Thesis
Optimisation of proton acceleration and synchrotron radiation in ultraintense laser-solid interactions
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2024
- Thesis identifier
- T17098
- Person Identifier (Local)
- 201991923
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- This thesis reports on numerical investigations of laser-solid interactions with peak laser intensities in the approximate range 1021–1024Wcm−2, where few experiments have yet taken place. Higher laser intensities enable the production of higher energy radiation whilst altering the physics of the interaction. Here, the generation of protons and gamma rays is optimised for laser intensities in the given range, now becoming accessible with improved petawatt and multi-petawatt laser facilities, and the dynamics of the interactions are analysed. The first investigation presented was centred on maximising the proton energies obtained with thin foil targets. The highest proton energies from CH targets are shown to occur when the foil becomes relativistically transparent as the peak of the temporal laser intensity profile reaches the target, for a wide range of laser intensities and both linear and circular laser light polarisation. The interaction dynamics are discussed, including the changes with earlier or later transparency times. Increased intensity of the laser pulse rising edge is demonstrated to increase the foil thickness which optimises the maximum proton energy, without significantly reducing the maximum proton energy. Finally, radiation reaction is shown to reduce the maximum proton energies from most targets by tens of percent. The second investigation reported was principally the optimisation of the synchrotron gamma ray emission from foil targets. Bayesian optimisation (a machine learning approach) was applied to optimise various objective functions corresponding to the energy converted into synchrotron radiation, peak angle-resolved emission and number of photons in the high energy spectral tail. Several objectives were also combined and optimised together. The results show the synchrotron emission is generally maximised for oblique incidence with the highest on-target laser intensity. Simultaneous reduction of bremsstrahlung emission also demonstrated optimised results with ultrathin targets. The role of the angle-of-incidence of the laser onto the target was explored, and 3D simulations enabled the additional role of the laser polarisation state to be determined. These results provide new understanding of gamma ray production in ultraintense laser-solid interactions, which could be used to improve the design of experiments and aid in the interpretation of experimental results.
- Advisor / supervisor
- McKenna, Paul
- Resource Type
- DOI
- Date Created
- 2023
关系
项目
| 缩略图 | 标题 | 上传日期 | 公开度 | 行动 |
|---|---|---|---|---|
|
|
PDF of thesis T17098 | 2024-12-03 | 公开 | 下载 |