流光和电介质表面之间存在高电场。我们表明该场的大小和衰减受正离子迁移率的影响。这是由于空气中相对较强的光电离作用。在模拟中，正流光和电介质表面之间存在高电场。我们表明该场的大小和衰减受正离子迁移率的影响。这是由于空气中相对较强的光电离作用。在模拟中，正流光和电介质表面之间存在高电场。我们表明该场的大小和衰减受正离子迁移率的影响。