Thesis
Hydrodynamic optical-field-ionized plasma waveguides for laser plasma accelerators
- Abstract:
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This thesis documents the experimental development of low-density hydrodynamic optical-field-ionized (HOFI) plasma channels. Results from two experiments are presented; the first, a proof of concept experiment, performed in Oxford, demonstrating for the first time that the formation of low-density (∼1017 cm-3) hydrodynamic plasma channels was possible using optical-field-ionization. The second experiment, performed at Astra-Gemini TA2, aimed to demonstrate the generation of low-density axicon-formed HOFI plasma waveguides and subsequently to demonstrate high-intensity guiding in those waveguides at the highest available repetition rate.
In the Oxford experiments, short (2-4mm) HOFI plasma channels were generated in hydrogen with a spherical lens and probed with longitudinal interferometry. The channels had on-axis densities between 1.6 × 1017 cm-3 and 1 × 1018 cm-3 and matched spot sizes of order 30μm to 60μm. A computational investigation into the guiding properties of the measured plasma channels indicated that they would be suitable as plasma waveguides.
In the experiments at Astra-Gemini TA2, HOFI plasma channels up to 16mm in length were generated in hydrogen using an axicon. These were probed with both longitudinal and transverse interferometry and had on-axis densities as low as 2 × 1017 cm-3 . These waveguides were subsequently used to successfully guide high-intensity (>1017 W cm-2) pulses over the full 16mm or 14.5 Rayleigh ranges, with a maximum throughput of 60 % observed for the higher intensities. The variation in guiding with pressure and with guided beam intensity was investigated experimentally. It was found that the high-intensity guided pulse modified the HOFI plasma channel, with the result of increasing the relative throughput of the guided beam.
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- Files:
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(Preview, pdf, 91.9MB, Terms of use)
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Authors
Contributors
- Department:
- University of Oxford
- Role:
- Supervisor
- Department:
- University of Oxford
- Role:
- Examiner
- Department:
- Université Paris-Sud
- Role:
- Examiner
- Grant:
- Grant number VH- VI-503
- DOI:
- Type of award:
- DPhil
- Level of award:
- Doctoral
- Awarding institution:
- University of Oxford
- Language:
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English
- Keywords:
- Subjects:
- UUID:
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uuid:aa7a03d0-2d64-423f-be42-40e01479d312
- Deposit date:
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2019-04-01
- ARK identifier:
Terms of use
- Copyright holder:
- Shalloo, R; Robert Shalloo. Robert Shalloo
- Copyright date:
- 2018
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