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Proceedings Paper

Optical diagnostics for a ring resonator FEL
Author(s): Mary L. Laucks; David H. Dowell; Andrew Richard Lowrey; Steven C. Bender; Alex H. Lumpkin; Melvin Paul Bentz
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Paper Abstract

The optical cavity of the Boeing visible free electron laser was reconfigured from a concentric cavity to a glancing incidence ring resonator in late 1989 and was operated until December 1990. the crucial requirement for the optical cavity of an FEL is to provide an optical mode which is spatially and temporally matched to the electron beam as it moves through the wiggler. Several new optical diagnostics were developed to determine when the above requirement was satisfied. This paper will discuss those diagnostics which achieved and maintained the alignment of the ring resonator within tolerance to lase and measured the quality of lasing. The new diagnostics included measurements of the focus position and Rayleigh range of the ring resonator optics to determine the spatial match of the optical mode through the wiggler, and a measurement of the position of the optical axis for multiple passes around the ring resonator to determine the stability of the resonator alignment. Accelerator performance was determined by measuring the electron beam pulse width and charge, which indicated electron beam brightness, and by measuring the width of the spontaneous emission spectrum, which gave an indication of the alignment between the electron beam and the optical axis. Temporal overlap of electron and optical pulses was assured by measuring the optical cavity length. In addition, several other diagnostics which indicated FEL performance will be described: optical energy per micropulse, small signal gain, ringdown loss, laser pulse width, laser wavelength, and time resolved spectroscopy.

Paper Details

Date Published: 1 June 1992
PDF: 10 pages
Proc. SPIE 1625, Design, Modeling, and Control of Laser Beam Optics, (1 June 1992); doi: 10.1117/12.58961
Show Author Affiliations
Mary L. Laucks, Boeing Aerospace & Electronics (United States)
David H. Dowell, Boeing Aerospace & Electronics (United States)
Andrew Richard Lowrey, Boeing Aerospace & Electronics (United States)
Steven C. Bender, Los Alamos National Lab. (United States)
Alex H. Lumpkin, Los Alamos National Lab. (United States)
Melvin Paul Bentz, Rockwell International Corp./Rocketdyne Div. (United States)

Published in SPIE Proceedings Vol. 1625:
Design, Modeling, and Control of Laser Beam Optics
Youssef Kohanzadeh; George N. Lawrence; John G. McCoy; Hugo Weichel, Editor(s)

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