Mechanism of O+ pitch-angle dispersion and asymmetric loss in flux tubes

Ascertain the physical mechanism responsible for the observed pitch-angle dispersion and asymmetric loss in the anti-parallel oxygen ion (O+) flux associated with isolated magnetospheric flux tubes during the recovery phase from the Alfvén wing state, and determine whether kinked flux tube geometry at scales comparable to O+ gyromotion accounts for the dispersion.

Background

During 15:00–15:22 UT, MMS observed multiple isolated convecting flux tubes with O+ enhancements and bidirectional field-aligned distributions. A gradual, asymmetric loss in the anti-parallel O+ flux (pitch-angle dispersion) was identified.

The authors explicitly state that the exact mechanism for this dispersion cannot be definitively determined. They propose a plausible scenario where kinks in the flux tube at scales similar to O+ gyromotion lead to loss into the solar wind, but confirmation is still needed.