IBIC2014 - List of Authors (Baboi, N.)

Paper	Title	Page
TUPF06	Commissioning of the Electronics for HOM-based Beam Diagnostics at the 3.9 GHz Accelerating Module at FLASH	311
	N. Baboi, O. Hensler, L. Shi, T. Wamsat DESY, Hamburg, Germany N. Eddy, B.J. Fellenz Fermilab, Batavia, Illinois, USA P. Zhang CERN, Geneva, Switzerland
	Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453. Transverse Higher Order Modes (HOM) excited by electron beams in the 3.9 GHz accelerating cavities at FLASH may damage the beam quality. They can be reduced by extracting their energy through special couplers and by aligning the beam in the cavity. Electronics has been designed at FNAL for monitoring some of the potentially most damaging HOMs. This may be used for beam centering and therefore reducing the HOM effects. Moreover, the signals can be potentially calibrated into beam offset, so that they could be used as beam position monitors (HOM-BPM). The specifications of the monitors have been defined during an extensive study on the 4-cavity accelerating module installed at FLASH. Signals around 5.44 GHz have been chosen for higher precision measurements. However these signals propagate into the entire 1.2 m long module. Therefore in addition modes at about 9 GHz were selected for localized measurements in each cavity. The electronics has been recently installed at FLASH. The commissioning results will be presented in this paper. Instabilities previously observed in a test electronics as well as the HOM-BPMs in 1.3 GHz cavities will also be investigated. This electronics will also serve as a prototype for the electronics developed for the 3.9 GHz cavities at the European XFEL. L. Shi et al., this Conference **T. Wamsat et al., this Conference
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TUPF07	FLASH Undulator BPM Commissioning and Beam Characterization Results	315
	D. Lipka, N. Baboi, D. Nölle, G. Petrosyan, S. Vilcins DESY, Hamburg, Germany R. Baldinger, R. Ditter, B. Keil, W. Koprek, R. Kramert, G. Marinkovic, M. Roggli, M. Stadler PSI, Villigen PSI, Switzerland
	Recently, the commissioning of FLASH2 has started, a new soft X-ray FEL undulator line at the DESY FLASH facility. In the FLASH2 undulator intersections, the beam positions are measured by 17 cavity beam position monitor (CBPM) pick-ups and electronics* developed for the European XFEL (E-XFEL). In addition four CBPMs are available at FLASH1 for test and development. The new CBPM system enables an unprecedented position and charge resolution at FLASH, thus allowing further analysis and optimization of the FLASH beam quality and overall accelerator performance. Results of first beam measurements as well as correlations with other FLASH diagnostics systems are reported. * M. Stadler et al., “Low-Q Cavity BPM Electronics for E-XFEL, FLASH-2 and SwissFEL”, this conference.
	Poster TUPF07 [1.112 MB]
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TUPF08	Design, Development and Commissioning of a MTCA-Based Button and Strip-Line BPM System for FLASH2	320
	B. Lorbeer, N. Baboi, L.P. Petrosyan, F. Schmidt-Föhre DESY, Hamburg, Germany
	The FLASH (Free Electron Laser in Hamburg) facility at DESY (Deutsches Elektronen-Synchrotron) in Germany has been extended by a new undulator line called FLASH2 to provide twice as many experimental stations for users in the future. After the acceleration of the electron bunch train up to 1.2GeV, a part can be kicked into FLASH2, while the other is going to the old undulator line. In order to tune the wavelength of the SASE (Self Amplified Spontaneous Emission), the new line is equipped with variable gap undulators. The commissioning phase of FLASH2 started in early 2014 and is planned to be continued parasitically during user operation in FLASH1. One key point during first beam commissioning is the availability of standard diagnostic devices such as BPM (Beam Position Monitor). In this paper we present the design and first operational experience of a new BPM system for button and strip-line monitors based on MTCA.4. This is referred to as LCBPM (low charge BPM) in contrast to the old systems at FLASH initially designed for bunch charges of 1nC and higher. We summarize the recent analog and digital hardware development progress[,***] and first commissioning experience of this new BPM system at FLASH2 and present a first estimation of its resolution in a large charge range from 1nC down to 100pC and smaller. flash2.desy.de B. Lorbeer et.al.,TUPA19, IBIC2012 * MTCA.4 (Micro Telecommunications Computing Architecture ) for physics **** Frank Schmidt-Foehre et.al.,IPAC2014 Dresden
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TUPF10	Stability Study of the Higher Order Mode Beam Position Monitors at the Accelerating Cavities at FLASH	327
	L. Shi, N. Baboi DESY, Hamburg, Germany R.M. Jones UMAN, Manchester, United Kingdom
	When electron beams traverse an accelerating structure, higher order modes (HOMs) are excited. They can be used for beam diagnostic purposes. Both 1.3 GHz and 3.9 GHz superconducting accelerating cavities at FLASH linac, DESY, are equipped with electronics for beam position monitoring, which are based on HOM signals from special couplers. These monitors provide the beam position without additional vacuum components and at low cost. Moreover, they can be used to align the beam in the cavities to reduce the HOM effects on the beam. However, the HOMBPM (Higher Order Mode based Beam Position Monitor) shows an instability problem over time. In this paper, we will present the status of studies on this issue. Several methods are utilized to calibrate the HOMBPMs. These methods include DLR (Direct Linear Regression), and SVD (Singular Value Decomposition). We found that SVD generally is more suitable for HOMBPM calibration. We focus on the HOMBPMs at 1.3 GHz cavities. Techniques developed here are applicable to 3.9 GHz modules. The work will pave the way for HOMBPMs of the E-XFEL (European X-Ray Free Electron Laser).
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TUPF12	First Tests of a Micro-TCA-Based Downconverter Electronic for 5GHz Higher Order Modes in Third Harmonic Accelerating Cavities at the XFEL	337
	T. Wamsat, N. Baboi DESY, Hamburg, Germany
	Beam excited higher order modes (HOM) in 3.9GHz accelerating cavities at the European XFEL are planned to be used for beam position monitoring. The specifications of the monitors have been defined during an extensive study on the 3.9GHz module at FLASH. Selected HOMs for precision measurement are located around 5440MHz and 9040MHz. An electronics developed by FNAL has been recently installed at FLASH* and provides a basis for the XFEL electronics. The paper will present the design and first test of the hardware for the μTCA (Micro Telecommunications Computing Architecture) standard used for the XFEL. The hardware consists of three different Rear Transition Modules (RTM), two four channel downconverter RTMs (5GHz and 9GHz) and a third RTM with two phase locked loop synthesizers on board for LO generation. Presently the 5GHz and the PLL RTMs are under construction. The first measurements with these cards will be presented. N.Baboi, N.Eddy at al., this conference *N.Baboi, N.Eddy at al., this conference
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THIXB1	Commissioning of the FLASH2 Electron Beam Diagnostics in Respect to its use at the European XFEL	712
	N. Baboi, D. Nölle DESY, Hamburg, Germany
	This report presents the first operation experience of the electron beam diagnostics at FLASH2. FLASH2 is a new undulator line at the FLASH linac at DESY. Most electron beam diagnostics installed, like the beam loss monitors, cavity beam position monitors, toroids, beam halo monitors, have been designed for the European XFEL, and will provide operational experience beforehand. A few systems, as for example the button beam position monitors and the ionization chambers, have been developed for FLASH. The controls use the new MTCA.4 standard. Both linacs, FLASH and the European XFEL, require similar performance of the diagnostics systems. Many beam parameters are similar: bunch charge of 0.1 to 1 nC, pulse repetition frequency of 10 Hz, while others will be more critical at the XFEL than the ones currently used at FLASH, like the bunch frequency of up to 4.5 MHz. versus 1 MHz. The commissioning of FLASH2 and its diagnostics is ongoing. The beam monitors have accompanied the first beam through the linac, fine tuning for some systems is still to be done. The achieved performance will be presented in view of their use at the European XFEL.
	Slides THIXB1 [3.875 MB]
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Paper

Title

Page

Commissioning of the Electronics for HOM-based Beam Diagnostics at the 3.9 GHz Accelerating Module at FLASH

311

N. Baboi, O. Hensler, L. Shi, T. Wamsat
DESY, Hamburg, Germany
N. Eddy, B.J. Fellenz
Fermilab, Batavia, Illinois, USA
P. Zhang
CERN, Geneva, Switzerland

Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453.
Transverse Higher Order Modes (HOM) excited by electron beams in the 3.9 GHz accelerating cavities at FLASH may damage the beam quality. They can be reduced by extracting their energy through special couplers and by aligning the beam in the cavity. Electronics has been designed at FNAL for monitoring some of the potentially most damaging HOMs. This may be used for beam centering and therefore reducing the HOM effects. Moreover, the signals can be potentially calibrated into beam offset, so that they could be used as beam position monitors (HOM-BPM). The specifications of the monitors have been defined during an extensive study on the 4-cavity accelerating module installed at FLASH. Signals around 5.44 GHz have been chosen for higher precision measurements. However these signals propagate into the entire 1.2 m long module. Therefore in addition modes at about 9 GHz were selected for localized measurements in each cavity. The electronics has been recently installed at FLASH. The commissioning results will be presented in this paper. Instabilities previously observed in a test electronics as well as the HOM-BPMs in 1.3 GHz cavities will also be investigated*. This electronics will also serve as a prototype for the electronics developed for the 3.9 GHz cavities at the European XFEL**.
*L. Shi et al., this Conference
**T. Wamsat et al., this Conference

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TUPF07

FLASH Undulator BPM Commissioning and Beam Characterization Results

315

D. Lipka, N. Baboi, D. Nölle, G. Petrosyan, S. Vilcins
DESY, Hamburg, Germany
R. Baldinger, R. Ditter, B. Keil, W. Koprek, R. Kramert, G. Marinkovic, M. Roggli, M. Stadler
PSI, Villigen PSI, Switzerland

Recently, the commissioning of FLASH2 has started, a new soft X-ray FEL undulator line at the DESY FLASH facility. In the FLASH2 undulator intersections, the beam positions are measured by 17 cavity beam position monitor (CBPM) pick-ups and electronics* developed for the European XFEL (E-XFEL). In addition four CBPMs are available at FLASH1 for test and development. The new CBPM system enables an unprecedented position and charge resolution at FLASH, thus allowing further analysis and optimization of the FLASH beam quality and overall accelerator performance. Results of first beam measurements as well as correlations with other FLASH diagnostics systems are reported.
* M. Stadler et al., “Low-Q Cavity BPM Electronics for E-XFEL, FLASH-2 and SwissFEL”, this conference.

Poster TUPF07 [1.112 MB]

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TUPF08

Design, Development and Commissioning of a MTCA-Based Button and Strip-Line BPM System for FLASH2

320

B. Lorbeer, N. Baboi, L.P. Petrosyan, F. Schmidt-Föhre
DESY, Hamburg, Germany

The FLASH (Free Electron Laser in Hamburg) facility at DESY (Deutsches Elektronen-Synchrotron) in Germany has been extended by a new undulator line called FLASH2 to provide twice as many experimental stations for users in the future*. After the acceleration of the electron bunch train up to 1.2GeV, a part can be kicked into FLASH2, while the other is going to the old undulator line. In order to tune the wavelength of the SASE (Self Amplified Spontaneous Emission), the new line is equipped with variable gap undulators. The commissioning phase of FLASH2 started in early 2014 and is planned to be continued parasitically during user operation in FLASH1. One key point during first beam commissioning is the availability of standard diagnostic devices such as BPM (Beam Position Monitor). In this paper we present the design and first operational experience of a new BPM system for button and strip-line monitors based on MTCA.4***. This is referred to as LCBPM (low charge BPM) in contrast to the old systems at FLASH initially designed for bunch charges of 1nC and higher. We summarize the recent analog and digital hardware development progress[**,****] and first commissioning experience of this new BPM system at FLASH2 and present a first estimation of its resolution in a large charge range from 1nC down to 100pC and smaller.
* flash2.desy.de
** B. Lorbeer et.al.,TUPA19, IBIC2012
*** MTCA.4 (Micro Telecommunications Computing Architecture ) for physics
**** Frank Schmidt-Foehre et.al.,IPAC2014 Dresden

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TUPF10

Stability Study of the Higher Order Mode Beam Position Monitors at the Accelerating Cavities at FLASH

327

L. Shi, N. Baboi
DESY, Hamburg, Germany
R.M. Jones
UMAN, Manchester, United Kingdom

When electron beams traverse an accelerating structure, higher order modes (HOMs) are excited. They can be used for beam diagnostic purposes. Both 1.3 GHz and 3.9 GHz superconducting accelerating cavities at FLASH linac, DESY, are equipped with electronics for beam position monitoring, which are based on HOM signals from special couplers. These monitors provide the beam position without additional vacuum components and at low cost. Moreover, they can be used to align the beam in the cavities to reduce the HOM effects on the beam. However, the HOMBPM (Higher Order Mode based Beam Position Monitor) shows an instability problem over time. In this paper, we will present the status of studies on this issue. Several methods are utilized to calibrate the HOMBPMs. These methods include DLR (Direct Linear Regression), and SVD (Singular Value Decomposition). We found that SVD generally is more suitable for HOMBPM calibration. We focus on the HOMBPMs at 1.3 GHz cavities. Techniques developed here are applicable to 3.9 GHz modules. The work will pave the way for HOMBPMs of the E-XFEL (European X-Ray Free Electron Laser).

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TUPF12

First Tests of a Micro-TCA-Based Downconverter Electronic for 5GHz Higher Order Modes in Third Harmonic Accelerating Cavities at the XFEL

337

T. Wamsat, N. Baboi
DESY, Hamburg, Germany

Beam excited higher order modes (HOM) in 3.9GHz accelerating cavities at the European XFEL are planned to be used for beam position monitoring. The specifications of the monitors have been defined during an extensive study on the 3.9GHz module at FLASH. Selected HOMs for precision measurement are located around 5440MHz and 9040MHz. An electronics developed by FNAL has been recently installed at FLASH* and provides a basis for the XFEL electronics. The paper will present the design and first test of the hardware for the μTCA (Micro Telecommunications Computing Architecture) standard used for the XFEL. The hardware consists of three different Rear Transition Modules (RTM), two four channel downconverter RTMs (5GHz and 9GHz) and a third RTM with two phase locked loop synthesizers on board for LO generation. Presently the 5GHz and the PLL RTMs are under construction. The first measurements with these cards will be presented. *N.Baboi, N.Eddy at al., this conference
**N.Baboi, N.Eddy at al., this conference

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THIXB1

Commissioning of the FLASH2 Electron Beam Diagnostics in Respect to its use at the European XFEL

712

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

This report presents the first operation experience of the electron beam diagnostics at FLASH2. FLASH2 is a new undulator line at the FLASH linac at DESY. Most electron beam diagnostics installed, like the beam loss monitors, cavity beam position monitors, toroids, beam halo monitors, have been designed for the European XFEL, and will provide operational experience beforehand. A few systems, as for example the button beam position monitors and the ionization chambers, have been developed for FLASH. The controls use the new MTCA.4 standard. Both linacs, FLASH and the European XFEL, require similar performance of the diagnostics systems. Many beam parameters are similar: bunch charge of 0.1 to 1 nC, pulse repetition frequency of 10 Hz, while others will be more critical at the XFEL than the ones currently used at FLASH, like the bunch frequency of up to 4.5 MHz. versus 1 MHz. The commissioning of FLASH2 and its diagnostics is ongoing. The beam monitors have accompanied the first beam through the linac, fine tuning for some systems is still to be done. The achieved performance will be presented in view of their use at the European XFEL.

Slides THIXB1 [3.875 MB]

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