Solar Orbiter’s particle (STEP), magnetic field (MAG), and power spectral densities of magnetic fluctuations acquired by Fourier transforms of the magnetic field data of the energetic storm particle event associated with the 2021 October 28 solar event. The local maximum frequency allowed by MHD, f_max, and the local proton cyclotron frequency, f_c, p, are depicted as the white and black lines, respectively. Additionally, three averaging windows to investigate local wave intensity (Fig. 8) are indicated by the black solid line borders and magenta shaded boxes.