Characters of the magnetotail plasma injection surveyed from Cluster observation

• The properties of proton (0 eV < E < 40 keV) in the plasma sheet are examined by means of a superposed epoch analysis, using 115 magnetotail plasma injection events which are identified from Cluster magnetotail orbit time in between 2001 and 2004. All events distribute in magnetic local time from 20 p.m. to 04 a. in. Five classes of magnetotail injection events are found to be similar with the geosynchronous observation: (1) pure ion injections; (2) ion injections followed a few minutes later by an electron injection; (3) simultaneous ion and electron injections; (4) electron injections followed a few minutes later by an ion injection; (5) pure electron injections. Proton shows a significant increase in temperature and density at the onset, and injects earthward with an increasing velocity more than the pre-injection average one. Super-posed epoch analysis on the simultaneous observation data of dusk-dawn electric field from the EFW (Electric Field and Waves) instrument, we found two different electric field configurations: ( I) electric field increases suddenly at the onset and the value is positive; (2) electric field changes the direction at the onset, and turns into a negative value. The simulation results of velocity vector after injection in equatorial plain, calculated in static magnetic (T89c) and electric (Volland-Stern) field models, agree with the statistical results mostly, and that suggests the electric drift caused by dawn-dusk convection electric field is one of the mechanisms of the particles injected earthward in magnetotail(-18 R-E < R < -10R(E)).

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

magnetotail plasma injection

Dawn-dusk convection electric field

T89c magnetic field

Volland-Stern electric field

electric drift

Physics

Fysik

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