Enhanced Gamma-Ray Generation and Collimation in Laser-Plasma Interactions via a Cone-Channel Target Design

Recent progress in ultraintense laser technology has opened new avenues for compact, all-optical gamma-ray sources based on nonlinear Compton scattering. However, the practical

deployment of these sources remains limited by low photon yields and conversion efficiencies. In this work, we present a systematic study of γ-ray emission driven by petawatt-class laser

pulses interacting with tailored plasma targets, using both two-dimensional (2D) and three-dimensional (3D) particle-in-cell (PIC) simulations. We compare a conventional plasma

channel with a novel target design consisting of a hollow cone tapering into a channel, both formed by overdense plasma walls.

The cone-channel configuration enhances performance through three key mechanisms: (1) improved laser focusing to higher on-target intensities, (2) efficient electron injection from the

cone walls into the laser path, and (3) altered mode structure within the channel that alters the collimation of the emission. Our simulations reveal a significant enhancement in γ-ray emission,

with the 3D cone-channel setup achieving an ∼8-fold increase in laser-to-photon conversion efficiency compared to the 2D case. This improvement is attributed to the additional degree of

focusing and enhanced electron dynamics in three dimensions. These results demonstrate that cone-guided plasma channels offer a highly effective platform for generating collimated, high-energy γ-rays with improved efficiency. The proposed target design is compatible with upcoming petawatt-class laser facilities and holds strong potential for

applications in nuclear physics, high-energy density science, and advanced imaging.