Injection and acceleration of electrons by radially polarized laser pulses in a plasma channel

We consider injection and subsequent acceleration of electrons in narrow plasma channels irradiated by linearly and radially polarized ultraintense laser pulses. Using three-dimensional particle-in-cell simulations, we show that radially polarized beams significantly promote electron release from the channel walls and lead to enhanced injection. We compare an f / 10 linearly polarized laser beam with two radially polarized cases: one focused more tightly ( f / 5 ) to match peak intensity, and one at equal f / 10 to capture polarization effects. The radially polarized f / 10 case injects approximately one-third more charge than the linearly polarized case, while the f / 5 radially polarized case outperforms the linearly polarized one by about a factor of two in terms of maximum electron energy. This work provides a controlled three-dimensional comparison that clarifies how laser polarization and focusing geometry influence electron injection efficiency, acceleration pathways, and beam collimation in plasma channels.