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Title: Theory and modelling of fast electron transport in laser-plasma interactions
Author: Williams, Brennig Elis Rhys
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2013
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The interaction of a high-intensity laser beam with a solid target generates a large number of fast electrons with long mean free paths. The study of these fast electrons is still the subject of active research, given their relevance to Tabak's [2] proposed fast-ignition approach to inertial confinement fusion. Conventional methods for simulating this system fall into two categories: kinetic and hybrid codes. Kinetic codes (Vlasov Fokker-Planck (VFP) and Particle in Cell (PIC) codes) provide an almost complete description of the system, but are often computationally expensive. Conventional hybrid codes simulate the fast-electrons well using a PIC code, but simplify the simulation of the background by using a rudimentary fluid model. In this thesis I present a new approach to modelling relativistic electrons propagating through a background plasma. This novel approach includes an improved classical transport description of the background plasma by using the VFP code IMPACT [21]. The fast electrons are modelled in two ways. Firstly, a 1D crude rigid beam model is used for the fast electrons. This gives rise to interesting transport effects in the background, such as transverse heat flow and non-local transport. It is found that the transverse heat flow is sufficient to reverse the `beam hollowing' effect of Davies et al [74] , allowing the reemergence of a fast electron collimating magnetic field over picosecond timescales. The second approach is to couple a PIC code into IMPACT to model the dynamic evolution of the fast electron beam. The scheme is tested against relevant beam-plasma phenomena. The code is used to model fast electron transport in 2D through a near-solid density background plasma. The significant result from this 2D investigation is the suppression of the filamentation instability by the resistively collimating field that surrounds the main beam.
Supervisor: Kingham, Robert Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available