Precipitation of fast ion beams from the plasma sheet boundary layer

This paper presents a model of precipitated fluxes from the PSBL and CPS. Simulation results and data from Aureol-3 spacecraft indicate the presence of velocity dispersed precipitated ion structures (VDIS) at the poleward edge of the auroral oval. These structures are associated with fast ion beams in the PSBL region of the Earth's magnetotail, confirming previous experimental results. The simulations also reveal possible substructuring of the VDIS. The bulk of the PSBL population which is not precipitated is very effectively thermalized and quasi-isotropized after multiple interactions with the magnetotail current layer. After each reflection cycle some part of the distribution is precipitated and forms multiple ‘echoes’ of VDIS. The CPS distributions occurring as a result of scattering, convection, multiple reflections and Fermi acceleration appear isotropic in the simulation model. This paper portrays the important role of the VDIS auroral region medium for complicated and energetically significant processes occurring in different regions of the distant magnetotail.

[1]  M. Ashour‐Abdalla,et al.  Large and Small scale structures in the plasma sheet: A signature of chaotic motion and resonance effects , 1991 .

[2]  L. Zelenyi,et al.  Velocity‐dispersed ion beams in the nightside auroral zone: AUREOL 3 observations , 1990 .

[3]  N. Tsyganenko.  A magnetospheric magnetic field model with a warped tail current sheet , 1989 .

[4]  A. Vampola,et al.  A general association between discrete auroras and ion precipitation from the tail , 1988 .

[5]  E. W. Hones,et al.  ISEE 1 and 2 observations of ion distributions at the plasma sheet‐tail lobe boundary , 1988 .

[6]  J. L. Green,et al.  Destiny of earthward streaming plasma in the plasmasheet boundary layer , 1986 .

[7]  T. Speiser,et al.  Comparison of an analytical approximation for particle motion in a current sheet with precise numerical calculations , 1984 .

[8]  T. Eastman,et al.  The plasma sheet boundary layer , 1983 .

[9]  M. K. Andrews,et al.  Ion jetting at the plasma sheet boundary: simultaneous observations of incident and reflected particles , 1981 .

[10]  D. Williams.  Energetic ion beams at the edge of the plasma sheet: ISEE 1 observations plus a simple explanatory model , 1981 .

[11]  W. Elsasser,et al.  The depth of mantle convection , 1979 .

[12]  L. Frank,et al.  Observations pertaining to the dynamics of the plasma sheet. [in geomagnetic tail] , 1977 .

[13]  H. Rosenbauer,et al.  Heos 2 plasma observations in the distant polar magnetosphere: The plasma mantle , 1975 .

[14]  T. Speiser.  Particle trajectories in model current sheets: 2. Applications to auroras using a geomagnetic tail model , 1967 .