Large ion-neutral drift velocities and plasma heating in partially ionized coronal rain blobs

Abstract

<p><em>[eng] In this paper we present a numerical study of the dynamics of partially ionized coronal rain blobs. We use a twofluid</em></p><p><em>model to perform a high-resolution 2D simulation that takes into account the collisional interaction between</em></p><p><em>the charged and neutral particles contained in the plasma. We follow the evolution of a cold plasma condensation</em></p><p><em>as it falls through an isothermal vertically stratified atmosphere that represents the much hotter and lighter solar</em></p><p><em>corona. We study the consequences of the different degrees of collisional coupling that are present in the system.</em></p><p><em>On the one hand, we find that at the dense core of the blob there is a very strong coupling and the charged and</em></p><p><em>neutral components of the plasma behave as a single fluid, with negligible drift velocities (of a few cm s−1). On the</em></p><p><em>other hand, at the edges of the blob the coupling is much weaker and larger drift velocities (of the order of</em></p><p><em>1 km s−1) appear. In addition, frictional heating causes large increases of temperature at the transition layers</em></p><p><em>between the blob and the corona. For the first time we show that such large drift velocities and temperature</em></p><p><em>enhancements can develop as a consequence of ion-neutral decoupling associated to coronal rain dynamics. This</em></p><p><em>can lead to enhanced emission coming from the plasma at the coronal rain-corona boundary, which possesses</em></p><p><em>transition region temperature.</em></p>