Hybrid Planar Wiggler for Higher Harmonic Lasing

Abstract A hybrid planar wiggler with a period of 20 mm has been studied as the simplest one which gives the strong field including some higher harmonic components by selecting proper sizes of the ferromagnetic and the permanent magnet. Small gap length of the wiggler and small width of permendur satisfy these conditions to a certain degree. Gain analysis of FEL suggests that for high wiggler field of K>1–1.6, higher harmonic gains are impoved primarily due to its strong field, and for low wiggler field of K<1–1.6, they are mainly due to the midification of the wiggler field distribution.