Abstract
Assuming that the formation of the ring current belt is a direct consequence of an enhanced crosstail electric field and hence of an enhanced convection, we calculate the total ring current kinetic energy ( K R ) and the ring current energy injection rate ( U R ) as a function of the cross-tail electric field ( E CT ); the cross-tail electric field is assumed to have a step function-like increase. The loss of ring current particles due to recombination and charge-exchange is assumed to be distributed over the whole ring current region. It is found that: (1) the steady-state ring current energy K R is approximately linearly proportional to E CT ; (2) the characteristic time t c for K R to reach the saturation level is 3–4 h; (3) the injection rate U R is proportional to E CT β where β ≅ 1.33−1.52; and (4) the characteristic time t p for U R to reach the peak value is 1–2 h and the peak U R value is 50% higher than the steady-state value. Since β is now determined specifically for an enhanced convection, an observational determination of the relationship between E CT (or φ CT ) and U R is essential to a better understanding of ring current formation processes. If the observed β is greater than 1.5, additional processes (e.g. an injection of heavy ions from the ionosphere to the plasma sheet and subsequently to the ring current region) may be required.
Published Version
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