Plasma Spectroscopy in Pinch Plasmas
Author(s)
Mercieca, Kayron
Type
Thesis
Abstract
Magnetic fields play a very important role in the dynamics of plasmas. Through interactions with the ions
and electrons within plasmas, their behaviour and evolution can be drastically influenced. It is the Zeeman
effect that is responsible for the splitting of radiative lines observed. Zeeman spectroscopy is a tool used for
the diagnosis of these magnetic fields within plasmas when the extent of this line splitting is observable.
Aluminium is chosen as an element to model as it is easy to place within a pinch plasma. It is also relatively
easy to ionise Aluminium into being Hydrogen-like within the conditions of pinch plasmas. The calculation
of Lyman Alpha and Lyman Beta spectral lineshapes for a Hydrogen-like Aluminium plasma is presented
from a fundamental standpoint. The Stark and Zeeman effects are explored and modelled. Modelling of the
former is aided by an adapted version of the APEX code by R. Lee in order to calculate the probability
distribution of electric fields around a radiator ion in the plasma. Both effects are calculated together as a
quantum perturbation to the π = 1, 2, 3 atomic energy levels including fine structure. The lineshapes
resulting from this calculation are compared with H-Line’s models (a code also by R. Lee) and shown to be
significantly more detailed, including visible Zeeman splitting for test external magnetic fields of B = 100 T
and B = 1000 T. Natural and Doppler broadening are also modelled. These extra broadening effects (in
particular Doppler) are shown to be destructive to discernable lineshape detail, largely preventing magnetic
field diagnosis through Zeeman spectroscopy. Lastly, Lyman Alpha and Lyman Beta are modelled for
plasmas with Z-pinch and X-pinch conditions in order to determine the viability of visible Zeeman line
splitting.
and electrons within plasmas, their behaviour and evolution can be drastically influenced. It is the Zeeman
effect that is responsible for the splitting of radiative lines observed. Zeeman spectroscopy is a tool used for
the diagnosis of these magnetic fields within plasmas when the extent of this line splitting is observable.
Aluminium is chosen as an element to model as it is easy to place within a pinch plasma. It is also relatively
easy to ionise Aluminium into being Hydrogen-like within the conditions of pinch plasmas. The calculation
of Lyman Alpha and Lyman Beta spectral lineshapes for a Hydrogen-like Aluminium plasma is presented
from a fundamental standpoint. The Stark and Zeeman effects are explored and modelled. Modelling of the
former is aided by an adapted version of the APEX code by R. Lee in order to calculate the probability
distribution of electric fields around a radiator ion in the plasma. Both effects are calculated together as a
quantum perturbation to the π = 1, 2, 3 atomic energy levels including fine structure. The lineshapes
resulting from this calculation are compared with H-Line’s models (a code also by R. Lee) and shown to be
significantly more detailed, including visible Zeeman splitting for test external magnetic fields of B = 100 T
and B = 1000 T. Natural and Doppler broadening are also modelled. These extra broadening effects (in
particular Doppler) are shown to be destructive to discernable lineshape detail, largely preventing magnetic
field diagnosis through Zeeman spectroscopy. Lastly, Lyman Alpha and Lyman Beta are modelled for
plasmas with Z-pinch and X-pinch conditions in order to determine the viability of visible Zeeman line
splitting.
Date Issued
2011-08
Date Awarded
2011-09
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Rose, Steven
Creator
Mercieca, Kayron
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)