Spectral evolution of turbulence energy density, E_w (top), and differential proton number density, N (bottom), for an SNR in the adiabatic stage at the age of 400 (red), 1000 (green), 3000 (blue) and 12 000 (gray) yr. Both the self-consistent treatment (thick lines) and Bohm-like diffusion (thin lines) are presented. Spectra for the location at r = 1.15 R_shock are averages over a shell with thickness 0.5 pc. Particles with kinetic energy of 1 GeV are resonant with waves of wavenumber k₀.