Speaker
Description
Developing a laser wakefield acceleration (LWFA) scheme by focusing few-TW laser pulses into a thin, dense gas target paves the way for generating high-average-current electron beams driven by a modern high-repetition-rate laser. Our previous study demonstrated that using a sub-mm nitrogen (N₂) gas cell facilitates the routine generation of 10-MeV-scale electron beams from few-TW LWFA with ionization-induced injection. However, excessive ionization-induced defocusing of the pump laser pulse tends to occur in an N₂ target, motivating the use of a helium (He) – nitrogen (N₂) mixture as the gas target to mitigate pump pulse defocusing in few-TW LWFA*. In this study, the effect of nitrogen doping ratio ranging from 0.5% to 5% was investigated using 40-fs, 1-TW pulses with a 0.4-mm-long gas cell. We found that a manifest peak repeatedly appears around 10 MeV in the energy spectra with the 99.5% He - 0.5% N₂ gas mixture - a result never observed with the pure N₂ cell. Using the He-N₂ mixture also leads to a noticeable increase in the charge of high-energy electrons (>5 MeV) and a reduction in the pointing fluctuation of the output beams compared to the pure N₂ target.
Footnotes
P. -W. Lai et al., Phys. Plasmas, 30, 010703 (2023).
*M. -W. Lin et al., Phys. Plasmas, 27, 013102 (2020).
Funding Agency
This work was supported by the National Science and Technology Council in Taiwan with Grant No. NSTC 113-2112-M-007-013 and NSTC 113-NU-E-007-006-NU.
| Region represented | Asia |
|---|---|
| Paper preparation format | Word |
