Numerical studies of strong focusing in planar undulators

The present trend towards short wavelength operation with long undulators places tight requirements on the electron beam quality and hence the need to maintain a well focused beam. This paper examines the performance of alternating gradient (AG) sextupole focusing in planar undulators. Numerical simulation results of free electron laser performance using AG sextupole focusing are compared to results using only natural focusing and to those using quadrupole focusing.