The understanding of plasma produced during the interaction of a short pulse and matter is essential to understand the different mechanisms of transfert energy between laser and fast particles. APOLLON facility’s laser is ideal for high-intensity experiments where laser parameters will be perfectly charaterized.
These experiments are even more important as the models to simulate very-high-flow interaction are still in their early stages. Indeed, the fluid modeles usually used for nanosecond interaction are no longer apply and particle model cannot answer every questions because the state equations are difficult to process.
The theorical and experimental study of plasma produced by intense and energetic lasers is a field of research with many applications in astrophysique but also for both particle and radiation sources.
One of the main interests of the APOLLON laser will be to provide extremely high laser intensities, such that electrons exposed to the laser field move at the speed of light. Therefore, by irradiating solid targets with such a laser beam, one can create a relativistic moving mirror –something that physicists have tried to obtain for decades. Such relativistic moving mirrors have three major scientific interests, which will be important research topics for the APOLLON facility.
First of all, plasma mirrors are ideal model systems to investigate the complex physics of light-matter interaction at extreme intensities.
By inducing a Doppler effect on the reflected light, they convert the laser light to much shorter wavelengths (potentially down to the X-ray range), and temporally compress the laser pulses to much shorter durations (down to a few attoseconds), thus providing a light source with unique properties for scientific applications.
Finally, plasma mirrors can be used to concentrate the light energy in space and time even more, and reach light intensities that remain totally inaccessible even to the most powerful lasers. Such intensities would provide a new way to test one of the most fundamental theories of Physics, Quantum Electrodynamics, and in particular to probe the complex structure of vacuum predicted by this theory.