Generation of Femtosecond Pulses of Synchrotron Radiation Schoenlein, R. W.; Chattopadhyay, S.; Chong, H. H. W. ...
Science (American Association for the Advancement of Science),
03/2000, Letnik:
287, Številka:
5461
Journal Article
Recenzirano
Femtosecond synchrotron pulses were generated directly from an electron storage ring. An ultrashort laser pulse was used to modulate the energy of electrons within a 100-femtosecond slice of the ...stored 30-picosecond electron bunch. The energy-modulated electrons were spatially separated from the long bunch and used to generate ∼300-femtosecond synchrotron pulses at a bend-magnet beamline, with a spectral range from infrared to x-ray wavelengths. The same technique can be used to generate ∼ 100-femtosecond x-ray pulses of substantially higher flux and brightness with an undulator. Such synchrotron-based femtosecond x-ray sources offer the possibility of applying x-ray techniques on an ultrafast time scale to investigate structural dynamics in condensed matter.
A novel approach for the generation of ultrabright attosecond electron bunches is proposed, based on acceleration in vacuum, by a short laser pulse. The laser-pulse profile is tailored such that the ...electrons are both focused and accelerated by the ponderomotive force of the light. Using time-averaged equations of motion, analytical criteria for optimal regime of acceleration are found. It is shown that for realistic laser parameters, a beam with up to 10(6) particles and normalized transverse and longitudinal emittances <10(-8) m can be produced.
We present a new method to generate steady and tunable, coherent, broadband terahertz radiation from a relativistic electron beam modulated by a femtosecond laser. We have demonstrated this in the ...electron storage ring at the Advanced Light Source. Interaction of an electron beam with a femtosecond laser pulse copropagating through a wiggler modulates the electron energies within a short slice of the electron bunch with about the same duration of the laser pulse. The bunch develops a longitudinal density perturbation due to the dispersion of electron trajectories, and the resulting hole emits short pulses of temporally and spatially coherent terahertz pulses synchronized to the laser. We present measurements of the intensity and spectra of these pulses. This technique allows tremendous flexibility in shaping the terahertz pulse by appropriate modulation of the laser pulse.
By analyzing the pulse to pulse intensity fluctuations of the radiation emitted by a charge particle in the incoherent part of the spectrum, it is possible to extract information about the spatial ...distribution of the beam. At the Advanced Light Source of the Lawrence Berkeley National Laboratory, we have developed and successfully tested a simple scheme based on this principle that allows for the absolute measurement of the rms bunch length. A description of the method and the experimental results are presented.
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