Investigation of jets in the magnetosheath using Cluster measurements

Sammanfattning: With the help of the measurements made by Cluster spacecrafts, an investigation of fast plasma flowcalled jets in the magnetosheath has been made. The investigation covers a large statistical study ofjets with two definitions of jets and therefore two different approaches to detect jets.The study has been divided into three parts. The first part is to automatically detect themagnetosheath. The second part of the study is to detect magnetosheath jets with the differentapproaches. The final part is to analyse the jets to obtain statistical results. All three parts were madepossible by analysing the Cluster data using MatLab. Several scripts were written in MatLab, toidentify magnetosheath, to detect magnetosheath jets, visualize the magnetosheath and themagnetosheath jets and to analyse the magnetosheath jets statistically. A short introduction of therelevant space physics in form of a short literature study is done to help the reader understand theinvestigation.Important results obtained in this study are the properties of jets such as an average duration ofabout 7-12 s, absolute ion velocity of about 200-322 kms-1, scale size of about 0.38-0.44 RE, particledensity of about 22-47 cm-3, kinetic energy density of about 1.7-3.3 nJm-3 and absolute value ofmagnetic field of about 14-92 nT along the positive x-coordinate in a geocentric solar eclipticcoordinate system. Jets are detected at both positive and negative x-coordinates in a geocentric solarecliptic coordinate system although they are more common on the positive side.