MMS Observations of Velocity-dispersed Ion Populations in Earth’s Magnetotail.
Thursday, 17 December 2015: 15:10
2018 (Moscone West)
The Fast Plasma Investigation suite (FPI) onboard NASA’s Magnetospheric MultiScale (MMS) mission enables measurement of the three dimensional distribution functions with unprecedented time resolution: 30 and 150 ms for electrons and ions, respectively. The high time resolution allows study of the fine structure of velocity-dispersed ion signatures observed by the MMS spacecraft during instrument commissioning in the magnetotail. The observed ion dispersions can be considered to result from plasma injections at a reconnection site that is distant from the spacecraft location. However, MMS observed many cases of double dispersed ion populations overlapped in time, which are consistent with similar signatures observed on the dayside and explained to result from double (or multiple) reconnection sites. This can be taken as evidence that the MMS spacecraft crossed field lines directly connected to the reconnection sites. We will present detailed, multi-instrument analyses of these observed velocity-dispersed structures concentrating on their origin and dynamics.