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In this paper, the results of a Particle-in-Cell (PIC) simulation of electrons accelerated using a 10 fs Top-hat (TH) beam with a limited pulse energy of 85 mJ, focused on a double nozzle gas target using an off-axis parabola (OAP), an axiparabola (AXP), and an axiparabola with additional spatial–temporal coupling (AXP+STC), are discussed. The energy of accelerated electrons was predominantly determined through self-focusing and the ionisation injection effects of the laser beam propagating in plasma. The maximal energy of electrons accelerated using an AXP+STC could be higher by 12% compared to the energy of electrons accelerated by the regular OAP. [ABSTRACT FROM AUTHOR]

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In this report, an efficient hybrid laser technique, nanosecond laser rear-side processing and femtosecond laser-assisted selective etching (FLSE) for the manufacturing of high-density gas capillary targets, is demonstrated. Cylindrical capillary nozzles for laser betatron X-ray sources were numerically simulated, manufactured from fused silica by 3D laser inscription and characterized using interferometry and gas density reconstruction. The dependence of gas concentration profiles on the wall roughness of cylindrical channels is presented.

Optical aberrations induced in thin-disk laser elements with an undoped layer, performing as an anti-ASE cap, are analyzed. A numerical model, used for calculations of the optical path difference (OPD) induced by temperature distribution inside the laser element and by deformation of surfaces, was confirmed experimentally. Results of numerical modeling manifest that adding an undoped layer on the thin-disk has detrimental effect on the reflected laser beam brightness and scaling. It is also shown that brightness of a thin-disk laser may be enhanced by the use of the Gaussian pump beam profile.