Enhancing the energy of the produced electron bunch in laser–plasma interaction: effects of transverse injection and various density profiles

Abstract

Plasma-basedacceleratorsareacompellingalternativetoconventionalradio-frequencyaccelerators,offeringthepotential for significantly higher accelerating gradients. In these systems, a plasma channel is crucial for extending the dephasing and laser pulse propagation lengths, enabling the acceleration of electron bunches to high energies. This work investigates a plasma channel design featuring a low-density core with rippled-density variations, surrounded by a higher-density plasma. Using fully relativistic particle-in-cell simulations, we demonstrate that this tailored channel structure significantly enhances energy gain compared to a simple homogeneous plasma channel. Our key finding is that the combination of transverse injection and oscillatory inhomogeneity within this plasma channel enhances the wakefield intensity, leading to an increase in the maximum achievable electron bunch energy (reaching approximately 1.5 GeV in our simulations). We also present a detailed analysis of the impact of channel density, surrounding plasma density, and laser parameters such as period and wavelength on the acceleration process.