FEL2012 - List of Authors (van der Meulen, P.)

Paper	Title	Page
TUPD13	Progress Towards HGHG and EEHG at FLASH	257
	K.E. Hacker, C. Behrens, H. Schlarb DESY, Hamburg, Germany G. Angelova Hamberg, V.G. Ziemann Uppsala University, Uppsala, Sweden A. Azima, J. Bödewadt Uni HH, Hamburg, Germany S. Khan, R. Molo DELTA, Dortmund, Germany P. Salén, P. van der Meulen FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
	Funding: BMBF 05K10PE1 and DESY New infrastructure was built at FLASH to enable 30-100 fs long, milliJoule pulses of 270 nm light to seed the electron beam with HGHG and EEHG techniques, targeting wavelengths in the range from 10 nm to 40 nm. HGHG, or High Gain Harmonic Generation, and EEHG, or Echo-Enabled Harmonic Generation, utilize an external laser together with chicanes and undulators in order to generate a bunched beam which will radiate in a subsequent undulator. In the case of HGHG, the beam is bunched at the seed laser wavelength, radiating harmonics thereof in the radiator. In the case of EEHG, the beam is bunched at a harmonic of the seed wavelength, radiating that same harmonic in the radiator. The properties of the setup, commissioning difficulties and the inital attempts at HGHG seeding at 38.5 nm will be described.

TUPD14	Optical Replica Synthesizer to be Recommissioned with 270 nm Seed at FLASH	261
	K.E. Hacker DESY, Hamburg, Germany G. Angelova Hamberg, V.G. Ziemann Uppsala University, Uppsala, Sweden S. Khan, R. Molo DELTA, Dortmund, Germany P. Salén, P. van der Meulen FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
	Funding: BMBF 05K010PE1, grant 621-2009-2926 and DESY The Optical Replica Synthesizer at FLASH was first commissioned in 2008 with an 800 nm seed. This wavelength proved to be problematic due to the fact that the COTR resulting from a microbunching instability at that wavelength was often as strong or stronger than the radiation from the seeded and bunched beam. It has since been observed that the microbunches which are responsible for the unwanted COTR can be smeared out in the dogleg if they are shorter than 600 nm. This opens the possibility to try the same experiment with a shorter wavelength and avoid the problems with the unwanted background signal from the microbunching instability. This is the motivation behind a new experimental design involving a new 270 nm seed laser and a new pulse length detection device to replace the old 800 nm seed and pulse length detection device. Details about the experiment design and commissioning plans will be described.

Paper

Title

Page

Progress Towards HGHG and EEHG at FLASH

257

K.E. Hacker, C. Behrens, H. Schlarb
DESY, Hamburg, Germany
G. Angelova Hamberg, V.G. Ziemann
Uppsala University, Uppsala, Sweden
A. Azima, J. Bödewadt
Uni HH, Hamburg, Germany
S. Khan, R. Molo
DELTA, Dortmund, Germany
P. Salén, P. van der Meulen
FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden

Funding: BMBF 05K10PE1 and DESY
New infrastructure was built at FLASH to enable 30-100 fs long, milliJoule pulses of 270 nm light to seed the electron beam with HGHG and EEHG techniques, targeting wavelengths in the range from 10 nm to 40 nm. HGHG, or High Gain Harmonic Generation, and EEHG, or Echo-Enabled Harmonic Generation, utilize an external laser together with chicanes and undulators in order to generate a bunched beam which will radiate in a subsequent undulator. In the case of HGHG, the beam is bunched at the seed laser wavelength, radiating harmonics thereof in the radiator. In the case of EEHG, the beam is bunched at a harmonic of the seed wavelength, radiating that same harmonic in the radiator. The properties of the setup, commissioning difficulties and the inital attempts at HGHG seeding at 38.5 nm will be described.

TUPD14

Optical Replica Synthesizer to be Recommissioned with 270 nm Seed at FLASH

261

K.E. Hacker
DESY, Hamburg, Germany
G. Angelova Hamberg, V.G. Ziemann
Uppsala University, Uppsala, Sweden
S. Khan, R. Molo
DELTA, Dortmund, Germany
P. Salén, P. van der Meulen
FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden

Funding: BMBF 05K010PE1, grant 621-2009-2926 and DESY
The Optical Replica Synthesizer at FLASH was first commissioned in 2008 with an 800 nm seed. This wavelength proved to be problematic due to the fact that the COTR resulting from a microbunching instability at that wavelength was often as strong or stronger than the radiation from the seeded and bunched beam. It has since been observed that the microbunches which are responsible for the unwanted COTR can be smeared out in the dogleg if they are shorter than 600 nm. This opens the possibility to try the same experiment with a shorter wavelength and avoid the problems with the unwanted background signal from the microbunching instability. This is the motivation behind a new experimental design involving a new 270 nm seed laser and a new pulse length detection device to replace the old 800 nm seed and pulse length detection device. Details about the experiment design and commissioning plans will be described.