Marta Fajardo, IST
How does matter behave under conditions of extreme temperature, pressure, density, and electromagnetic fields? High Energy Density matter states occur in astrophysical scenarios, but also during every high intensity laser-solid interaction, when a solid is heated to the plasma state. Although easy to produce, such high densities last only briefly, and since visible radiation cannot penetrate it, traditional diagnostics leave us with an incomplete picture of these plasmas.
High harmonic radiation from laser-gas interactions, with photon energies in the XUV, is capable of probing solid density matter. This source has many unique qualities. It holds the record for the shortest pulses ever produced, in the attosecond range (1e-18s), and essentially behaves like a laser, with linear polarization, small divergence, full spatio-temporal coherence, but with bonus: a multi-coloured discrete spectrum. These characteristics allow for applications such as nanometer-scale coherent imaging. Different techniques such as diffraction imaging and 3D holography have been demonstrated by many groups including ours. In recent years, improvements in the yield have allowed single-shot imaging and opened the way for attosecond time resolution.
In this talk we will show how we have used HHG used for opacity measurements and developed an XUV plasma refractive index diagnostic using a wavefront sensor, as well as recent advances in XUV holography, and how we plan to measure warm dense plasmas produced at the LCLS with these techniques.
Tapping into the potential of HHG sources as a probe, our ultimate goal is to shine some light into matter under extreme conditions through ultrafast imaging of dense plasmas.
