The 4th International Conference on Matter and Radiation at Extremes (ICMRE 2019)

432 / 2019-03-01 17:41:12

Towards atomic diagnostics for ultra-high laser intensities

high-field diagnostic

Plenary track > Fundamental Physics at Extremes

We present an approach for direct measurement [1] of ultrahigh laser intensities in the range 10ˆ20 - 10ˆ24 W/cmˆ2. The method is based on the use of multiple sequential tunneling ionization of heavy atoms with adequately high ionization potentials. We show that, due to the highly nonlinear dependence of tunneling ionization rates on the electromagnetic field strength, an off-set in the charge distribution of ions appears to be clearly sensitive to the peak value of intensity in the laser focus. Based on the tunnel-ionization mechanism, a simple analytic theory helps estimating the maximal charge state produced at a given laser intensity Our theory also allows calculating qualitatively a distribution in charge states generated in different zones of the laser focus. These qualitative predictions are in excellent agreement with numerical simulations of the tunneling cascades, developed in the interaction of a short tightly focused laser pulse with low-density noble gas targets.