A Statistical Study of Electron Scattering during Magnetopause Reconnection in the Presence of a Guide Field

Sammanfattning

Magnetic reconnection at the dayside magnetopause is an important process for transferring energy and plasma from thesolar wind into Earth’s magnetosphere. In this thesis, electron scattering during asymmetric magnetopause reconnection wasinvestigated using MMS observations. A total of 533 magnetopause current-sheet crossings were selected from an existingMMS event database. For each event, quantities related to electron scattering were analyzed, including the electron gyroradiusrge, the magnetic-field curvature radius RcB, the κ parameter, and the electron temperatureratio T⊥/T∥. The results show that events with low minimum κ tend to have more isotropic electron temperatures, withT⊥/T∥ approaching 1 near the minimum value of κ → 1. This is consistent with pitch angle scattering and reduced electronmagnetization. Events with stronger guide fields generally show less evidence of electron scattering, suggesting that theguide field causes a stronger magnetization of the electrons during the reconnection. The location of κmin relative to thereconnection geometry is partly consistent with hypothesised expectations, although the trends are affected by event-to-eventvariability, uncertainties in the LMN coordinate system, and the difficulty of identifying clear reconnection signatures in allevents. Previous published studies have mainly investigated these relationships in individual events. This study, therefore,provides a statistical investigation of electron scattering under moderate guide-field magnetopause reconnection using in situ MMS measurements.