A modular path length corrector for recirculating linacs

We present a novel modular magnetic system that can introduce a large and continuously variable path length difference without simultaneous variation of the longitudinal dispersion. This is achieved by using a combination of an electrically adjustable magnetic chicane and a mechanically adjustable focusing chicane. We describe how such a system may be made either isochronous or with a given longitudinal dispersion, and show that the nonlinear terms in such a system are relatively small.

► We propose a new modular method of adjusting path length in a recirculating linac.
► The new method allows path length to be varied without changing the bunch compression.
► Illustrative modular path corrector designs are described for low- and high-energy electron beams.
► This method may be used in recirculating linacs, particularly energy-recovery linacs.