IRF Uppsala
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Swedish Institute of Space Physics (59o50.272'N, 17o38.786'E)
Student project at IRF Uppsala

Project work (30 c)/Examensarbete (30 hp)

Electron heating in the Earth's bow shock

Student: Martin Svensson, Luleå University of Technology
Supervisor: Andreas Johlander
Period: Autumn 2017

[Another nice picture]
Illutration of Earth’s magnetosphere. Image credit: ESA/C. T. Russell.


Characterize electron heating in Earth's quasi-perpendicular bow shock using MMS data.


MMS is a NASA mission launched in 2015 and studying the Earth's magnetosphere. Important science topics addressed by MMS are magnetic reconnection, turbulence and shocks. To address those questions there are different instruments on-board. IRF, Uppsala is contributing to one of the MMS instruments (FIELDS-SDP) measuring electric field. MMS is four-spacecraft mission where the separation of spacecraft is as small as 7 km. This, for the first time, allows to explore the electron scale physics in plasmas in very high detail. One such fundamental problem is electron heating at the shocks. Shocks occur in many astrophysical locations, such as planetary magnetospheres, interplanetary shocks, galaxy collisions, supernova shocks, etc. Much of the information from astrophysical plasma environments is coming as a radiation generated by electrons that has been heated in shocks and therefore it is crucial to understand the heating mechanisms. The Earth's bow shock is the nearest space environment where the electron shock physics can be studied in detail. Until now there are few experimental studies of electron heating at shocks and those has been mainly carried out with lower resolution instrumentation. Recent data from the ESA mission Cluster have suggested that electron heating may occur on very small electron scales, however even Cluster's resolution was not sufficient to resolve this in detail. MMS will for the first time allow to address these questions in detail.


The project would focus on analysing several Earth bow shock crossings using data from MMS mission, identifying the spatial scales at which electron heating happens and physical mechanisms responsible for that. For the project, crossings will be selected from the quasi-perpendicular shocks which are easier to analyse. The shocks will have to be selected from the Phase 1b of the mission when satellite separation is smallest - about 7 km. Several shocks with different Mach number and shock angle will have to be analysed. Multi-spacecraft measurements will be needed to characterize the spatial scales of electron heating. This will have to be compared with the magnetic and electric field structure to identify the heating mechanisms. Particularly interesting will be to look into the contribution from betatron heating versus electron acceleration due to electric fields.


[A nice picture]
Tycho’s supernova remnant in X-rays by Chandra X-ray Observatory. Image credit: NASA/CXC/SAO.
last modified on Friday, 08-Sep-2017 14:23:57 CEST