Dokument: Supra-thermal ion emission of solid density ultra-short pulse laser plasma

Titel:	Supra-thermal ion emission of solid density ultra-short pulse laser plasma
URL für Lesezeichen:	https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=73965
URN (NBN):	urn:nbn:de:hbz:061-20260723-131850-1
Kollektion:	Dissertationen
Sprache:	Deutsch
Dokumententyp:	Wissenschaftliche Abschlussarbeiten » Dissertation
Medientyp:	Text
Autor:	Riedlinger, Jan [Autor]
Dateien:	[Dateien anzeigen] Adobe PDF [Details] 10,89 MB in einer Datei [ZIP-Datei erzeugen] Dateien vom 16.07.2026 / geändert 16.07.2026
Beitragende:	Pretzler, Georg [Gutachter] PD Dr. Lehmann, Götz [Gutachter]
Dewey Dezimal-Klassifikation:	500 Naturwissenschaften und Mathematik » 530 Physik
Beschreibung:	Unconfined,high-energy-densitylaserplasmasinducedbyultra-shortlaserpulsesareknownto emit broadband ion spectra in terms of species and their kinetic energy. Under the right con ditions, the interaction of such femtosecond laser pulses, in the sub 1018 Wcm−2 regime, with a solid generates ion emission of bimodal nature, which consists of a slower thermal, and faster supra-thermal part. The main objective of this thesis is to optimize the ion source in terms of the supra-thermal emission and reveal information which they carry about early state plasma properties. Therefore, the first sub-goal of this thesis is to develop an optimized diagnostic and evaluation scheme, which is designed for this specific application. The diagnostic of choice is the Thomson Parabola method, which is well studied for the parti cle energies in the MeV range. In this work, however, the spectrometer is required to function down to energies of a few keV.Advancingintothisregimerequires anaccurateknowledgeofthe spectrometer fields, which were precisely determined by simulations and measurements. Fur thermore, the dynamicrangewassubstantially increased by adopting a compactelectromagnet instead of a permanent one. We demonstrate how the field parameters can be chosen for ob taining exceptionally broad spectra, while keeping the energy uncertainty minimal. With such a precise spectrometer, together with the developed special numeric methods, we were able to study the conditions to obtain supra-thermal ion emission. Here, emphasisisplacedonthelaserintensity, fluence, andduration, andtheirinfluenceonthe ion properties. For this purpose, supra-thermal emission is generated over a wide range of laser parameters in single- and double-pulse configurations. A key aspect of such plasmas is the high electron density paired with a steep density gradient at the target-vacuum interface. These high densities result in fast thermodynamic equilibra tion, compared to the time-frame of the emission. Thus, the results are analyzed using the Saha equations to determine the prevalent plasma conditions during emission, assuming local ther modynamic equilibrium (LTE). Thereby, the temporal and spatially localized nature of the ion ejection mechanism is leveraged to obtain a snapshot of the plasma temperature and density in early states of the plasma. Additionally, one dimensional hydrodynamic simulations were performed using the MULTI-FS code to gain insight into the plasma evolution on picosecond timescales, to compare the results to the experimental findings, and to reaffirm the LTE assumption. The presented results high light the optimal laser conditions, as well as limitations, to improve the prospects of laser-based ion sources for possible future applications.Unconfined,high-energy-densitylaserplasmasinducedbyultra-shortlaserpulsesareknownto emit broadband ion spectra in terms of species and their kinetic energy. Under the right con ditions, the interaction of such femtosecond laser pulses, in the sub 1018 Wcm−2 regime, with a solid generates ion emission of bimodal nature, which consists of a slower thermal, and faster supra-thermal part. The main objective of this thesis is to optimize the ion source in terms of the supra-thermal emission and reveal information which they carry about early state plasma properties. Therefore, the first sub-goal of this thesis is to develop an optimized diagnostic and evaluation scheme, which is designed for this specific application. The diagnostic of choice is the Thomson Parabola method, which is well studied for the parti cle energies in the MeV range. In this work, however, the spectrometer is required to function down to energies of a few keV.Advancingintothisregimerequires anaccurateknowledgeofthe spectrometer fields, which were precisely determined by simulations and measurements. Fur thermore, the dynamicrangewassubstantially increased by adopting a compactelectromagnet instead of a permanent one. We demonstrate how the field parameters can be chosen for ob taining exceptionally broad spectra, while keeping the energy uncertainty minimal. With such a precise spectrometer, together with the developed special numeric methods, we were able to study the conditions to obtain supra-thermal ion emission. Here, emphasisisplacedonthelaserintensity, fluence, andduration, andtheirinfluenceonthe ion properties. For this purpose, supra-thermal emission is generated over a wide range of laser parameters in single- and double-pulse configurations. A key aspect of such plasmas is the high electron density paired with a steep density gradient at the target-vacuum interface. These high densities result in fast thermodynamic equilibra tion, compared to the time-frame of the emission. Thus, the results are analyzed using the Saha equations to determine the prevalent plasma conditions during emission, assuming local ther modynamic equilibrium (LTE). Thereby, the temporal and spatially localized nature of the ion ejection mechanism is leveraged to obtain a snapshot of the plasma temperature and density in early states of the plasma. Additionally, one dimensional hydrodynamic simulations were performed using the MULTI-FS code to gain insight into the plasma evolution on picosecond timescales, to compare the results to the experimental findings, and to reaffirm the LTE assumption. The presented results high light the optimal laser conditions, as well as limitations, to improve the prospects of laser-based ion sources for possible future applications.
Lizenz:	Dieses Werk ist lizenziert unter einer Creative Commons Namensnennung 4.0 International Lizenz
Fachbereich / Einrichtung:	Mathematisch- Naturwissenschaftliche Fakultät » WE Physik » Laser- und Plasmaphysik
Dokument erstellt am:	23.07.2026
Dateien geändert am:	23.07.2026
Promotionsantrag am:	24.03.2026
Datum der Promotion:	10.07.2026