Experience and initial measurements of magnetic linearisation in the MAX IV linac bunch compressors

The MAX IV Linac is now in routine operation for injection into two storage rings, and as a high-brightness driver for a Short Pulse Facility (SPF). In short-pulse mode the electron bunch is created in a photo cathode gun and compressed in two double achromat bunch compressors that also linearise longitudinal phase space with the second order transfer matrix element T566. T566 in the compressors canbe tweaked with weak sextupoles located at high dispersion. In this paper we present the current experience from operating the bunch compressors at MAX IV and results from initial measurements of longitudinal phase space using our version of the the zero-crossing method.