High-energy proton beam generation via combined radiation pressure acceleration and laser wakefield acceleration in modulated plasma channels

High-energy proton beams are essential for fundamental research and applied physics. The combined acceleration mechanism based on radiation pressure acceleration has made great progress in obtaining high-energy protons. However, Rayleigh-Taylor instability (RTI) is still a potential influencing factor that will limit the quality of high-energy proton beams. Different from the previous suppression and neglect of RTI, this paper introduces a parabolic density plasma channel to accelerate protons by virtue of the characteristics of RTI. Three-dimensional Particle-in-cell simulations reveal that this scheme achieves high-energy protons with cut-off energy of 39 GeV, total charge of 0.97 nC, and the emittance of 1.12 mm mrad in both the y and z directions. There are locally distributed electrons in the parabolic density plasma channel, and the focusing field around them can effectively focus protons. Compared with the uniform density plasma channel, the parabolic density plasma channel can significantly improve the quality of the proton beam, which could offer significant guidance for the generation and application of high-energy proton beams.