Dokument: Stable laser-driven proton acceleration in ultra-relativistic laser-plasma interaction
| Titel: | Stable laser-driven proton acceleration in ultra-relativistic laser-plasma interaction | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=19533 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20111011-142138-0 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Dr. Yu, Tongpu [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Pukhov, Alexander [Gutachter] Prof. Dr. Spatschek, Karl-Heinz [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 530 Physik | |||||||
| Beschreibung: | With a lot of potential applications in oncology, proton imaging and inertial confinement fusion, laser-driven ion acceleration has drawn increasing attention these years. In this dissertation, one of the most efficient and promising ion acceleration mechanisms, so-called
radiation pressure acceleration or light-sail regime is re-visited and studied in detail by multi-dimensional particle-in-cell (PIC) simulations. Based on a simple "flying plasma mirror" model, we derive accurate scaling laws of the final ion energy, velocity, and energy coupling efficiency in the light-sail regime. These laws have been well demonstrated by a series of one-dimensional PIC simulations. However, when we extend the model to multi-dimensional cases, several issues take place such as foil target deformation and transverse instabilities. To overcome the foil target deformation, a shaped foil target (SFT) is suggested, which can help keeping the acceleration structure for a longer time as compared to a normal flat target. The final energy spectrum shows a monoenergetic character. To demonstrate the robustness of the scheme, several facts such as the surface roughness and the transverse profile of the shaped foil are evaluated. Furthermore, an alternative scheme, namely, density modulated foil target (DMFT) is proposed. In this case, the initial foil target is a flat one, but the transverse plasma density follows a Gaussian distribution to match the laser intensity profile. Both 2D and 3D simulations show that the protons from the center part of the target can be monochromatically accelerated and are well collimated in the forward direction. Overall, the beam quality is much improved as compared to the case using a SFT. Multi-dimensional PIC simulations also show that Rayleigh-Taylor-like (RT) instability can be significantly suppressed by using the additionally proposed two-ion-species shaped foil. A simple three-interface model is proposed to interpret the suppression of the proton-RT instability, which agrees well with the numerical observations in a variety of cases. This should be attributed to two effects: ion species separation and heavier ion spreading in space. The heavier ions (carbon ions) act to buffer the compact lighter layer (protons) from the RT-like instability. It is also found that with the decrease of the carbon ions charge state, both the RT instability and Coulomb explosion become increasingly violent and tend to degrade the monoenergetic proton beam. In view of intense laser pulses in the light-sail regime, we also study the radiation reaction effects on the ion acceleration. The PIC code is modified according to the momentum conservation law. At any given time, we suppose that the radiation spectrum is synchrotron-like and the relativistic electrons emit radiation along their momentum direction. By using the modified code, we study the electron dynamics in the light-sail regime and observe the generation of GeV spiral electron bunches with an obvious attosecond structure. The electrons move together with the protons longitudinally and rotate dramatically around the latter in the transverse direction. When the oscillation frequency of the electron gets close to the laser frequency as witnessed by the electron, a betatron-like resonance occurs and an effective energy exchange between the laser and electron takes place. Such energetic spiral electron bunches would be of great interest for the emission of efficient betatron-like X-ray and even gamma burst, which might have diverse applications, e.g., in oncology and plasma diagnostics. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Physik » Theoretische Physik | |||||||
| Dokument erstellt am: | 11.10.2011 | |||||||
| Dateien geändert am: | 11.10.2011 | |||||||
| Promotionsantrag am: | 18.10.2008 | |||||||
| Datum der Promotion: | 06.10.2011 |
