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INVESTIGATION OF X-PINCH PLASMA DYNAMICS USING A PS TIME-RESOLVED X-RAY STREAK CAMERA

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2024-06-13
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Abstract

Hybrid X-pinches (HXPs) consist of two conical electrodes connected by a single few mm long wire as the load of a pulsed power generator. They are of interest to the high energy density research community due to the formation of micropinches, ~1-µm, sub-ns high density, and temperature bright X-ray radiation sources produced as a result of azimuthally symmetric instabilities. These micropinches are widely used in for point-projection X-ray radiography. In this dissertation, we focused on understanding their formation dynamics and characteristics. A variety of experimental diagnostics, including a ps time-resolution X-ray streak camera, a pinhole camera, a slit-step wedge camera, an array of silicon diodes, and photoconductive detectors, were used to investigate micropinches. Reproducibility studies were conducted on the Hybrid X-pinch configuration to determine the number of micropinches formed along with their timing as a function of the length of the connecting wire. We found that a gap distance of 0.5 - 1 mm was optimal for producing a single pinch and that a 40µm Ti wire load with a 3 mm electrode gap distance had the highest probability of reproducible time of occurrence for the first X-ray burst. We also developed a technique for studying radiation in the < 1 keV energy range on oscilloscopes with a sub-ns temporal resolution by placing a silicon diode at the focal point of an x-ray crystal. In addition, we conducted the first dynamic gas-puff X-pinch experiments, a controllable, high-yield X-ray source that can operate with or without a central wire and is suitable for point X-ray source applications. Finally, we used a time-resolved X-ray streak camera to investigate the dynamics of micropinches in HXPs and proposed a formation model based on the experimental data together with the results obtained from a two-dimensional extended MHD code coupled to a collisional-radiative spectral analysis code.

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2023-05

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HEDP; Hotspots; Radiography; Spectroscopy; X-pinches; X-rays

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Hammer, David

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Lovelace, Richard
Fennie, Craig

Degree Discipline

Electrical and Computer Engineering

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Ph. D., Electrical and Computer Engineering

Degree Level

Doctor of Philosophy

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dissertation or thesis

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