Energy scaling of monoenergetic electron beams generated by the laser-driven plasma based accelerator

Abstract

Monoenergetic electron beams were generated in the self-modulated laser wakefield acceleration regime using a 2–6TW, 50fs Ti:sapphire laser system. The monoenergetic electron beams of energies up to 15MeV and 30MeV, with a plasma density around 1.5×1020cm−3 and 3.5×1019cm−3, respectively, were observed. The monoenergetic energy was found to be inversely proportional to the plasma density. The monoenergetic electron beam was generated at only specific plasma densities for each experimental condition. The plasma density dependence of the electron energy spectrum, the forward scattered light spectrum, and the side scattered light image of the laser pulse was studied in detail. The conditions for monoenergetic electron beam generation are discussed based on the results of the plasma diagnostics.