We want to design a spherical vacuum capacitor, formed by an inner spherical conductor with radius…

We want to design a spherical vacuum capacitor, formed by an
inner spherical conductor with radius b
and an outer spherical shell of given radius a.
We want to design a spherical vacuum capacitor, formed by an inner spherical conductor with radius b and an outer spherical shell of given radius a. We want the capacitor to be able to store the greatest amount of electrical energy subject to the constraint that the electric field strength at the surface of the inner sphere may not exceed Eo- What radius b should be chosen for the inner spherical conductor and how much energy can be stored? For convenience, choose b=ka, with k-constant