Studies of Electron Acceleration Mechanisms in Relativistic Laser-Plasma Interactions
Author(s)
Nagel, Sabrina Roswitha
Type
Thesis
Abstract
Laser-plasma interactions have many potential applications, such as medical treatments,
x-ray generation, particle acceleration and inertial confinement fusion (ICF).
In all of these applications, understanding how laser energy is absorbed by the material
and converted into energetic electrons is very important. Therefore it is vital
to enhance the understanding of how these energetic electrons are created and what
mechanisms influence them.
This Thesis comprises experimental studies of electron acceleration mechanisms
in laser-plasma interactions, as well as simulations relevant to these experiments.
The experiments described were conducted at the Rutherford Appleton Laboratory
utilising the VULCAN laser facility, and investigate laser interactions with both underdense
and overdense plasmas.
In the underdense regime, the intensity dependence of the accelerated electrons
has been studied experimentally, as well as the impact of the focusing geometry on
the generation of hot electrons. For high intensities, experimental measurements
show a scaling of the temperature of the electrons with a0. Density and f-number
dependencies of the accelerated electrons are also observed.
The effect of laser polarisation and target thickness on the escaping electrons
is studied for laser interactions with solid targets, or overdense plasmas. It was
found that the effective temperature of the electrons depends on both the laser
polarisation and the target thickness. The electron production from ultra-thin foils,
and the effect of laser pre-pulse are also investigated.
x-ray generation, particle acceleration and inertial confinement fusion (ICF).
In all of these applications, understanding how laser energy is absorbed by the material
and converted into energetic electrons is very important. Therefore it is vital
to enhance the understanding of how these energetic electrons are created and what
mechanisms influence them.
This Thesis comprises experimental studies of electron acceleration mechanisms
in laser-plasma interactions, as well as simulations relevant to these experiments.
The experiments described were conducted at the Rutherford Appleton Laboratory
utilising the VULCAN laser facility, and investigate laser interactions with both underdense
and overdense plasmas.
In the underdense regime, the intensity dependence of the accelerated electrons
has been studied experimentally, as well as the impact of the focusing geometry on
the generation of hot electrons. For high intensities, experimental measurements
show a scaling of the temperature of the electrons with a0. Density and f-number
dependencies of the accelerated electrons are also observed.
The effect of laser polarisation and target thickness on the escaping electrons
is studied for laser interactions with solid targets, or overdense plasmas. It was
found that the effective temperature of the electrons depends on both the laser
polarisation and the target thickness. The electron production from ultra-thin foils,
and the effect of laser pre-pulse are also investigated.
Date Issued
2009-06
Date Awarded
2009-09
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Krushelnick, Karl
Najmudin, Zulfikar
Creator
Nagel, Sabrina Roswitha
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)