Time-resolved investigation of a high-repetition-rate gas-jet target for high-harmonic generation

Abstract

High-repetition-rate gas targets constitute an essential component in intense laser matter interaction studies. The technology becomes challenging as the repetition rate approaches the kilohertz regime. In this regime, cantilever-based gas valves are employed, which can open and close in tens of microseconds, resulting in a unique kind of gas characteristics in both the spatial and temporal domain. Here we characterize piezo cantilever-based kilohertz pulsed gas valves in the low density regime, where it provides sufficient peak gas density for high-harmonic generation while releasing a significantly smaller amount of gas reducing the vacuum load within the interaction chamber, suitable for high-vacuum applications. In order to obtain reliable information of the gas density in the target jet, space-time resolved characterization is performed. The gas-jet system is validated by conducting interferometric gas density estimations and high-harmonic generation measurements at the Extreme Light Infrastructure Attosecond Light Pulse Source facility. Our results demonstrate that while employing such targets for optimal high-harmonic generation, the high intensity interaction should be confined to a suitable time window, after the cantilever opening. The measured gas density evolution correlates well with the integrated high-harmonic flux and state-of-the-art three-dimensional simulation results, establishing the importance of such metrology.