In this paper neutral point (coalescence) instability (NPI) of plasmoids (PMD) associated with tailward streaming O+, H+ and e− particles and diffusion region (spatial extent and particle life time) are studied. Also, radial and pitch angle diffusion studies have been carried out in the near-earth region (10 and 11 RE during substorm onset. Our study revealed that coalescence instability is favoured by a heavier ion like O+ and the time required for a heavier ion to reach from one X point to an adjacent X point is minimum. Near an X type neutral line (diffusion region) ions spend a fairly long time and gain a significant amount of energy. Radial and pitch angle diffusion studies showed that higher energy particles are largely confined near the reconnection region (near-earth region) and lower energy particles are rapidly depleted from the near-earth region during substorm onset.
Volume 129, 2020
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