Automatic Electrolytic Tank and Digital Computer Program for Calculations of Ion Trajectories in Crossed Electric and Magnetic Fields

Abstract

This paper describes an automatic electrolytic tank facility and a digital computer program for studies of ion trajectories in a time‐varying electric field with superimposed magnetic field. The electrolytic tank system features a probe, the motion of which is motor controlled to allow automatic measurements of electric fields in the form of two dimensional arrays of data points rather than equipotential lines. The voltage at each point of the rectangular grid is automatically balanced to ground by a self‐balancing bridge and the value punched on an IBM card. The computer program is written in FORTRAN and integrates the relativistic equations of motion in Cartesian coordinates numerically by the Runga‐Kutta method. The electric field is carried as a rectangular grid of potential values as obtained from the tank measurements. Magnetic field information is represented in the form of a Fourier series in azimuth, with average field and Fourier coefficients tabulated at radial increments. The program was written for orbit calculations in the center of a cyclotron, but it can be used or adapted for many other problems of charged particle motion in crossed electric and magnetic fields.