Staged Electron Laser Acceleration (STELLA) and application to laser wakefield acceleration

Summary form only given. The Staged Electron Laser Acceleration (STELLA) experiment demonstrated for the first time a number of important capabilities needed for developing practical laser-driven electron accelerators (laser linac). The first is staging between two laser-driven devices in which the primary challenge is rephasing the femtoseconds-long electron microbunches formed from the first device with the laser field in the second device. The second is trapping these microbunches in the laser field ponderomotive potential well with high efficiency and, third, accelerating the trapped electrons while maintaining a narrow energy spread. For convenience, STELLA used inverse free electron lasers (IFEL) as the laser-driven devices; however, the STELLA approach is a general one that can be applied to other laser acceleration methods. In particular, the next chapter of the STELLA program, called STELLA-LW, is to apply the STELLA approach to laser wake-field acceleration (LWFA). During Phase I of the STELLA-LW experiment, the terawatt CO/sub 2/ laser beam at the Brookhaven National Laboratory Accelerator Test Facility (ATF) will be used to drive a wakefield in a capillary discharge. The electrons from the ATF microwave-driven linac will be injected into the wakefield and accelerated. This will be the first time that LWFA is achieved using a CO/sub 2/ laser beam. During this presentation the STELLA experimental results and comparisons with the model will be given. The STELLA-LW experiment will be described including a discussion of the pseudo-resonant LWFA process, which plays a critical role in this experiment.