A Hybrid Technique for Computing Courant-Snyder Parameters from Beam Profile Data

Abstract

We present novel techniques for computing Courant-Snyder (C-S) parameters of a charged-particle beam from profile measurement data. These methods have robust convergence properties by combining both deterministic and non-deterministic methods. The basic ideas is as follows: given a model of the beamline, in the zero space charge case it is possible to compute the C-S parameters directly from profile data using a deterministic, linear-algebraic approach. For finite space charge we either a) iterate this deterministic solution or b) construct a smooth curve of these deterministic solutions starting from the zero-current solution and terminating at the finite-current case. This selects the finite-current solution connected to the zero-current C-S parameters. Both approaches avoid convergence issues associated with fully iterative, non-deterministic methods. The details of the techniques are outlined and an example is presented using data taken from the SNS accelerator.