Proposed Strong Field Ionization Experiments on the Texas Petawatt Laser

We present experimental plans for studying strong-field ionization of noble gas atoms on the Texas Petawatt Laser at intensity exceeding $10^{20}$ W/cm$^{2}$. We propose indirect measurement of the K-shell ionization yields by using plastic scintillators to detect the high-energy ATI electrons produced by these ionization events. A new f/1.4 focal geometry we are commissioning on the Texas Petawatt will allow peak intensity exceeding $10^{20}$ W/cm$^{2}$ on rod amplifier shots and $3 \times 10^{21}$ W/cm$^{2}$ for full-energy system shots, enabling the exploration of neon and argon K-shell ionization. The methods we propose should be scalable to intensity beyond $10^{21}$ W/cm$^{2}$, an intensity regime where ponderomotive scattering of ions from the focus will complicate direct measurements of the ion charge state yields by ion time-of-flight.