This thesis reports on research performed on high harmonic generation and ion acceleration, processes that are based on the interaction of gaseous and solid media with high-intensity laser pulses. High harmonic generation leads to the production of beams of ultrashort, laser-like radiation in the wavelength range reaching from the extreme ultraviolet (XUV) to soft X-rays. Ion acceleration generates highly energetic protons and ions in the form of highly directional and pulsed beams with an ultrashort duration. The scope of this thesis is to present novel investigations and methods towards an enhancement of the flux and maximum energy of the accelerated ions and the harmonic radiation via an improved understanding of the underlying physics and, to provide a more complete identification of the actual requirements of the laser and the target for optimum output. The first part of this work concerns the construction and testing of a setup to generate high harmonics in gaseous media. The setup employs a capillary waveguide in which we implemented a novel manner of differential pumping. We performed an experiment on an enhancement technique, called Harmonic Excitation, and demonstrated for the first time that this technique can be applied in a capillary waveguide. The second part of the research concerns ion acceleration and high-order harmonic generation from solid-state targets using high-intensity laser pulses with ultra-high contrast. We investigated the coherence properties of high-order harmonic generation via coherent wake emission. Special attention was given to the preparation and investigation of extremely thin foils, i.e. freestanding nanofoils, to enter a very promising, but largely unexplored, regime. We experimentally investigated ion acceleration in this, so-called, transparent regime for the first time, and compared the results with predictions from improved numerical calculations. We also investigated for the first time high-order harmonic generation in the transparent regime, experimentally and via numerical modeling.
|Award date||18 Sep 2009|
|Place of Publication||Enschede|
|Publication status||Published - 18 Sep 2009|