A model of Io's local electric field for a combined Alfvénic and unipolar inductor far‐field coupling
A model of Io's local electric field for a combined Alfvénic and unipolar inductor far‐field coupling
复制标题
Alfvénic 和单极电感器远场耦合组合的 Io 局部电场模型
DOI：
10.1029/2002ja009354
复制
发表时间：
2004
影响因子：
--
通讯作者：
J. Saur
中科院分区：
文献类型：
--
作者：
J. Saur
在本文中，我们建立了一个包含木卫一非均匀电导和各向异性电导的木卫一电场/电势方程，并在单极电感和Alfven翼模型两种极限下处理木卫一的远场相互作用。我们在椭圆形状的爱奥尼亚电离层内求解了恒定电导的方程，从而得到了爱奥的局部相互作用的有用解析表达式，特别是由爱奥的相互作用驱动的总电流。以前的几次计算把总电流低估了两倍。阿尔芬尼电流系统的过度简化可能是原因之一。我们的表达式还表明，它不是横跨木卫一电离层的电压，通常认为，这是物理上与电流有关；但它是电场和电离层在两个方向上的延伸。此外，我们还表明，Alfvenic和单极电感模型导致木卫一局部相互作用的不同性质，例如，在Alfvenic耦合情况下，木卫一周围的最大等离子体速度更高。
[1] In this paper we develop an equation for Io's electric field/electric potential which includes Io's inhomogeneous and anisotropic conductances and treats Io's far-field interaction in both limits: the unipolar inductor and the Alfven wing models. We solve this equation for constant conductances within an elliptically shaped Ionian ionosphere, which leads to useful analytic expressions for properties of Io's local interaction, specifically, the total electric current driven by Io's interaction. Several previous calculations underestimated the total electric current by a factor of two. Oversimplifications of the Alfvenic current system might be one of the reasons. Our expressions also show that it is not the voltage across Io's ionosphere, as often assumed, that is physically related to the electric current; but it is the electric field and the extensions of the ionosphere in both directions. We show in addition that the Alfvenic and unipolar inductor models lead to different properties of Io's local interaction, e.g., the maximum plasma speed up around Io is higher in the Alfvenic coupling case.