Turbulence in coronal mass ejections

The magnetic fields measured by the ISEE 3 spacecraft are used to study MHD turbulence within coronal mass ejections (CMEs). The spectral indices of the turbulence inside CMEs are compared with spectral indices found in solar wind undisturbed by CMEs. Irrespective of the CME velocities, the spectra within CMEs are found to differ from those determined for the fast solar wind from coronal holes. Instead, the CME spectra more closely resemble those found in the slow solar wind. Since both CMEs and the plasma sheet are associated with closed magnetic structures in. the solar corona, it appears that the turbulence in the solar wind arising from closed coronal regions is fundamentally different from the turbulence in wind from coronal holes. Helical properties of magnetic fields-within CMEs at different scales are studied. Preliminary results indicate that, in small scales, helical fields are distributed in a random fashion with alternating signs of twisting structures. In addition however. CMEs have large-scale helical structures. In the case of the magnetic cloud of day 302, 1978 this structure is interpreted as a part of the helical structure identified previously by fitting the data to a force-free flux rope configuration.