Heliosheath Magnetic Field and Plasma Observed by Voyager2 during 2012 in the Rising Phase of Solar Cycle 24
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چکیده
We discuss magnetic field and plasma observations of the heliosheath made by Voyager 2 (V2) during 2012, when V2 was observing the effects of increasing solar activity following the solar minimum in 2009. The average magnetic field strength B was 0.14 nT and B reached 0.29 nT on day 249. V2 was in a unipolar region in which the magnetic polarity was directed away from the Sun along the Parker spiral 88% of the time, indicating that V2 was poleward of the heliospheric current sheet throughout most of 2012. The magnetic flux at V2 during 2012 was constant. A merged interaction region (MIR) was observed, and the flow speed increased as the MIR moved past V2. The MIR caused a decrease in the >70MeV nuc cosmic-ray intensity. The increments of B can be described by a q-Gaussian distribution with q=1.2±0.1 for daily averages and q=1.82±0.03 for hour averages. Eight isolated current sheets (“PBLs”) and four closely spaced pairs of current sheets were observed. The average change of B across the current sheets was a factor of ≈2, and B increased or decreased with equal probability. Magnetic holes and magnetic humps were also observed. The characteristic size of the PBLs was ≈6 RL, where RL is the Larmor radius of protons, and the characteristic sizes of the magnetic holes and humps were ≈38 RL and ≈11 RL, respectively.
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تاریخ انتشار 2016