Author: Biedron, S.
Paper Title Page
Novel Seeding and Wavelength Shifting in Free Electron Lasers  
  • N. Sipahi, S. Biedron, S.V. Milton
    CSU, Fort Collins, Colorado, USA
  Free Electron Lasers provide the opportunity for continuous tunability of light from the mm-wave region to hard x-rays. For example, single-pass SASE operation allows very short wavelength operation without using optical cavity structure; unfortunately, the resulting photon beam is poor in terms of longitudinal coherence and shot-to-shot stability. Seeding can greatly improved the longitudinal coherence and shot-to-shot stability but this is dependent on the availability of a suitable seed pulse and then the challenge remains of switching the wavelength quickly. Here a new concept is investigated, one called wavelength shifting where a solid seed source is utilized and then the resultant wavelength shifted to the desired result. This new idea can improve the longitudinal coherence as well as stabilize the shot-to-shot output power while permitting continuous wavelength tunability.  
Thoughts on the New Technologies for Compact FEL Devices  
  • S. Biedron, J. Einstein, S.V. Milton
    CSU, Fort Collins, Colorado, USA
  • G. Dattoli, E. Di Palma, E. Sabia, I.P. Spassovsky
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • V. Petrillo
    Universita' degli Studi di Milano, Milano, Italy
  • J.V. Rau
    ISM-CNR, Rome, Italy
  The possibility to merge different solutions exploiting wave undulators, laser plasma acceleration and other schemes, allows the design of compact Free Electron Laser (FEL) sources operating in the extreme UV-X-ray region of the spectrum. Newly developed high peak power lasers have opened indeed effective possibilities of driving coherent light sources operating with laser plasma accelerated beams and wave undulators. We combine different ideas including also the concept of sheared beam configuration to achieve compact and reliable FEL devices. We finally comment on the perspective use of Radio Frequency (RF) undulators, which seems to be fairly good candidates for opening a new technological strategy for the design of FEL oscillators, including bi-harmonic and multi-frequency operation.  
Free Electron Laser Oscillator: Short Pulses, Mode Locking, Harmonic Generation and Tapering  
  • G. Dattoli, E. Sabia
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • S. Biedron, S.V. Milton
    CSU, Fort Collins, Colorado, USA
  • V. Petrillo
    Universita' degli Studi di Milano, Milano, Italy
  • P.J.M. van der Slot
    Mesa+, Enschede, The Netherlands
  In Free Electron Laser oscillators the growth of the intracavity laser power determines the most interesting aspects of the system dynamics. In the case of short pulses operation the system undergoes genuine mode-locking mechanisms, which provide a wealth of interesting phenomena associated with the possibility of generating very short pulses. We explore the mechanisms of superradiance in FEL operating in the over-saturated regime and analyze the emerging short pulse structures and the relevant physical meaning. We also explore the pulse shape of the higher order harmonics generated in this regime and the possibility of modelling the pulse width and power by suitable combination of cavity length control and of undulator tapering.  
slides icon Slides WEA02 [13.588 MB]