Simulations of the proposed TJNAF 100kW free electron laser and comparison with TJNAF low power experiments

Abstract

One transitional step for the development of a 1 MW power directed energy weapon is the proposed l00 kW upgrade of the Thomas Jefferson National Accelerator Facilityαs Free Electron Laser (FEL). To improve the performance of the FEL, the use of the step-taper undulator is explored. Steady-state gain, final steady-state power, and the induced electron spread as a function of desynchronism and taper rates are determined. Comparisons are made to the conventional periodic and linearly tapered undulators. The multimode simulations used showed that the TJNAF 100kW FEL is feasible. Simulations results with Q =10 show that the inverse step -taper undulator D = -p achieved the highest final power of 190 kW at a desynchronism value of d = 0.01, while maintaining the induced energy spread well below the engineering limit. The validity of our results is verified against experiments conducted in the TJNAF FEL facility. The simulations and the experimental data are in good agreement and consistent with analytic theory.