TY  - JOUR
AU  - Ferrari, Eugenio
TI  - Twin Echo Enabled Harmonic Generation with Frequency Down-Conversion for Unprecedented Coherent Bunching at Short Wavelengths
JO  - Physical review accelerators and beams
VL  - 27
IS  - 11
SN  - 2469-9888
CY  - College Park, MD
PB  - American Physical Society
M1  - PUBDB-2024-05328
SP  - 110705
PY  - 2024
AB  - Harmonic up-conversion schemes represent the most successful approach in externally seeded free-electron lasers (FELs) for obtaining radiation with laser-like properties at short wavelengths. They are however limited in the shortest achievable wavelengths, as the harmonic conversion efficiency decreases with increasing harmonic number, even for echo-enabled harmonic generation (EEHG). In the following, we introduce a novel externally seeded cascaded FEL scheme based on two EEHG stages, the second of which working in harmonic down-conversion, i.e. going towards (slightly) longer wavelengths, capable of obtaining unprecedented bunching fraction that is independent on the final FEL wavelength.Its performance at 4 nm and shorter is investigated, demonstrating the ability to achieve multi-GW level, fully coherent pulses with laser-like properties and paving the way for externally seeded radiation at 1 nm and beyond.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:001371913100003
DO  - DOI:10.1103/PhysRevAccelBeams.27.110705
UR  - https://bib-pubdb1.desy.de/record/612376
ER  -