High current Betatron

In a conventional Betatron, space charge limits the electron current during injection. By adding a toroidal magnetic field and injecting electrons with the inductive charging method we expect to increase the current limit by a factor of 10⁴–10⁶. After the beam has been accelerated to high energy the toroidal field is no longer necessary and can be reduced to facilitate extraction of the beam. The effect of the toroidal magnetic field on space charge instabilities is investigated. An experimental Betatron has been constructed with a major radius of 40 cm and a minor radius of 5 cm. On the basis of previous experimental results with inductive charging the current limit should be a few kilo-amperes.