Optically Pumped Free-Electron Laser with Electrostatic Reacceleration

A numerical model of a two-stage free-electron laser (FEL) was developed that considers optical pumping and time-dependent electrostatic acceleration in the laser interaction region. Analytical solutions were obtained in weakand strong-signal limits that provide confidence in the predictions of the numerical model. The validated model predicts encouraging FEL performance when a high-current electrostatic accelerator is used as the electron source for the two-stage concept. Although the model neglects diffraction, refractive guiding, and three-dimensional and collective effects, their inclusion would not be expected to change the general conclusions reached in the present study.