Parametric up-conversion of a microwave off a relativistic electron beam in a waveguide

Journal Article · Tue Dec 01 04:00:00 EST 1987 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.339057· OSTI ID:5914996

Maheshwari, K P; Tripathi, V K

An electron beam traveling through a waveguide Raman up-converts a microwave traveling in the opposite direction, thus generating a coherent laser radiation. The frequency of the laser is tunable by the relativistic factor ..gamma.. of the beam. A theory of this process is developed for an electron beam of arbitrary size. The pump and the laser eigenmodes are determined by the size of the waveguide, whereas the beam mode is confined to exist within the beam. The coupled eigenmode equations for the daughter waves are solved by first-order perturbation technique. To simplify the problem, a nonmagnetized relativistic electron beam in which the electron density is parabolic with a maximum in the center (on the axis) is considered. An analytic expression for the growth rate of the scattered wave is obtained. It is found that the growth rate is roughly (a/b)/sup 1//sup ///sup 2/ times the growth rate for stimulated Raman scattering in an infinite plasma with a uniform pump, where 2b is the separation of conducting planes and a is the half-width of beam mode. This is because the mode extent of the sideband wave extends to a width approx.b, whereas the region of parametric instability is approx.a. Our results show that for a given value of b/a, the growth rate becomes maximum for a particular value of pump frequency. We plot our results for the growth rate of the TE/sub 1/ mode of the scattered wave as a function of the pump wave frequency.

• Research Organization: Department of Physics, Indian Institute of Technology, New Delhi 110 016, India
• OSTI ID: 5914996
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 62:11; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420300* -- Engineering-- Lasers-- (-1989)
BEAM OPTICS
BEAMS
ELECTROMAGNETIC RADIATION
ELECTRON BEAMS
ENERGY RANGE
FREE ELECTRON LASERS
FREQUENCY SELECTION
INSTABILITY
LASERS
LEPTON BEAMS
MICROWAVE RADIATION
PARAMETRIC INSTABILITIES
PARTICLE BEAMS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
RADIATIONS
RAMAN EFFECT
RELATIVISTIC RANGE
SCATTERING
TUNING
WAVEGUIDES