We study theoretically and numerically the acceleration of protons by a combination of laser radiation pressure acceleration and Coulomb repulsion of carbon ions in a multi-ion thin foil made of carbon and hydrogen. The carbon layer helps to delay the proton layer from disruption due to the Rayleigh–Taylor instability, to maintain the quasi-monoenergetic proton layer and to accelerate it by the electron-shielded Coulomb repulsion for much longer duration than the acceleration time using single-ion hydrogen foils. Particle-in-cell simulations with a normalized peak laser amplitude of a_0 = 5 show a resulting quasi-monoenergetic proton energy of about 70 MeV with the foil made of 90% carbon and 10% hydrogen, in contrast to 10 MeV using a single-ion hydrogen foil. An analytical model is presented to explain quantitatively the proton energy evolution; this model is in agreement with the simulation results. The energy dependence of the quasi-monoenergetic proton beam on the concentration of carbon and hydrogen is also studied.
- ion acceleration
- quasi-monoenergetic protons
- thin multi-ion foils
- laser radiation pressure acceleration
- shielded Coulomb repulsion
Liu, T-C., Shao, X., Liu, C-S., He, M., Eliasson, B., Tripathi, V., Su, J-J., Wang, J., & Chen, S-H. (2013). Generation of quasi-monoenergetic protons from thin multi-ion foils by a combination of laser radiation pressure acceleration and shielded Coulomb repulsion. New Journal of Physics, 15, . https://doi.org/10.1088/1367-2630/15/2/025026