Radiation characteristics in a novel Smith-Purcell interaction structure

A novel Smith-Purcell interaction structure is presented. It is a coaxial structure including the outer curved mirrors and the middle cylindrical gratings of arbitrary shaped section. Inverting the curved mirrors and changing the position of gratings turn the structure into the improved one, in which greater current can be obtained with bigger-radius ring beam. And the radiation power increases by one order of magnitude. Theoretical analyses and numerical simulation results indicate that coherent radiation with peak power of a few hundred of MW can be achieved from the improved experimental model．