TitlePlasma Waves near the Electron Cyclotron Frequency in the Near-Sun Solar Wind
Publication TypeJournal Article
Year of Publication2020
AuthorsMalaspina, DM, Halekas, J, Berčič, L, Larson, D, Whittlesey, P, Bale, SD, Bonnell, JW, de Wit, TDudok, Ergun, RE, Howes, G, Goetz, K, Goodrich, K, Harvey, PR, MacDowall, RJ, Pulupa, M, Case, AW, Kasper, JC, Korreck, KE, Livi, R, Stevens, ML
JournalThe Astrophysical Journal Supplement Series
Date Published02/2020
KeywordsAstrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Space Physics; Solar Probe Plus

Data from the first two orbits of the Sun by Parker Solar Probe reveal that the solar wind sunward of 50 solar radii is replete with plasma waves and instabilities. One of the most prominent plasma wave power enhancements in this region appears near the electron cyclotron frequency (fce). Most of this wave power is concentrated in electric field fluctuations near 0.7 fce and fce, with strong harmonics of both frequencies extending above fce. At least two distinct, often concurrent, wave modes are observed, preliminarily identified as electrostatic whistler-mode waves and electron Bernstein waves. Wave intervals range in duration from a few seconds to hours. Both the amplitudes and number of detections of these near-fce waves increase significantly with decreasing distance to the Sun, suggesting that they play an important role in the evolution of electron populations in the near-Sun solar wind. Correlations are found between the detection of these waves and properties of solar wind electron populations, including electron core drift, implying that these waves play a role in regulating the heat flux carried by solar wind electrons. Observation of these near-fce waves is found to be strongly correlated with near-radial solar wind magnetic field configurations with low levels of magnetic turbulence. A scenario for the growth of these waves is presented, which implies that regions of low-turbulence near-radial magnetic field are a prominent feature of the solar wind structure near the Sun.  

Short TitleApJS

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