Influence of Parabolic Plasma Channel Radius on Electron Injection and Betatron Radiation in Laser Wakefield Acceleration

ABSTRACT Parabolic plasma channels provide an additional degree of control over laser wakefield acceleration by modifying the transverse density curvature experienced by the driving pulse. Using quasi‐3D particle‐in‐cell simulations in the nonlinear blowout regime, we perform a systematic scan of channel radii to examine their impact on electron injection, acceleration, and betatron radiation. Varying the channel width regulates laser envelope oscillations, thereby modulating bubble expansion and the timing of self‐injection. This controlled injection shapes the transverse phase space of accelerated electrons and leads to a non‐monotonic dependence of betatron radiation yield on channel radius. An intermediate channel width yields optimal emission, resulting from a balance between sustained energy gain and sufficiently large transverse oscillation amplitudes. These results identify channel radius as an effective and experimentally accessible parameter for tuning betatron radiation in laser wakefield accelerators.