In many astrophysical environments the plasma is only partially ionized, and therefore the interaction of charged and neutral particles may alter both the triggering of reconnection and its subsequent dynamical evolution. We derive the tearing mode maximum growth rate for partially ionized plasmas in the cases of weak and strong coupling between the plasma and the neutrals. In addition, critical scalings for current sheet aspect ratios are presented in terms of Lundquist number and ion–neutral collision frequencies for which the tearing mode becomes fast, or ideal. In the decoupled regime the standard tearing mode is recovered with a small correction that depends on the ion–neutral collision frequency; in the intermediate regime collisions with neutrals are shown to stabilize current sheets, resulting in larger critical aspect ratios for ideal tearing to occur. In the coupled regime, the growth rate depends on the density ratio between ions and neutrals through the collision frequency between these two species.

在许多天体物理环境中，等离子体只是部分电离，因此带电粒子和中性粒子的相互作用可能会改变重联的触发及其随后的动力学演化。我们推导出在等离子体和中性粒子之间存在弱耦合和强耦合的情况下部分电离等离子体的撕裂模式最大增长率。此外，根据 Lundquist 数和离子-中性碰撞频率呈现当前片材纵横比的关键比例，对于这些频率，撕裂模式变得快速或理想。在解耦状态下，标准撕裂模式通过根据离子-中性碰撞频率进行的小幅修正恢复；在中间状态下，与中性点的碰撞被证明可以稳定电流片，导致发生理想撕裂的更大临界纵横比。在耦合状态下，生长速率取决于离子和中性物质之间通过这两种物质之间的碰撞频率的密度比。