When I enable gridlines, x axis label is not displayed:
Plot[5.939663571812609`*^-15 Sqrt[
1.9380043062246294`*^26 - 1.4020134775864955`*^30/d^2], {d, 0,
1000}, PlotRange -> {{86, 1000}, All}, Frame -> True,
GridLines -> {d2, d1}, AxesLabel -> {"d", "Angle"}]
AxesStyle -> Directive[Black, 24]
doesn't work either.