Measurements of Magnetic Compression and Melt of Electrically Thick Metals Driven by Lineal Current Densities Characteristic of Pulsed-Power-Driven Fusion Devices
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Authors
Klemmer, Aidan
Issue Date
2025
Type
Dissertation
Language
en_US
Keywords
ETI , Fusion , MRT , PDV , Pulsed-power , Z-pinch
Alternative Title
Abstract
Photonic Doppler velocimetry (PDV) has enabled high-resolution measurements of surface motion on z-pinches, revealing previously unobserved phenomena such as pre-melt radial magnetic compression followed by changes in acceleration corresponding to the solid-liquid phase transition of the surface of current-driven conductors. Experimental campaigns at the Sandia National Laboratories Mykonos linear transformer driver studied the conditions seeding electrothermal instabilities in electrically thick conductors. These instabilities, driven by localized non-uniform current density and Ohmic heating, play a critical role in the stability and performance of fusion concepts such as magnetized liner inertial fusion (MagLIF). A host of diagnostics, such as high-speed imaging, PDV, and laser shadowgraphy, tracked the surface motion and instability growth on mm-diameter aluminum rods driven to megampere currents in less than 200 ns. The experimental measurements are being used to benchmark magnetohydrodynamic calculations and thereby inform the choice of equation-of-state and conductivity tables for modeling. Complementary work on the Zap Energy FuZE-Q Z-pinch has focused on plasma impurity radiation studies of concern for electrode degradation and radiative loss mechanisms. FuZE-Q employs sheared-flow to suppress disruptive instabilities and sustain quiescent plasma conditions. A recently developed extreme ultraviolet spectrometer diagnostic on FuZE-Q identified plasma impurities, providing data for radiative loss calculations. Together, these experiments advance the understanding of impurity generation and radiative losses, contributing to fundamental plasma physics and the development of pulsed-power-driven fusion generators.