Talk-Polywell.org

When positrons meet electrons, they destroy one another, releasing a 2.2 Mev gamma ray. The whole point of the polywell design is to have an excess of electrons in the core, so that the positively charged protons and B11 nuclei are attracted to the high density core, smack into one another and fuse.

There is no potential difference from any point inside a charged sphere. That doesn't mean there is no electric field, just that all points inside would experience no potential voltage. With a charged core region, there IS a potential difference, as in Polywell.