Seminar: The sources of intense electron acceleration in magnetic reconnection

Magnetic reconnection is a fundamental process responsible for explosive conversion of magnetic energy to kinetic energy of charged particles in solar and astrophysical plasmas. Around Earth, magnetic reconnection takes place both at the dayside magnetopause and in the magnetotail, where fast jets are generated and flow towards the Earth. Thermal energy electrons in these jets can be heated and accelerated to relativistic energies by different processes, namely betatron, Fermi, and parallel electric field accelerations. The relative contributions of these different mechanisms, the location relative to the reconnection site in which each of them dominates, and the conditions under which they act are the focus of this PhD project. Using in-situ magnetotail measurements from the Magnetosphere MultiScale (MMS) mission we will study these acceleration mechanisms in multiple reconnection events to better understand how electrons can be accelerated to relativistic energies.

In the first project, we quantify the betatron acceleration of electrons at dipolarization fronts, which form at the leading boundaries of reconnection jets in the magnetotail. Using the guiding center theory and data from MMS we calculate and show the energy gained by electrons due to betatron acceleration for one dipolarization front. We also show the location of maximum betatron contribution relative to the front boundary and the region where we observe electrons with energies much higher than the thermal energy. We will investigate whether this type of acceleration acts at regions where electrons exhibit perpendicular temperature anisotropy and if that is accompanied by whistler waves, which isotropize the electron distribution.

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We shall leave for lunch at around 12:15. There might be fika after the seminar.