Strong Perpendicular Velocity-space Diffusion in Proton Beams Observed by Parker Solar Probe

J. L. Verniero; B. D.G. Chandran; D. E. Larson; K. Paulson; B. L. Alterman; S. Badman; S. D. Bale; J. W. Bonnell; T. A. Bowen; T. Dudok De Wit; J. C. Kasper; K. G. Klein; E. Lichko; R. Livi; M. D. McManus; A. Rahmati; D. Verscharen; J. Walters; P. L. Whittlesey

doi:10.3847/1538-4357/ac36d5

Strong Perpendicular Velocity-space Diffusion in Proton Beams Observed by Parker Solar Probe

J. L. Verniero, B. D.G. Chandran, D. E. Larson, K. Paulson, B. L. Alterman, S. Badman, S. D. Bale, J. W. Bonnell, T. A. Bowen, T. Dudok De Wit, J. C. Kasper, K. G. Klein, E. Lichko, R. Livi, M. D. McManus, A. Rahmati, D. Verscharen, J. Walters, P. L. Whittlesey

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Abstract

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 hr ion-scale wave storm and show results from a preliminary attempt at quantifying the occurrence of ion-strahl broadening through three-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.

Original language	English (US)
Article number	112
Journal	Astrophysical Journal
Volume	924
Issue number	2
DOIs	https://doi.org/10.3847/1538-4357/ac36d5
State	Published - Jan 10 2022

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/1538-4357/ac36d5

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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. D., Kasper, J. C., Klein, K. G., Lichko, E., Livi, R., McManus, M. D., Rahmati, A., Verscharen, D., Walters, J., & Whittlesey, P. L. (2022). Strong Perpendicular Velocity-space Diffusion in Proton Beams Observed by Parker Solar Probe. Astrophysical Journal, 924(2), Article 112. https://doi.org/10.3847/1538-4357/ac36d5

Verniero, JL, Chandran, BDG, Larson, DE, Paulson, K, Alterman, BL, Badman, S, Bale, SD, Bonnell, JW, Bowen, TA, De Wit, TD, Kasper, JC, Klein, KG, Lichko, E, Livi, R, McManus, MD, Rahmati, A, Verscharen, D, Walters, J & Whittlesey, PL 2022, 'Strong Perpendicular Velocity-space Diffusion in Proton Beams Observed by Parker Solar Probe', Astrophysical Journal, vol. 924, no. 2, 112. https://doi.org/10.3847/1538-4357/ac36d5

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title = "Strong Perpendicular Velocity-space Diffusion in Proton Beams Observed by Parker Solar Probe",

abstract = "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 hr ion-scale wave storm and show results from a preliminary attempt at quantifying the occurrence of ion-strahl broadening through three-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.",

author = "Verniero, {J. L.} and Chandran, {B. D.G.} and Larson, {D. E.} and K. Paulson and Alterman, {B. L.} and S. Badman and Bale, {S. D.} and Bonnell, {J. W.} and Bowen, {T. A.} and {De Wit}, {T. Dudok} and Kasper, {J. C.} and Klein, {K. G.} and E. Lichko and R. Livi and McManus, {M. D.} and A. Rahmati and D. Verscharen and J. Walters and Whittlesey, {P. L.}",

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AU - Chandran, B. D.G.

AU - Larson, D. E.

AU - Paulson, K.

AU - Alterman, B. L.

AU - Badman, S.

AU - Bale, S. D.

AU - Bonnell, J. W.

AU - Bowen, T. A.

AU - De Wit, T. Dudok

AU - Kasper, J. C.

AU - Klein, K. G.

AU - Lichko, E.

AU - Livi, R.

AU - McManus, M. D.

AU - Rahmati, A.

AU - Verscharen, D.

AU - Walters, J.

AU - Whittlesey, P. L.

PY - 2022/1/10

Y1 - 2022/1/10

N2 - 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 hr ion-scale wave storm and show results from a preliminary attempt at quantifying the occurrence of ion-strahl broadening through three-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.

AB - 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 hr ion-scale wave storm and show results from a preliminary attempt at quantifying the occurrence of ion-strahl broadening through three-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.

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Strong Perpendicular Velocity-space Diffusion in Proton Beams Observed by Parker Solar Probe

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