High Harmonic Generation for the XUV seeding experiment at FLASH
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Beschreibung
The Free electron LASer in Hamburg (FLASH), operating in the Self-Amplified Sponta- neous Emission (SASE) mode, is currently the most intense femtosecond light source in the eXtreme-UltraViolet (XUV) regime. However, the statistical nature of SASE leads to intensity fluctuations of the Free Electron Laser (FEL) pulses. Moreover, the elec- tron acceleration process introduces arrival-time fluctuations of the electron bunch at the undulator entrance, which leads to a temporal jitter with respect to the synchroniza- tion system. This jitter limits the resolution of corresponding pump-probe experiments. In order to reduce these pulse-to-pulse fluctuations, a seeding section for the electron bunch has been installed in 2009/2010. Here, XUV seed pulses from a High-Harmonic Generation (HHG) source are overlapped in space and time with the electron bunches in new variable-gap undulators installed upstream the existing SASE undulator. Behind the undulator section, the seeded FEL radiation will be deflected by a mirror into an experimental container for beam characterization. A fraction of the optical laser, used as the driving laser for HHG, is also transported into the experimental container, thus, tem- poral diagnostics like cross-correlations between the synchronized seeded FEL and optical pulses are possible. Emphasis of this work is the construction and characterization of the HHG source.
The Free electron LASer in Hamburg (FLASH), operating in the Self-Amplified Sponta- neous Emission (SASE) mode, is currently the most intense femtosecond light source in the eXtreme-UltraViolet (XUV) regime. However, the statistical nature of SASE leads to intensity fluctuations of the Free Electron Laser (FEL) pulses. Moreover, the elec- tron acceleration process introduces arrival-time fluctuations of the electron bunch at the undulator entrance, which leads to a temporal jitter with respect to the synchroniza- tion system. This jitter limits the resolution of corresponding pump-probe experiments. In order to reduce these pulse-to-pulse fluctuations, a seeding section for the electron bunch has been installed in 2009/2010. Here, XUV seed pulses from a High-Harmonic Generation (HHG) source are overlapped in space and time with the electron bunches in new variable-gap undulators installed upstream the existing SASE undulator. Behind the undulator section, the seeded FEL radiation will be deflected by a mirror into an experimental container for beam characterization. A fraction of the optical laser, used as the driving laser for HHG, is also transported into the experimental container, thus, tem- poral diagnostics like cross-correlations between the synchronized seeded FEL and optical pulses are possible. Emphasis of this work is the construction and characterization of the HHG source.
Autor*in
Manuel Mittenzwey