Results for PSP encounters 1 to 14, split into distinct heliocentric distance intervals. Spectral index of the magnetic power α_B as a function of the background magnetic field STD. The slope of the red linear fit γ and the values of this fit at the far left and far right of the figure are indicated. All fits have a P-value of P < 0.001, except for the fit for 60 R_⊙ < r, which instead has P < 0.06.