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

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

File(s)
Elshafiey_cornellgrad_0058_13472.pdf (2.9 MB)
Permanent Link(s)
https://doi.org/10.7298/cc52-kq44
https://hdl.handle.net/1813/114025
Collections
Cornell Theses and Dissertations
Author
Elshafiey, Ahmed
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.

Date Issued
2023-05
Keywords
HEDP
•
Hotspots
•
Radiography
•
Spectroscopy
•
X-pinches
•
X-rays
Committee Chair
Hammer, David
Committee Member
Lovelace, Richard
Fennie, Craig
Degree Discipline
Electrical and Computer Engineering
Degree Name
Ph. D., Electrical and Computer Engineering
Degree Level
Doctor of Philosophy
Type
dissertation or thesis
Link(s) to Catalog Record
https://newcatalog.library.cornell.edu/catalog/16176706

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