Origin of the plasma sheet

Author:
  • THT. W. Hill
    T. W. Hill
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Abstract
The plasma sheet is a region of hot plasma (∼107 °K) that surrounds the earth, filling the distant magnetosphere and separating the northern and southern lobes of the magnetospheric tail; its origin is one of the basic outstanding problems of magnetospheric physics. A critical review of the available observations indicates that the plasma sheet source must provide roughly 1025–1026 particles/s to balance known loss mechanisms operating in the quiet time magnetosphere and that an adiabatic or quasi‐adiabatic (ΔE ∝ E) acceleration mechanism must provide most of the observed particle energy. These constraints together with auroral helium ion measurements indicate that the plasma sheet particles must originate in the solar wind rather than in the terrestrial ionosphere. The available hypotheses for a solar wind source are examined, and it is concluded that a two‐step process of magnetopause diffusion plus electrostatic acceleration is the simplest source mechanism that is consistent with the available observations.

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