The Physic at High Intensity (PHI) group of DSM/DRECAM studies the behaviour of solid density plasmas submitted to ultra-short (<60fs) and ultra-intense (1018-1019W/cm2) laser pulses. Following the recent progress concerning laser contrast improvement (2004), the interaction between a laser and a plasma at solid density is now possible. Extreme contrast as high as 1010, prevents the creation of an expanding underdense preplasma in front of the target, as observed in the past, that avoid direct interaction with the target. It opens a new field of research with both a fundamental interest and significant application perspectives: the ultra relativistic solid-like matter-laser interaction. Due to the high focused intensity, the target is ionized to generate overdense plasma on the leading edge of the pulse. The interaction is followed by a strong emission, of relativistic electrons, of energetic ions or by intense X-rays. We are involved in the fundamental study of these generation mechanisms. Three main programs are developed by our group and dedicated to the study of:
- Attosecond pulses: the aim is to study and use the extreme non linearity which can be induced by ultra-intense laser reflecting on a plasma, which can tolerate arbitrary intensities. The efficient emission of very energetic attosecond pulse trains in the XUV domain is expected.
- Particle acceleration: we study the generation of ultra-short (5MeV) particle bunches from laser interaction with ultra-thin target [ref]. We plan to use these particle beams to study solid matter heating with a sub-picosecond temporal resolution. These studies should help to understand the creation and evolution of irradiation damages as well as “warm dense matter” properties.
- Ultra-fast plasma diagnostics: fundamental studies on attosecond pulses and particle generation seed the development of original diagnostics, of interest for laser-matter community. Specific efforts are made to characterise dense and hot plasmas of sub-picosecond time scale.
These activities are performed on the UHI10 laser facility (SLIC-Saclay), delivering 60fs duration pulses at 10Hz. Regarding the high intensity reached at focus (as high as 1019W/cm2) it is one of the three most powerful French Ti:Sa laser systems. It is fully equipped in terms of diagnostics. The main asset of the system is to deliver ultra-high temporal contrasted pulses (1010), allowing the realisation of the scientific program described above. The whole installation, due to its characteristics, scientific equipments, radio-protected area, is an absolutely unique facility.