Measurements of the spectral and temporal evolution of FEL macropulses

John A. Kozub; Bibo Feng; William E. Gabella

doi:10.1117/12.461375

1 April 2002 Measurements of the spectral and temporal evolution of FEL macropulses

John A. Kozub, Bibo Feng, William E. Gabella

Proceedings Volume 4633, Commercial and Biomedical Applications of Ultrafast and Free-Electron Lasers; (2002) https://doi.org/10.1117/12.461375
Event: High-Power Lasers and Applications, 2002, San Jose, California, United States

Abstract

The Vanderbilt Mark III FEL is a tunable source of coherent mid-infrared radiation occurring as a train of high- intensity (picosecond) micropulses with a repetition rate of 3GHz that continues for 3-5 microseconds (the macropulse). We have measured the spectral output of the Vanderbilt FEL as a function of time during the macropulse with ~10nm resolution in wavelength and ~20ns resolution in time. The measurement takes about one minute and gives a representation of the micropulse spectral width average over many macropulses. Data collected thus far indicates a surprising amount of structure produced by overlapping periods of growth, saturation, and decay within the macropulse. It is found that the central wavelength of the FEL slips over the course of the macropulse, and that the instantaneous output typically has a much smaller spectral bandwidth than the macropulse bandwidth. Thus, a user slicing portion fo the macropulse with a Pockel's Cell can obtain different central wavelengths by slicing at different times during the macropulse. The evolution of the macropulse spectrum as a function of cavity de-tuning and electron beam parameters is studied with the goal of improving the stability and spectral density of the FEL output.

Citation Download Citation

John A. Kozub, Bibo Feng, and William E. Gabella "Measurements of the spectral and temporal evolution of FEL macropulses", Proc. SPIE 4633, Commercial and Biomedical Applications of Ultrafast and Free-Electron Lasers, (1 April 2002); https://doi.org/10.1117/12.461375

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