Executive Summary : | This project proposal aims to design and build a prototype two frequency asymmetric undulator (TFAU) for free electron laser applications. The undulator is made up of pure permanent magnets with Halbach arrangement of dipole magnets, providing Lorentz forces to relativistic electrons. The transverse electron oscillations and acceleration result in radiation emission. In the free electron laser, relativistic electrons exchange kinetic energy to a co-propagating laser and amplify it. The proposed undulator will be of both periodic and quasiperiodic structure. Conventional planar and helical undulators are periodic magnet structures, producing emission at the fundamental undulator frequency and odd harmonics due to the electron's sinusoidal trajectory. However, adding phase error intentionally at select locations along the undulator length can effectively reduce higher harmonics. The proposed undulator will have different period lengths for the lower and upper rows, resulting in a two frequency asymmetric undulator (TFAU). Characterizing these undulators and prescribing the merit of schemes for free electron laser application will be interesting. The proposed undulator will be designed with a tapered gap, which helps maintain resonance conditions over the undulator length. The project will investigate various types of tapered undulators and their effects on field integral and phase error measurement, as well as the spectrum of undulator radiation and free electron laser gain. In conclusion, this project aims to improve the technology of free electron lasers by designing and building prototypes with different undulator structures. |