Cerenkov free electron lasers in the infrared

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6201169

Murphy, J B

We evaluate the Cerenkov free electron laser (CFEL) as a potential infrared radiation source. The model we consider consists of a relativistic electron beam grazing the surface of a single slab dielectric waveguide. Properties of the resonator such as transverse mode spacing, scaling of the output frequency with slab thickness and dielectric constant are examined. We find the single slab waveguide, with a thickness on the order of the output wavelength, operating in the TM1 mode, to be suitable choice as a resonator for a CFEL. The small signal gain of the device is computed for the single particle interaction mechanism for the cases of an infinite and zero magnetic guide field. An examination of the expression for the gain shows it to be independent of the dielectric material for operation in the infrared regime. Although a low dielectric constant (epsilon/sup approx./ 2 to 4) is desirable as it provides for thicker waveguides capable of handling higher power outputs. In the mm regime the gain of the CFEL is enhanced by using materials with moderately high dielectric constants (epsilon/sup approx./ 10 to 25). We compared the small signal gain of the CFEL to that of an undulator device. If one requires the CFEL to use same high energy beams (..gamma../sup approx./ 10 to 80) as the undulator device, the undulator offers higher gain. The Cerenkov device has the advantage that it can operate at a desired frequency with a lower energy beam. When this fact is taken into account the CFEL is the more attractive device. We estimate the nonlinear saturation based on a particle trapping model. The losses in the dielectric are assessed and found not to be prohibitively large. We conclude that operation of a CFEL in the infrared portion of the spectrum is a realistic possibility.

• OSTI ID: 6201169
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420300* -- Engineering-- Lasers-- (-1989)
AMPLIFICATION
CHERENKOV RADIATION
DESIGN
DIELECTRIC MATERIALS
ELECTROMAGNETIC RADIATION
FREE ELECTRON LASERS
GAIN
INFRARED RADIATION
LASER CAVITIES
LASER MATERIALS
LASERS
LOSSES
MATERIALS
MATHEMATICAL MODELS
OPERATION
RADIATIONS