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Title: Development of harmonic generation sources and characterisation of UV and XUV radiation at high power and free-electron lasers
Author: Hage, Arvid
ISNI:       0000 0004 5372 6518
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2015
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The main topic of this thesis was to develop XUV sources for direct seeding and UV sources for high-gain harmonic generation (HGHG) at the second undulator beamline of the Free-Electron Laser in Hamburg (FLASH2). The thesis is divided into three topics: (i) UV- and (ii) XUV-seed sources and (iii) the seeding and diagnostic setups of FLASH2. In the UV section the opportunity to seed FLASH2 with HGHG is investigated. The seed radiation is generated with a purpose-built optical parametric chirped pulse amplifier (OPCPA) operating in a 10 Hz burst mode with an intra burst repetition rate of 100 kHz. The infra-red radiation is converted by third harmonic generation (THG) based on sum-frequency generation (SFG) in BBO-crystals to the UV region. In the XUV chapter, experiments with different XUV sources were carried out to investigate the option of direct XUV seeding at FLASH2. Two different concepts are considered in this thesis to enhance the conversion efficiency especially at short wavelengths. One approach is quasi-phase matching (QPM) using two different gases for the generation and the phase tuning of the XUV radiation, while the second approach is the generation of XUV radiation from ions. In addition the gas density distribution of the QPM dual gas foil target was measured with a Mach-Zehnder interferometer enabling a three dimensional analysis of the influence of adjacent jets on each other. The third section treats the development and implementation of the required equipment for seeding FLASH2. In particular the XUV spectrometer, which was used to analyse the first FEL radiation of FLASH2.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available