Z-Pinch Interferometry Analysis With the Fourier-Based TNT Code

Abstract

We present the analysis of interferometry diagnostics with the user-friendly Talbot Numerical Tool (TNT), a Fourier-based postprocessing code that enables real-time assessment of plasma systems. TNT performance was explored with visible and infrared interferometry in pulsed-power-driven Z-pinch configurations to expand its capabilities beyond Talbot X-ray interferometry in the high-intensity laser environment. TNT enabled accurate electron density characterization of magnetically driven plasma flows and shocks through phase-retrieval methods that did not require data modification or masking. TNT demonstrated enhanced resolution, detecting below 4% fringe shift, which corresponds to $8.7\times 10^{15}$ cm−2 within $28~\mu $ m, approaching the laser probing system limit. TNT was tested against a well-known interferometry analysis software, delivering an average resolving power nearly ten times better ( $\sim 28~\mu $ m versus $\sim 210~\mu $ m) when resolving plasma ablation features. TNT demonstrated higher sensitivity when probing sharp electron density gradients in supersonic shocks. A maximum electron areal density of $4.1\times 10^{17}$ cm−2 was measured in the shocked plasma region, and a minimum electron density detection of $\sim 1.0\times 10^{15}$ cm−2 was achieved. When probing colliding plasma flows, the calculations of the effective adiabatic index and the associated errors were improved from $\gamma ^{*}=2.6 ~\pm ~1.6$ – $1.4~\pm ~ 0.2$ with TNT postprocessing, contributing valuable data for the interpretation of radiative transport. Additional applications of TNT in the characterization of pulsed-power plasmas and beyond are discussed.