Identification of Small Scale Structures from PSP Observations

The Parker Solar Probe observed a coronal mass ejection (CME) event during its first orbit around the sun. This event is analyzed by applying a wavelet analysis technique to the MHD invariants, namely the magnetic helicity, cross helicity, and residual energy. Our results show that the CME, as large scale magnetic flux rope, possess high magnetic helicity, relatively low cross helicity, and highly negative residual energy, thus pointing to a magnetic fluctuation dominated structure. Using the same technique, we also search for small-scale coherent magnetic flux rope structures, which are intrinsic to MHD turbulence in the solar wind during other periods. Multiple structures with duration between 8 and 360 minutes are identified from PSP in situ spacecraft measurements through analyzing the magnetic helicity, cross helicity and residual energy. The location and scales of these structures are characterized by wavelet spectra. Transport theory suggests that these small-scale magnetic flux ropes may be contribute to the acceleration of charged particles through reconnection processes, and the dissipation of these structures may be important for understanding the coronal heating processes.