FEL2011 - List of Keywords (quadrupole)

Paper	Title	Other Keywords	Page
TUPA18	Considerations about Optics-Based Phase-Space Measurements at Linac-Based FEL Facilities	optics, lattice, emittance, diagnostics	231
	B. Beutner, E. Prat Paul Scherrer Institut, Villigen, Switzerland
	Transverse phase-space measurements are an essential issue for FEL facilities. After acceleration in the injector the energy is sufficiently high to bring the beam out of the space-charge dominated regime, thus optics based techniques are favored. The beam moments at a given point in the machine are fitted to beam size values downstream with different phase advances between the reconstruction and the measurement point. Two principle methods are possible. Beam sizes can be measured at different positions in the beam line keeping the lattice unchanged. The other possibility is to actively change quadrupoles and use only one screen. These two techniques are compared in this paper including monte-carlo studies on systematic errors using the SwissFEL Injector Test Facility as an example. On the other hand beam size measurements, which are done with OTR screens at SwissFEL Injector Test Facility, are critical for such measurements. An analysis of these images can be an issue, especially if the signal-to-noise is compromised for example by low bunch charges. This study on the phase-space measurement techniques will be completed by a discussion of the image post-processing procedures.

WEPB02	Study of Highly Isochronous Beamlines for FEL Seeding	bunching, FEL, undulator, laser	391
	C. Sun, H. Nishimura, G. Penn, M.W. Reinsch, D. Robin, F. Sannibale, C. Steier, W. Wan LBNL, Berkeley, California, USA
	Recently seeding schemes, such as ECHO for short (nm) wavelength FELs, have been proposed. These schemes require that the nm level longitudinal bunch structure be preserved over distance of several meters. This poses a challenge for the beamline design. In this paper we present our studies of several solutions for beamlines that are nearly isochronous.

WEPB04	Position Stability Monitoring of the LCLS Undulator Quadrupoles	undulator, controls, ground-motion, monitoring	398
	H.-D. Nuhn, G.L. Gassner, F. Peters SLAC, Menlo Park, California, USA
	Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515 In the era of SASE FELs, the demand for position stability of undulator components scales down to the range of sub-micrometers per day. Simultaneously, the undulator length increases significantly, in order to reach X-ray wavelengths. To minimize the impact of the outside environment, the LCLS undulator is placed underground, but reliable data about ground motion inside such a tunnel were not available in the required stability range. Therefore, a new position monitor system has been developed and installed for the LCLS undulator. That system is capable to measure X-, Y- and Roll positions of each of the 33 undulator quadrupoles, with respect to stretched wires. Instrument resolution is about 20 nm and instrument drift is negligible small. Position data of individual quadrupoles can be correlated along the entire undulator, which has a length of 132 m. The system is under continuous operation since 2009. The report describes long term experience with the running system and the observed position stability of the undulator quadrupoles.

THPB25	EXPERIMENT AND SIMULATIONS OF SUB-PS ELECTRON BUNCH TRAIN GENERATION AT FERMILAB PHOTOINJECTORS	dipole, electron, cavity, simulation	609
	Y.-E. Sun, M.D. Church Fermilab, Batavia, USA P. Piot, C.R. Prokop Northern Illinois University, DeKalb, Illinois, USA
	Funding: The work was supported by the US DOE Contracts No. DE-AC02-07CH11359 with the Fermi Research Alliance, LLC. and No. DE-FG02-08ER41532 with Northern Illinois University. Recently the generation of electron bunch trains with sub-picosecond time structure has been experimentally demonstrated at the A0 photoinjector of Fermilab using a transverse-longitudinal phase-space exchange beamline. The temporal profile of the bunch train can be easily tuned to meet the requirements of the applications of modern accelerator beams. In this paper we report the A0 bunch-train experiment and explore numerically the possible extension of this technique to shorter time scales at the Fermilab SRF Accelerator Test Facility, a superconducting linear electron accelerator currently under construction in the NML building.

THPB31	Multiple FELs from the One LCLS Undulator	undulator, FEL, electron, linac	629
	F.-J. Decker, P. Emma, J.C. Frisch, K. Horovitz, Z. Huang, R.H. Iverson, J. Krzywinski, H. Loos, S.P. Moeller, H.-D. Nuhn, J.L. Turner, J.J. Welch, J. Wu SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Science, under Contract DE-AC02-76SF00515. The FEL of the Linac Coherent Light Source (LCLS) at SLAC is generated in a 132 m long undulator. By introducing a kink in the undulator setup and launching different electron pulses with a small kick, we achieved two FEL beams with a separation of about 10 σ. These beams were separated at down stream mirrors and brought to the entrances of the soft and hard X-ray hutches. This was done at low energy creating soft X-rays which require only a shorter length to get to saturation. At high energy the whole undulator has to be "re-pointed" pulse by pulse. This can be done using 33 undulator correctors creating two straight lines for the photons with small angle to point the FEL to different mirrors pulse by pulse even at high energy. Experiments will be presented and further ideas discussed to get different energy photons created and sent to the soft and hard X-ray mirrors and experiments.

Paper

Title

Other Keywords

Page

TUPA18

Considerations about Optics-Based Phase-Space Measurements at Linac-Based FEL Facilities

optics, lattice, emittance, diagnostics

231

B. Beutner, E. Prat
Paul Scherrer Institut, Villigen, Switzerland

Transverse phase-space measurements are an essential issue for FEL facilities. After acceleration in the injector the energy is sufficiently high to bring the beam out of the space-charge dominated regime, thus optics based techniques are favored. The beam moments at a given point in the machine are fitted to beam size values downstream with different phase advances between the reconstruction and the measurement point. Two principle methods are possible. Beam sizes can be measured at different positions in the beam line keeping the lattice unchanged. The other possibility is to actively change quadrupoles and use only one screen. These two techniques are compared in this paper including monte-carlo studies on systematic errors using the SwissFEL Injector Test Facility as an example. On the other hand beam size measurements, which are done with OTR screens at SwissFEL Injector Test Facility, are critical for such measurements. An analysis of these images can be an issue, especially if the signal-to-noise is compromised for example by low bunch charges. This study on the phase-space measurement techniques will be completed by a discussion of the image post-processing procedures.

WEPB02

Study of Highly Isochronous Beamlines for FEL Seeding

bunching, FEL, undulator, laser

391

C. Sun, H. Nishimura, G. Penn, M.W. Reinsch, D. Robin, F. Sannibale, C. Steier, W. Wan
LBNL, Berkeley, California, USA

Recently seeding schemes, such as ECHO for short (nm) wavelength FELs, have been proposed. These schemes require that the nm level longitudinal bunch structure be preserved over distance of several meters. This poses a challenge for the beamline design. In this paper we present our studies of several solutions for beamlines that are nearly isochronous.

WEPB04

Position Stability Monitoring of the LCLS Undulator Quadrupoles

undulator, controls, ground-motion, monitoring

398

H.-D. Nuhn, G.L. Gassner, F. Peters
SLAC, Menlo Park, California, USA

Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515
In the era of SASE FELs, the demand for position stability of undulator components scales down to the range of sub-micrometers per day. Simultaneously, the undulator length increases significantly, in order to reach X-ray wavelengths. To minimize the impact of the outside environment, the LCLS undulator is placed underground, but reliable data about ground motion inside such a tunnel were not available in the required stability range. Therefore, a new position monitor system has been developed and installed for the LCLS undulator. That system is capable to measure X-, Y- and Roll positions of each of the 33 undulator quadrupoles, with respect to stretched wires. Instrument resolution is about 20 nm and instrument drift is negligible small. Position data of individual quadrupoles can be correlated along the entire undulator, which has a length of 132 m. The system is under continuous operation since 2009. The report describes long term experience with the running system and the observed position stability of the undulator quadrupoles.

THPB25

EXPERIMENT AND SIMULATIONS OF SUB-PS ELECTRON BUNCH TRAIN GENERATION AT FERMILAB PHOTOINJECTORS

dipole, electron, cavity, simulation

609

Y.-E. Sun, M.D. Church
Fermilab, Batavia, USA
P. Piot, C.R. Prokop
Northern Illinois University, DeKalb, Illinois, USA

Funding: The work was supported by the US DOE Contracts No. DE-AC02-07CH11359 with the Fermi Research Alliance, LLC. and No. DE-FG02-08ER41532 with Northern Illinois University.
Recently the generation of electron bunch trains with sub-picosecond time structure has been experimentally demonstrated at the A0 photoinjector of Fermilab using a transverse-longitudinal phase-space exchange beamline. The temporal profile of the bunch train can be easily tuned to meet the requirements of the applications of modern accelerator beams. In this paper we report the A0 bunch-train experiment and explore numerically the possible extension of this technique to shorter time scales at the Fermilab SRF Accelerator Test Facility, a superconducting linear electron accelerator currently under construction in the NML building.

THPB31

Multiple FELs from the One LCLS Undulator

undulator, FEL, electron, linac

629

F.-J. Decker, P. Emma, J.C. Frisch, K. Horovitz, Z. Huang, R.H. Iverson, J. Krzywinski, H. Loos, S.P. Moeller, H.-D. Nuhn, J.L. Turner, J.J. Welch, J. Wu
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Science, under Contract DE-AC02-76SF00515.
The FEL of the Linac Coherent Light Source (LCLS) at SLAC is generated in a 132 m long undulator. By introducing a kink in the undulator setup and launching different electron pulses with a small kick, we achieved two FEL beams with a separation of about 10 σ. These beams were separated at down stream mirrors and brought to the entrances of the soft and hard X-ray hutches. This was done at low energy creating soft X-rays which require only a shorter length to get to saturation. At high energy the whole undulator has to be "re-pointed" pulse by pulse. This can be done using 33 undulator correctors creating two straight lines for the photons with small angle to point the FEL to different mirrors pulse by pulse even at high energy. Experiments will be presented and further ideas discussed to get different energy photons created and sent to the soft and hard X-ray mirrors and experiments.