Intense laser-plasma interactions

Doktorsavhandling, 2019

Contemporary lasers are capable of reaching intensities equivalent to focusing all sunlight hitting the Earth down to the tip of a hair. At these intensities, lasers are capable of rapidly stripping atoms of their electrons and creating a plasma. Even more remarkable, these intensities are enough to push electrons to speeds near that of light within just one laser cycle, or to trigger the creation of antimatter.

Despite its scarcity on Earth, plasma is the most common state of matter in the universe, a majority of which is contained in stars. A plasma can be thought of as a charged fluid and is capable of interacting with both itself and its surroundings over large distances through self-generated electromagnetic fields. As a result, it can exhibit a wide range of complex phenomena, lending itself to be exploited for numerous unique applications. Perhaps most famous amongst these is the prospect of clean energy through controlled nuclear fusion, by mimicking the extreme environment of the sun. Because of the ability of high-intensity lasers to create such environments, they can be used for inertial confinement fusion and laboratory astrophysics.

Through their properties as charged media, plasmas are also capable of sustaining the immense acceleration gradients created by an intense laser field, making it possible to accelerate particles to high energies over very short, centimeter-scale, distances. At sufficiently high intensities, the field can also trigger the emission of high-energy photons and the creation of electron-positron pairs. High-intensity lasers have therefore become instrumental in creating compact particle accelerators and radiation sources, which themselves have a wide range of applications within materials, fundamental and medical sciences, and can as an example be used for various imaging techniques.

This thesis is concerned with the topics of particle acceleration and radiation generation using intense laser fields, focusing in particular on the acceleration of light ions, such as protons, and the generation of gamma radiation. Using state-of-the-art numerical codes, we have investigated a novel ion acceleration scheme allowing for a greater control over the acceleration process as well as the use of optimally focused laser radiation promising an efficient generation of gamma radiation at both current and upcoming laser facilities.