FEL2013 - List of Keywords (quadrupole)

Paper	Title	Other Keywords	Page
TUOCNO06	Slice Emittance Optimization at the SwissFEL Injector Test Facility	emittance, optics, gun, laser	200
	E. Prat, M. Aiba, S. Bettoni, B. Beutner, M.W. Guetg, R. Ischebeck, S. Reiche, T. Schietinger PSI, Villigen PSI, Switzerland
	Slice emittance measurements in the SwissFEL injector test facility have demonstrated emittances for the 10pC-200pC bunch charges which are well below the tight requirements of SwissFEL. Results, emittance tuning strategy and measurement methods are reported.
	Slides TUOCNO06 [0.537 MB]

TUPSO01	Corrector Response Based Alignment at FERMI	alignment, FEL, linac, wakefield	205
	M. Aiba, M. Böge PSI, Villigen PSI, Switzerland D. Castronovo, S. Di Mitri, L. Fröhlich, G. Gaio Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The components of an FEL accelerator generally need to be beam-based aligned in order to meet the design performance. We are developing new technique, where dipole corrector responses are used instead of orbit difference measurements. When an orbit feedback is running, any change in beam orbit is compensated by the actuators, i.e., the dipole correctors. For example, the spurious dispersion through linac rf structures, which is a source of emittance degradation, is measured through orbit differences for various beam momenta in the conventional way while dipole corrector responses are examined in the new method. The advantages are localization of misalignments, stable measurement as the orbit is kept constant, and automatic averaging and beam jitter filtering by the feedback loop. Furthermore, this method potentially allows us to detect transverse wakefield kicks, which are also an emittance degradation source, by looking into the dipole corrector responses to a change in bunch charge or bunch length. The results from a series of machine development shifts will be presented.

TUPSO22	Status of SwissFEL Undulator Lines	undulator, dipole, electron, alignment	263
	R. Ganter, M. Aiba, H.-H. Braun, M. Calvi, P. Heimgartner, G. Janzi, H. Jöhri, R. Kobler, F. Löhl, M. Negrazus, L. Patthey, E. Prat, S. Reiche, S. Sanfilippo, U. Schaer, T. Schmidt, L. Schulz, V. Vranković, J. Wickstroem PSI, Villigen PSI, Switzerland
	An overview of the Aramis Hard-X ray FEL line of SwissFEL is presented, showing its future integration in the tunnel as well as the space reservation for possible future upgrades: Athos Soft X-ray FEL line, post-undulator deflecting cavities. The design of the FEL components like the energy collimator, the matching sections or the dog leg transfer line linking the linac to the future Athos line are almost completed. The characterization of the in-vacuum undulator prototype is described in a companion paper. The installation of the components will start in spring 2015 while the first photons are planned for December 2016 with the alignment and adjustment of the undulators foreseen for first SASE operation by spring 2017 .

TUPSO24	Dispersion Based Beam Tilt Correction	FEL, sextupole, emittance, electron	267
	M.W. Guetg, B. Beutner, E. Prat, S. Reiche PSI, Villigen PSI, Switzerland
	In Free Electron Lasers (FEL), a transverse centroid misalignment of longitudinal slices in an electron bunch reduces the effective overlap between radiation field and electron bunch and therefore the FEL performance. The dominant sources of slice misalignments for FELs are the incoherent and coherent synchrotron radiation within bunch compressors as well as transverse wake fields in the accelerating cavities. This is of particular importance for over-compression which is required for one of the key operation modes for the SwissFEL planned at the Paul Scherrer Institute. The centroid shift is corrected using corrector magnets in dispersive sections, e.g. the bunch compressors. First and second order corrections are achieved by pairs of sextupole and quadrupole magnets in the horizontal plane while skew quadrupoles correct to first order in the vertical plane. Simulations and measurements at the SwissFEL Injector Test Facility are done to investigate the proposed correction scheme for SwissFEL. This paper presents the methods and results obtained.

TUPSO32	Project of the Short Pulse Facility at KAERI	electron, gun, kicker, bunching	287
	N. Vinokurov, S.V. Miginsky BINP SB RAS, Novosibirsk, Russia S. Bae, B.A. Gudkov, B. Han, K.H. Jang, Y.U. Jeong, H.W. Kim, K. Lee, S.V. Miginsky, J. Mun, S. H. Park, G.I. Shim, N. Vinokurov KAERI, Daejon, Republic of Korea N. Vinokurov NSU, Novosibirsk, Russia
	Funding: This work is supported by the WCI Program of the National Research Foundation of Korea funded by the Ministry of Education, Science, and Technology of Korea (NRF Grant No. WCI 2011-001). The low-energy electron accelerator with subpicosecond electron bunches is under construction at Korea Atomic Energy Research Institute (KAERI). It will serve as the user facility for high-energy ultrafast electron difraction and synchronized high-power terahertz pulse and short x-ray pulse generation. The accelerator consists of RF gun with photocathode and 20-MeV linac. The bunching of accelerated beam is achieved in the ninety-degree achromatic bend. After that fast kicker deflects some of bunches to the target for x-ray generation, other bunches come to terahertz radiator (undulator or multifoil). Bunches from the RF gun are also planned to use for ultrafast electron difraction. Some detailes of the design, current status of the project and future plans are described.

TUPSO46	Analysis and Measurement of Focusing Effects in a Traveling Wave Linear Accelerator	acceleration, focusing, electron, simulation	329
	H. Maesaka, T. Asaka, H. Ego, T. Hara, T. Inagaki, Y. Otake, T. Sakurai, H. Tanaka, K. Togawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	We propose a further precise model of the transverse dynamics in a traveling wave linear accelerator (TWA) and report experimental results to demonstrate the validity of the model. In SACLA, the beam orbit is calculated by using a transfer matrix based on the transverse dynamics model of each component and the matrix is utilized for orbit stabilization, beam envelop matching etc. For the TWA part, a transfer matrix including an emittance damping effect and an edge focusing effect [] is employed. However, the beam orbit measured by rf cavity beam position monitors (RF-BPM) [] did not agree with the calculated orbit, especially for the off-crest acceleration part. Therefore, focusing effects in a TWA structure were analyzed by using a 3-dimensional rf simulation code. The analysis indicated that the transverse dynamics model of the TWA should include an additional quadrupole edge focusing effect. The amount of the additional focusing effect of the TWA was measured in SACLA and the rf simulation result was confirmed to be consistent with the measurement. After the modification of the transverse dynamics model, the beam orbit measured by RF-BPM agrees with the calculation. T. Hara et al., Nucl. Instrum. Methods A 624, 65 (2010). ** H. Maesaka et al., Nucl. Instrum. Methods A 696, 66 (2012).

Paper

Title

Other Keywords

Page

TUOCNO06

Slice Emittance Optimization at the SwissFEL Injector Test Facility

emittance, optics, gun, laser

200

E. Prat, M. Aiba, S. Bettoni, B. Beutner, M.W. Guetg, R. Ischebeck, S. Reiche, T. Schietinger
PSI, Villigen PSI, Switzerland

Slice emittance measurements in the SwissFEL injector test facility have demonstrated emittances for the 10pC-200pC bunch charges which are well below the tight requirements of SwissFEL. Results, emittance tuning strategy and measurement methods are reported.

Slides TUOCNO06 [0.537 MB]

TUPSO01

Corrector Response Based Alignment at FERMI

alignment, FEL, linac, wakefield

205

M. Aiba, M. Böge
PSI, Villigen PSI, Switzerland
D. Castronovo, S. Di Mitri, L. Fröhlich, G. Gaio
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The components of an FEL accelerator generally need to be beam-based aligned in order to meet the design performance. We are developing new technique, where dipole corrector responses are used instead of orbit difference measurements. When an orbit feedback is running, any change in beam orbit is compensated by the actuators, i.e., the dipole correctors. For example, the spurious dispersion through linac rf structures, which is a source of emittance degradation, is measured through orbit differences for various beam momenta in the conventional way while dipole corrector responses are examined in the new method. The advantages are localization of misalignments, stable measurement as the orbit is kept constant, and automatic averaging and beam jitter filtering by the feedback loop. Furthermore, this method potentially allows us to detect transverse wakefield kicks, which are also an emittance degradation source, by looking into the dipole corrector responses to a change in bunch charge or bunch length. The results from a series of machine development shifts will be presented.

TUPSO22

Status of SwissFEL Undulator Lines

undulator, dipole, electron, alignment

263

R. Ganter, M. Aiba, H.-H. Braun, M. Calvi, P. Heimgartner, G. Janzi, H. Jöhri, R. Kobler, F. Löhl, M. Negrazus, L. Patthey, E. Prat, S. Reiche, S. Sanfilippo, U. Schaer, T. Schmidt, L. Schulz, V. Vranković, J. Wickstroem
PSI, Villigen PSI, Switzerland

An overview of the Aramis Hard-X ray FEL line of SwissFEL is presented, showing its future integration in the tunnel as well as the space reservation for possible future upgrades: Athos Soft X-ray FEL line, post-undulator deflecting cavities. The design of the FEL components like the energy collimator, the matching sections or the dog leg transfer line linking the linac to the future Athos line are almost completed. The characterization of the in-vacuum undulator prototype is described in a companion paper. The installation of the components will start in spring 2015 while the first photons are planned for December 2016 with the alignment and adjustment of the undulators foreseen for first SASE operation by spring 2017 .

TUPSO24

Dispersion Based Beam Tilt Correction

FEL, sextupole, emittance, electron

267

M.W. Guetg, B. Beutner, E. Prat, S. Reiche
PSI, Villigen PSI, Switzerland

In Free Electron Lasers (FEL), a transverse centroid misalignment of longitudinal slices in an electron bunch reduces the effective overlap between radiation field and electron bunch and therefore the FEL performance. The dominant sources of slice misalignments for FELs are the incoherent and coherent synchrotron radiation within bunch compressors as well as transverse wake fields in the accelerating cavities. This is of particular importance for over-compression which is required for one of the key operation modes for the SwissFEL planned at the Paul Scherrer Institute. The centroid shift is corrected using corrector magnets in dispersive sections, e.g. the bunch compressors. First and second order corrections are achieved by pairs of sextupole and quadrupole magnets in the horizontal plane while skew quadrupoles correct to first order in the vertical plane. Simulations and measurements at the SwissFEL Injector Test Facility are done to investigate the proposed correction scheme for SwissFEL. This paper presents the methods and results obtained.

TUPSO32

Project of the Short Pulse Facility at KAERI

electron, gun, kicker, bunching

287

N. Vinokurov, S.V. Miginsky
BINP SB RAS, Novosibirsk, Russia
S. Bae, B.A. Gudkov, B. Han, K.H. Jang, Y.U. Jeong, H.W. Kim, K. Lee, S.V. Miginsky, J. Mun, S. H. Park, G.I. Shim, N. Vinokurov
KAERI, Daejon, Republic of Korea
N. Vinokurov
NSU, Novosibirsk, Russia

Funding: This work is supported by the WCI Program of the National Research Foundation of Korea funded by the Ministry of Education, Science, and Technology of Korea (NRF Grant No. WCI 2011-001).
The low-energy electron accelerator with subpicosecond electron bunches is under construction at Korea Atomic Energy Research Institute (KAERI). It will serve as the user facility for high-energy ultrafast electron difraction and synchronized high-power terahertz pulse and short x-ray pulse generation. The accelerator consists of RF gun with photocathode and 20-MeV linac. The bunching of accelerated beam is achieved in the ninety-degree achromatic bend. After that fast kicker deflects some of bunches to the target for x-ray generation, other bunches come to terahertz radiator (undulator or multifoil). Bunches from the RF gun are also planned to use for ultrafast electron difraction. Some detailes of the design, current status of the project and future plans are described.

TUPSO46

Analysis and Measurement of Focusing Effects in a Traveling Wave Linear Accelerator

acceleration, focusing, electron, simulation

329

H. Maesaka, T. Asaka, H. Ego, T. Hara, T. Inagaki, Y. Otake, T. Sakurai, H. Tanaka, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

We propose a further precise model of the transverse dynamics in a traveling wave linear accelerator (TWA) and report experimental results to demonstrate the validity of the model. In SACLA, the beam orbit is calculated by using a transfer matrix based on the transverse dynamics model of each component and the matrix is utilized for orbit stabilization, beam envelop matching etc. For the TWA part, a transfer matrix including an emittance damping effect and an edge focusing effect [*] is employed. However, the beam orbit measured by rf cavity beam position monitors (RF-BPM) [**] did not agree with the calculated orbit, especially for the off-crest acceleration part. Therefore, focusing effects in a TWA structure were analyzed by using a 3-dimensional rf simulation code. The analysis indicated that the transverse dynamics model of the TWA should include an additional quadrupole edge focusing effect. The amount of the additional focusing effect of the TWA was measured in SACLA and the rf simulation result was confirmed to be consistent with the measurement. After the modification of the transverse dynamics model, the beam orbit measured by RF-BPM agrees with the calculation.
* T. Hara et al., Nucl. Instrum. Methods A 624, 65 (2010).
** H. Maesaka et al., Nucl. Instrum. Methods A 696, 66 (2012).