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 amore »
Free, publicly-accessible full text available January 1, 2023
