Thonemann's concept was to replace the radio frequency injection used by Thonemann and arrange the reactor like a betatron, that is, wrapping the torus in a large magnet and using its field to induce a current in the torus in a fashion similar to an electrical transformer. Betatrons had a natural limitation that the number of electrons in them was limited due to their self-repulsion, known as the space charge limit. Some had suggested introducing a gas to the chamber; when ionized by the accelerated electrons, the leftover ions would produce a positive charge that would help neutralize the chamber as a whole. Experiments to this end instead showed that collisions between the electrons and ions would scatter so rapidly that the number of electrons remaining was actually lower than before. This effect, however, was precisely what was desired in a fusion reactor, where the collisions would heat the deuterium ions.