Linear optics correction for linacs and free electron lasers

Abstract

Linear optics errors in the linac, the transport line, and the undulator section of a free electron laser (FEL) can significantly impact the FEL performance. In this paper we propose two methods to measure and correct the linear optics of one-pass systems using trajectory scan data. The methods have been successfully applied to data taken on the Linac Coherent Light Source (LCLS) to find the quadrupole errors and beam position monitor (BPM) gains.