Novel structure of short-period twisted undulator spontaneous emission properties

A novel short-period undulator scheme is developed. The geometry looks like helical transformation applied to an original linear undulator structure and provides a combination of fast and slow oscillations of the electron beam. The following properties of the radiation are considered: (i) reduction of relative content of higher odd harmonics as the `slow´ helical field increases; (ii) radiation enhancement as the number of helical turns increases; (iii) spectral line splitting and intensity adjustability along with circular polarization of the radiation for the short-period twisted structure