Simulations of the proposed TJNAF 20 KW Free Electron Laser

Abstract

As the Navy's role as peace enforcer in support of ground troops draws Navy combatants into the littoral warfare environment, surface combatants will have to deal with decreased reaction times while engaging ever faster antiship missile threats. The Phalanx Close In Weapon System (CIWS) does not offer sufficient accuracy or engagement ranges to fight these threats, and conventional chemical lasers, which operate at fixed wavelengths, lack the tunability to operate in a dynamic ocean environment. The Free Electron Laser (FEL) offers the wavelength tunability, fast reaction times, and the pinpoint accuracy necessary to ensure protection of Navy surface combatants into the future. In support of this goal, the Navy is funding a proposed 20 kW FEL at Thomas Jefferson National Accelerator Facility (TJNAF) in Newport News, VA. This FEL will feature a klystron undulator, designed to improve gain in weak optical fields, and a loop that will feed electrons back to the accelerator. Simulations in this thesis vary the dispersive section strengths of the klystron undulator and desynchronism between the optical and electron pulses in order to find dispersive strength and desynchronism values that optimize the effects on final power and weak field gain, while maintaining an electron energy spread less than TJNAF's goal of 6% to ensure proper feedback of electrons to the accelerator. Results show TJNAF's 20 kW FEL design will reach a final power of 19.2 kW with an energy spread of 6% at desynchronism of d=0.03 using a conventional undulator