Structure of the Plasma near the Heliospheric Current Sheet as seen by WISPR/Parker Solar Probe from Inside the Streamer Belt

Parker Solar Probe crossed the Heliospheric Current Sheet (HCS) near perihelion on Encounters E8 and E11, enabling the Wide-field Imager for Solar Probe (WISPR) to image the streamer belt plasma in high resolution while flying through it. With perihelia of 16~R$_\sun$ and 13~R$_\sun$ for E8 and E11, respectively, WISPR images enable investigation of the structure of density encasing the HCS at much higher resolution than reported previously. As PSP flies closer to the Sun, fine scale structure is resolved within the rays of the streamer belt. Near the HCS, WISPR observes a fan of rays of varying size and brightness, indicating large density variations along the HCS. Near perihelion, when PSP’s speed exceeds the solar co-rotation speed, some rays exhibit large changes in \textit{apparent} latitude as the HCS is encountered and rays pass over and under the spacecraft. The multiple viewpoints provided during the HCS crossing enable us to extract the coordinates of a few rays in a heliocentric frame. The rays were found to lie near the HCS from a PFSS model. We compare their locations to the location of the streamers as seen in synoptic maps from the Large Angle and Spectrometric COronagraph (LASCO), and find that the rays generally fall within the bright/high density regions seen in these maps, which confirms that they are features of the streamer belt plasma along the HCS. We speculate that the density variations in the helmet streamer plasma result from continuous interchange reconnection along the coronal hole boundaries.