Parker Solar Probe observations of proton beams simultaneous with ion-scale waves. (arXiv:2004.03009v1 [physics.space-ph])

Parker Solar Probe observations of proton beams simultaneous with ion-scale waves. (arXiv:2004.03009v1 [physics.space-ph])
<a href="http://arxiv.org/find/physics/1/au:+Verniero_J/0/1/0/all/0/1">J. L. Verniero</a>, <a href="http://arxiv.org/find/physics/1/au:+Larson_D/0/1/0/all/0/1">D. E. Larson</a>, <a href="http://arxiv.org/find/physics/1/au:+Livi_R/0/1/0/all/0/1">R. Livi</a>, <a href="http://arxiv.org/find/physics/1/au:+Rahmati_A/0/1/0/all/0/1">A. Rahmati</a>, <a href="http://arxiv.org/find/physics/1/au:+McManus_M/0/1/0/all/0/1">M. D. McManus</a>, <a href="http://arxiv.org/find/physics/1/au:+Pyakurel_P/0/1/0/all/0/1">P. Sharma Pyakurel</a>, <a href="http://arxiv.org/find/physics/1/au:+Klein_K/0/1/0/all/0/1">K. G. Klein</a>, <a href="http://arxiv.org/find/physics/1/au:+Bowen_T/0/1/0/all/0/1">T. A. Bowen</a>, <a href="http://arxiv.org/find/physics/1/au:+Bonnell_J/0/1/0/all/0/1">J. W. Bonnell</a>, <a href="http://arxiv.org/find/physics/1/au:+Alterman_B/0/1/0/all/0/1">B. L. Alterman</a>, <a href="http://arxiv.org/find/physics/1/au:+Whittlesey_P/0/1/0/all/0/1">P. L. Whittlesey</a>, <a href="http://arxiv.org/find/physics/1/au:+Malaspina_D/0/1/0/all/0/1">David M. Malaspina</a>, <a href="http://arxiv.org/find/physics/1/au:+Bale_S/0/1/0/all/0/1">S. D. Bale</a>, <a href="http://arxiv.org/find/physics/1/au:+Kasper_J/0/1/0/all/0/1">J. C. Kasper</a>, <a href="http://arxiv.org/find/physics/1/au:+Case_A/0/1/0/all/0/1">A. W. Case</a>, <a href="http://arxiv.org/find/physics/1/au:+Goetz_K/0/1/0/all/0/1">K. Goetz</a>, <a href="http://arxiv.org/find/physics/1/au:+Harvey_P/0/1/0/all/0/1">P. R. Harvey</a>, <a href="http://arxiv.org/find/physics/1/au:+Korreck_K/0/1/0/all/0/1">K. E. Korreck</a>, <a href="http://arxiv.org/find/physics/1/au:+MacDowall_R/0/1/0/all/0/1">R. J. MacDowall</a>, <a href="http://arxiv.org/find/physics/1/au:+Pulupa_M/0/1/0/all/0/1">M. Pulupa</a>, <a href="http://arxiv.org/find/physics/1/au:+Stevens_M/0/1/0/all/0/1">M. L. Stevens</a>, <a href="http://arxiv.org/find/physics/1/au:+Wit_T/0/1/0/all/0/1">T. Dudok de Wit</a>

Parker Solar Probe (PSP), NASA’s latest and closest mission to the Sun, is on
a journey to investigate fundamental enigmas of the inner heliosphere. This
paper reports initial observations made by the Solar Probe Analyzer for Ions
(SPAN-I), one of the instruments in the Solar Wind Electrons Alphas and Protons
(SWEAP) instrument suite. We address the presence of secondary proton beams in
concert with ion-scale waves observed by FIELDS, the electromagnetic fields
instrument suite. We show two events from PSP’s 2nd orbit that demonstrate
signatures consistent with wave-particle interactions. We showcase 3D velocity
distribution functions (VDFs) measured by SPAN-I during times of strong wave
power at ion-scales. From an initial instability analysis, we infer that the
VDFs departed far enough away from local thermodynamic equilibrium (LTE) to
provide sufficient free energy to locally generate waves. These events
exemplify the types of instabilities that may be present and, as such, may
guide future data analysis characterizing and distinguishing between different
wave-particle interactions.

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