Plasma density characterization at SPARC_LAB through Stark broadening of Hydrogen spectral lines

Plasma-based acceleration techniques are of great interest for future, compact accelerators due to their high accelerating gradient. Both particle-driven and laser-driven Plasma Wakefield Acceleration experiments are foreseen at the SPARC_LAB Test Facility (INFN National Laboratories of Frascati, Italy), with the aim to accelerate high-brightness electron beams. In order to optimize the efficiency of the acceleration in the plasma and preserve the quality of the accelerated beam, the knowledge of the plasma electron density is mandatory. The Stark broadening of the Hydrogen spectral lines is one of the candidates used to characterize plasma density. The implementation of this diagnostic for plasma-based experiments at SPARC_LAB is presented. •Stark broadening of Hydrogen lines has been measured to determine plasma density.•Plasma density diagnostic tool for plasma-based experiments at SPARC_LAB is presented.•Plasma density in tapered laser triggered ablative capillary discharge was measured.•Results of plasma density measurements in ablative capillaries are shown.