Commissioning and use of ARC for pair-plasma generation on NIF*

Relativistic electron-positron pair plasmas are unique in plasma physics and are thought to play a fundamental role in high energy astrophysical processes such as gamma ray bursts.  Short pulse lasers have been shown to generate high density and high-flux pair plasmas.  Pair plasma experiments fielded at the National Ignition Facility (NIF) using the Advanced Radiographic Capability (ARC) have demonstrated the creation of electron-positron pairs.  ARC currently uses two NIF beamlines, each split into 2 sub-aperture beamlets with 1-38 ps pulse length capability and energies up to 1 kJ per beamlet.  By adding a parabolic cone to the front of the target, the light from ARC was re-focused to a high intensity sufficient to generate positrons.  Based on the measured electron slope temperature of T_e ~ 2-3 MeV, the inferred effective illumination intensity with the cone was approximately 4x10¹⁸ W/cm², higher than expected based on the measured statistical pointing and timing performance for ARC.  We will present a summary of ARC performance, describe the pair plasma platform and relevance to future laboratory astrophysics studies.