Evolution of the volume-averaged magnetic energy in both the r and ϕ components of the magnetic field normalized to the initial magnetic energy in a shell from r_out/40 to r_out in model L1. In this model, the magnetic field is amplified only by flux freezing. As v_θ∼ 0, there is almost no amplification of the θ component of the field, so it is not shown. The growth of each component is defined as δB²_r,θ,ϕ = (〈B²_r,θ,ϕ〉_V−B²_r,θ,ϕ,0), where 〈〉_V denotes volume average and B₀ is the initial field strength.