Are Dipolarization Fronts a Typical Feature of Magnetotail Plasma Jets Fronts?

Abstract

Plasma jets are ubiquitous in the Earth's magnetotail. Plasma jet fronts (JFs) are the seat of particle acceleration and energy conversion. JFs are commonly associated with dipolarization fronts (DFs) representing solitary sharp and strong increases in the northward component of the magnetic field. However, MHD and kinetic instabilities can develop at JFs and disturb the front structure which questions on the occurrence of DFs at the JFs. We investigate the structure of JFs using 5 years (2017-2021) of the Magnetospheric Multiscale observations in the CPS in the Earth's magnetotail. We compiled a database of 2394 CPS jets. We find that about half (42\%) of the JFs are associated with large amplitude changes in $B_z$. DFs constitute a quarter of these large-amplitude events, while the rest are associated with more complicated magnetic field structures. We conclude that the ``classical" picture of DFs at the JFs is not the most common situation.