FEL2011 - List of Keywords (LLRF)

Paper	Title	Other Keywords	Page
WEPA15	S-band High Gradient Linac for a Compact XFEL	linac, klystron, acceleration, FEL	356
	F. Wang SLAC, Menlo Park, California, USA
	With the successful operation of the first hard X-ray FEl, LCLS, other XFEL facilities are being developed worldwide. Due to the limited site size, many proposed XFELs are based on C-band technology. Switching from S-band to C-band enables a higher acceleration gradient (>35 MV/m) that is nearly double that of the SLAC S-band Linac. Based on the high gradient research, it found that the actually operational gradient is scaled as 1/6 power of the required rf pulse length at constant rf breakdown rate. Therefore, it is possible to have a S-band linac at higher gradient (>35MV/m) operated at very short rf pulse length, such like the single/two bunch operating XFEL.

WEPB05	Experiments on Femtosecond Stabilization of Fiber Link for Shanghai Soft-XFEL	laser, FEL, electron, controls	402
	X.P. Ma IHEP, Beijing, People's Republic of China B. Liu SINAP, Shanghai, People's Republic of China
	The Shanghai Soft X-ray Free Electron Laser (SXFEL) facility will be constructed in the Shanghai Synchrotron Radiation Facility (SSRF) campus. SXFEL will operate in the HGHG and/or EEHG mode and require a femtosecond timing distribution system as well as the synchronization between femtosecond pulsed lasers, femtosecond pulsed X-rays, CW microwave signals and electron bunches with 10 fs precision. The pulsed fiber laser based femtosecond T&S system which has been proposed by the MIT/DESY team is adopted. In this paper the status of the femtosecond T&S system for SXFEL is introduced. Some initial progress of the phase stabilization by electronics control when laser pulses transport though long optical fibers is presented.

THPA12	Beam Energy Measurements in the FLASH Injector using Synchrotron Radiation and Bunch Arrival Monitors	feedback, electron, synchrotron, synchrotron-radiation	489
	C. Gerth, M.K. Bock, M. Hoffmann, F. Ludwig, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany
	The high beam energy stability required for stable operation of linac-driven free-electron lasers demands for precise cavity RF field regulation. This is in particular true for the accelerator modules at low beam energies which are used to induce an energy correlation on the electron beam for longitudinal bunch compression in magnetic chicanes. At FLASH, a major upgrade of the injector has taken place in the shutdown 2009/2010 including the installation of a 3rd harmonic accelerating module, exchange of modulators and re-cabling and temperature stabilization of the low-level RF electronics. Several beam-based techniques have been developed recently which can be used to monitor the beam energy with high precision or as fast feedbacks for the RF regulation. In this paper, we report on bunch-resolved energy measurements recorded independently with a synchrotron radiation monitor and two bunch arrival monitors. Good agreement between the monitors was found and the measurement data are compared with the results from RF detection.

THPA14	Upgrade of the Optical Synchronization System for FLASH II	laser, FEL, electron, feedback	496
	M. Felber, M.K. Bock, M. Bousonville, P. Gessler, T. Lamb, S. Ruzin, H. Schlarb, B. Schmidt, S. Schulz DESY, Hamburg, Germany
	The optical synchronization system at FLASH has been in operation since 2008. Due to continuous improvement and several upgrades it has become an integral part of the machine operation and of pump-probe experiments as both rely on its performance. In summer 2013, a second FEL section, called FLASH II, which is using the same accelerator as FLASH will start its operation to increase the number of user experiments and to test new seeding schemes. This also requires a major extension of the synchronization system since new clients have to be supplied with a 10 fs-stable timing signal. Six additional stabilized fiber links and the according end stations like bunch arrival time monitors and laser synchronization setups will be installed.

Paper

Title

Other Keywords

Page

WEPA15

S-band High Gradient Linac for a Compact XFEL

linac, klystron, acceleration, FEL

356

F. Wang
SLAC, Menlo Park, California, USA

With the successful operation of the first hard X-ray FEl, LCLS, other XFEL facilities are being developed worldwide. Due to the limited site size, many proposed XFELs are based on C-band technology. Switching from S-band to C-band enables a higher acceleration gradient (>35 MV/m) that is nearly double that of the SLAC S-band Linac. Based on the high gradient research, it found that the actually operational gradient is scaled as 1/6 power of the required rf pulse length at constant rf breakdown rate. Therefore, it is possible to have a S-band linac at higher gradient (>35MV/m) operated at very short rf pulse length, such like the single/two bunch operating XFEL.

WEPB05

Experiments on Femtosecond Stabilization of Fiber Link for Shanghai Soft-XFEL

laser, FEL, electron, controls

402

X.P. Ma
IHEP, Beijing, People's Republic of China
B. Liu
SINAP, Shanghai, People's Republic of China

The Shanghai Soft X-ray Free Electron Laser (SXFEL) facility will be constructed in the Shanghai Synchrotron Radiation Facility (SSRF) campus. SXFEL will operate in the HGHG and/or EEHG mode and require a femtosecond timing distribution system as well as the synchronization between femtosecond pulsed lasers, femtosecond pulsed X-rays, CW microwave signals and electron bunches with 10 fs precision. The pulsed fiber laser based femtosecond T&S system which has been proposed by the MIT/DESY team is adopted. In this paper the status of the femtosecond T&S system for SXFEL is introduced. Some initial progress of the phase stabilization by electronics control when laser pulses transport though long optical fibers is presented.

THPA12

Beam Energy Measurements in the FLASH Injector using Synchrotron Radiation and Bunch Arrival Monitors

feedback, electron, synchrotron, synchrotron-radiation

489

C. Gerth, M.K. Bock, M. Hoffmann, F. Ludwig, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany

The high beam energy stability required for stable operation of linac-driven free-electron lasers demands for precise cavity RF field regulation. This is in particular true for the accelerator modules at low beam energies which are used to induce an energy correlation on the electron beam for longitudinal bunch compression in magnetic chicanes. At FLASH, a major upgrade of the injector has taken place in the shutdown 2009/2010 including the installation of a 3rd harmonic accelerating module, exchange of modulators and re-cabling and temperature stabilization of the low-level RF electronics. Several beam-based techniques have been developed recently which can be used to monitor the beam energy with high precision or as fast feedbacks for the RF regulation. In this paper, we report on bunch-resolved energy measurements recorded independently with a synchrotron radiation monitor and two bunch arrival monitors. Good agreement between the monitors was found and the measurement data are compared with the results from RF detection.

THPA14

Upgrade of the Optical Synchronization System for FLASH II

laser, FEL, electron, feedback

496

M. Felber, M.K. Bock, M. Bousonville, P. Gessler, T. Lamb, S. Ruzin, H. Schlarb, B. Schmidt, S. Schulz
DESY, Hamburg, Germany

The optical synchronization system at FLASH has been in operation since 2008. Due to continuous improvement and several upgrades it has become an integral part of the machine operation and of pump-probe experiments as both rely on its performance. In summer 2013, a second FEL section, called FLASH II, which is using the same accelerator as FLASH will start its operation to increase the number of user experiments and to test new seeding schemes. This also requires a major extension of the synchronization system since new clients have to be supplied with a 10 fs-stable timing signal. Six additional stabilized fiber links and the according end stations like bunch arrival time monitors and laser synchronization setups will be installed.