Development of focusing undulators on the basis of side magnet arrays

Hybrid focusing undulators were designed, manufactured and tested for some high power FEL and FEM projects. The magnetic fields of the undulators themselves provide electron beam focusing in both transverse directions during e-beam transport through the interaction region. The new element of these devices is a side magnet array. The focusing transverse magnetic field profile and enhancement of the magnetic field amplitudes resulted from these side magnets. It is shown that wide range tunable focusing strengths can be ensured by a simple variation of the configuration of the side magnets. A flexible combination of quadrupole focusing and sextupole periodic focusing is possible with using of these schemes.