I have been really fascinated with the dielectric breakdown artwork by Bert Hickman seen here. He is using a 5MeV accelerator to embed electrons in acrylic. He then discharges them to create beautiful fractal patterns. I emailed him last year asking how to calculate the penetration depth of the electrons and he responded that it was depended on the density of the acrylic and the energy of the electrons. A more specific explanation can be found here. I am trying to find a way to do this (safely) without renting out a particle accelerator. This is a hobby after all. In order to do this with a CRT for example (~25KeV) I would need a target that has an impossibly low density. About 0.5% the density of acrylic, Even so, this assumes the behavior is linear, and valid, for such low energies. A large assumption indeed. Has anyone come across a novel way to embed charge densities in an insulator? It could be any charge, It doesn't have to be electrons. It could also be very gradual. Hours or days is OK.