• R.R. Lindberg, K.-J. Kim, Yu. Shvyd'ko
  ANL, Argonne
• W.M. Fawley
  LBNL, Berkeley, California

Simulations of the x-ray free-electron laser (FEL) oscillator are presented that include transverse effects and realistic Bragg mirror properties with the two-dimensional FEL code GINGER. In the present cases considered, the radiation divergence is much narrower than the mirror acceptance, and the numerical algorithm can be simplified by ignoring the finite angular bandwidth of the mirror. In this regime GINGER shows that the saturated x-ray pulses have 10⁹ photons and are nearly Fourier limited with peak powers in excess of 10 MW. We also include preliminary results for a four-mirror cavity that can be tuned in wavelength over a few percent, with future plans to incorporate the full transverse response of the Bragg mirrors into GINGER to more accurately model this tunable source.