Magnetic Reconnection in Plasmas

Cluster observations of magnetopause reconnection and associated electron heating at sub-proton scales

Not scheduled

25m

132:028 (Nordita, Stockholm)

Invited Workshop, August 10-14

Speaker

Dr Alessandro Retinò (Laboratoire de Physique des Plasmas, Palaiseau, France)

Description

The microphysics of magnetic reconnection (i.e. the physics at proton scales and below) is one of the most important aspects of reconnection and the target of the recently launched NASA/MMS mission. Among different open issues related to the microphysics, understanding the mechanisms of particle heating and acceleration is one of the most important. The Earth’s magnetopause is an excellent laboratory for studying such problem, especially at the subsolar point where reconnection is relatively steady and easier to investigate with spacecraft data. Despite of being initially a high- latitude mission, the ESA/Cluster spacecraft have crossed the subsolar magnetopause starting from 2008. During such orbits two spacecraft are separated by ~10s-100s km (proton/sub-proton scales) while being apart ~ 1000s km (fluid scales) from the others. This special configuration allows novel studies of the microphysics of reconnection with two-points measurements, while the large-scale context of reconnection is provided by the other spacecraft. Here we present a few examples of subsolar magnetopause reconnection from such orbits. For one such case, the observation of a jet reversal indicates that the spacecraft are close to the X-line. Two-point observations around the X- line are used to identify a very thin rotational discontinuity (having a thickness of ~ 15 electron gyroradii) and to study electron heating mechanisms therein. We discuss the relevance of such Cluster measurements for the reconnection science that will be done with data from upcoming MMS magnetopause orbits.