Ion Optics in Long, High Voltage Accelerator Tubes

Abstract

In the past, the ion optics of long, high voltage accelerator tubes has been a problem usually dealt with experimentally. Based upon a description of a high voltage tube presented by McKibben, a first-order focusing theory is developed essentially through the combined application of geometric optics and Gans' method. The analysis indicates the need for a description of the optical properties of the ion source and its associated electrodes before focusing, magnification, and other characteristics of the over-all accelerator tube can be determined. The application of the theory to a tube and a simple source system is illustrated by an analysis of the focusing characteristics of the Rockefeller accelerator at the Massachusetts Institute of Technology. The results of this analysis yield computed focusing voltages in agreement with those used.