Confirming the theoretical foundation of steady-state microbunching

Steady-State Microbunching (SSMB) has been proposed as a concept to generate coherent synchrotron radiation at an electron storage ring. SSMB promises to supply kilowatt level average power radiation in the extreme ultraviolet regime, meeting the power level demands for lithography applications that presently cannot be fulfilled by established accelerator technologies. SSMB is under theoretical and experimental study, building on a proof-of-principle (PoP) experiment at the Metrology Light Source which previously showed the viability of the idea. Here we report experimental findings from systematic studies in the ongoing SSMB PoP experiment, where microbunching is generated from an energy modulation imposed by a laser of wavelength 1064 nm. The results confirm the expected dependence of the microbunching process on modulation amplitude and show that the influence of transverse-longitudinal coupling dynamics is as predicted. This confirmation of key parts of the SSMB theory establishes a solid footing for continuing the proof-of-principle efforts towards the goal of constructing a prototype SSMB light source facility. Steady-State Microbunching (SSMB) is emerging as a new concept for accelerator-based light sources to meet demands for high average power radiation at short wavelengths. The authors present findings from a proof-of-principle experiment that agree with theoretical expectations in multiple aspects, laying the foundation for the future realization of SSMB.