Propagation and Interactions of Ultrahigh Power Light: Relativistic Nonlinear Optics

: We present the results of our research on the study of the propagation and interaction of ultrahigh-power light. We implemented new techniques to characterize, control, and optimize the spectral and spatial characteristics of a high-power laser leading to diffraction-limited and transform-limited pulses on target. We simultaneously optimized the on-target characteristics of two pulses at different wavelengths (800 and 400 nm). These improvements resulted in breakthrough scientific applications. We demonstrated tunable laser-driven wakefield acceleration of electron beams with minimal dark current. A novel electron accelerator with separate injection and acceleration stages was developed. It produces electron beams with high charge to ensure the electron beam parameters (charge, energy spread, and divergence) remain constant as the central energy is tuned over 50-300 MeV. Another significant achievement was the development of a tunable (50 keV 10 MeV), narrowband x-ray source with brightness 3 to 4 orders of magnitude higher than conventional sources. Detailed numerical simulations were performed to understand the physics of these processes. The advances described in this report lend themselves to our planned research in nonlinear Compton scattering