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Description
First lasing and stable operation of a direct-amplification enabled harmonic generation (DEHG) free-electron laser were achieved, with the harmonic number up to 12th from a single-stage modulation and 30th from two-stage modulations employing the beam-echo effect. This work demonstrates that high harmonic HGHG and EEHG FEL generation can be facilitate through the DEHG scheme using only one single seed laser with significantly reduced power. The continuous radiation-beam coupling in the direct amplification process induces an efficient energy modulation, and the FEL gain-guiding dynamics naturally purify the seed laser. The required one single seed laser makes the operation both simplified and more stable. The substantially reduced seed laser power means high repetition rate external seeded EUV and X-ray FELs are feasible now. Looking forward, this scheme also holds great promise in the generation of deep X-ray seeded FELs using directly the short wavelength high-order harmonic generation (HHG) pulses from noble gases.
Footnotes
*Z. Qi et al., Phys. Rev. Lett. 135, 035001 (2025)
| Paper status | No proceeding expected for this contribution. |
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