Developing a high-intensity laser-plasma experimental capability for the Pair Plasma Discovery Science campaign on NIF-ARC*

The Advanced Radiographic Capability (ARC) laser at the NIF produces high-energy pulses (up to 4 kJ) but has a large focal spot with sub-relativistic intensities (1e18 W/cm2) below that needed for applications such as radiography, and pair creation. Results from the first high-intensity shots on ARC demonstrated a surprisingly high electron temperature of 2.2 MeV [1]. 2D PIC simulations show a dephasing acceleration mechanism where electrons sample a large area of changing laser phase, only achievable using long pulse durations with large spatial scales. The electron temperature was then increased by using parabolic focusing plasma optics [2] where inferred intensity was an order of magnitude compared to a flat target. This enabled the observation of pairs on ARC for the first time [3]. This newly developed high-intensity platform benefits a range of short-pulse, high-intensity laser applications at NIF.