Implementation of a single-shot metrology system for a TW-class laser in a particle accelerator facility

Abstract

Electron generation from a laser-plasma accelerator (LPA) requires a good knowledge of the laser beam delivered on target, as many parameters are involved and represents a complex non-linear system. The next step towards a high repetition rate generation of stable and high-quality electron beams also requires to measure and monitor in real time and in single-shot the laser parameters, which may be a tough task for fs high-power laser systems. In this article, conducted at the LAPLACIAN LPA facility, we propose a simple way to measure all important laser parameters in real time without disturbing the main beam delivered on target, while ensuring to thwart intrinsic issues such as aberrations and dispersion. The beam leakage from the last mirror, just after the focusing optics, is used and sent towards a dedicated setup where, mainly, the energy, the pulse duration, the FF and NF profile (implying beam pointing and size), the spectrum and the M2 are measured. A prismatic blade has been designed to compensate aberrations introduced during the leakage process, and also chirped mirrors are used to compensate the dispersion. This real-time laser metrology system is fully operational to monitor what is reaching the target, and it should help in the future to have a better understanding on the electron beam generation and its instabilities.