In this talk, I present the results from two different experiments in which extreme states of matter are created using short-pulse high-intensity lasers.

The first experiment was conducted with the laser Phelix at GSI Darmstadt. We studied the interaction of a high-intensity laser with mass-limited Ti-wires. The laser was focused up to 7 × 1020 W/cm2, with contrast of 10−10 to produce relativistic electrons. High-spatial-resolution X-ray spectroscopy was used to measure isochoric heating induced by hot electrons propagating along the wire up to 1mm depth. Our measurements allowed distinguishing the surface target regions heated by mixed plasma mechanisms from those heated only by the hot electrons that generate warm dense matter with temperatures up to 50 eV. Our results are compared to simulations that highlight both the role of electron confinement inside the wire and the importance of resistive stopping powers in warm dense matter.

The second experiment was performed at LOA in Palaiseau with the goal of demonstrating shock generation with ultra- short (24 fs) and low-energy (J) laser pulse, following the energy deposition in the target by fast electrons. Due to the short duration of the pulse, this shock is not supported in time and takes the form of a blast wave travelling in the solid material. For a target with 50μm thickness we have clearly inferred the generation of pressure ≥100Mbar. We also show that such blast wave can be used to provide information on compressed matter. We have measured the colour temperature of the emitting target rear side at breakout time (T ≈ 0.6 eV), which resulted in good agreement with predictions from equation-of-state models (SESAME tables) and hydrodynamic simulations.