TY - JOUR

T1 - Energetic particle injection during short isolated bubble as seen in RCM simulation and spacecraft observations in the flow braking region.

AU - Сергеев, Виктор Андреевич

AU - Yang, Jian

AU - Sun, Weiqin

AU - Runov, A. V.

AU - Angelopoulos, V.

AU - Artemyev, Anton

PY - 2023/12/7

Y1 - 2023/12/7

N2 - Although energetic particle (EP) injections are commonly thought to be formed by the flow burst intrusion from the magnetotail, important details and quantitative aspects of their transport, acceleration and flow braking need further investigation and understanding. Motivated by frequent observations of short transient EP injections being not associated with substorms, we analyze high-resolution Rice Convection Model simulations of a short (5-min long) localized (∼3RE width) density depletion (evacuating 90% of flux tube content) initiated at the tailward simulation boundary (∼18RE) and allowed to evolve within an otherwise typical plasma sheet environment. We note that, driven by betatron-like acceleration, the peak EP flux at fixed energy dramatically increases in a couple of minutes when the bubble head enters the inner magnetosphere at r < 8–10 RE giving rise to a localized injection of subsequently drifting EP clouds. Here the 50–200 keV electron flux reaches values as high as #105 (cm2 s sr keV)−1, and even higher energies (up to 1 MeV) may briefly appear. Surprisingly, at a later stage of bubble penetration, after termination of bubble jet from the tail, the injection boundary of high energy (HE) particles detaches from the bubble earthward boundary while the latter continues moving inward. Time History of Events and Macroscale Interactions during Substorms multi-spacecraft mission observations of a short bubble-like flow burst at the spacecraft cluster located near the flow stopping point, show much similarity with simulation results but also reveal important differences between responses of HE protons and electrons attributed to the finite gyroradius effect.

AB - Although energetic particle (EP) injections are commonly thought to be formed by the flow burst intrusion from the magnetotail, important details and quantitative aspects of their transport, acceleration and flow braking need further investigation and understanding. Motivated by frequent observations of short transient EP injections being not associated with substorms, we analyze high-resolution Rice Convection Model simulations of a short (5-min long) localized (∼3RE width) density depletion (evacuating 90% of flux tube content) initiated at the tailward simulation boundary (∼18RE) and allowed to evolve within an otherwise typical plasma sheet environment. We note that, driven by betatron-like acceleration, the peak EP flux at fixed energy dramatically increases in a couple of minutes when the bubble head enters the inner magnetosphere at r < 8–10 RE giving rise to a localized injection of subsequently drifting EP clouds. Here the 50–200 keV electron flux reaches values as high as #105 (cm2 s sr keV)−1, and even higher energies (up to 1 MeV) may briefly appear. Surprisingly, at a later stage of bubble penetration, after termination of bubble jet from the tail, the injection boundary of high energy (HE) particles detaches from the bubble earthward boundary while the latter continues moving inward. Time History of Events and Macroscale Interactions during Substorms multi-spacecraft mission observations of a short bubble-like flow burst at the spacecraft cluster located near the flow stopping point, show much similarity with simulation results but also reveal important differences between responses of HE protons and electrons attributed to the finite gyroradius effect.

KW - магнитосфера

KW - инжекции плазмы

KW - радиационный пояс

KW - высыпания

KW - энергичные частицы

KW - injections

KW - energetic particles

KW - magnetotail

KW - substorms

KW - plasma bubbles

UR - https://www.mendeley.com/catalogue/a70ebe17-a344-3f90-9a00-e927fc829298/

U2 - 10.1029/2023ja031906

DO - 10.1029/2023ja031906

M3 - Article

VL - 128

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

SN - 2169-9380

IS - 12

M1 - e2023JA031906

ER -