Steady-state microbunching based on transverse-longitudinal coupling

Abstract In this study, three specific scenarios of a novel accelerator light source mechanism called steady-state microbunching (SSMB) were studied: longitudinal weak focusing, longitudinal strong focusing, and generalized longitudinal strong focusing (GLSF). At present, GLSF is the most promising method for realizing high-power short-wavelength coherent radiation with mild requirements on modulation laser power. Its essence is to exploit the ultrasmall natural vertical emittance of an electron beam in a planar storage ring for efficient microbunching formation, like a partial transverse-longitudinal emittance exchange in the optical laser wavelength range. Based on an in-depth investigation of related beam physics, a solution for a GLSF SSMB storage ring that can deliver 1 kW average-power EUV light is presented. The work in this paper, such as the generalized Courant–Snyder formalism, analysis of theoretical minimum emittances, transverse-longitudinal coupling dynamics, and derivation of the bunching factor and modulation strengths for laser-induced microbunching schemes, is expected to be useful not only for the development of SSMB but also for future accelerator light sources in general that demand increasingly precise electron beam phase space manipulations.