Coaxial-hybrid-iron (CHIRON) type twisters

To obtain the high fields at short periods characteristic of CHIRON wiggler type free electron lasers (FELs), we have designed a circularly polarized radiation source or twister that operates on the same principle. As in the wiggler, the field sources are poles produced on surfaces of iron saturated by externally applied axial magnetic fields. Because of the much higher saturation magnetization of iron, the pole densities are greater than can appear on permanent magnet surfaces and therefore can produce higher magnetic fields. Such structures are compared to permanent magnet twisters with regard to field strength, bulk and ease of manufacture.