DIPAC2011 - List of Keywords (undulator)

Paper	Title	Other Keywords	Page
MOOA02	Beam Instrumentation for X-ray FELs	cavity, FEL, feedback, diagnostics	1
	H. Loos SLAC, Menlo Park, California, USA
	Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC03-76SF00515. The performance of X-ray Free-electron lasers depends strongly on the achieved quality of the high brightness electron beam and its shot by shot stability. The requirements and challenges of the instrumentation needed to tune and optimize such electron beams will be discussed. Of particular interest are measurements of the beam orbit, emittance, energy, and bunch length and the different measurement techniques for these transverse and longitudinal beam parameters and their implementation for routine operation will be addressed in detail, particularly the necessary instrumentation to fulfill different user requirements in terms of beam energy and bunch length. Specific requirements for the initial commissioning, routine optimization and feedback applications will be presented as well.
	Slides MOOA02 [2.114 MB]

MOOB01	An Aperture Backscatter X-ray Beam Position Monitor at Diamond	photon, vacuum, polarization, scattering	6
	C. Bloomer, G. Rehm, C.A. Thomas Diamond, Oxfordshire, United Kingdom
	This paper presents the design and first results of a new XBPM developed at Diamond that images the backscatter from an aperture in the Front End to measure the beam centre of mass. This is of particular interest for monitoring the emission from elliptically polarizing undulators where the profile of the beam varies strongly with change of beam polarization. Traditional four-blade Front End XBPMs struggle to resolve a beam centre of mass for EPUs because of this. We have developed an XBPM that observes the backscattered photons from a copper aperture through a pinhole. This solution is capable of operating with the full white beam, and has been designed to fit into the same physical space as the standard front end XBPMs in use at Diamond. This offers the potential to easily replace traditional XBPMs where beneficial and required.
	Slides MOOB01 [7.211 MB]

MOOC03	The Fermi@Elettra Cavity BPM System: Description and Commissioning Results	cavity, pick-up, controls, FEL	26
	M. Ferianis, A.O. Borga, P. Craievich, R. De Monte, G. Gaio, M. Predonzani ELETTRA, Basovizza, Italy M. Dal Forno DIEIT, Trieste, Italy
	The Fermi@elettra cavity BPM (C-BPM) system is based on an original implementation of the C-BPM scheme as the pick-up, operating at 6.5GHz, is coupled to a dedicated, self-calibrating electronics based on a novel concept. The system has been developed in-house; both the E-M and the mechanical design of the pick-up have been carried out, including an original frequency tuning scheme. The detector electronics directly obtains the envelope of the sum and difference signals by means of an RF 180° hybrid; no mixer for the RF signal down conversion is used. The detector is based on 3 blocks: an RF front-end, a baseband analogue transmission module and a digital back-end unit, based on a micro-TCA platform. The digital back-end is equipped with a powerful Virtex 5 FPGA and several real-time tasks have been implemented on it, including intra-pulse calibration. Ten C-BPM stations have been installed so far, fully integrated in the FERMI control System, enabling a real-time control of this key FEL diagnostics. Results on performances with beam are also presented; the scale factor of C-BPMs is obtained with beam, as two-axis micrometer translation stages have been installed.
	Slides MOOC03 [2.733 MB]

MOPD09	Electron Beam Diagnostics for FLASH II	diagnostics, electron, radiation, laser	53
	N. Baboi, D. Nölle DESY, Hamburg, Germany
	Up to now, the FLASH linac serves one SASE (Self-Amplified Spontaneous Emission) undulator. The radiation produced can be guided to one of 5 beamlines in the experimental hall. In order to increase the availability of the machine, an extension, FLASH II, will be built in the next few years. A second undulator section will be built to generate SASE light. A HHG (High Harmonic Generation) laser will alternatively be used to produce seeded radiation in the undulators. The electron beam diagnostics in FLASH II has to enable the precise control of the beam position, size, timing, as well as the overlap of the electron beam with the HHG laser. The losses have to be kept under control, and the beam has to terminate safely in the beam dump. In comparison to FLASH, which was designed to run with rather high charge, the dynamic range of the diagnostics has to be between 0.1 to 1 nC, similar to the European XFEL. This paper gives an overview of the diagnostics for FLASH II.

MOPD54	Commissioning Results of the Photon-Electron Diagnostic Unit at sFLASH	laser, electron, diagnostics, FEL	173
	J. Bödewadt, E. Hass, J. Roßbach Uni HH, Hamburg, Germany
	Funding: Supported by the Federal Ministry of Education and Research of Germany under contract 05 ES7GU1 Recently a seeded free-electron laser operating in the extreme ultra-violet (XUV) spectral range was installed and commissioned at the free-electron laser FLASH. The seed beam is generated by higher harmonics of near infrared laser pulses. A dedicated transport system guides the radiation into the electron accelerator environment. Within the seed undulator section compact diagnostic units were installed to control the transverse overlap of the photon and the electron beam. These units contain a BPM, horizontal and vertical wire scanners and an OTR screen for the electron diagnostic. A Ce:YAG screen and a MCP readout for the wire scanner are used to measure the photon beam position. This paper presents the commissioning results and the performance of the diagnostic units.

MOPD90	Cause Identification of Beam Losses in PETRA III by Time Correlation of Alarms	status, beam-losses, dumping, power-supply	257
	T. Lensch, M. Werner DESY, Hamburg, Germany
	PETRA III is a high brilliant synchrotron light-source operating at 6 GeV at the DESY site in Hamburg. The Machine Protection System (MPS) of PETRA III is under operation since the beginning of the commissioning of PETRA III in April 2009. Under certain alarm conditions the MPS generates a dump command and protects the machine against damage. As a functional extension the MPS hardware examines the time correlation of alarm sequences after a beam loss. The alarm sequences are evaluated in a software based system so that the cause of a beam loss can be displayed in the control room immediately. This paper describes the hardware implementation as well as the software rules.
	Poster MOPD90 [0.548 MB]

TUOA04	Instrumentation for Machine Protection at FERMI@Elettra	FEL, radiation, diagnostics, electron	286
	L. Fröhlich, A.I. Bogani, K. Casarin, G. Cautero, G. Gaio, D. Giuressi, A. Gubertini, R.H. Menk, E. Quai, G. Scalamera, A. Vascotto ELETTRA, Basovizza, Italy L. Catani, D. Di Giovenale INFN-Roma II, Roma, Italy
	FERMI@Elettra is a linac-driven free-electron laser currently under commissioning at Sincrotrone Trieste, Italy. In order to protect the facility's permanent undulator magnets from radiation-induced demagnetization,beam losses and radiation doses are monitored closely by an active machine protection system. The talk focuses on the design and performance of its main diagnostic subsystems: Beam loss position monitors based on the detection of Cherenkov light in quartz fibers with multi-pixel photon counters, conventional ionization chambers with a new frontend electronics package, and solid-state RadFET dosimeters providing an online measurement of the absorbed dose in the undulator magnets.
	Slides TUOA04 [2.559 MB]

TUPD14	Commissioning of the Cavity BPM for the FERMI@Elettra FEL Project	cavity, electron, FEL, polarization	329
	P. Craievich, T. Borden, A.O. Borga, R. De Monte, M. Ferianis, M. Predonzani ELETTRA, Basovizza, Italy M. Dal Forno, R. Vescovo DIEIT, Trieste, Italy
	The cavity Beam Position Monitor (BPM) is a fundamental beam diagnostic device that allows the measurements of the electron beam trajectory in a non-destructively way and with sub-micron resolution. Ten cavity BPM systems have been installed along the undulators chain in the FERMI@Elettra FEL1 project. In this paper we discuss the installation, commissioning and performance of these cavity BPM systems. We have carried out preliminary operations during a pre-beam period, such as the alignment and fine tuning of the RF cavities under vacuum. During the commissioning each BPM has been calibrated by mechanically moving the support on which the BPM is mounted. We have estimated the single shot resolution in presence of beam jitter by reading the beam position synchronously over many electron bunches from three or more BPMs. The algorithms have been subsequently improved, and the results are described.
	Poster TUPD14 [0.460 MB]

TUPD43	XFEL Beam Loss Monitor System	electron, beam-losses, controls, high-voltage	401
	A. Kaukher, I. Krouptchenkov, B. Michalek, D. Nölle, H. Tiessen DESY, Hamburg, Germany
	European XFEL will have a sophisticated Machine Protection System, part of which - Beam Loss Monitors(BLM). The monitors will detect losses of electron beam, in order to protect the components of the XFEL from damage and excessive activation. For protection of undulators, BLMs with a scintillator bar will be used. BLMs at places with high radiation load will be equipped with fused silica rods. Beam dumps of the XFEL will be instrumented with glass-fiber BLMs. The BLMs were tested with an electron test-beam at DESY, as well as at FLASH. Due to large amount of light produced by scintillator and high gain of the used photomultiplier, no optical grease is needed in front of the photomultiplier' window, while typical cathode voltage is only 500-600 volt. The prototype with quartz glass was typically operated at higher cathode voltage. Good operation of all three types of BLMs prototypes was obtained. It is planned to use same monitors also for the FLASH2 project. Current status of the XFEL BLM system development will be presented.

TUPD73	Fast Orbit Stabilization System for Tandem APPLE-II Undulators at the KEK-PF	kicker, controls, power-supply, polarization	479
	T. Obina, K. Harada, R. Takai KEK, Ibaraki, Japan
	A rapid-polarization switching source has been developed in the KEK-PF 2.5-GeV electron storage ring. The source consists of two tandem APPLE-II type elliptically polarizing undulators (EPU) and five fast kicker magnets. The kicker magnets produce a local bump orbit at the frequency up to 100 Hz. Amplitude and phase of these magnets must be tuned precisely in order to minimize the leakage of residual orbit outside of the kicker bump. A fast orbit stabilization system which consists of ADC/FPGA/DAC are also developed to reduce the remaining orbit fluctuations in vertical and horizontal planes. In this paper, design and the preliminary result of the fast orbit compensation system is presented.

TUPD79	Preliminary Tune Feedback Study in the Taiwan Light Source	feedback, insertion, insertion-device, controls	491
	C.H. Kuo, J. Chen, P.C. Chiu, K.T. Hsu, K.H. Hu NSRRC, Hsinchu, Taiwan
	There are many difference type insertion devices are disturbed in the storage ring of TLS. The traditional feed-forward control to correct orbit change and tune shift that isn’t enough when difference type insertion devices are operated with various condition. There is global orbit feedback to solve global orbit problem. In the tune shift, the tune feedback will be proposed to make up it for various insertion devices operation. The stable tune measurement and compensation will be discussed in this report.

Paper

Title

Other Keywords

Page

MOOA02

Beam Instrumentation for X-ray FELs

cavity, FEL, feedback, diagnostics

1

H. Loos
SLAC, Menlo Park, California, USA

Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC03-76SF00515.
The performance of X-ray Free-electron lasers depends strongly on the achieved quality of the high brightness electron beam and its shot by shot stability. The requirements and challenges of the instrumentation needed to tune and optimize such electron beams will be discussed. Of particular interest are measurements of the beam orbit, emittance, energy, and bunch length and the different measurement techniques for these transverse and longitudinal beam parameters and their implementation for routine operation will be addressed in detail, particularly the necessary instrumentation to fulfill different user requirements in terms of beam energy and bunch length. Specific requirements for the initial commissioning, routine optimization and feedback applications will be presented as well.

Slides MOOA02 [2.114 MB]

MOOB01

An Aperture Backscatter X-ray Beam Position Monitor at Diamond

photon, vacuum, polarization, scattering

6

C. Bloomer, G. Rehm, C.A. Thomas
Diamond, Oxfordshire, United Kingdom

This paper presents the design and first results of a new XBPM developed at Diamond that images the backscatter from an aperture in the Front End to measure the beam centre of mass. This is of particular interest for monitoring the emission from elliptically polarizing undulators where the profile of the beam varies strongly with change of beam polarization. Traditional four-blade Front End XBPMs struggle to resolve a beam centre of mass for EPUs because of this. We have developed an XBPM that observes the backscattered photons from a copper aperture through a pinhole. This solution is capable of operating with the full white beam, and has been designed to fit into the same physical space as the standard front end XBPMs in use at Diamond. This offers the potential to easily replace traditional XBPMs where beneficial and required.

Slides MOOB01 [7.211 MB]

MOOC03

The Fermi@Elettra Cavity BPM System: Description and Commissioning Results

cavity, pick-up, controls, FEL

26

M. Ferianis, A.O. Borga, P. Craievich, R. De Monte, G. Gaio, M. Predonzani
ELETTRA, Basovizza, Italy
M. Dal Forno
DIEIT, Trieste, Italy

The Fermi@elettra cavity BPM (C-BPM) system is based on an original implementation of the C-BPM scheme as the pick-up, operating at 6.5GHz, is coupled to a dedicated, self-calibrating electronics based on a novel concept. The system has been developed in-house; both the E-M and the mechanical design of the pick-up have been carried out, including an original frequency tuning scheme. The detector electronics directly obtains the envelope of the sum and difference signals by means of an RF 180° hybrid; no mixer for the RF signal down conversion is used. The detector is based on 3 blocks: an RF front-end, a baseband analogue transmission module and a digital back-end unit, based on a micro-TCA platform. The digital back-end is equipped with a powerful Virtex 5 FPGA and several real-time tasks have been implemented on it, including intra-pulse calibration. Ten C-BPM stations have been installed so far, fully integrated in the FERMI control System, enabling a real-time control of this key FEL diagnostics. Results on performances with beam are also presented; the scale factor of C-BPMs is obtained with beam, as two-axis micrometer translation stages have been installed.

Slides MOOC03 [2.733 MB]

MOPD09

Electron Beam Diagnostics for FLASH II

diagnostics, electron, radiation, laser

53

N. Baboi, D. Nölle
DESY, Hamburg, Germany

Up to now, the FLASH linac serves one SASE (Self-Amplified Spontaneous Emission) undulator. The radiation produced can be guided to one of 5 beamlines in the experimental hall. In order to increase the availability of the machine, an extension, FLASH II, will be built in the next few years. A second undulator section will be built to generate SASE light. A HHG (High Harmonic Generation) laser will alternatively be used to produce seeded radiation in the undulators. The electron beam diagnostics in FLASH II has to enable the precise control of the beam position, size, timing, as well as the overlap of the electron beam with the HHG laser. The losses have to be kept under control, and the beam has to terminate safely in the beam dump. In comparison to FLASH, which was designed to run with rather high charge, the dynamic range of the diagnostics has to be between 0.1 to 1 nC, similar to the European XFEL. This paper gives an overview of the diagnostics for FLASH II.

MOPD54

Commissioning Results of the Photon-Electron Diagnostic Unit at sFLASH

laser, electron, diagnostics, FEL

173

J. Bödewadt, E. Hass, J. Roßbach
Uni HH, Hamburg, Germany

Funding: Supported by the Federal Ministry of Education and Research of Germany under contract 05 ES7GU1
Recently a seeded free-electron laser operating in the extreme ultra-violet (XUV) spectral range was installed and commissioned at the free-electron laser FLASH. The seed beam is generated by higher harmonics of near infrared laser pulses. A dedicated transport system guides the radiation into the electron accelerator environment. Within the seed undulator section compact diagnostic units were installed to control the transverse overlap of the photon and the electron beam. These units contain a BPM, horizontal and vertical wire scanners and an OTR screen for the electron diagnostic. A Ce:YAG screen and a MCP readout for the wire scanner are used to measure the photon beam position. This paper presents the commissioning results and the performance of the diagnostic units.

MOPD90

Cause Identification of Beam Losses in PETRA III by Time Correlation of Alarms

status, beam-losses, dumping, power-supply

257

T. Lensch, M. Werner
DESY, Hamburg, Germany

PETRA III is a high brilliant synchrotron light-source operating at 6 GeV at the DESY site in Hamburg. The Machine Protection System (MPS) of PETRA III is under operation since the beginning of the commissioning of PETRA III in April 2009. Under certain alarm conditions the MPS generates a dump command and protects the machine against damage. As a functional extension the MPS hardware examines the time correlation of alarm sequences after a beam loss. The alarm sequences are evaluated in a software based system so that the cause of a beam loss can be displayed in the control room immediately. This paper describes the hardware implementation as well as the software rules.

Poster MOPD90 [0.548 MB]

TUOA04

Instrumentation for Machine Protection at FERMI@Elettra

FEL, radiation, diagnostics, electron

286

L. Fröhlich, A.I. Bogani, K. Casarin, G. Cautero, G. Gaio, D. Giuressi, A. Gubertini, R.H. Menk, E. Quai, G. Scalamera, A. Vascotto
ELETTRA, Basovizza, Italy
L. Catani, D. Di Giovenale
INFN-Roma II, Roma, Italy

FERMI@Elettra is a linac-driven free-electron laser currently under commissioning at Sincrotrone Trieste, Italy. In order to protect the facility's permanent undulator magnets from radiation-induced demagnetization,beam losses and radiation doses are monitored closely by an active machine protection system. The talk focuses on the design and performance of its main diagnostic subsystems: Beam loss position monitors based on the detection of Cherenkov light in quartz fibers with multi-pixel photon counters, conventional ionization chambers with a new frontend electronics package, and solid-state RadFET dosimeters providing an online measurement of the absorbed dose in the undulator magnets.

Slides TUOA04 [2.559 MB]

TUPD14

Commissioning of the Cavity BPM for the FERMI@Elettra FEL Project

cavity, electron, FEL, polarization

329

P. Craievich, T. Borden, A.O. Borga, R. De Monte, M. Ferianis, M. Predonzani
ELETTRA, Basovizza, Italy
M. Dal Forno, R. Vescovo
DIEIT, Trieste, Italy

The cavity Beam Position Monitor (BPM) is a fundamental beam diagnostic device that allows the measurements of the electron beam trajectory in a non-destructively way and with sub-micron resolution. Ten cavity BPM systems have been installed along the undulators chain in the FERMI@Elettra FEL1 project. In this paper we discuss the installation, commissioning and performance of these cavity BPM systems. We have carried out preliminary operations during a pre-beam period, such as the alignment and fine tuning of the RF cavities under vacuum. During the commissioning each BPM has been calibrated by mechanically moving the support on which the BPM is mounted. We have estimated the single shot resolution in presence of beam jitter by reading the beam position synchronously over many electron bunches from three or more BPMs. The algorithms have been subsequently improved, and the results are described.

Poster TUPD14 [0.460 MB]

TUPD43

XFEL Beam Loss Monitor System

electron, beam-losses, controls, high-voltage

401

A. Kaukher, I. Krouptchenkov, B. Michalek, D. Nölle, H. Tiessen
DESY, Hamburg, Germany

European XFEL will have a sophisticated Machine Protection System, part of which - Beam Loss Monitors(BLM). The monitors will detect losses of electron beam, in order to protect the components of the XFEL from damage and excessive activation. For protection of undulators, BLMs with a scintillator bar will be used. BLMs at places with high radiation load will be equipped with fused silica rods. Beam dumps of the XFEL will be instrumented with glass-fiber BLMs. The BLMs were tested with an electron test-beam at DESY, as well as at FLASH. Due to large amount of light produced by scintillator and high gain of the used photomultiplier, no optical grease is needed in front of the photomultiplier' window, while typical cathode voltage is only 500-600 volt. The prototype with quartz glass was typically operated at higher cathode voltage. Good operation of all three types of BLMs prototypes was obtained. It is planned to use same monitors also for the FLASH2 project. Current status of the XFEL BLM system development will be presented.

TUPD73

Fast Orbit Stabilization System for Tandem APPLE-II Undulators at the KEK-PF

kicker, controls, power-supply, polarization

479

T. Obina, K. Harada, R. Takai
KEK, Ibaraki, Japan

A rapid-polarization switching source has been developed in the KEK-PF 2.5-GeV electron storage ring. The source consists of two tandem APPLE-II type elliptically polarizing undulators (EPU) and five fast kicker magnets. The kicker magnets produce a local bump orbit at the frequency up to 100 Hz. Amplitude and phase of these magnets must be tuned precisely in order to minimize the leakage of residual orbit outside of the kicker bump. A fast orbit stabilization system which consists of ADC/FPGA/DAC are also developed to reduce the remaining orbit fluctuations in vertical and horizontal planes. In this paper, design and the preliminary result of the fast orbit compensation system is presented.

TUPD79

Preliminary Tune Feedback Study in the Taiwan Light Source

feedback, insertion, insertion-device, controls

491

C.H. Kuo, J. Chen, P.C. Chiu, K.T. Hsu, K.H. Hu
NSRRC, Hsinchu, Taiwan

There are many difference type insertion devices are disturbed in the storage ring of TLS. The traditional feed-forward control to correct orbit change and tune shift that isn’t enough when difference type insertion devices are operated with various condition. There is global orbit feedback to solve global orbit problem. In the tune shift, the tune feedback will be proposed to make up it for various insertion devices operation. The stable tune measurement and compensation will be discussed in this report.