On the ring current energy injection rate |
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| Authors: | LC Lee G Corrick S-I Akasofu |
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| Institution: | Geophysical Institute, University of Alaska, Fairbanks, AK 99701, U.S.A. |
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| 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 (KR) and the ring current energy injection rate (UR) as a function of the cross-tail electric field (ECT); 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 KR is approximately linearly proportional to ECT; (2) the characteristic time tc for KR to reach the saturation level is 3–4 h; (3) the injection rate UR is proportional to ECTβ where β ? 1.33?1.52; and (4) the characteristic time tp for UR to reach the peak value is 1–2 h and the peak UR 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 ECT(or φCT) and UR 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. |
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