The Production and Focusing of Intense Positive Ion Beams

Abstract

Based on a suggestion by Dr. F. L. Mohler, a high intensity source of positive ions utilizing a gaseous low voltage arc constricted by a metal capillary has been developed. With 250 watts input and 10-cc gas flow per hour, this source delivers controllable positive ion currents up to 1.5 milliamperes through a probe canal 1 mm in diameter. The focusing of weak and intense positive ion beams by various electrostatic lens arrangements has been empirically investigated, giving additional data on quantitative design concerning the multiple section high voltage tubes long in use in the laboratory of the Department of Terrestrial Magnetism of the Carnegie Institution of Washington, and indicating the requirements met in delivering the total ion current from the source onto a target at the far end of such a tube.