Free electron lasers with slowly varying beam and undulator parameters

Self-amplified spontaneous emission free-electron laser with an energy-chirped electron beam and undulator tapering.

We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a self-amplified spontaneous emission mode free-electron laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental...

Limitations of Electron Beam Conditioning for Free-Electron Lasers

Several ideas have been proposed to ‘condition’ an electron beam prior to the undulator of a Free-Electron Laser (FEL) by increasing each particle’s energy in proportion to the square of its transverse betatron amplitude. This conditioning enhances FEL gain by reducing the axial velocity spread within the electron bunch. We demonstrate that for symplectic beamlines, and independent of the metho...

Beam conditioning for free electron lasers: Consequences and methods

080701-1 The consequences of beam conditioning in four example cases [VISA, a soft x-ray free-electron laser (FEL), LCLS, and a ‘‘Greenfield’’ FEL] are examined. It is shown that in emittance limited cases, proper conditioning reduces sensitivity to the transverse emittance and, furthermore, allows for stronger focusing in the undulator. Simulations show higher saturation power, with gain lengt...

I Free Electron Lasers*

Free-electron lasers

CURRENT SCIENCE, VOL. 87, NO. 8, 25 OCTOBER 2004 1066 Srinivas Krishnagopal and Vinit Kumar are in the Centre for Advanced Technology, Indore 452 013, India; Srinivas Krishnagopal and S. K. Sarkar are in the Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India; Sudipta Maiti and S. S. Prabhu are in the Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, In...