FEL2014 - List of Keywords (controls)

Paper	Title	Other Keywords	Page
MOP008	Temperature Effects of the FLASH2 Undulators	undulator, operation, feedback, insertion-device	34
	M. Tischer, A. Schöps, P. Vagin DESY, Hamburg, Germany
	FELs are very sensitive to small changes in the resonance condition of the emitted radiation. As a consequence, permanent magnet undulators in FELs usually require extensive temperature control in order to assure stable operation conditions. In principle, the temperature dependence of permanent magnet material is well known but more things need to be considered like different thermal expansion of various mechanical parts or thermally induced deformation which do not only affect the K parameter but also the field quality. We have performed temperature dependent magnetic measurements in a range from 19 to 28 degrees Celsius and have analyzed the magnetic performance of the undulator. The results of this case study can be transferred to all FLASH2 undulators and shall allow for a simple temperature dependent gap correction in order to make the spectral properties insensitive to temperature changes of the insertion devices.

MOP021	Commissioning of a Dual-sweep Streak Camera with Applications to the ASTA Photoinjector Drive Laser	laser, timing, cavity, gun	66
	A.H. Lumpkin, D.R. Edstrom, J. Ruan, J.K. Santucci Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The high-power electron beams for the Advanced Superconducting Test Accelerator (ASTA) facility will be generated in a photoinjector based on a UV drive laser and the L-band rf photocathode (PC) gun cavity. The initial objectives of these studies were: 1) the evaluation of the amplified UV component’s bunch length and phase stability and 2) the commissioning of the laser room Hamamatsu C5680 streak camera system. We used a new readout camera based on the Prosilica GC1380 digital CCD with Gig-E readout that was compatible with our image processing tools. We observed a longer than expected UV bunch length of 4 ps σ and an unexpected peak multiplicity (with spacing of about 70 ps) in the synchronous sum of 5 UV micropulses. We have now systematically investigated the issues of whether the multiplicity was with each micropulse of the 3-MHz pulse train. We describe our extensive investigations that indicated both issues originated in the multi-pass amplifier. We have replaced the MPA with three single-pass devices, measured 3.5-ps bunch lengths without the multiplicity, and generated photoelectrons from the gun successfully.

MOP032	PAL-XFEL Magnet Power Supply System	power-supply, quadrupole, dipole, status	87
	S.-H. Jeong, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, K.-H. Park, H.S. Suh, Y.G. Young-Gyu PAL, Pohang, Kyungbuk, Republic of Korea
	This paper presents an overview of the magnet power supply(MPS) for the PAL-XFEL. The number of total MPS is 628 and they will be installed along the accelerator and the undulator sections. The power capacity of the MPS was ranging from about 1 A to 300 A. These MPSs were required to meet the high stability that was subjected from the beam dynamics specifications. This paper described the overall MPS requirements, MPS assembling, test process, control scheme, installation plan and so on.

MOP049	Oxygen Scintillation in the LCLS	detector, laser, instrumentation, electron	137
	J.L. Turner, R.C. Field 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 Oxygen is tested as a replacement for Nitrogen in the Gas Detector system in the Linac Coherent Light Source (LCLS) x-ray Free Electron Laser (FEL) at the SLAC National Accelerator Center. The attenuation and energy monitors for LCLS use Nitrogen, but for experiments at the Nitrogen K 1S energy of about 410eV this functionality is gone due to energy fluctuations above and below the K-edge. Oxygen was tested as a scintillating gas at 400eV and 8.3keV.

TUP093	A Beam Test of Corrugated Structure for Passive Linearizer	simulation, quadrupole, electron, linac	593
	H.-S. Kang, J.H. Hong PAL, Pohang, Kyungbuk, Republic of Korea
	A dechirper which is a vacuum chamber of two corrugated, metallic plates with adjustable gap was successfully tested at Pohang, in August 2013. Another beam test was carried out to test the same structure to see if the corrugated plates may work as a linearizer. The test result will be presented together with the simulation result.

THA02	Experimental Characterization of FEL Polarization Control with Cross Polarized Undulators	polarization, undulator, FEL, radiation	644
	E. Ferrari, E. Allaria, G. De Ninno, B. Diviacco, D. Gauthier, L. Giannessi, G. Penco, C. Spezzani Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy J. Buck, M. Ilchen XFEL. EU, Hamburg, Germany G. De Ninno, D. Gauthier University of Nova Gorica, Nova Gorica, Slovenia L. Giannessi ENEA C.R. Frascati, Frascati (Roma), Italy Z. Huang, A.A. Lutman SLAC, Menlo Park, California, USA G. Lambert, B. Mahieu LOA, Palaiseau, France J. Viefhaus DESY, Hamburg, Germany
	Polarization control of the coherent radiation is becoming an important feature of recent and future short wavelength free electron laser facilities. While polarization tuning can be achieved taking advantage of specially designed undulators, a scheme based on two consecutive undulators emitting orthogonally polarized fields has also been proposed. Developed initially in synchrotron radiation sources, crossed polarized undulator schemes could benefit from the coherent emission that characterize FELs. In this work we report the first detailed experimental characterization of the polarization properties of an FEL operated with crossed polarized undulators in the Soft-X-Rays. Aspects concerning the average degree of polarization and the shot to shot stability are investigated together with a comparison of the performance of various schemes to control and switch the polarization
	Slides THA02 [5.383 MB]

THB04	Electron Beam Diagnostics and Feedback for the LCLS-II	cavity, feedback, diagnostics, undulator	666
	J.C. Frisch, P. Emma, A.S. Fisher, P. Krejcik, H. Loos, T.J. Maxwell, T.O. Raubenheimer, S.R. Smith SLAC, Menlo Park, California, USA
	Funding: work supported by DOE contract DE-AC02-76-SF00515 The LCLS_II is a CW superconducting accelerator driven, hard and soft X-ray Free Electron Laser which is planned to be constructed at SLAC. It will operate with a variety of beam modes from single shot to approximately 1 MHz CW at bunch charges from 10pc to 300pC with average beam powers up to 1.2 MW. A variety of types of beam instrumentation will be used, including stripline and cavity BPMS, fluorescent and OTR based beam profile monitors, fast wire scanners and transverse deflection cavities. The beam diagnostics system is designed to allow tuning and continuous measurement of beam parameters, and to provide signals for fast beam feedbacks.
	Slides THB04 [1.501 MB]

THP020	Electron Beam Dynamics Optimization Using A Unified Differential Evolution Algorithm	emittance, electron, cavity, solenoid	726
	J. Qiang, C.E. Mitchell LBNL, Berkeley, California, USA
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231. Accelerator beam dynamics design depends heavily on the use of control parameter optimization to achieve the best performance. In this paper, we report on electron beam dynamics optimization of a model photoinjector using a new unified differential evolution algorithm. We present the new unified differential evolution algorithm and benchmark its performance using several test examples. We also discuss the application of the algorithm in the multi-objective optimization of the photoinjector.

THP033	Mechanical Design for a Corrugated Plate Dechirper System for LCLS	wakefield, vacuum, quadrupole, electron	785
	M.A. Harrison, P. Frigola, D.W. Martin, A.Y. Murokh, M. Ruelas RadiaBeam Systems, Santa Monica, California, USA Z. Huang, R.H. Iverson, T.J. Maxwell, Z. Zhang SLAC, Menlo Park, California, USA
	Funding: This work is supported by Department of Energy grant number DE-SC0009550. RadiaBeam Systems is developing a novel passive chirp removal system using corrugated plates as studied by Bane and Stupakov.* Following on from low-energy experiments at BNL-ATF,** RBS will install a much larger and powerful system for removing the chirp from the 3-GeV beams in the LTU section at LCLS. The larger plates will present new challenges in the areas of manufacturing and mechanical control. In this paper we review the requirements for the dimensions of the corrugated plates for proper operation and the infrastructure necessary for precisely placing the plates so as not to adversely disrupt the beam. * K. Bane, et al "Corrugated Pipe as a Beam Dechirper," SLAC-PUB-14925, 2012 ** Harrison, M., et al "Removal of Residual Chirp in Compressed Beams Using a Passive Wakefield Technique." NaPAC13, 2013

THP040	Status of Pump-probe Laser Development for the European XFEL	laser, timing, software, hardware	807
	L.-G. Wißmann, M. Emons, M. Kellert, K. Kruse, M. Lederer, G. Palmer, M. Pergament, G. Priebe, J. Wang, U. Wegner XFEL. EU, Hamburg, Germany
	The European XFEL is under construction and is designed to become a multi-user facility. Three SASE beam lines with two experimental areas each are foreseen to guarantee a high user throughput. In order to enable the full scientific potential of the facility, optical laser pulses for either pumping or probing samples will be deployed regularly. We are presenting the pump-probe laser concept and the current status of the development, showing some experimental results of the prototype laser, achieved to date. The main emphasis of the presentation lies on the integration of the laser system into Karabo, the emerging control system of the European XFEL.

THP043	Model-based Klystron Linearization in the SwissFEL Test Facility	klystron, high-voltage, power-supply, feedback	820
	A. Řežaeizadeh, R. Kalt, T. Schilcher PSI, Villigen PSI, Switzerland A. Řežaeizadeh, R. Smith Automatic Control Laboratory, ETH Zurich, Zurich, Switzerland
	Funding: Paul Scherrer Institut An automatic procedure is developed to provide the optimal operating point of a klystron. Since klystrons are nonlinear with respect to the input amplitude, a model-based amplitude controller is introduced which uses the klystron characteristic curves to obtain the appropriate high voltage power supply and amplitude, such that the operating point is close to the saturation. An advantage of the proposed design is that the overall open-loop system (from the input to the RF station to the klystron output amplitude) is linearized. The method has been successfully tested on a full scale RF system running at nominal power. Ch.Rapp, Effects of HPA-Nonlinearity on a 4-DPSK/OFDM-Signal …,Euro. Conf. on Satellite Communi.,1991. <CR> *A.Cann, Nonlinearity Model With Variable Knee…,IEEE Trans. Aerosp. Electron. Syst.,1980

THP044	RF Pulse Flattening in the SwissFEL Test Facility based on Model-free Iterative Learning Control	klystron, electron, feedback, flattop	824
	A. Řežaeizadeh, R. Smith Automatic Control Laboratory, ETH Zurich, Zurich, Switzerland A. Řežaeizadeh, T. Schilcher PSI, Villigen PSI, Switzerland
	Funding: Paul Scherrer Institut This paper introduces an iterative approach to producing flat-topped radio frequency (RF) pulses for driving the pulsed linear accelerators in the Swiss free electron laser (SwissFEL). The method is based on model-free iterative learning control which iteratively updates the input pulse shape in order to generate the desired amplitude and phase pulses at the output of the RF system. The method has been successfully applied to the klystron output to improve the flatness of the amplitude and phase pulse profiles. * P. Janssens,et.al, "Model-free iterative learning control for LTI systems …", 18th IFAC. <CR> ** N. Amann, et.al , "ILC for discrete-time systems …", IEE Control Theory Apps.

THP052	Affordable Short Pulse Marx Modulator	high-voltage, linear-collider, network, collider	849
	R.A. Phillips, G. DelPriore, M.P.J. Gaudreau, M.K. Kempkes Diversified Technologies, Inc., Bedford, Massachusetts, USA J.A. Casey Rockfield Research Inc., Las Vegas, Nevada, USA
	Funding: DOE Contract DE-SC0004251 High voltage short-pulse klystron modulators are required for numerous X-Band accelerator designs. At the very high voltages required for these transmitters, all of the existing designs are based on pulse transformers, which significantly limits their performance and efficiency. There is not a fully optimized, transformer-less modulator design capable of meeting the demanding requirements of very peak power, short pulse RF stations. Under a U.S. Department of Energy grant, Diversified Technologies, Inc. (DTI) is developing a short pulse, solid-state Marx modulator. The modulator is designed for high efficiency in the 100 kV to 500 kV range, for currents up to 250 A, pulse lengths of 0.2 to 5.0 μs, and risetimes <300 ns. Key objectives of the development effort are modularity and scalability, combined with low cost and ease of manufacture. For short-pulse modulators, this Marx topology provides a means to achieve fast risetimes and flattop control that are not available with hard switch or transformer-coupled topologies. The system is in the final stages of testing prior to installation at Yale University.

THP070	A Tool for Real Time Acquisitions and Correlation Studies at FERMI	FEL, GUI, electron, TANGO	898
	E. Allaria, W.M. Fawley, E. Ferrari Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy E. Ferrari Università degli Studi di Trieste, Trieste, Italy
	In this work we report the recent implementation of a Matlab based acquisition program that, exploiting the real time capabilities of TANGO, can be used at FERMI for acquiring various machine parameter and electron beam properties together with most FEL signals. Analysis of the saved datafiles is performed with a second code that allows to retrieve correlations and to study dependence of FEL properties on machine parameters. An overview of the two codes is reported.

THP080	A Low-Cost, High-Reliability Femtosecond Laser Timing System for LCLS	laser, timing, software, cavity	917
	K. Gumerlock, J.C. Frisch, B.L. Hill, J. May, D.J. Nelson, S.R. Smith SLAC, Menlo Park, California, USA
	Funding: Work supported by DOE Contract DE-AC02-76-SF00515 LCLS has developed a low-cost, high-reliability radio-frequency-based locking system which provides phase locking with sub-25-femtosecond jitter for the injector and experiment laser systems. This system does not add significantly to the X-ray timing jitter from the accelerator RF distribution. The system uses heterodyne RF locking at 3808 MHz with an I/Q vector phase shifter and variable event receiver triggers to control the timing of the emission of the amplified laser pulse. Controls software provides full automation with a single process variable to control the laser timing over a 600 microsecond range with up to 4 femtosecond resolution, as well as online diagnostics and automatic error correction and recovery. The performance of this new locking system is sufficient for experiments with higher-precision timing needs that use an X-ray/optical cross-correlator to record relative photon arrival times.

THP098	CameraLink High-Speed Camera for Bunch Profiling	FPGA, feedback, monitoring, hardware	968
	D. Llorente Sancho, H. Brands, R. Ischebeck, P. Pollet, V. Schlott PSI, Villigen PSI, Switzerland
	In the context of upcoming SwissFEL linear accelerator, we are working on a high-speed high-resolution instrument capable of delivering good sensitivity even in dark conditions. The camera selected is a PCO. Edge with SCMOS technology and an ultra-low noise sensor with 2560x2160 pixel resolution working at 100Hz. This allows for single bunch monitoring in SwissFEL, allowing eventually for on-the-fly inter-bunch image processing. The communication between the PCO. Edge camera and a last-generation Kintex7 FPGA has been demonstrated using a prototyping evaluation board and an 850-nm optical link connected to a 10Gbit SFP+ transceiver. Rudimentary packet processing has been implemented to confirm the satisfactory operation of the new link-layer protocol X-CameraLinkHS, specifically development for high-speed image transmission. We aim for online image processing and investigating the feasibility of achieving inter-bunch feedback (< 10 ms).

Paper

Title

Other Keywords

Page

MOP008

Temperature Effects of the FLASH2 Undulators

undulator, operation, feedback, insertion-device

34

M. Tischer, A. Schöps, P. Vagin
DESY, Hamburg, Germany

FELs are very sensitive to small changes in the resonance condition of the emitted radiation. As a consequence, permanent magnet undulators in FELs usually require extensive temperature control in order to assure stable operation conditions. In principle, the temperature dependence of permanent magnet material is well known but more things need to be considered like different thermal expansion of various mechanical parts or thermally induced deformation which do not only affect the K parameter but also the field quality. We have performed temperature dependent magnetic measurements in a range from 19 to 28 degrees Celsius and have analyzed the magnetic performance of the undulator. The results of this case study can be transferred to all FLASH2 undulators and shall allow for a simple temperature dependent gap correction in order to make the spectral properties insensitive to temperature changes of the insertion devices.

MOP021

Commissioning of a Dual-sweep Streak Camera with Applications to the ASTA Photoinjector Drive Laser

laser, timing, cavity, gun

66

A.H. Lumpkin, D.R. Edstrom, J. Ruan, J.K. Santucci
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The high-power electron beams for the Advanced Superconducting Test Accelerator (ASTA) facility will be generated in a photoinjector based on a UV drive laser and the L-band rf photocathode (PC) gun cavity. The initial objectives of these studies were: 1) the evaluation of the amplified UV component’s bunch length and phase stability and 2) the commissioning of the laser room Hamamatsu C5680 streak camera system. We used a new readout camera based on the Prosilica GC1380 digital CCD with Gig-E readout that was compatible with our image processing tools. We observed a longer than expected UV bunch length of 4 ps σ and an unexpected peak multiplicity (with spacing of about 70 ps) in the synchronous sum of 5 UV micropulses. We have now systematically investigated the issues of whether the multiplicity was with each micropulse of the 3-MHz pulse train. We describe our extensive investigations that indicated both issues originated in the multi-pass amplifier. We have replaced the MPA with three single-pass devices, measured 3.5-ps bunch lengths without the multiplicity, and generated photoelectrons from the gun successfully.

MOP032

PAL-XFEL Magnet Power Supply System

power-supply, quadrupole, dipole, status

87

S.-H. Jeong, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, K.-H. Park, H.S. Suh, Y.G. Young-Gyu
PAL, Pohang, Kyungbuk, Republic of Korea

This paper presents an overview of the magnet power supply(MPS) for the PAL-XFEL. The number of total MPS is 628 and they will be installed along the accelerator and the undulator sections. The power capacity of the MPS was ranging from about 1 A to 300 A. These MPSs were required to meet the high stability that was subjected from the beam dynamics specifications. This paper described the overall MPS requirements, MPS assembling, test process, control scheme, installation plan and so on.

MOP049

Oxygen Scintillation in the LCLS

detector, laser, instrumentation, electron

137

J.L. Turner, R.C. Field
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
Oxygen is tested as a replacement for Nitrogen in the Gas Detector system in the Linac Coherent Light Source (LCLS) x-ray Free Electron Laser (FEL) at the SLAC National Accelerator Center. The attenuation and energy monitors for LCLS use Nitrogen, but for experiments at the Nitrogen K 1S energy of about 410eV this functionality is gone due to energy fluctuations above and below the K-edge. Oxygen was tested as a scintillating gas at 400eV and 8.3keV.

TUP093

A Beam Test of Corrugated Structure for Passive Linearizer

simulation, quadrupole, electron, linac

593

H.-S. Kang, J.H. Hong
PAL, Pohang, Kyungbuk, Republic of Korea

A dechirper which is a vacuum chamber of two corrugated, metallic plates with adjustable gap was successfully tested at Pohang, in August 2013. Another beam test was carried out to test the same structure to see if the corrugated plates may work as a linearizer. The test result will be presented together with the simulation result.

THA02

Experimental Characterization of FEL Polarization Control with Cross Polarized Undulators

polarization, undulator, FEL, radiation

644

E. Ferrari, E. Allaria, G. De Ninno, B. Diviacco, D. Gauthier, L. Giannessi, G. Penco, C. Spezzani
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
J. Buck, M. Ilchen
XFEL. EU, Hamburg, Germany
G. De Ninno, D. Gauthier
University of Nova Gorica, Nova Gorica, Slovenia
L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
Z. Huang, A.A. Lutman
SLAC, Menlo Park, California, USA
G. Lambert, B. Mahieu
LOA, Palaiseau, France
J. Viefhaus
DESY, Hamburg, Germany

Polarization control of the coherent radiation is becoming an important feature of recent and future short wavelength free electron laser facilities. While polarization tuning can be achieved taking advantage of specially designed undulators, a scheme based on two consecutive undulators emitting orthogonally polarized fields has also been proposed. Developed initially in synchrotron radiation sources, crossed polarized undulator schemes could benefit from the coherent emission that characterize FELs. In this work we report the first detailed experimental characterization of the polarization properties of an FEL operated with crossed polarized undulators in the Soft-X-Rays. Aspects concerning the average degree of polarization and the shot to shot stability are investigated together with a comparison of the performance of various schemes to control and switch the polarization

Slides THA02 [5.383 MB]

THB04

Electron Beam Diagnostics and Feedback for the LCLS-II

cavity, feedback, diagnostics, undulator

666

J.C. Frisch, P. Emma, A.S. Fisher, P. Krejcik, H. Loos, T.J. Maxwell, T.O. Raubenheimer, S.R. Smith
SLAC, Menlo Park, California, USA

Funding: work supported by DOE contract DE-AC02-76-SF00515
The LCLS_II is a CW superconducting accelerator driven, hard and soft X-ray Free Electron Laser which is planned to be constructed at SLAC. It will operate with a variety of beam modes from single shot to approximately 1 MHz CW at bunch charges from 10pc to 300pC with average beam powers up to 1.2 MW. A variety of types of beam instrumentation will be used, including stripline and cavity BPMS, fluorescent and OTR based beam profile monitors, fast wire scanners and transverse deflection cavities. The beam diagnostics system is designed to allow tuning and continuous measurement of beam parameters, and to provide signals for fast beam feedbacks.

Slides THB04 [1.501 MB]

THP020

Electron Beam Dynamics Optimization Using A Unified Differential Evolution Algorithm

emittance, electron, cavity, solenoid

726

J. Qiang, C.E. Mitchell
LBNL, Berkeley, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
Accelerator beam dynamics design depends heavily on the use of control parameter optimization to achieve the best performance. In this paper, we report on electron beam dynamics optimization of a model photoinjector using a new unified differential evolution algorithm. We present the new unified differential evolution algorithm and benchmark its performance using several test examples. We also discuss the application of the algorithm in the multi-objective optimization of the photoinjector.

THP033

Mechanical Design for a Corrugated Plate Dechirper System for LCLS

wakefield, vacuum, quadrupole, electron

785

M.A. Harrison, P. Frigola, D.W. Martin, A.Y. Murokh, M. Ruelas
RadiaBeam Systems, Santa Monica, California, USA
Z. Huang, R.H. Iverson, T.J. Maxwell, Z. Zhang
SLAC, Menlo Park, California, USA

Funding: This work is supported by Department of Energy grant number DE-SC0009550.
RadiaBeam Systems is developing a novel passive chirp removal system using corrugated plates as studied by Bane and Stupakov.* Following on from low-energy experiments at BNL-ATF,** RBS will install a much larger and powerful system for removing the chirp from the 3-GeV beams in the LTU section at LCLS. The larger plates will present new challenges in the areas of manufacturing and mechanical control. In this paper we review the requirements for the dimensions of the corrugated plates for proper operation and the infrastructure necessary for precisely placing the plates so as not to adversely disrupt the beam.
* K. Bane, et al "Corrugated Pipe as a Beam Dechirper," SLAC-PUB-14925, 2012
** Harrison, M., et al "Removal of Residual Chirp in Compressed Beams Using a Passive Wakefield Technique." NaPAC13, 2013

THP040

Status of Pump-probe Laser Development for the European XFEL

laser, timing, software, hardware

807

L.-G. Wißmann, M. Emons, M. Kellert, K. Kruse, M. Lederer, G. Palmer, M. Pergament, G. Priebe, J. Wang, U. Wegner
XFEL. EU, Hamburg, Germany

The European XFEL is under construction and is designed to become a multi-user facility. Three SASE beam lines with two experimental areas each are foreseen to guarantee a high user throughput. In order to enable the full scientific potential of the facility, optical laser pulses for either pumping or probing samples will be deployed regularly. We are presenting the pump-probe laser concept and the current status of the development, showing some experimental results of the prototype laser, achieved to date. The main emphasis of the presentation lies on the integration of the laser system into Karabo, the emerging control system of the European XFEL.

THP043

Model-based Klystron Linearization in the SwissFEL Test Facility

klystron, high-voltage, power-supply, feedback

820

A. Řežaeizadeh, R. Kalt, T. Schilcher
PSI, Villigen PSI, Switzerland
A. Řežaeizadeh, R. Smith
Automatic Control Laboratory, ETH Zurich, Zurich, Switzerland

Funding: Paul Scherrer Institut
An automatic procedure is developed to provide the optimal operating point of a klystron. Since klystrons are nonlinear with respect to the input amplitude, a model-based amplitude controller is introduced which uses the klystron characteristic curves to obtain the appropriate high voltage power supply and amplitude, such that the operating point is close to the saturation. An advantage of the proposed design is that the overall open-loop system (from the input to the RF station to the klystron output amplitude) is linearized. The method has been successfully tested on a full scale RF system running at nominal power.
*Ch.Rapp, Effects of HPA-Nonlinearity on a 4-DPSK/OFDM-Signal …,Euro.
Conf. on Satellite Communi.,1991. <CR>
**A.Cann, Nonlinearity Model With Variable Knee…,IEEE Trans. Aerosp. Electron. Syst.,1980

THP044

RF Pulse Flattening in the SwissFEL Test Facility based on Model-free Iterative Learning Control

klystron, electron, feedback, flattop

824

A. Řežaeizadeh, R. Smith
Automatic Control Laboratory, ETH Zurich, Zurich, Switzerland
A. Řežaeizadeh, T. Schilcher
PSI, Villigen PSI, Switzerland

Funding: Paul Scherrer Institut
This paper introduces an iterative approach to producing flat-topped radio frequency (RF) pulses for driving the pulsed linear accelerators in the Swiss free electron laser (SwissFEL). The method is based on model-free iterative learning control which iteratively updates the input pulse shape in order to generate the desired amplitude and phase pulses at the output of the RF system. The method has been successfully applied to the klystron output to improve the flatness of the amplitude and phase pulse profiles.
* P. Janssens,et.al, "Model-free iterative learning control for LTI systems …", 18th IFAC. <CR>
** N. Amann, et.al , "ILC for discrete-time systems …", IEE Control Theory Apps.

THP052

Affordable Short Pulse Marx Modulator

high-voltage, linear-collider, network, collider

849

R.A. Phillips, G. DelPriore, M.P.J. Gaudreau, M.K. Kempkes
Diversified Technologies, Inc., Bedford, Massachusetts, USA
J.A. Casey
Rockfield Research Inc., Las Vegas, Nevada, USA

Funding: DOE Contract DE-SC0004251
High voltage short-pulse klystron modulators are required for numerous X-Band accelerator designs. At the very high voltages required for these transmitters, all of the existing designs are based on pulse transformers, which significantly limits their performance and efficiency. There is not a fully optimized, transformer-less modulator design capable of meeting the demanding requirements of very peak power, short pulse RF stations. Under a U.S. Department of Energy grant, Diversified Technologies, Inc. (DTI) is developing a short pulse, solid-state Marx modulator. The modulator is designed for high efficiency in the 100 kV to 500 kV range, for currents up to 250 A, pulse lengths of 0.2 to 5.0 μs, and risetimes <300 ns. Key objectives of the development effort are modularity and scalability, combined with low cost and ease of manufacture. For short-pulse modulators, this Marx topology provides a means to achieve fast risetimes and flattop control that are not available with hard switch or transformer-coupled topologies. The system is in the final stages of testing prior to installation at Yale University.

THP070

A Tool for Real Time Acquisitions and Correlation Studies at FERMI

FEL, GUI, electron, TANGO

898

E. Allaria, W.M. Fawley, E. Ferrari
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
E. Ferrari
Università degli Studi di Trieste, Trieste, Italy

In this work we report the recent implementation of a Matlab based acquisition program that, exploiting the real time capabilities of TANGO, can be used at FERMI for acquiring various machine parameter and electron beam properties together with most FEL signals. Analysis of the saved datafiles is performed with a second code that allows to retrieve correlations and to study dependence of FEL properties on machine parameters. An overview of the two codes is reported.

THP080

A Low-Cost, High-Reliability Femtosecond Laser Timing System for LCLS

laser, timing, software, cavity

917

K. Gumerlock, J.C. Frisch, B.L. Hill, J. May, D.J. Nelson, S.R. Smith
SLAC, Menlo Park, California, USA

Funding: Work supported by DOE Contract DE-AC02-76-SF00515
LCLS has developed a low-cost, high-reliability radio-frequency-based locking system which provides phase locking with sub-25-femtosecond jitter for the injector and experiment laser systems. This system does not add significantly to the X-ray timing jitter from the accelerator RF distribution. The system uses heterodyne RF locking at 3808 MHz with an I/Q vector phase shifter and variable event receiver triggers to control the timing of the emission of the amplified laser pulse. Controls software provides full automation with a single process variable to control the laser timing over a 600 microsecond range with up to 4 femtosecond resolution, as well as online diagnostics and automatic error correction and recovery. The performance of this new locking system is sufficient for experiments with higher-precision timing needs that use an X-ray/optical cross-correlator to record relative photon arrival times.

THP098

CameraLink High-Speed Camera for Bunch Profiling

FPGA, feedback, monitoring, hardware

968

D. Llorente Sancho, H. Brands, R. Ischebeck, P. Pollet, V. Schlott
PSI, Villigen PSI, Switzerland

In the context of upcoming SwissFEL linear accelerator, we are working on a high-speed high-resolution instrument capable of delivering good sensitivity even in dark conditions. The camera selected is a PCO. Edge with SCMOS technology and an ultra-low noise sensor with 2560x2160 pixel resolution working at 100Hz. This allows for single bunch monitoring in SwissFEL, allowing eventually for on-the-fly inter-bunch image processing. The communication between the PCO. Edge camera and a last-generation Kintex7 FPGA has been demonstrated using a prototyping evaluation board and an 850-nm optical link connected to a 10Gbit SFP+ transceiver. Rudimentary packet processing has been implemented to confirm the satisfactory operation of the new link-layer protocol X-CameraLinkHS, specifically development for high-speed image transmission. We aim for online image processing and investigating the feasibility of achieving inter-bunch feedback (< 10 ms).