A Raman FEL (Free Electron Laser) at 2mm Wavelength. Design of an Efficiency-Enhanced Raman FEL Oscillator.

The nonlinear physics of the free electron laser (FEL) involves waves set up in a nearly cold electron beam when it passes through the undulator. In addition to the pump field and the growing scattered EM wave moving parallel to the electrons, there is a disturbance in the beam space charge caused by the ponderomotive force. In this paper we discuss initial experimentation using a simple Raman oscillator and amplifier. The purpose of the oscillator and amplifier. The purpose of the oscillator is to define initially the regions of substantial gain by observing the emission wavelength. Following this, the gain is observed in and amplifier configuration, using a CO sub 2 laser pumping an NH sub 3 gaseous laser at 140 GHz (2.14mm).