Magnetic reconnection in partially ionized gases
Magnetic reconnection in partially ionized gases
复制标题
部分电离气体中的磁重联
DOI：
--
复制
发表时间：
1989
期刊：
影响因子：
--
通讯作者：
E. Zweibel
中科院分区：
文献类型：
--
作者：
E. Zweibel
等离子体中的磁力线以阿尔芬速度的比例重新连接。在部分电离的气体中，有两种自然的阿尔芬速度：一种是由电离质量密度单独决定的，这适用于离子中性摩擦可以忽略不计的情况；另一种是由总质量密度决定的，这适用于离子中性摩擦很强的情况。当电离率较低时，如在密集的分子云中，这两种速度相差好几个数量级。考虑了部分电离气体中随时间变化的撕裂模式和稳态磁重联，并描述了带电组分和中性组分强、中、弱耦合的状态。分子云可能处于中间状态，而太阳日珥中的重联可能具有很强的离子-中性耦合。耦合不强时，重连接进行得更快。参25。
Magnetic field lines in a plasma reconnect at a rate scaled by the Alfven speed. In a partially ionized gas there are two natural Alfven speeds: one determined by the ionized mass density alone, which applies when ion-neutral friction is negligible, and one determined by the total mass density, which applies when ion-neutral friction is strong. When the ionization fraction is low, as in a dense molecular cloud, these two speeds differ by several orders of magnitude. Both time-dependent tearing modes and steady-state magnetic reconnection in partially ionized gas are considered, and the regimes in which the charged and neutral components are strongly, intermediately, and weakly coupled are delineated. Molecular clouds are probably in the intermediate regime, while reconnection in solar prominences probably has strong ion-neutral coupling. Reconnection proceeds more rapidly when coupling is not strong. 25 refs.