Titel: Towards modeling of electron-impact ionization in warm dense matter
Sprache: Englisch
Autor*in: Bekx, John Jasper
Schlagwörter: Electron-structure; impact-ionization; warm-dense-matter
Erscheinungsdatum: 2020
Tag der mündlichen Prüfung: 2020-11-13
The unique properties of x-ray free-electron lasers (XFELs), such as their
immense brilliance, ultrashort pulse duration, and high photon energies,
make XFELs an incredibly useful tool in a plethora of different scientific
fields. Their applications include unique imaging techniques used in struc-
tural biology and bio-engineering, the study of new effects in nanophysics,
and the creation and probing of exotic states of matter used to investigate
astrophysical objects and phenomena. Due to the development of XFELs
over the last few decades, there has been an increasing need to theoretically
describe the x-ray–matter interactions, and subsequent radiation-induced
interactions, that are prevalent in various kinds of irradiated systems. This
dissertation is dedicated to the theoretical modeling of electron-impact ion-
ization in warm dense matter (WDM). Electron-impact ionization is a pre-
dominant contributor to radiation damage induced by an XFEL pulse in
dense materials.
The first part considers the process of electron-impact ionization for an
isolated atom. Specifically, I consider how the cross section for this process
changes for different electronic configurations of the same ion. I find that
this change may be quite substantial. It depends on the charge state of the
ion, the energy of the ionizing electron, and on how much the two electronic
configurations being compared differ from each other.
The second part revolves around the theoretical description of warm
dense matter states. I develop a novel toolkit called xcrystal, which cal-
culates electronic states present in a transient state of nonisothermal WDM
from first principles. With xcrystal, I calculate the electronic energies for
these WDM states, which allows for predictions of the ionization potential
depression caused by the presence of a dense and charged environment. In
addition, I investigate the temperature dependence of the band structure of
a WDM system and provide physical justifications for the observed trends.
The third and final part uses the results of the previous two parts to
model electron-impact ioinization in the warm dense matter states described
by xcrystal. Here, I develop the theory to calculate the cross section in this
system and provide an in-depth discussion on its practical implementation.
URL: https://ediss.sub.uni-hamburg.de/handle/ediss/8723
URN: urn:nbn:de:gbv:18-ediss-88839
Dokumenttyp: Dissertation
Betreuer*in: Ziaja-Motyka, Beata
Santra, Robin
Enthalten in den Sammlungen:Elektronische Dissertationen und Habilitationen

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