Enhanced gamma-ray generation and collimation in laser-plasma interactions via a cone-channel target design

Recent advancements in high-intensity lasers have made all-optical nonlinear Compton scattering a promising method for generating ultrashort, brilliant γ-rays in compact systems, although currently these sources are still limited by low conversion efficiencies and spectral intensities. In this study, we explore laser–target driven γ-ray emission through two-dimensional (2D) and three-dimensional (3D) particle-in-cell simulations using two setups: one with a standard channel—used many times to control the laser plasma interaction—and one with a cone tapering into the channel, all using overdense walls. The cone alters the performance in three notable ways: 1) focusing the laser to a higher intensity; 2) entraining electrons from the cone walls and injecting them into the channel; 3) coupling the laser to the channel so as to alter the mode structure within the channel. Our simulations predict improved conversion efficiencies into high-energy gamma rays and greater collimation with the cone. These findings persist in 3D, where simulations reveal an ∼8-fold improvement in laser-to-photon conversion efficiency with the cone plasma setup, in comparison with the 2D cone plus channel case, corresponding with the added dimensionality of focusing. These findings suggest that the cone + channel setup can serve as an effective element at petawatt laser facilities to enable efficient γ-ray sources with broad applications.