Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

After the interaction of ultra-short high intensity laser pulses with thin solid targets, strong electric fields within the resulting plasma can accelerate ions to energies of tens of MeV. The performance of such laser driven ion sources critically depends on the initial conditions of the target plasma at the arrival time of the driving laser pulse. Pre-pulses and pedestals in the intrinsic temporal laser contrast can cause dielectric breakdown of the target long before the arrival of the main laser pulse, causing the target to ionize and pre-expand uncontrolledly.

Here, we present a study of the laser-induced breakdown (LIB) threshold intensity of 300nm thin formvar foils as well as cryogenic solid hydrogen jets, which are both used as targets for ion accleration at the Draco laser facility at Helmholtz-Zentrum Dresden-Rossendorf. By stretching the pump laser pulse, the dependence of LIB threshold intensity on laser pulse duration is investigated. This helps to understand and model the pre-plasma formation during the rising flank of a high power laser pulse impinging on a thin dielectric target.