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This thesis is structured into 7 chapters:
• Chapter 2 gives an overview of the ultrashort high intensity laser interaction with matter. The laser interaction with an induced plasma is described, starting from the kinematics of single electron motion, followed by collective electron effects and the ponderamotive motion in the laser focus and the plasma transparency for the laser beam. The three different mechanisms prepared to accelerate and propagate electrons through matter are discussed. The following indirect acceleration of protons is explained by the Target Normal Sheath Acceleration (TNSA) mechanism. Finally some possible applications of laser accelerated protons are explained briefly.
• Chapter 3 deals with the modeling of geometry and field mapping of magnetic lens. Initial proton and electron distributions, fitted to PHELIX measured data are generated, a brief description of employed codes and used techniques in simulation is given, and the aberrations at the solenoid focal spot is studied.
• Chapter 4 presents a simulation study for suggested corrections to optimize the proton beam as a later beam source. Two tools have been employed in these suggested corrections, an aperture placed at the solenoid focal spot as energy selection tool, and a scattering foil placed in the proton beam to smooth the radial energy beam profile correlation at the focal spot due to chromatic aberrations. Another suggested correction has been investigated, to optimize the beam radius at the focal spot by lens geometry controlling.
• Chapter 5 presents a simulation study for the de-neutralization problem in TNSA caused by the fringing fields of pulsed magnetic solenoid and quadrupole. In this simulation, we followed an electrostatic model, wherethe evolution of both, self and mutual fields through the pulsed magnetic solenoid could be found, which is not the case in the quadrupole and only the growth of self fields could be found. The field mapping of magnetic elements is generated by the Matlab program, while the TraceWin code is employed to study the tracking through magnetic elements.
• Chapter 6 describes the PHELIX laser parameters at GSI with chirp pulse amplification technique (CPA), and Gafchromic Radiochromic film RCF) as a spatial energy resolver film detector. The results of experiments with laser proton acceleration, which were performed in two experimental areas at GSI (Z6 area and PHELIX Laser Hall (PLH)), are presented in section 6.3.
• Chapter 7 includes the main results of this work, conclusions and gives a perspective for future experimental activities.
In this thesis, a novel 257 kHz chopper device was numerically developed, technically designed and experimentally commissioned; a 4-solenoid, low-energy ion beam transport line was numerically investigated, installed and experimentally commissioned; and a novel massless beam-separation system was numerically developed.
The chopper combines a pulsed electric field with a static magnetic field in an ExB or Wien-filter type field configuration. Chopped beam pulses with a 257 kHz repetition rate and rise times of 110 ns were experimentally achieved using a 14 keV helium beam.
Due to the achieved results, the complete LEBT line for the future Frankfurt Neutron Source FRANZ is ready to deliver a dc or a pulsed beam. At the same time, the LEBT section represents an attractive test stand for the study of low-energy ion beams. It combines magnetic lenses, which allow space-charge compensated beam transport, and a chopper system capable of producing short beam pulses in the hundred nanosecond range. Since these beam pulses are transported onwards, their longitudinal and transverse properties can be analyzed. The pulse duration and time of flight are well below the rise time for the space-charge compensation through residual gas ionization. This opens the possibility for dedicated investigations of the transport of short, low-energy beam pulses including longitudinal and transverse space-charge effects and of relevant issues like the dynamics of space-charge compensation and electron effects in short pulses.
Nichtinvasive Detektoren für ortsaufgelöste Strahlprofilmessungen gewinnen mit zunehmenden Strahlströmen und -energien immer mehr an Bedeutung. An der Universität Frankfurt im Institut für Angewandte Physik (IAP) wird ein “Figure Eight”-förmiger magnetostatischer Speichering mit Stellarator-Konfiguration (F8SR) entwickelt. Einige Aspekte der Strahldynamik in einem solchen Ring können mit einem experimentellen Aufbau am IAP untersucht werden. Die Herausforderung bei der Entwicklung eines Detektors an einem (F8SR) liegt auf der einen Seite darin den Strahl nichtinvasiv zu detektieren, und andererseits müssen magnetisch unempfindliche Komponenten für den Detektor ausgewählt werden. Dabei sollte der Detektor so flexibel sein, dass der Strahl entlang der Flugbahn transversal gemessen werden kann. In dieser Arbeit geht es um einen Detektor mit radial um den Strahl angeordneten Photodioden, mit deren Hilfe die strahlinduzierte Fluoreszenz detektiert wird und mit einem geeigneten Rekonstruktionsverfahren, Strahlposition und den Strahldurchmesser ermittelt werden kann. Die Messungen werden mit einem weiteren schon erprobten Detektor - einem Szintillationsschirm verglichen.