Laser Wakefield Acceleration Driven by ATF CO2 Laser (STELLA-LW)

Abstract

A new experiment has begun that builds upon the successful Staged Electron Laser Acceleration (STELLA) experiment, which demonstrated high‐trapping efficiency and narrow energy spread in a staged laser‐driven accelerator. STELLA was based upon inverse free electron lasers (IFEL); the new experiment, called STELLA‐LW, is based upon laser wakefield acceleration (LWFA). The first phase of STELLA‐LW will be to demonstrate LWFA in a capillary discharge driven by the Brookhaven National Laboratory Accelerator Test Facility (ATF) terawatt CO2 laser beam. This will be the first time LWFA is conducted at 10.6‐μm laser wavelength. It will also be operating in an interesting pseudo‐resonant regime where the laser pulse length is too long for resonant LWFA, but too short for self‐modulated LWFA. Analysis has shown that in pseudo‐resonant LWFA, pulse‐steepening effects occur on the laser pulse that permits generation of strong wakefields. Various approaches are being explored for the capillary discharge including polypropylene and hydrogen‐filled capillaries. Planned diagnostics for the experiment include coherent Thomson scattering (CTS) to detect the wakefield generation. This will be one of the first times CTS is used on a capillary discharge.