Mitigation of CSR induced spectral broadening in EEHG FEL
Externally seeded schemes have offered a major leap in improving the longitudinal coherence of FELs in the EUV and soft X-ray range. The Echo Enabled Harmonic Generation (EEHG) technique creates bunching at wavelengths of a few nanometers in two stages of longitudinal phase space manipulation, each consisting of an energy modulator and a chicane. Compared to other seeding techniques, EEHG is less