Modelling of laser plasma interaction with applications to particle acceleration and radiation generation
Doktorsavhandling, 2019

The development of laser systems with ultra-high intensities has allowed the study of the relativistic interaction of laser light and ionized matter, plasmas, as well as opened up prospects for compact particle accelerators, generation of high intensity X-ray, XUV radiation, and probing QED-effects, which are present in the high intensity regime. To describe laser matter interaction, it is necessary to self-consistently account for the paths of a large number of particles and the corresponding electromagnetic fields, with the addition of stochastic effects at high laser intensities. Although analytical work can capture the essence of the dynamics in a range of situations, the rich dynamics in laser-plasma interaction results in that numerical modelling, and in particular the Particle-In-Cell (PIC) method, is critical to gain a detailed description of the dynamics. This is a stochastic method in which phase-space is sampled with macro-particles and allows for efficient modelling of high dimensional problems, but has limitations due to statistical noise.

For some applications, for example shock acceleration and instability growth, continuum methods, i.e. solving the Vlasov-Maxwell system of equations on a phase-space grid, may be preferable to accurately describe the plasma dynamics. In the first two papers in this thesis, we address the problem of implementing efficient continuum methods for the Vlasov-Maxwell system of equations. Furthermore, we treat ion shock acceleration using continuum methods. In the following papers, we address scalings of the electron spectrum in the electron sheath, formed at the vacuum-plasma boundary through the interaction of a relativistic laser and moderately overdense plasma. This is important to determine the spectral properties of high harmonic radiation generated from the laser plasma interaction. We also explore electron wakefield acceleration driven by laser pulses with wavelength in the X-ray regime generated from laser plasma interaction in the moderately overdense regime. By reducing the wavelength, the quantum parameter is enhanced, leading to comparable electron and photon energies already at moderate relativistic amplitudes although with more infrequent emission of photons than at optical wavelengths, preventing radiation losses from becoming a roadblock for the acceleration process.

plasma

ion acceleration

continuum methods

electron wakefield acceleration

raditation generation

coherent X-ray pulses

Vlasov-Maxwell equations

PJ lecture hall
Opponent: Professor Caterina Riconda

Författare

Benjamin Svedung Wettervik

Chalmers, Fysik, Teoretisk fysik

Vlasov modelling of laser-driven collisionless shock acceleration of protons

Physics of Plasmas,; Vol. 23(2016)p. 053103-

Artikel i vetenskaplig tidskrift

Relativistic Vlasov-Maxwell modelling using finite volumes and adaptive mesh refinement

European Physical Journal D,; Vol. 71(2017)p. 157-

Artikel i vetenskaplig tidskrift

Prospects and limitations of wakefield acceleration in solids

Physics of Plasmas,; Vol. 25(2018)

Artikel i vetenskaplig tidskrift

Physics of the laser-plasma interface in the relativistic regime of interaction

Physics of Plasmas,; Vol. 26(2019)

Artikel i vetenskaplig tidskrift

Lasers have in the past decades been able to reach intensities exceeding what is equivalent to focusing all sunlight hitting the earth to the tip of a hair. This is an extreme amount of energy which instantly ionizes matter – creating a state, with freely moving electrons and ions which interact through collective long-range forces, known as plasma. Although plasma is the most common state of matter in the universe, it is less familiar from our immediate surroundings in everyday life. Plasma exhibits a rich behaviour and the interaction of lasers and plasma both enables laboratory experiment of phenomena otherwise only present in the far distances of space, as well as numerous applications. Applications range from inertial confinement fusion, which may provide a source of clean energy, to compact particle acceleration and sources of intense short wavelength radiation in the X-ray/XUV regime. These areas relate on one hand to medical applications such as cancer treatment and diagnosis/imaging, but also have potential to increase the highest attainable energies by particle accelerators and probing high energy density physics. However, modelling of plasma is challenging: Plasma contains of many particles, which are not tractable to account for individually. At the same time, even if the number of degrees of freedom is reduced by using statistical methods the resulting equations still present a major challenge. This thesis makes a contribution to a range of these topics, including the numerical modelling of plasmas, particle acceleration and radiation generation.

Fundament

Grundläggande vetenskaper

Ämneskategorier

Atom- och molekylfysik och optik

Annan fysik

Fusion, plasma och rymdfysik

ISBN

978-91-7905-152-5

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4619

Utgivare

Chalmers tekniska högskola

PJ lecture hall

Opponent: Professor Caterina Riconda

Mer information

Senast uppdaterat

2019-08-23