Spectral properties of mesoscale fluctuations in ICMEs

ICME plasma fluctuates across a broad range of scales, with fluctuations that display many similar spectral properties to other kinds of solar wind. These fluctuations, which may represent turbulence, waves or structures in the plasma, are not well understood holistically in the ICME context. Using data from Parker Solar Probe and Solar Orbiter, we present analysis of magnetic field spectra from ICME flux ropes at scales between the flux rope radial width and the magnetic field correlation length. The presence of the global flux rope causes significant steepening of the spectra at these scales, with spectral indices as steep as -2. The underlying fluctuations, in contrast, show much shallower spectral slopes. Key properties of the fluctuations are determined and compared to those found at the same scales in other solar wind types. Interpretations of the fluctuations as an energy source for turbulence at smaller scales or as mesoscale ICME substructure are discussed.