High laser field effects and laser-produced plasmas in a near QED regime

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The proposed scientific program aims to explore laser-produced plasmas in a regime close to the Quantum Electrodynamics (QED) effects intensity threshold (around 1023W/cm2) that can now be reached with the new generation of high peak power ultrafast lasers. The applicant upgraded the high peak power laser, from 200TW to 750TW, at the Advanced Laser Light Source (ALLS) facility at INRS in Varennes (Qc). This new infrastructure is ready (October 2015) with higher energies (up to 12J) in shorter (16fs) pulse duration. It will provide an unprecedented opportunity to achieve intensities on target close to 1023W/cm2 and explore high field frontier science. The new ALLS infrastructure and the proposed research program will help to maintain Canada at the forefront of a very competitive and novel science. The proposed program includes two major directions related to the interaction of very high laser fields with plasmas and is seen as a background for more complex experiments with more powerful lasers (multi-PW) at higher intensities in the QED regime. ***The first sub-program aims to explore, in a controlled geometry, the effect of strong longitudinal oscillating electric fields on electrons in plasma. Such fields will be a key component in the complex strong field QED regime. We will study electron acceleration directly by the longitudinal field created by the tight focusing of the radially polarized (TM01 mode) 750TW beam. Electrons will be either produced and accelerated directly by the main laser pulse from mass limited targets positioned inside the focal spot or accelerated from a plasma preformed by a first beam and injected with appropriate delay in the focal volume. Scaling laws as a function of the laser pulse duration (down to near single cycle pulse) and of the focusing numerical aperture will be established to benchmark modeling. *** The second sub-program is on the generation and study of plasmas in a radiation-dominated regime. Hot dense matter heated to extreme temperature (specific energy densities >106MJ/kg) will be produced from extremely thin foils to study the unexplored regime of atomic physics in radiation-dominated regime and in regimes where very high E and B oscillating fields are key parameters. Atomic physics (ionization dynamics, equilibrium) and the generation and effect of short wavelength radiation (up to the gamma-ray range) will be studied with high-resolution X-ray spectroscopy. Plasmas dynamics will be probed on the femtosecond time scale using femtosecond betatron radiation to realize the first ever femtosecond time resolved X-ray absorption spectroscopy of very hot dense matter.***This scientific program involves complex tools and methodologies, which for most of them have already been tested by the applicant's group, to produce adequate targets, measure electron beams on attosecond and femtosecond time scales, and shape beam in time and frequency with Gaussian and exotic modes.**