Experimental characterization of nonlinear harmonic generation in planar and helical undulators.
We present an experimental characterization of the process of coherent harmonic generation in single-pass free electron lasers. The harmonic radiation is obtained by seeding the electron beam stored in the Elettra storage ring with a Ti:sapphire laser. Different methods for generating harmonics are compared between them, and a detailed characterization of the emitted light is performed for different polarizations. Our results also contribute to the debate about the possible presence of a coherent on-axis signal in helical undulators. In this respect, we provide an experimental confirmation of recent theoretical studies that predict no coherent on-axis signal.
Sincrotrone Trieste, S.S. 14 km 163.5, Trieste, I-34012 Italy.
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E
Allaria
F
F
Curbis
M
M
Coreno
M
M
Danailov
B
B
Diviacco
C
C
Spezzani
M
M
Trovó
G
G
De Ninno
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G
Deninno