Sv. Benson et al., OPTICAL MODELING OF THE JEFFERSON LABORATORY IR DEMO FEL, Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 407(1-3), 1998, pp. 401-406
The Thomas Jefferson National Accelerator Facility (Jefferson Lab) is
in the process of a building a 1 kW free-electron laser operating 3 mu
m The details of the accelerator driver are given in other papers in
these proceedings. The optical cavity consists of a near-concentric re
sonator with transmissive outcoupling. Though several free-electron la
sers have used similar designs, they have not had to confront the high
average-power loading present in this laser. It is useful to know the
limits of this type of optical cavity design. The optical system of t
he laser has been modeled using the commercial code GLAD(R) by using a
Beer's-law region to mimic the FEL interaction. The effects of mirror
heating have been calculated and compared with analytical treatments.
The magnitude of the distortion for several materials and wave length
s has been estimated. The model developed here allows one to quickly d
etermine whether the mirror substrates and coatings are adequate for o
peration at a given optical power level once the absorption of the coa
tings, substrate, and transmission are known. Results of calculations
of the maximum power level expected using several different sets of mi
rrors will be presented, Measurements of the distortion in calcium flu
oride from absorption of carbon dioxide laser light are planned to ben
chmark the simulations. Multimode simulations using the code ELIXER ha
ve been carried out to characterize the saturated optical mode quality
. The results will be presented. (C) 1998 Elsevier Science B.V. All ri
ghts reserved.