Lasl Free Electron Laser Experiments

The accomplishment of a high-power, free-electron laser (FEL) is dependent on efficient transfer of electron energy to the laser electromagnetic field and efficient recovery of the remaining electron energy. Electron energy transfer to the laser field occurs in a "wiggler". In the past, wigglers with a uniform period have been used. Recently, however, it has been proposed that a tapered wiggler would enhance the efficiency of energy transfer. In the Los Alamos Scientific Laboratory (LASL) experiments, the efficiency of energy transfer in tapered wigglers will be studied and recovery of a portion of the electron energy will be investigated. First, an amplifier experiment will be performed to demonstrate efficient energy extraction and laser gain of a tapered wiggler. In the second experiment, the FEL amplifier will be converted to an oscillator by increasing the duration of the electron beam pulse and by adding laser mirrors. In the third experiment, a racetrack beam-transport system will be added to the FEL oscillator to determine the recovery efficiency of the remaining electron energy.