Dokument: Hybrid particle-in-cell simulations of relativistic plasmas

Titel:	Hybrid particle-in-cell simulations of relativistic plasmas
URL für Lesezeichen:	https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=23952
URN (NBN):	urn:nbn:de:hbz:061-20130319-125633-3
Kollektion:	Dissertationen
Sprache:	Englisch
Dokumententyp:	Wissenschaftliche Abschlussarbeiten » Dissertation
Medientyp:	Text
Autor:	Tückmantel, Tobias [Autor]
Dateien:	[Dateien anzeigen] Adobe PDF [Details] 14,73 MB in einer Datei [ZIP-Datei erzeugen] Dateien vom 28.02.2013 / geändert 28.02.2013
Beitragende:	Prof. Dr. Pukhov, Alexander [Gutachter] Prof. Dr. Schädle, Achim [Gutachter]
Stichwörter:	Particle-in-Cell, hybrid, Plasma wake field acceleration, computational fluid dynamics
Dewey Dezimal-Klassifikation:	500 Naturwissenschaften und Mathematik » 530 Physik
Beschreibung:	The particle-in-cell concept offers a versatile tool for the simulation of various non-equilibrium plasma effects. There is, however, a large number of applications where enhancements of the method can greatly improve the computational efficiency. The main focus of this thesis is the development, implementation and application of hybrid modules for the particle-in-cell (PIC) plasma simulation code Virtual Laser Plasma Lab (VLPL). Within this PIC/fluid hybrid concept, a plasma can be modeled either with the PIC method, or via methods of grid-based computational fluid dynamics(CFD). Based on a linearized fluid model, a Mollified Impulse exponential integrator was developed and implemented in collaboration with the Institute for Applied Mathematics, HHU Düsseldorf. It uses a three-component push-oscillate-splitting scheme, as well as filter functions to avoid unphysical resonances. The stability of this integrator does not depend on the plasma frequency, hence plasmas of arbitrary densities can be simulated. After the implementation, it has been successfully tested using several physical examples. Another, non-linear, hybrid scheme was designed specially for the simulation of extremely long wake fields. This module uses primitive fluid variables on a staggered grid to avoid interpolations. It was implemented into the VLPL code, forming the H-VLPL3D hybrid code. We demonstrate its superior capabilities in wake field modeling, presenting various physical benchmarks. This code was then used for the simulation of the self-modulated proton driven plasma wake field acceleration effect (SM-PDPWFA). Within this concept, a long proton bunch as delivered by the Super Proton Synchrotron (SPS) at CERN propagates through plasma. Small wake fields lead to self-modulation of the proton bunch; this causes strong longitudinal electric fields, which can be used for electron acceleration. We show that the phase velocity of the wake depends on, and is strongly connected to the growth rate of the self-modulation instability. Contrasting previous results on the phase velocity, we demonstrate that it rises during the non-linear stage, giving good conditions for electron injection. Using multi-staged simulations, the effectiveness of electron side injection into that wake is shown. Also, the wake phase velocity can be altered via background density gradients; with additional simulations, we demonstrate the significant change in phase velocity achieved by this method. The detection of self-modulation and/or hosing of the proton bunch can be done using Coherent Transition Radiation. The problem of the total current not being altered by self-modulation is overcome by utilizing Transverse Coherent Transition Radiation (TCTR). We present approximate analytical descriptions for the radiated field, and illustrate the radiation patterns for both beam shapes.
Lizenz:	Urheberrechtsschutz
Fachbereich / Einrichtung:	Mathematisch- Naturwissenschaftliche Fakultät » WE Physik » Theoretische Physik
Dokument erstellt am:	19.03.2013
Dateien geändert am:	19.03.2013
Promotionsantrag am:	24.09.2012
Datum der Promotion:	12.10.2012