Small-period electromagnet wigglers for free-electron lasers

Abstract

A new configuration for wiggler magnets compatible with free-electron laser (FEL) deployment is described and demonstrated experimentally. The configuration is simple and inexpensive to fabricate and allows for continuous control of magnetic field amplitude. Because ferromagnetic cores are used, the wiggler fields are strong (∼0.1 T), while the wiggler period can be very small, on the order of 1 mm. It is shown that high power millimeter and submillimeter FEL’s could be built using such wigglers together with sheet electron beams, and that they would have substantially reduced electron energy requirements when compared with FEL’s employing larger period wigglers.