Strong perpendicular velocity-space in proton beams observed by Parker Solar Probe
| Autor: | Verniero, J. L., Chandran, B. D. G., Larson, D. E., Paulson, K., Alterman, B. L., Badman, S., Bale, S. D., Bonnell, J. W., Bowen, T. A., de Wit, T. Dudok, Kasper, J. C., Klein, K. G., Lichko, E., Livi, R., McManus, M. D., Rahmati, A., Verscharen, D., Walters, J., Whittlesey, P. L. |
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| Rok vydání: | 2021 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.3847/1538-4357/ac36d5 |
| Popis: | The SWEAP instrument suite on Parker Solar Probe (PSP) has detected numerous proton beams associated with coherent, circularly polarized, ion-scale waves observed by PSP's FIELDS instrument suite. Measurements during PSP Encounters 4-8 revealed pronounced complex shapes in the proton velocity distribution functions (VDFs), in which the tip of the beam undergoes strong perpendicular diffusion, resulting in VDF level contours that resemble a `hammerhead.' We refer to these proton beams, with their attendant `hammerhead' features, as the ion strahl. We present an example of these observations occurring simultaneously with a 7-hour ion-scale wave storm and show results from a preliminary attempt at quantifying the occurrence of ion-strahl broadening through 3-component ion-VDF fitting. We also provide a possible explanation of the ion perpendicular scattering based on quasilinear theory and the resonant scattering of beam ions by parallel-propagating, right circularly polarized, fast-magnetosonic/whistler waves. Comment: 13 pages, 8 figures, Under Review in the Astrophysical Journal |
| Databáze: | arXiv |
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