Measurement of ion beam parameters with electrostatic induction electrodes

Abstract

One source of information concerning ion beam parameters is the electromagnetic field which can be sensed in a non-destructive manner by means of electrostatic induction electrodes. It is shown that the response of an electrode system is a solution of the Laplace equation with boundary conditions specified by the weighting function of the system. Electrode systems as integral devices can provide information on the beam intensity, transverse beam coordinates, and some coefficients associated with the beam profile. A new class of electrode systems based on the Walsh weighting functions is introduced. Methods are studied for computing the response of electrode systems of a circular as well as of a rectangular cross section. A lower bound, known as the Cramer-Rao bound, on the performance of a measuring system using an electrode system is presented. A concept of spatial filtering is discussed and a novel closed-loop scan generator is proposed. Finally, a brief discussion on the applications of electrode systems indicates that the systems meet requirements for non-destructive sensors suitable for automated equipment employing continuous ion beams.