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abstract:
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We propose a significant enhancement of the electron
peak current entering a SASE undulator by inducing an en-
ergy modulation in an upstream wiggler magnet via res-
onant interaction with an optical laser, followed by mi-
crobunching of the energy-modulated electrons at the ac-
celerator exit. This current enhancement allows a reduc-
tion of the FEL gain length. The x-ray output consists of
a series of uniformly spaced spikes, each spike being tem-
porally coherent. The duration of this series is controlled
by the laser pulse and in principle can be narrowed down
to just a single, -attosecond spike. Given potentially
absolute temporal synchronization of the x-ray spikes to
the energy-modulating laser pulse, this scheme naturally
makes pump-probe experiments available to SASE FEL’s.
We also study various detrimental effects related to the high
electron peak current .
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