Magnetic Reconnection

Plasma is the most common state of matter in the observable Universe and can be described as a gas of charged particles exhibiting collective behavior through electromagnetic fields. The plasma is often permeated by magnetic fields that can originate from stars, planets, other astrophysical objects, or manmade devices.

Magnetic reconnection is a fundamental plasma process that changes the magnetic field topology and converts magnetic field energy into kinetic energy of charged particles, heating and accelerating them, and allowing for plasma transport across otherwise closed magnetic boundaries. This process enables phenomena such as the solar wind escaping from the Sun’s corona and entering planetary magnetospheres. Magnetic reconnection is observed in various environments, including laboratory devices, the Sun, solar wind, planetary magnetospheres, and even in more extreme environments like supernovae. The Earth's magnetosphere, with its dynamic and accessible nature, serves as an excellent laboratory to study these fundamental processes. Magnetic reconnection occurs at multiple locations in the magnetosphere, including the magnetopause on the dayside, the magnetotail on the nightside, and at the cusps in the polar regions. The Earth is currently orbited by several space missions that consist of more than one spacecraft, allowing us to study both temporal and spatial phenomena in great detail.

Spacecraft observations

Spacecraft observations have significantly advanced our understanding of magnetic reconnection. The European Space Agency’s (ESA) Cluster mission, consisting of four identical spacecraft, has been in orbit around Earth since 2000. These spacecraft, equipped with a set of eleven instruments to study electric and magnetic fields and charged particles, have varied their separation distance over the years, allowing for the study of magnetic reconnection at different scales. The Swedish Institute of Space Physics (Uppsala) is a key contributor of the Electric Fields and Waves (EFW) instrument on Cluster.

More recently, NASA's Magnetospheric Multiscale (MMS) mission, launched in 2015, has provided even higher temporal resolution and 3D electric field measurements with a smaller separation distance between spacecraft. This mission aims to answer critical questions about the mechanisms responsible for breaking the frozen-in condition and to study the regions where reconnection occurs. The Swedish Institute of Space Physics contributes to this mission through the Spin-Plane Double Probe (SDP) electric field instrument, which is part of the FIELDS instrument consortium on MMS.

Since its launch, the MMS mission have provided valuable insights into magnetic reconnection. For example, intermittent reconnection events observed in the terrestrial magnetotail have showcased the dynamic nature of reconnection, where periods of active reconnection are followed by quiet intervals with complex plasma behavior, including current sheet thickening and thinning, and the formation of dipolarization fronts. Furthermore, our studies have highlighted the importance of the magnetosheath's dynamic properties in influencing magnetic reconnection. The angle between the bow shock normal and the solar wind magnetic field significantly affects the magnetosheath's behavior, leading to different plasma environments that impact processes such as turbulence, heating, and wave-particle interactions.

Our research involves the study of these processes related to the onset, development, and consequences of magnetic reconnection on the plasma environment by using spacecraft data and advanced numerical simulations. Understanding these processes is crucial not only for comprehending how Earth is affected by its near-space environment but also for applying this knowledge to similar plasma environments throughout the Universe that are inaccessible to in situ measurements, as well as to plasma devices on Earth.

Team

• Yuri Khotyaintsev works with wave activity and particle acceleration
• Daniel Graham studies wave activity and electron dynamics in the vicinity of magnetic reconnection sites
• Cecilia Norgren studies small scale plasma waves in the vicinity of magnetic reconnection regions

Master and bachelor projects

There are good possibilities to do a master or bachelor thesis project at the Swedish Institute of Space Physics. Visit our website for project suggestions or contact us directly for further information.