Study of escaping electron dynamics and applications from high-power laser-plasma interactions

• Main Author: Rusby, Dean Richard
• Published: University of Strathclyde 2017
• Subjects: 530
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.736872

In recent years, high intensity laser-matter interactions (> 1018 W/cm2) have been shown to produce bright, compact sources of many different particles. These include x-rays, neutrons, protons and electrons, which can be used in applications such as x-ray and electron radiography. The potential use of these sources for industrial applications is promising. However, the scalability and tuning of the sources needs to be understood at a fundamental level. This thesis reports on three aspects of the development and application of these sources; the first two discuss applications of laser-plasma interactions. Firstly, the generation, characterisation and tunability of high-energy x-rays (= 200 keV) produced by the hot-electrons generated inside a solid target for the application of x-ray radiography. The characterisation of the x-ray source is conducted using a novel scintillator based absorption spectrometer. This source of x-rays was then used to radiograph a high density test object. Secondly, a novel technique of x-ray backscatter is investigated numerically and demonstrated experimentally for the first time on a laser facility. This uses the high energy electrons generated via wakefield acceleration to probe deeper into materials than traditional backscatter techniques. Finally, an investigation is reported examining the fundamental dynamics of electrons escaping from solid targets under different irradiation conditions. Experimentally, the number of escaping electrons was shown to maximise for certain laser illumination conditions; this was also explored using PIC simulations. The new results discussed in these three sections produce important new understanding of laser-driven x-ray generation and its application to penetrative probing and imaging for possible future industrial applications as well as the understanding of escaping electron dynamics.