A magnetic chicane for bunch compression

The ELBE accelerator beamline contains a magnetic chicane after the first accelerator cryomodule. The chicane consists of four dipole magnets all of equal field strength and magnetic length. As a result the electrons just take a "detour" through the chicane while the beam direction at the exit remains unchanged. The amount of deflection can be adjusted by altering the field (the current) of the magnets.

  In such a chicane electrons with lower energy (with respect to the reference energy of the accelerated beam) take longer flight paths and are delayed in comparison to electrons with higher energy. This opens up the possibility of a bunch compression for the typical energy-phase correlated beams delivered by linear accelerators with (partial) off-crest acceleration.
Alternatively, the introduced by the chicane energy-phase correlation can be used to reduce the energy spread of the beam by a subsequent off-crest acceleration.