Relation between the internal magnetic field B_int and the numerical coefficient k is drawn according to Eq. (9). The black horizontal line represents the maximum value of the internal magnetic field limited by Eq. (2) when the magnetosphere radius R_m = 10⁶ cm. In addition, the green lines show the relationship between B_int and k drawn from Eq. (9). We show two different conditions, B_dip ∼ 0.1 B_int and B_dip ∼ B_int. The colored area shows the allowable region.