Low-energy-spread laser wakefield acceleration using ionization injection with a tightly focused laser in a mismatched plasma channel
Published in Plasma Physics and Controlled Fusion, 2016
Abstract: An improved ionization injection scheme for laser wakefield acceleration using a tightly focused laser pulse, with intensity near the ionization threshold to trigger the injection in a mismatched plasma channel, has been proposed and examined via 3D particle-in-cell (PIC) simulations. In this scheme, the key to achieving a very low energy spread is shortening the injection distance through the fast diffraction of the tightly focused laser. Furthermore, the oscillation of the laser envelope in the mismatched plasma channel can induce multiple low-energy-spread injections with an even distribution in both space and energy. The envelope oscillation can also significantly enhance the energy gain of the injected beams compared to the standard non-evolving wake scenario due to the rephasing between the electron beam and the laser wake. A theoretical model has been derived to precisely predict the injection distance, the ionization degree of injection atoms/ions, the electron yield as well as the ionized charge for given laser-plasma parameters. Through 3D PIC simulations, we show that an injection distance as short as tens of microns can be achieved, which leads to ultrashort fs electron bunches with a narrow absolute energy spread around 2 MeV (rms). Such low-energy-spread electron beams may have potential applications for future coherent light sources driven by laser-plasma accelerators.
Recommended citation: Fei Li, Chaojie Zhang, Yang Wan, Yipeng Wu, Xinlu Xu, Jianfei Hua, Chi-Hao Pai, Wei Lu, Yuqiu Gu, Warren B. Mori, Chan Joshi, "Low-energy-spread laser wakefield acceleration using ionization injection with a tightly focused laser in a mismatched plasma channel," Plasma Phys. Control. Fusion 58, 034004 (2016).
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