Engineering design of the interaction waveguide for high-power accelerator-driven microwave free-electron lasers

Linear induction accelerators (LIAs) operating at beam energies of a few million electronvolts and currents of a few thousand amperes are suitable drivers for free-electron lasers (FELs). Such lasers are capable of producing gigawatts of peak power and megawatts of average power at microwave frequencies. Such devices are being studied as possible power sources for future high-gradient accelerators and are being constructed for plasma heating applications. At high power levels, the engineering design of the interaction waveguide presents a challenge. Several concerns, including electrical breakdown and metal fatigue limits, choice of material, and choice of operating propagation mode, are addressed.<>