Steady-state microbunching in a storage ring at EUV wavelengths

Steady-state microbunching (SSMB) uses laser modulators for longitudinal focusing in a low-momentum-compaction ring so that electrons stay in optical-scale microbunches turn after turn; retention of laser-induced microbunching at a $1.064 \times 10^{-4}\,\mathrm{cm}$ wavelength over successive turns was reported at the Metrology Light Source, Berlin, in 2021 (Deng et al., https://doi.org/10.1038/s41586-021-03203-0). Determine whether a ring can hold microbunches of rms length below $\sim 2 \times 10^{-7}\,\mathrm{cm}$ in steady state, with quantum excitation, intrabeam scattering and laser phase noise included, giving coherent radiation at $1.35 \times 10^{-6}\,\mathrm{cm}$ ($13.5\,\mathrm{nm}$) with average power near $10^{10}\,\mathrm{erg}/\mathrm{s}$.

Measured steady-state coherent emission at the target wavelength whose power scales as the square of the number of electrons per microbunch.