Plasmoids and Magnetic Field Dipolarizations During Juno's First 47 Orbits: Is Ion Acceleration Always Observed in the Dipolarizations?

• Published in: Journal of geophysical research. Space physics Vol. 129; no. 10
• Main Authors: Blöcker, A., Kronberg, E. A., Grigorenko, E. E., Ebert, R. W., Clark, G.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01-10-2024
• Subjects: Energetic particles; Flow velocity; Ion acceleration; Ion dynamics; Ions; Juno; Jupiter; Jupiter probes; magnetic field dipolarization; Magnetic fields; Magnetic properties; nonadiabatic acceleration; Orbits; Particle acceleration; Planetary magnetic fields; Planetary magnetotails; Plasmas (physics); plasmoids; Reconfiguration
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2024JA032853

Plasmoids and magnetic field dipolarizations are reconnection‐related phenomena often resulting in reconfiguration of the magnetic field and energetic particle acceleration in planetary magnetotail. Building on the work of Blöcker et al. (2023) (10.1029/2023JA031312), we selected seven specific events from their magnetic field dipolarization analysis, each exhibiting distinct ion dynamics during the time interval of the magnetic field dipolarizations. To gain further insights into the understanding why certain events were associated with ion intensity variations while others were not, we analyzed plasma moments, specifically ion flow velocity and density, for these selected events. Our findings revealed that certain magnetic field dipolarizations within our database exhibit sub‐Alfvénic flows and lack the properties typically associated with reconnection‐related magnetic field dipolarizations. These magnetic field dipolarizations also do not accelerate ions. Furthermore, we present a survey of Jovian plasmoids and magnetic field dipolarizations during the first 47 orbits of Juno. Applying Juno magnetic field data, we identified 119 magnetic field dipolarizations and 94 plasmoids within a local time range of 18:00–06:00. The majority of plasmoids were detected in the predawn sector, whereas magnetic field dipolarizations were observed closer to Jupiter and were not limited to a specific local time. Combining the statistics of plasmoids and dipolarizations is useful for contextualizing them within the framework of reconnection.
Key Points
Certain magnetic field dipolarizations exhibit sub‐Alfvénic flows and deviate from typical reconnection‐related properties
Nonadiabatic ion acceleration is only observed in magnetic field dipolarizations with super‐Alfvénic ion flows
Plasmoids are concentrated in the predawn sector, while dipolarizations are distributed from 20:00 to 5:00 local time closer to Jupiter