Wiggler and free electron laser

In this article are described the wiggler, the helical wiggler and the free electron laser. Section 1 reviews the whole field of subjects. Section 2 describes the wiggler as a source of synchrotron orbital radiation with the wavelength shorter and the intensity greater than those of the usual synchrotron orbital radiation of the storage rings. Section 3 presents the standard theory of synchrotron orbital radiation. Section 4 reviews the present status of the development of the wiggler magnets in the world. Sections 5 and 6 describe the undulator and the helical wiggler as a monochromatic X-ray source. The problems which are expected to arise when they are incorporated in a storage ring are also discussed. Section 7 describes the quantum mechanical theory of the free electron laser in the weak field limit. Section 8 presents the Stanford experiment on the first operation of the free electron laser. Section 9 describes the classical theory of the free electron laser applicable to the strong signal case. Section 10 describes the possibilities and limitations of the free electron laser supposed to operate in a storage ring. (author)