We describe a technique for the generation of a solitary attosecond x-ray pulse in a free-
electron laser (FEL), via a process of self-amplified spontaneous emission. In this method,
electrons experience an energy modulation upon interacting with laser pulses having a
duration of a few cycles within single-period wiggler magnets. Two consecutive modulation
sections, followed by compression in a dispersive section, are used to obtain a single,
subfemtosecond spike in the electron peak current. This region of the electron beam …

We describe a technique for the generation of a solitary attosecond X-ray pulse in a free
electron laser (FEL), via a process of self-amplified spontaneous emission. In this method,
electrons experience an energy modulation upon interacting with laser pulses having a
duration of a few cycles within single-period wiggler magnets. Two consecutive modulation
sections, followed by compression in a dispersive section, are used to obtain a single, sub-
femtosecond spike in the electron peak current. This region of the electron beam …