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Title: Mode structure of a tapered-wiggler free-electron laser stable oscillator

Abstract

The transverse mode structure of a tapered-wiggler free electron laser (FEL) oscillator operating at full saturated intensity is analyzed numerically. The unique features of the FEL geometry, and particularly the refractive property of the e-beam, which acts like a series of small focusing lenses, tend to produce a steady-state mode structure different from the TEM/sub 00/ mode of the cavity. The higher order mode content is especially evident in confocal cavities, since higher order modes constructively interfere on different round trips. Constructive addition of higher-order modes is also expected in practical FEL's operating at substantial power levels using near-concentric cavities. The presence of higher order modes has unusual effects on the intracavity intensity distribution of a confocal cavity, including different spot sizes on the front and rear mirrors and different transverse structure on forward and reverse passes. Nevertheless, the output beam quality is nearly diffraction limited for the low gain, low Fresnel number cases studied. Noticeable higher order mode content is also expected for near-concentric cavities.

Authors:
;
Publication Date:
Research Org.:
Mathematical Sciences Northwest, Inc., Bellevue, WA 98004
OSTI Identifier:
5679832
Resource Type:
Journal Article
Journal Name:
IEEE J. Quant. Electron.; (United States)
Additional Journal Information:
Journal Volume: 19:5
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; FREE ELECTRON LASERS; OSCILLATORS; ELECTRON BEAMS; FRESNEL COEFFICIENT; GEOMETRY; LASER CAVITIES; LASER MIRRORS; MODE CONTROL; NUMERICAL ANALYSIS; OSCILLATION MODES; REFRACTIVITY; BEAMS; CONTROL; ELECTRONIC EQUIPMENT; EQUIPMENT; LASERS; LEPTON BEAMS; MATHEMATICS; MIRRORS; OPTICAL PROPERTIES; PARTICLE BEAMS; PHYSICAL PROPERTIES; 420300* - Engineering- Lasers- (-1989)

Citation Formats

Quimby, D C, and Slater, J. Mode structure of a tapered-wiggler free-electron laser stable oscillator. United States: N. p., 1983. Web. doi:10.1109/JQE.1983.1071928.
Quimby, D C, & Slater, J. Mode structure of a tapered-wiggler free-electron laser stable oscillator. United States. https://doi.org/10.1109/JQE.1983.1071928
Quimby, D C, and Slater, J. Sun . "Mode structure of a tapered-wiggler free-electron laser stable oscillator". United States. https://doi.org/10.1109/JQE.1983.1071928.
@article{osti_5679832,
title = {Mode structure of a tapered-wiggler free-electron laser stable oscillator},
author = {Quimby, D C and Slater, J},
abstractNote = {The transverse mode structure of a tapered-wiggler free electron laser (FEL) oscillator operating at full saturated intensity is analyzed numerically. The unique features of the FEL geometry, and particularly the refractive property of the e-beam, which acts like a series of small focusing lenses, tend to produce a steady-state mode structure different from the TEM/sub 00/ mode of the cavity. The higher order mode content is especially evident in confocal cavities, since higher order modes constructively interfere on different round trips. Constructive addition of higher-order modes is also expected in practical FEL's operating at substantial power levels using near-concentric cavities. The presence of higher order modes has unusual effects on the intracavity intensity distribution of a confocal cavity, including different spot sizes on the front and rear mirrors and different transverse structure on forward and reverse passes. Nevertheless, the output beam quality is nearly diffraction limited for the low gain, low Fresnel number cases studied. Noticeable higher order mode content is also expected for near-concentric cavities.},
doi = {10.1109/JQE.1983.1071928},
url = {https://www.osti.gov/biblio/5679832}, journal = {IEEE J. Quant. Electron.; (United States)},
number = ,
volume = 19:5,
place = {United States},
year = {1983},
month = {5}
}