Single-Shot, Multi-Timestep Optical Probe Method for High Temporal Resolution Reconstruction of Plasma Waveguide Evolution*

A continuing fundamental need in the field of High Energy Density ( and plasma physics is the accurate and precise spatial and temporal characterization of laser-plasmas as they evolve, which would provide valuable insight into the foundational physics that drive laser-plasma interactions (LPIs). LPIs are complex, rapidly evolving, and highly sensitive to shot-to-shot variations in laser parameters, such as laser peak intensity, pulse duration, pre-pulse, and focal spot, and/or thermal instabilities. Even under nominally identical laser conditions, small variations can drastically influence outcomes. However, in typical HED experiments currently, the very fast fs-ps timescales of the laser interaction and the high energy of the laser can mean that some measurements must be taken prior to the actual experiment in a surrogate shot. To understand these interactions, on-shot experimental techniques must be developed and implemented. This work discusses the design, development, and first use of a new single-frame technique for reconstruction of plasma electron density profiles at multiple timesteps within each shot using a single probe pulse. This new method uses just two components to simultaneously take multiple time-resolved electron density measurements. This data captures the complete 2D evolution of the laser plasma waveguide, from seeding through drilling and eventually expansion, on a single laser shot and encodes the full event on a single camera frame.