Fig. 5
From: Origin of two-band chorus in the radiation belt of Earth
Schematic illustration of the generation mechanism of two-band chorus waves. a The anisotropic velocity distribution of freshly injected electrons and b the generation of one-band chorus emissions. c The electron distribution after Landau resonant acceleration taking place, resulting in two separate anisotropic parts, d The excitation of the upper and the lower band chorus emissions by the low-energy and high-energy anisotropic electrons, respectively. The red solid and dashed lines represent fce and 0.5 fce, respectively. Since the Landau resonant acceleration and the formation of two anisotropic components occur very rapidly, the two-band chorus waves are more commonly observed than the one-band chorus waves. The measured electron distribution associated with the one-band and two-band chorus waves are shown in Supplementary Fig. 6
