IBIC2014 - List of Keywords (HOM)

Paper	Title	Other Keywords	Page
TUPF06	Commissioning of the Electronics for HOM-based Beam Diagnostics at the 3.9 GHz Accelerating Module at FLASH	electronics, cavity, alignment, dipole	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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TUPF10	Stability Study of the Higher Order Mode Beam Position Monitors at the Accelerating Cavities at FLASH	dipole, cavity, electronics, polarization	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	higher-order-mode, monitoring, electronics, cavity	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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TUPF18	Development of a Button BPM for the LCLS-II project	diagnostics, wakefield, electron, feedback	361
	A. Lunin, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	A high sensitivity button BPM is under development for a linac section of the LCLS-II project. Since the LCLS-II linac will operate with bunch charge as low as 10 pC, we analyse various options for pickup button and feedthrough in order to maximize the BPM output signal at low charge regime. As a result the conceptual BPM design is proposed including an analytical estimation of the BPM performance as well as numerical simulation with CST Particle Studio and ANSYS HFSS. Both numerical methods show a good agreement of BPM output signals for various design parameters. Finally we describe the signal processing scheme and the electronics we are going to use.
	Poster TUPF18 [0.846 MB]
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Paper

Title

Other Keywords

Page

TUPF06

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

electronics, cavity, alignment, dipole

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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TUPF10

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

dipole, cavity, electronics, polarization

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

higher-order-mode, monitoring, electronics, cavity

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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TUPF18

Development of a Button BPM for the LCLS-II project

diagnostics, wakefield, electron, feedback

361

A. Lunin, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

A high sensitivity button BPM is under development for a linac section of the LCLS-II project. Since the LCLS-II linac will operate with bunch charge as low as 10 pC, we analyse various options for pickup button and feedthrough in order to maximize the BPM output signal at low charge regime. As a result the conceptual BPM design is proposed including an analytical estimation of the BPM performance as well as numerical simulation with CST Particle Studio and ANSYS HFSS. Both numerical methods show a good agreement of BPM output signals for various design parameters. Finally we describe the signal processing scheme and the electronics we are going to use.

Poster TUPF18 [0.846 MB]

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