Fig. 7
From: Stability and symmetry of ion-induced surface patterning
Wavelength spectrum for linear (top) and nonlinear (bottom) evolution cases. The distribution function of the surface is shown prior to evolution, after 10 h, and after 30 h to demonstrate the changes throughout evolution. The effect of nonlinearities shows the emergence of a wavelength at later times, which is half the analytical result according to linear theory. After 10 hours, both evolution regimes show similar results