A Series of Small-Scale Magnetic Flux Ropes Originating from the Narrow Longitudinal and Latitudinal Region Identified in Co-Rotating Observation of Parker Solar Probe

Small-scale magnetic flux ropes (SMFRs) in the solar wind have a similar magnetic topology to large-scale interplanetary flux ropes such as magnetic clouds, while their origins are still under debate. Since the Parker Solar Probe (PSP) operates the closest to the Sun, its in-situ observations allow one to seek the origin of SMFRs closest to the Sun ever. For a few tens hours near the perihelion, PSP travels co-rotating with the solar surface, as called co-rotation interval, only radial operation. In this work, we investigate SMFRs identified from the fifth PSP encounter observations on the verge of the neutral sheet as inferred from the potential field source surface (PFSS) map. We find a series of low plasma beta SMFRs (~10 events) which were successfully modeled by force-free fitting technique. From the co-rotating frame of the Sun, they were found during ~30 hrs over several solar radii ranges (between 35 Rs to 45 Rs) within a very narrow longitudinal and latitudinal zone (< a few degrees). We presume that they were generated repetitively from the same source region below the PSP location near the heliospheric current sheet or they may be a bunch of flux ropes separated by a short radial distance across some (undetermined) radial distance ranges, which were transported outward at a slow speed (< 300 km/s). Further, we determine whether they are mixed with or distinguished from Alfven waves based on cross helicity and residual energy. We suggest the generation site of these compact series of SMFRs inferred from the detection data.