Author: Kleinman, H.
Paper Title Page
WEB04 Saturation Dynamics, Fine Spectrum, and Chirp Control in a CW FEL Oscillator 580
  • H. S. Marks, A. Gover, H. Kleinman
    University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
  • D. Borodin, A. Damti, A. Friedman, Y. Vashdi
    Ariel University, Ariel, Israel
  • M. Einat, M. Kanter, Y. Lasser, Yu. Lurie, A. Yahalom
    Ariel University Center of Samaria, Faculty of Engineering, Ariel, Israel
  As in conventional laser physics, the saturation dynamics of a long-pulse Electrostatic Accelerator FEL (EA-FEL) oscillator consists of oscillations build-up, resonator modes competition, and establishment of narrow linewidth single mode lasing. In EA-FEL the gain curve drifts to lower frequencies during the long laser pulse due to inevitable droop in the acceleration voltage. This post-saturation drift renders fine chirp of the single mode laser frequency due to the oscillator frequency pulling effect. We have integrated a voltage-ramping element into the electrostatic accelerator terminal that makes it possible to control the acceleration voltage throughout the lasing pulse. This allows us to keep the voltage constant throughout the e-beam pulse, and so increase the single mode lasing time, avoiding mode-hopping during the pulse due to the drift of the gain curve. Furthermore, by adjusting the voltage ramp rate and polarity we obtained controllable positive/negative laser frequency chirp that can be used in a single pulse sweep for fine spectral line (10-6) gas-spectroscopy. The study was conducted on the Israeli EA-FEL that operates at tunable frequencies between 95-110 GHz.  
slides icon Slides WEB04 [2.310 MB]  
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