FEL2012 - List of Authors (Stephan, F.)

Paper	Title	Page
MOPD59	PITZ Status, Recent Measurements and Tests	181
	M. Krasilnikov, H.-J. Grabosch, M. Groß, I.I. Isaev, Ye. Ivanisenko, M. Khojoyan, G. Klemz, G. Kourkafas, M. Mahgoub, D. Malyutin, B. Marchetti, A. Oppelt, M. Otevřel, B. Petrosyan, A. Shapovalov, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany K. Kusoljariyakul FNRF, Chiang Mai, Thailand J. Li USTC/NSRL, Hefei, Anhui, People's Republic of China D. Richter HZB, Berlin, Germany S. Rimjaem Chiang Mai University, Chiang Mai, Thailand I. Will MBI, Berlin, Germany
	The photo injector test facility at DESY, Zeuthen site (PITZ) is dedicated to the development and optimization of a high-brightness electron source for the European XFEL. Recently a significant upgrade has been done at the facility. A new RF system has been installed for the PITZ gun, enabling higher attainable peak power in the cavity which is important for efficient LLRF regulation. First long-term tests for a stable gun operation at high duty cycle have been performed. Two major components for electron beam diagnostics - a transverse deflecting cavity for time resolved electron bunch characterization, and a second high energy dispersive arm for precise longitudinal phase space measurements - have been installed. First results of their commissioning will be reported.

MOPD60	Optimization of the Transverse Projected Emittance of the Electron Beam at PITZ	185
	G. Vashchenko, M. Groß, L. Hakobyan, I.I. Isaev, Ye. Ivanisenko, M. Krasilnikov, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, S. Rimjaem, A. Shapovalov, F. Stephan DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria M. Khojoyan ANSL, Yerevan, Armenia D. Richter HZB, Berlin, Germany
	High brightness electron sources for linac based free-electron lasers operating at short wavelength such as the Free-Electron Laser in Hamburg at DESY, Hamburg Site (FLASH) and the European X-Ray Laser Project XFEL (European XFEL) are characterized and optimized at the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ). One of the most important parameters influencing the FEL process is the normalized transverse projected emittance of the electron beam. The major part of the experimental program at PITZ is devoted to its optimization. Detailed simulations of the present facility setup are performed for a 1 nC bunch charge in order to optimize the transverse projected emittance of the electron beam. Cathode laser pulse length and transverse spot size at the photo cathode, gun and booster accelerating gradients and their launching phases as well as the main solenoid current are optimized. Simulations results together with experimental data are presented.

MOPD61	Laser Pulse Train Management with an Acousto-optic Modulator	189
	M. Groß, H.-J. Grabosch, L. Hakobyan, I.I. Isaev, Ye. Ivanisenko, M. Khojoyan, G. Klemz, G. Kourkafas, M. Krasilnikov, K. Kusoljariyakul, J. Li, M. Mahgoub, D. Malyutin, B. Marchetti, A. Oppelt, M. Otevřel, B. Petrosyan, A. Shapovalov, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany D. Richter HZB, Berlin, Germany H. Schlarb, S. Schreiber DESY, Hamburg, Germany
	Photo injector laser systems for linac based FELs often have the capability of generating pulse trains with an adjustable length. For example, the currently installed laser at the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ) can generate pulse trains containing up to 800 pulses. Repetition frequencies are 10 Hz for the pulse trains and 1 MHz for the pulses within a train, respectively. Mostly due to thermal effects caused by absorption in amplifier and frequency doubling crystals, pulse properties are changing slightly within a pulse train and also shot-to-shot, depending on the pulse train length. To increase stability and repeatability of the laser it is desirable to run it under constant conditions. To achieve this while still being able to freely choose pulse patterns a pulse picker to sort the wanted from the unwanted pulses can be installed at the laser output. A promising candidate for this functionality is an acousto-optic modulator which currently is being tested at PITZ. First experimental results will be presented and discussed towards the possibility of including this device into an FEL photo injector.

WEPD55	Tunable IR/THz Source for Pump Probe Experiments at the European XFEL	503
	M. Krasilnikov, F. Stephan DESY Zeuthen, Zeuthen, Germany E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	We present a concept of an accelerator based source of powerful, coherent THz radiation for pump-probe experiments at the European XFEL. The electron accelerator is similar to that operating at the PITZ facility. It consists of rf gun and warm accelerating section (energy up to 30 MeV). The radiation is generated in a 5 meter long APPLE-type undulator with a period length of 4 cm, thus providing polarization control. Radiation with wavelength below 200 micrometers is generated using the mechanism of SASE FEL. Powerful coherent radiation with wavelength above 200 micrometers is generated in the undulator by a tailored (compressed) electron beam. Properties of the radiation are: wavelength range is 10 to 1000 micrometers (30 THz - 0.3 THz), radiation pulse energy is up to a few hundreds microjoles, peak power is 10 to 100 MW, spectrum bandwidth is 2 - 3%. It is important to note that the time structure of the THZ source ideally matches with the time structure of the x-ray pulses since the THZ source is based on the same technology as the injector of the European XFEL. A similar scheme can be also realized at LCLS, SACLA, or SWISS FEL with S-band rf accelerator technology.

Paper

Title

Page

PITZ Status, Recent Measurements and Tests

181

M. Krasilnikov, H.-J. Grabosch, M. Groß, I.I. Isaev, Ye. Ivanisenko, M. Khojoyan, G. Klemz, G. Kourkafas, M. Mahgoub, D. Malyutin, B. Marchetti, A. Oppelt, M. Otevřel, B. Petrosyan, A. Shapovalov, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
K. Kusoljariyakul
FNRF, Chiang Mai, Thailand
J. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China
D. Richter
HZB, Berlin, Germany
S. Rimjaem
Chiang Mai University, Chiang Mai, Thailand
I. Will
MBI, Berlin, Germany

The photo injector test facility at DESY, Zeuthen site (PITZ) is dedicated to the development and optimization of a high-brightness electron source for the European XFEL. Recently a significant upgrade has been done at the facility. A new RF system has been installed for the PITZ gun, enabling higher attainable peak power in the cavity which is important for efficient LLRF regulation. First long-term tests for a stable gun operation at high duty cycle have been performed. Two major components for electron beam diagnostics - a transverse deflecting cavity for time resolved electron bunch characterization, and a second high energy dispersive arm for precise longitudinal phase space measurements - have been installed. First results of their commissioning will be reported.

MOPD60

Optimization of the Transverse Projected Emittance of the Electron Beam at PITZ

185

G. Vashchenko, M. Groß, L. Hakobyan, I.I. Isaev, Ye. Ivanisenko, M. Krasilnikov, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, S. Rimjaem, A. Shapovalov, F. Stephan
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
M. Khojoyan
ANSL, Yerevan, Armenia
D. Richter
HZB, Berlin, Germany

High brightness electron sources for linac based free-electron lasers operating at short wavelength such as the Free-Electron Laser in Hamburg at DESY, Hamburg Site (FLASH) and the European X-Ray Laser Project XFEL (European XFEL) are characterized and optimized at the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ). One of the most important parameters influencing the FEL process is the normalized transverse projected emittance of the electron beam. The major part of the experimental program at PITZ is devoted to its optimization. Detailed simulations of the present facility setup are performed for a 1 nC bunch charge in order to optimize the transverse projected emittance of the electron beam. Cathode laser pulse length and transverse spot size at the photo cathode, gun and booster accelerating gradients and their launching phases as well as the main solenoid current are optimized. Simulations results together with experimental data are presented.

MOPD61

Laser Pulse Train Management with an Acousto-optic Modulator

189

M. Groß, H.-J. Grabosch, L. Hakobyan, I.I. Isaev, Ye. Ivanisenko, M. Khojoyan, G. Klemz, G. Kourkafas, M. Krasilnikov, K. Kusoljariyakul, J. Li, M. Mahgoub, D. Malyutin, B. Marchetti, A. Oppelt, M. Otevřel, B. Petrosyan, A. Shapovalov, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
D. Richter
HZB, Berlin, Germany
H. Schlarb, S. Schreiber
DESY, Hamburg, Germany

Photo injector laser systems for linac based FELs often have the capability of generating pulse trains with an adjustable length. For example, the currently installed laser at the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ) can generate pulse trains containing up to 800 pulses. Repetition frequencies are 10 Hz for the pulse trains and 1 MHz for the pulses within a train, respectively. Mostly due to thermal effects caused by absorption in amplifier and frequency doubling crystals, pulse properties are changing slightly within a pulse train and also shot-to-shot, depending on the pulse train length. To increase stability and repeatability of the laser it is desirable to run it under constant conditions. To achieve this while still being able to freely choose pulse patterns a pulse picker to sort the wanted from the unwanted pulses can be installed at the laser output. A promising candidate for this functionality is an acousto-optic modulator which currently is being tested at PITZ. First experimental results will be presented and discussed towards the possibility of including this device into an FEL photo injector.

WEPD55

Tunable IR/THz Source for Pump Probe Experiments at the European XFEL

503

M. Krasilnikov, F. Stephan
DESY Zeuthen, Zeuthen, Germany
E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

We present a concept of an accelerator based source of powerful, coherent THz radiation for pump-probe experiments at the European XFEL. The electron accelerator is similar to that operating at the PITZ facility. It consists of rf gun and warm accelerating section (energy up to 30 MeV). The radiation is generated in a 5 meter long APPLE-type undulator with a period length of 4 cm, thus providing polarization control. Radiation with wavelength below 200 micrometers is generated using the mechanism of SASE FEL. Powerful coherent radiation with wavelength above 200 micrometers is generated in the undulator by a tailored (compressed) electron beam. Properties of the radiation are: wavelength range is 10 to 1000 micrometers (30 THz - 0.3 THz), radiation pulse energy is up to a few hundreds microjoles, peak power is 10 to 100 MW, spectrum bandwidth is 2 - 3%. It is important to note that the time structure of the THZ source ideally matches with the time structure of the x-ray pulses since the THZ source is based on the same technology as the injector of the European XFEL. A similar scheme can be also realized at LCLS, SACLA, or SWISS FEL with S-band rf accelerator technology.