Speaker
Description
Laser wakefield acceleration is strongly influenced by the spatial and spatiotemporal structure of the drive laser pulse, yet the role of controlled wavefront aberrations at petawatt power remains largely unexplored. In this work, we investigate the effect of manually induced laser wavefront aberrations on GeV-scale electron beams and betatron X-ray emission produced at the ZEUS facility. Using a 12-inch deformable mirror, we systematically applied 45-degree astigmatism, horizontal coma, and 0-degree trefoil to a 1.12 PW, f/61 laser pulse driving ionization-injection wakefield acceleration in a 6 cm gas cell at a plasma density of approximately 5×$10^{17}$ cm$^{−3}$. Controlled aberrations were found to significantly modify both electron and X-ray beam properties. Astigmatism increased the ellipticity and divergence of the betatron X-ray profile, while all tested aberrations generally reduced the X-ray flux. Reconstructed betatron spectra suggest that astigmatism and trefoil soften the X-ray spectrum, whereas moderate horizontal coma may increase the inferred critical energy. Electron spectra showed reduced maximum energy at larger coma and trefoil strengths, while astigmatism had a weaker effect on peak energy. Measurements from a newly commissioned electron beam profiler revealed that increasing astigmatism can increase the fraction of charge contained in the central beam relative to the surrounding halo. This trapping-efficiency trend was qualitatively reproduced in reduced-scale FBPIC simulations using an astigmatic laser driver. Overall, these results demonstrate that controlled wavefront aberrations provide a useful handle for modifying injection, electron beam structure, and betatron X-ray emission in petawatt-class laser wakefield accelerators.
| Working group | WG1 |
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