All-optical Control of Electron Beam transverse Motion in Laser Plasma Wakefield

Аbstract

Laser plasma accelerator could provide high-intensity X-ray radiation as the basis for next generation compact radiation source. However, there is still lack of the tunability of radiation polarization, especially of the circular polarization. In this report, I will introduce two all-optical methods for controlling the transverse motion of ionization injected electron beam. Firstly, by utilizing the transversely asymmetrical wakefield via adjusting the shape of the laser focal spot. When the laser spot shape is changed from the circular to the obliquely elliptic in experiment, the electron beam shape becomes from elliptic to three different shapes. The 3D-PIC simulation results agree well with experiment, and it shows the trajectories of the accelerated electrons change from undulation to helix. Secondly, introducing a new method for achieving circularly polarized X-ray via circularly polarized laser pulses with a power of 15 TW driving plasma wakefield acceleration in the regime of ionization injection. By utilizing the laser pulses cover the plasma bubble, not only the ionization injected electrons would possess angular momentum, but these electrons would be resonant with the laser pulses which resulting in that their trajectories present the helix structure in the process of acceleration. Such the two all-optical methods could be useful for convenient control of the transverse motion of an electron beam which results in synchrotron radiation with orbit angular momentum.

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