Numerical experiment of radiation self-absorption and radiation dynamics in the dense plasma focus using Lee model

Radial dynamics and plasma focus pinch were influenced in slow compression mode by optically thick plasma due to radiation self-absorption. In this study, the role of radiation self-absorption in Mather type dense plasma focus (DPF) device was investigated. The impact of opacity in slow compression...

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Main Author:	Ali, Zahra
Format:	Thesis
Language:	English
Published:	2013
Subjects:	QC Physics
Online Access:	http://eprints.utm.my/id/eprint/35873/5/ZahraAliPFS2013.pdf
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spelling	my-utm-ep.358732017-07-05T04:14:05Z Numerical experiment of radiation self-absorption and radiation dynamics in the dense plasma focus using Lee model 2013-07 Ali, Zahra QC Physics Radial dynamics and plasma focus pinch were influenced in slow compression mode by optically thick plasma due to radiation self-absorption. In this study, the role of radiation self-absorption in Mather type dense plasma focus (DPF) device was investigated. The impact of opacity in slow compression phase and the behaviour of optically thick plasma towards radiation emission were explored. The numerical modelling of self-absorption effect on radiation dynamics, focusing, cooling, collapse and influence of self-absorption on the radiation emission was performed. Lee Model was used for numerical simulation. The model was developed incorporating the various energy balances including thermodynamics, kinematics, radiation dynamics and was capable of yielding the plasma structure and trajectories. The snowplow model describes the axial rundown phase and slug model in radial phase of pinch. Numerical simulations were performed for the absorption of radiation within dense and optically thick plasma. It was found that a steady state pinch with constant radius was only possible at the Pease–Braginskii (PB) current of 1.2 to 1.6 MA for hydrogen and deuterium DPF. For lower and higher values of input current as compared to PB current, the pinch expands and collapses respectively. This current was reduced for heavier gases like Neon (Ne), Argon (Ar), Krypton (Kr) and Xenon (Xe) due to the emission of significant amount of line radiation. For Ne, Ar, Kr and Xe gases with different DPF configurations more severe radiative collapse was observed as compared without the self-absorption factor. It was found that for Ar with no self-absorption, the pinch boundary collapsed in only a few nanoseconds to the radius of 0.1 mm set as cut-off in the model. The pinch does not attain the cut-off radius with self-absorption. In the case of Ne, there was no radiative collapse with self-absorption factor but radiative collapse occurs without self-absorption. A severe radiative collapse was also observed in both cases of Kr and Xe. It was inferred that the pinch radius collapses less when self-absorption was taken into account. The plasma opacity reduces the amount of radiation loss. Thus, self-absorption phenomenon was significant during the slow compression phase and needs to be considered in the design of a new DPF device. 2013-07 Thesis http://eprints.utm.my/id/eprint/35873/ http://eprints.utm.my/id/eprint/35873/5/ZahraAliPFS2013.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:69998?site_name=Restricted Repository phd doctoral Universiti Teknologi Malaysia, Faculty of Science Faculty of Science
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	QC Physics
spellingShingle	QC Physics Ali, Zahra Numerical experiment of radiation self-absorption and radiation dynamics in the dense plasma focus using Lee model
description	Radial dynamics and plasma focus pinch were influenced in slow compression mode by optically thick plasma due to radiation self-absorption. In this study, the role of radiation self-absorption in Mather type dense plasma focus (DPF) device was investigated. The impact of opacity in slow compression phase and the behaviour of optically thick plasma towards radiation emission were explored. The numerical modelling of self-absorption effect on radiation dynamics, focusing, cooling, collapse and influence of self-absorption on the radiation emission was performed. Lee Model was used for numerical simulation. The model was developed incorporating the various energy balances including thermodynamics, kinematics, radiation dynamics and was capable of yielding the plasma structure and trajectories. The snowplow model describes the axial rundown phase and slug model in radial phase of pinch. Numerical simulations were performed for the absorption of radiation within dense and optically thick plasma. It was found that a steady state pinch with constant radius was only possible at the Pease–Braginskii (PB) current of 1.2 to 1.6 MA for hydrogen and deuterium DPF. For lower and higher values of input current as compared to PB current, the pinch expands and collapses respectively. This current was reduced for heavier gases like Neon (Ne), Argon (Ar), Krypton (Kr) and Xenon (Xe) due to the emission of significant amount of line radiation. For Ne, Ar, Kr and Xe gases with different DPF configurations more severe radiative collapse was observed as compared without the self-absorption factor. It was found that for Ar with no self-absorption, the pinch boundary collapsed in only a few nanoseconds to the radius of 0.1 mm set as cut-off in the model. The pinch does not attain the cut-off radius with self-absorption. In the case of Ne, there was no radiative collapse with self-absorption factor but radiative collapse occurs without self-absorption. A severe radiative collapse was also observed in both cases of Kr and Xe. It was inferred that the pinch radius collapses less when self-absorption was taken into account. The plasma opacity reduces the amount of radiation loss. Thus, self-absorption phenomenon was significant during the slow compression phase and needs to be considered in the design of a new DPF device.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Ali, Zahra
author_facet	Ali, Zahra
author_sort	Ali, Zahra
title	Numerical experiment of radiation self-absorption and radiation dynamics in the dense plasma focus using Lee model
title_short	Numerical experiment of radiation self-absorption and radiation dynamics in the dense plasma focus using Lee model
title_full	Numerical experiment of radiation self-absorption and radiation dynamics in the dense plasma focus using Lee model
title_fullStr	Numerical experiment of radiation self-absorption and radiation dynamics in the dense plasma focus using Lee model
title_full_unstemmed	Numerical experiment of radiation self-absorption and radiation dynamics in the dense plasma focus using Lee model
title_sort	numerical experiment of radiation self-absorption and radiation dynamics in the dense plasma focus using lee model
granting_institution	Universiti Teknologi Malaysia, Faculty of Science
granting_department	Faculty of Science
publishDate	2013
url	http://eprints.utm.my/id/eprint/35873/5/ZahraAliPFS2013.pdf
_version_	1747816376639160320

Numerical experiment of radiation self-absorption and radiation dynamics in the dense plasma focus using Lee model

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