A selfconsistent analysis of farinfrared and submillimeter wavelength metalgrating free electron lasers
Abstract
A theoretical exploration of the characteristics and operational requirements of farinfrared and submillimeter wavelength metalgrating freeelectron lasers is presented. In the device an open planar type of quasioptical resonator is loaded with a strip of rectangular metalgrating, and driven by a moderate energy electron beam. The basic tuning features and energy storage capacity of the resonator are described by the dispersion relation of the periodic slowwave structure. To give a complete description of electron and wave dynamics in the laser oscillator, a set of selfconsistent equations are derived through the use of the Lorentz force equation and the Maxwell's equations. Small signal gain and output efficiency of the device are developed from the selfconsistent model. The nonlinear saturation is examined with a strongfield technique which is based upon a simple nonlinear ordinary differential equation of Duffing type. A detailed evaluation of the startcurrent, optimum interaction length, and output efficiency of the laser oscillator at farinfrared and submillimeter wavelength region, indicates that the operations at wavelengths from 1 mm to 100 microns could be optimized at the output efficiencies around 1 percent with the use of a 100 keV to 1 MeV electron beam of current densities from 10 to 100(A/sq cm) and a 10 to 20 cm long grating section. A theory of klystron type metalgrating free electron lasers is also developed. Results of the proofofprinciple tests in the lowermillimeter wavelength region show that the klystron type devices generate more coherent radiations with startcurrent below 0.5A, output power and efficiency up to 600 watts, and 2 percent at about 35 GHz.
 Publication:

Ph.D. Thesis
 Pub Date:
 1990
 Bibcode:
 1990PhDT.........3X
 Keywords:

 Free Electron Lasers;
 Infrared Lasers;
 Klystrons;
 Laser Outputs;
 Lorentz Force;
 Maxwell Equation;
 Electron Beams;
 Far Infrared Radiation;
 Optical Filters;
 Submillimeter Waves;
 Wavelengths;
 Lasers and Masers