Controlling electron acceleration process to produce harmonic spectral continuum and single harmonic

Abstract

In this paper, a potential scheme to produce both the harmonic spectral continuum and single harmonic has been proposed and investigated by using the combined chirped pulses. It is found that with the proper combination of the two-color second-order chirped pulse, both the harmonic spectral continuum and single harmonic can be obtained. Further, with the introduction of the third pulse, the harmonic yield can be enhanced. However, the single harmonic generation is almost independent on the chirp of the third pulse. As a result, the isolated attosecond pulses (IAPs) of sub-40 as can be obtained from the harmonic spectral continua and the adjustable single harmonics from 194th order to 360th order can also be found. While with the introduction of the third-order or fourth-order chirped pulses, only the harmonic spectral continua can be obtained. The generations of the harmonic spectral continua and single harmonics have been analyzed by using the three-step theory and the time-profiles of the harmonic generation.