MOOA :: Opening Session: Introduction and FEL Prize Talks

Date/Time: 22-Aug-05 :: 08:30—10:30
Chair: A.F.G. van der Meer, FOM Rijnhuizen, Nieuwegein

Paper Title Page
MOOA001 Dream of Isochronous Ring Again 1
 
  • H. Hama
    LNS, Sendai
 
 

More than 20 years ago, D.A.G. Deacon proposed an isochronous storage ring for FEL to avoid bunch heating and decreasing instantaneous gain [1]. Some of low momentum compaction (alpha) operations have been carried out, and recently coherent infrared radiation are observed on a 3rd generation light source. Because the 3rd generation rings are optimized to obtain very low emittance beam, the dispersion function in the arc sections are much reduced by introducing large bending radius, so that those are very big machines. Meanwhile N.A. Vinokurov et al. recently proposed a ring type SASE FEL based on a complete isochronous bending transport [2]. At least, experimental and theoretical study of the isochronous ring so far suggests nonlinear effects resulted from higher order dispersion and chromaticity declines the "complete" isochronous system. On the other hand, in a wavelength region of THz, tolerance of the path length along a turn of the ring seems to be within our reach. A concept to preserve of a form factor of microbunch or very short bunch by using no-dispersion bend for a ring source of THz coherent radiation and its extension toward short wavelength and SASE FEL will be discussed.

[1] D.A.G. Deacon, Phys. Rep. 76 (1981) 349. [2] N.A. Vinokurov, O.A. Shevchenko, Nucl. Instr. and Meth. A 528 (2004) 491.

 
   
MOOA002 Optics-Free FEL Oscillator
 
  • V. Litvinenko
    BNL, Upton, Long Island, New York
 
 

Funding: Work performed under the auspices of the U.S. Department of Energy

Optics-free FEL oscillators will combine two of most attractive FEL features, wavelength tunability and high power capability, with high laser beam quality and its spectral purity. High losses make optical feedback impractical in many interesting ranges of spectrum. The concept of "electron out-coupling", invented in 1985 by Nikolay Vinokurov, became the basis of a feed-back schemes using bunched electron beam. The e-beam feedback does not suffer from optics shortcomings, such wavelength and power limitations, but instead requires a high quality electron beams. In this paper will focus on an optics-free oscillator using a single FEL system with one or two electron beams. We will discuss the limitation of this scheme and present two examples of its possible realization in FIR and X-ray ranges of spectrum.