A comparison of the FEL and CRM operating simultaneously at two resonant frequencies

We compare the operation of the FEL and the CRM operating simultaneously at two resonant frequencies. This is done using a unified approach to the description of dispersion space. Both steady state and pulsed regimes are investigated. It is found that, in general, the growth of the higher frequency dominates the FEL evolution. In the CRM the lower frequency is usually dominant, however two different methods of lower frequency suppression are demonstrated possibly allowing for stable CRM operation at higher frequencies.