Air Core Betatrons Reexamined

Theoretical studies on the possibility of increasing both current and energy of the air core betatron indicate (1) the principal current limit is set by the betatron radius, which should be small for higher currents (2) the principal energy limit is also set by the radius, with a large radius preferred, but also by the energy storage and the time profile of the voltage applied to the primary coils, together with the mutual inductance per turn, M\´, of the primary and secondary coils. The "Helmoltz-coil" configuration appears to be superior in maximizing M\´.