FEL2014 - List of Keywords (klystron)

Paper	Title	Other Keywords	Page
MOP062	FEL Proposal Based on CLIC X-Band Structure	linac, FEL, undulator, linear-collider	186
	A.A. Aksoy, O. Yavaş Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey E. Adli University of Oslo, Oslo, Norway D. Angal-Kalinin, J.A. Clarke STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom M.J. Boland, T.K. Charles, R.T. Dowd, G. LeBlanc SLSA, Clayton, Australia N. Charitonidis, A. Grudiev, A. Latina, D. Schulte, I. Syratchev, W. Wuensch CERN, Geneva, Switzerland G. D'Auria, S. Di Mitri Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy W. Fang, Q. Gu SINAP, Shanghai, People's Republic of China E.N. Gazis National Technical University of Athens, Athens, Greece M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann Uppsala University, Uppsala, Sweden Z. Nergiz Nigde University, Nigde, Turkey
	A linear accelerating structure with an average loaded gradient of 100 MV/m at X-Band frequencies has been demonstrated in the CLIC study. Recently, it has been proposed to use this structure to drive an FEL linac. In contrast to CLIC the linac would be powered by klystrons not by an RF source created by a drive beam. The main advantage of this proposal is achieving the required energies in a very short distance, thus the facility would be rather compact. In this study, we present the structure choice and conceptual design parameters of a facility which could generate laser photon pulses below Angstrom. Shorter wavelengths can also be reached with slightly increasing the energy.

TUA04	Status of the SwissFEL C-band Linac	linac, network, electron, free-electron-laser	322
	F. Löhl, J. Alex, H. Blumer, M. Bopp, H.-H. Braun, A. Citterio, U. Ellenberger, H. Fitze, H. Jöhri, T. Kleeb, L. Paly, J.-Y. Raguin, L. Schulz, R. Zennaro, C. Zumbach PSI, Villigen PSI, Switzerland
	The linear accelerator of SwissFEL will be based on C- band technology. This paper summarizes the latest results that were achieved with the first prototype components. Fur- thermore, the progress and plans of the series production are discussed.
	Slides TUA04 [11.482 MB]

TUB02	Generation of Intense XVUV Pulses with an Optical Klystron Enhanced Self- amplified Spontaneous Emission Free Electron Laser	FEL, electron, laser, radiation	332
	G. Penco, E. Allaria, G. De Ninno, E. Ferrari, L. Giannessi Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. De Ninno University of Nova Gorica, Nova Gorica, Slovenia L. Giannessi ENEA C.R. Frascati, Frascati (Roma), Italy
	Fermi is a seeded FEL operating in high gain harmonic generation mode. The FEL layout is constituted by a modulator and six radiators separated by a dispersive section. The modulator and the radiators can be tuned to the same resonant frequency to set up an asymmetric optical klystron configuration where self amplified spontaneous emission can be generated and studied. This paper presents the experiment consisting in the analysis of the enhancement of the self-amplified spontaneous emission (SASE) radiation by the dispersion in the optical klystron. The FEL pulses produced with the optical klystron configuration are several order of magnitude more intense than in pure SASE mode with the dispersion set to zero, The experimental observations are in good agreement with simulation results and theoretical expectations. A comparison with the typical high-gain harmonic generation seeded Fel operation is also provided.
	Slides TUB02 [12.835 MB]

THB03	Femtosecond-Stability Delivery of Synchronized RF-Signals to the Klystron Gallery over 1-km Optical Fibers	laser, timing, detector, experiment	663
	J. Kim, K. Jung, J. Lim, J. Shin, H. Yang KAIST, Daejeon, Republic of Korea H.-S. Kang, C.-K. Min PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: This work was supported by the PAL-XFEL Project and the National Research Foundation (Grant number 2012R1A2A2A01005544) of South Korea. We present our recent progress in optical frequency comb-based remote optical and RF distribution system at PAL-XFEL. A 238 MHz mode-locked Er-laser is used as an optical master oscillator (OMO), which is stabilized to a 2.856 GHz RF master oscillator (RMO) using a fiber- loop optical-microwave phase detector (FLOM-PD). We partly installed a pair of 1.15 km long fiber links through a cable duct to connect and OMO room to a klystron gallery in the PAL-XFEL Injector Test Facility (ITF). The fiber links are stabilized using balanced optical cross- correlators (BOC). A voltage controlled RF oscillator (VCO) is locked to the delivered optical pulse train using the second FLOM-PD. Residual timing jitter and drift between the two independently distributed optical pulse train and RF signal is measured at the klystron gallery. The results are 6.6 fs rms and 31 fs rms over 7 hours and 62 hours, respectively. This is the first comb-based optical/RF distribution and phase comparison in the klystron gallery environment.
	Slides THB03 [7.478 MB]

THP002	Beam Energy Management and RF Failure Compensation Scenarios for the European XFEL	linac, operation, optics, quadrupole	672
	B. Beutner DESY, Hamburg, Germany
	The operation of complex systems as the driver linacs for free-electron-lasers is limited by the reliability of the individual components. Failures of RF systems can therefore constrict FEL availability. Typically reserves are included in the overall linac voltage capacity to allow for redistribution of acceleration in case of an RF failure. However, such redistributions of the acceleration of the linac affects the beam dynamics of the machine. While the effects on the optics can easily be compensated by rescaling of the quadrupole magnet strength, the bunch compression set-up requires a more involved investigation. In this paper we discuss studies for an energy management system for the European XFEL.

THP043	Model-based Klystron Linearization in the SwissFEL Test Facility	high-voltage, power-supply, feedback, controls	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	controls, 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.

THP051	Thyratron Replacement	operation, network, target, linear-collider	847
	I. Roth, M.P.J. Gaudreau, M.K. Kempkes Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Funding: DOE Contract DE-SC0011292 Semiconductor thyristers have long been used as a replacement for thyratrons, at least in low power or long pulse RF systems. To date, however, such thyristor assemblies have not demonstrated the reliability needed for installation in short pulse, high peak power RF stations used with many pulsed electron accelerators. The difficulty is that a fast rising current in a thyristor tends to be carried in a small region, rather than across the whole device, and this localized current concentration can cause a short circuit failure. It is not clear that this failure mode can be overcome with currently available device designs. An alternate solid-state device, the insulated-gate bipolar transistor (IGBT), can readily operate at the speed needed for the accelerator, but commercial IGBTs cannot handle the voltage and current required. Diversified Technologies, Inc. (DTI) has patented and refined the technology required to build these arrays of series-parallel connected switches. Under DOE contract, DTI is currently developing an affordable, reliable, form-fit-function replacement for the klystron modulator thyratrons at SLAC capable of pulsing at 360 kV, 420 A, 6 μs, and 120 Hz.

THP056	The SwissFEL C-band RF Pulse Compressor: Manufacturing and Proof of Precision by RF Measurements	vacuum, cavity, coupling, resonance	859
	U. Ellenberger, H. Blumer, M. Heusser, M. Kleeb, L. Paly, M. Probst, T. Stapf Paul Scherrer Institute, Villigen PSI, Switzerland M. Bopp, A. Citterio, R. Zennaro PSI, Villigen PSI, Switzerland
	A pulse compressor is required to compress the RF power distributed to the four accelerating structures of a single C-band (5712 GHz) module of the SwissFEL. The pulse compressor is of the barrel open cavity (BOC) type. A total of 26 BOC devices are necessary to operate the linear accelerator (26 modules or 10⁴ C-band structures) of SwissFEL X-ray laser. The C-band BOC combines the advantages of compactness and large RF efficiency i.e. large compression factor. Key features of the BOC are described and how they have been implemented in the manufacturing and tuning processes. RF measurements of the BOC are presented to account for the mechanical precision reached by manufacturing. Up to August 2014 about 6 BOCs have been manufactured in-house and one has been high power tested in a RF test stand to simulate the operation in SwissFEL.

THP058	Solid-State Switch for a Klystron Modulator for Stable Operation of a THz- FEL	FEL, electron, operation, linac	868
	G. Isoyama, M. Fujimoto, S. Funakoshi, K. Furukawa, A. Irizawa, R. Kato, K. Kawase, K. Miyazaki, A. Tokuchi, R. Tsutsumi, M. Yaguchi ISIR, Osaka, Japan F. Kamitsukasa Osaka University, Graduate School of Science, Osaka, Japan
	We have been conducting studies on upgrade of the THz-FEL and its applications, using the L-band electron linac at ISIR, Osaka University. The stability of the FEL is crucial for these studies and the operation of the FEL depends on characteristics of the electron beam, especially on stability of the electron energy, which is strongly affected by the RF power and its phase provided to the linac. We uses a klystron modulator with the a highly stable charging system to the PFN with a fractional variation of 8×10^-5 (peak-to-peak), but the klystron voltage varies by one order of magnitude larger due probably to the thyratron used as a high voltage and high current switch in the klystron modulator. In order to make the stability of the FEL higher, we have developed a solid-state switch using static induction thyristors. The performance of the switch is as follows; the maximum holding voltage is 25 kV, the maximum current is 6 kA for the pulse duration of 10 us, the switching time is 270 ns, and the maximum repetition frequency is 10 Hz. The intensity fluctuation of the FEL macropulse is reduced to a few percents using the solid state switch.

Paper

Title

Other Keywords

Page

MOP062

FEL Proposal Based on CLIC X-Band Structure

linac, FEL, undulator, linear-collider

186

A.A. Aksoy, O. Yavaş
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
E. Adli
University of Oslo, Oslo, Norway
D. Angal-Kalinin, J.A. Clarke
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M.J. Boland, T.K. Charles, R.T. Dowd, G. LeBlanc
SLSA, Clayton, Australia
N. Charitonidis, A. Grudiev, A. Latina, D. Schulte, I. Syratchev, W. Wuensch
CERN, Geneva, Switzerland
G. D'Auria, S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
W. Fang, Q. Gu
SINAP, Shanghai, People's Republic of China
E.N. Gazis
National Technical University of Athens, Athens, Greece
M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann
Uppsala University, Uppsala, Sweden
Z. Nergiz
Nigde University, Nigde, Turkey

A linear accelerating structure with an average loaded gradient of 100 MV/m at X-Band frequencies has been demonstrated in the CLIC study. Recently, it has been proposed to use this structure to drive an FEL linac. In contrast to CLIC the linac would be powered by klystrons not by an RF source created by a drive beam. The main advantage of this proposal is achieving the required energies in a very short distance, thus the facility would be rather compact. In this study, we present the structure choice and conceptual design parameters of a facility which could generate laser photon pulses below Angstrom. Shorter wavelengths can also be reached with slightly increasing the energy.

TUA04

Status of the SwissFEL C-band Linac

linac, network, electron, free-electron-laser

322

F. Löhl, J. Alex, H. Blumer, M. Bopp, H.-H. Braun, A. Citterio, U. Ellenberger, H. Fitze, H. Jöhri, T. Kleeb, L. Paly, J.-Y. Raguin, L. Schulz, R. Zennaro, C. Zumbach
PSI, Villigen PSI, Switzerland

The linear accelerator of SwissFEL will be based on C- band technology. This paper summarizes the latest results that were achieved with the first prototype components. Fur- thermore, the progress and plans of the series production are discussed.

Slides TUA04 [11.482 MB]

TUB02

Generation of Intense XVUV Pulses with an Optical Klystron Enhanced Self- amplified Spontaneous Emission Free Electron Laser

FEL, electron, laser, radiation

332

G. Penco, E. Allaria, G. De Ninno, E. Ferrari, L. Giannessi
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. De Ninno
University of Nova Gorica, Nova Gorica, Slovenia
L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy

Fermi is a seeded FEL operating in high gain harmonic generation mode. The FEL layout is constituted by a modulator and six radiators separated by a dispersive section. The modulator and the radiators can be tuned to the same resonant frequency to set up an asymmetric optical klystron configuration where self amplified spontaneous emission can be generated and studied. This paper presents the experiment consisting in the analysis of the enhancement of the self-amplified spontaneous emission (SASE) radiation by the dispersion in the optical klystron. The FEL pulses produced with the optical klystron configuration are several order of magnitude more intense than in pure SASE mode with the dispersion set to zero, The experimental observations are in good agreement with simulation results and theoretical expectations. A comparison with the typical high-gain harmonic generation seeded Fel operation is also provided.

Slides TUB02 [12.835 MB]

THB03

Femtosecond-Stability Delivery of Synchronized RF-Signals to the Klystron Gallery over 1-km Optical Fibers

laser, timing, detector, experiment

663

J. Kim, K. Jung, J. Lim, J. Shin, H. Yang
KAIST, Daejeon, Republic of Korea
H.-S. Kang, C.-K. Min
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This work was supported by the PAL-XFEL Project and the National Research Foundation (Grant number 2012R1A2A2A01005544) of South Korea.
We present our recent progress in optical frequency comb-based remote optical and RF distribution system at PAL-XFEL. A 238 MHz mode-locked Er-laser is used as an optical master oscillator (OMO), which is stabilized to a 2.856 GHz RF master oscillator (RMO) using a fiber- loop optical-microwave phase detector (FLOM-PD). We partly installed a pair of 1.15 km long fiber links through a cable duct to connect and OMO room to a klystron gallery in the PAL-XFEL Injector Test Facility (ITF). The fiber links are stabilized using balanced optical cross- correlators (BOC). A voltage controlled RF oscillator (VCO) is locked to the delivered optical pulse train using the second FLOM-PD. Residual timing jitter and drift between the two independently distributed optical pulse train and RF signal is measured at the klystron gallery. The results are 6.6 fs rms and 31 fs rms over 7 hours and 62 hours, respectively. This is the first comb-based optical/RF distribution and phase comparison in the klystron gallery environment.

Slides THB03 [7.478 MB]

THP002

Beam Energy Management and RF Failure Compensation Scenarios for the European XFEL

linac, operation, optics, quadrupole

672

B. Beutner
DESY, Hamburg, Germany

The operation of complex systems as the driver linacs for free-electron-lasers is limited by the reliability of the individual components. Failures of RF systems can therefore constrict FEL availability. Typically reserves are included in the overall linac voltage capacity to allow for redistribution of acceleration in case of an RF failure. However, such redistributions of the acceleration of the linac affects the beam dynamics of the machine. While the effects on the optics can easily be compensated by rescaling of the quadrupole magnet strength, the bunch compression set-up requires a more involved investigation. In this paper we discuss studies for an energy management system for the European XFEL.

THP043

Model-based Klystron Linearization in the SwissFEL Test Facility

high-voltage, power-supply, feedback, controls

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

controls, 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.

THP051

Thyratron Replacement

operation, network, target, linear-collider

847

I. Roth, M.P.J. Gaudreau, M.K. Kempkes
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: DOE Contract DE-SC0011292
Semiconductor thyristers have long been used as a replacement for thyratrons, at least in low power or long pulse RF systems. To date, however, such thyristor assemblies have not demonstrated the reliability needed for installation in short pulse, high peak power RF stations used with many pulsed electron accelerators. The difficulty is that a fast rising current in a thyristor tends to be carried in a small region, rather than across the whole device, and this localized current concentration can cause a short circuit failure. It is not clear that this failure mode can be overcome with currently available device designs. An alternate solid-state device, the insulated-gate bipolar transistor (IGBT), can readily operate at the speed needed for the accelerator, but commercial IGBTs cannot handle the voltage and current required. Diversified Technologies, Inc. (DTI) has patented and refined the technology required to build these arrays of series-parallel connected switches. Under DOE contract, DTI is currently developing an affordable, reliable, form-fit-function replacement for the klystron modulator thyratrons at SLAC capable of pulsing at 360 kV, 420 A, 6 μs, and 120 Hz.

THP056

The SwissFEL C-band RF Pulse Compressor: Manufacturing and Proof of Precision by RF Measurements

vacuum, cavity, coupling, resonance

859

U. Ellenberger, H. Blumer, M. Heusser, M. Kleeb, L. Paly, M. Probst, T. Stapf
Paul Scherrer Institute, Villigen PSI, Switzerland
M. Bopp, A. Citterio, R. Zennaro
PSI, Villigen PSI, Switzerland

A pulse compressor is required to compress the RF power distributed to the four accelerating structures of a single C-band (5712 GHz) module of the SwissFEL. The pulse compressor is of the barrel open cavity (BOC) type. A total of 26 BOC devices are necessary to operate the linear accelerator (26 modules or 10⁴ C-band structures) of SwissFEL X-ray laser. The C-band BOC combines the advantages of compactness and large RF efficiency i.e. large compression factor. Key features of the BOC are described and how they have been implemented in the manufacturing and tuning processes. RF measurements of the BOC are presented to account for the mechanical precision reached by manufacturing. Up to August 2014 about 6 BOCs have been manufactured in-house and one has been high power tested in a RF test stand to simulate the operation in SwissFEL.

THP058

Solid-State Switch for a Klystron Modulator for Stable Operation of a THz- FEL

FEL, electron, operation, linac

868

G. Isoyama, M. Fujimoto, S. Funakoshi, K. Furukawa, A. Irizawa, R. Kato, K. Kawase, K. Miyazaki, A. Tokuchi, R. Tsutsumi, M. Yaguchi
ISIR, Osaka, Japan
F. Kamitsukasa
Osaka University, Graduate School of Science, Osaka, Japan

We have been conducting studies on upgrade of the THz-FEL and its applications, using the L-band electron linac at ISIR, Osaka University. The stability of the FEL is crucial for these studies and the operation of the FEL depends on characteristics of the electron beam, especially on stability of the electron energy, which is strongly affected by the RF power and its phase provided to the linac. We uses a klystron modulator with the a highly stable charging system to the PFN with a fractional variation of 8×10^-5 (peak-to-peak), but the klystron voltage varies by one order of magnitude larger due probably to the thyratron used as a high voltage and high current switch in the klystron modulator. In order to make the stability of the FEL higher, we have developed a solid-state switch using static induction thyristors. The performance of the switch is as follows; the maximum holding voltage is 25 kV, the maximum current is 6 kA for the pulse duration of 10 us, the switching time is 270 ns, and the maximum repetition frequency is 10 Hz. The intensity fluctuation of the FEL macropulse is reduced to a few percents using the solid state switch.