Electron pitch angle variations recorded at the high magnetic latitude boundary layer by the NUADU instrument on the TC-2 spacecraft

L Lu,S Y Fu,J Balaz,H Gunell,Z X Liu,K Brinkfeldt,J K Shi,T L Zhang,I Strharsky,J B Cao,C Carr,C Shen,I Dandouras,K Kudela,E C Roelof,S Mckenna-Lawlor,A Fazakerley,S Barabash,P C Brandt

doi:10.5194/angeo-23-2953-2005

Abstract

Abstract. The NUADU (NeUtral Atom Detector Unit) experiment aboard TC-2 recorded, with high temporal and spatial resolution, 4π solid angle images of electrons (~50-125 keV) spiraling around geomagnetic field lines at high northern magnetic latitudes (L>10), during its in-orbit commissioning phase (September 2004). The ambient magnetic field, as well as electrons in other energy ranges, were simultaneously measured by the TC-2 magnetometer (FGM), the plasma electron and current experiment (PEACE), the low energy ion detector (LEID) and the high energy electron detector (HEED). The NUADU data showed that up-flowing electron beams could form "ring-like" and "dumbbell-type" pitch angle distributions (PADs) in the region sampled. Changes in these pitch angle distributions due to transient magnetic variations are suggested to have been associated with electron acceleration along the geomagnetic field lines. A nested magnetic bottle configuration that formed due to the propagation towards the Earth of a magnetic pulse, is proposed to have been associated with this process.

Highlights

The Chinese Space Agency launched the second of a pair of spacecraft (TC-2), forming the Double Star Mission, into a polar orbit on 25 July 2004
TC-2 carries a payload designed to investigate various features of geo-space, both on a stand-alone basis and in co-operation with the CLUSTER mission already launched by the European Space Agency
During its on-orbit commissioning in September 2004, the NUADU instrument imaged the spherical pitch angle distributions (PADs) of ambient electrons in the keV range at high temporal and spatial resolution, at high northern latitudes (L>10)

Summary

Introduction

The Chinese Space Agency launched the second of a pair of spacecraft (TC-2), forming the Double Star Mission, into a polar orbit on 25 July 2004. During its on-orbit commissioning in September 2004, the NUADU instrument imaged the spherical pitch angle distributions (PADs) of ambient electrons in the keV range at high temporal and spatial resolution, at high northern latitudes (L>10). This provided an opportunity to investigate, in detail, the formation and evolution of these PADs. The measurement and investigation of pitch angle distributions provide insight into the physical mechanisms pertaining to energetic plasmas. L. Lu et al.: Electron pitch angle variations at the high magnetic latitude boundary layer. Red arrows point to the flux peaks formed at the locations of the rings

Instrumentation

Ring-like PADs

Findings

Discussion and conclusion