Figure 4

Panel (a): Fold increase of the total flux with respect to a homogeneously absorbing spheroid as function of the mean reactivity K, for spheroids with increasing aspect ratio \(\gamma\). Panels (b, c, d): the optimal local reactivity \(\kappa (\cos \beta )\) as a function of the position parametrized by the polar spheroidal angle \(\beta\), for three values of the mean reactivity.