IBIC2014 - List of Keywords (betatron)

Paper	Title	Other Keywords	Page
MOPD04	Synchronisation of the LHC Betatron Coupling and Phase Advance Measurement System	timing, detector, FPGA, controls	139
	J. Olexa, M. Gąsior CERN, Geneva, Switzerland
	The new LHC Diode ORbit and OScillation (DOROS) system will provide beam position readings with sub-micrometre resolution and at the same time will be able to perform measurements of local betatron coupling and beam phase advance with micrometre beam excitation. The oscillation sub-system employs gain-controlled RF amplifiers, shared with the orbit system, and followed by dedicated diode detectors to demodulate the beam oscillation signals into the kHz frequency range, subsequently digitized by multi-channel 24-bit ADCs. The digital signals are processed in each front-end with an FPGA and the results of reduced throughput are sent using an Ethernet protocol to a common concentrator, together with the orbit data. The phase advance calculation between multiple Beam Position Monitors (BPMs) requires that all DOROS front-ends have a common phase reference. This paper presents methods used to generate such a reference and to maintain a stable synchronous sampling on all system front-ends. The performance of the DOROS prototype synchronisation is presented based upon laboratory measurements.
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TUCZB1	Novel Emittance Diagnostics for Diffraction Limited Light Sources Based on X-ray Fresnel Diffractometry	emittance, electron, radiation, diagnostics	274
	M. Masaki, Y. Shimosaki, S. Takano, M. Takao JASRI/SPring-8, Hyogo-ken, Japan
	A novel emittance diagnostics technique with high sensitivity using X-ray Fresnel diffraction by a single slit has been developed to measure micron-order electron beam sizes at insertion devices (IDs) of photon beamlines. The X-ray Fresnel diffractometry (XFD)* is promising for diagnostics especially of a so-called diffraction limited storage ring (DLSR) with ultra-low emittance. In the DLSR, due to inevitable field errors of strong quadrupole and sextupole magnets, unwanted distortion of lattice functions and local betatron coupling will result in a different light source size at each beamline. Therefore, measurements of electron beam sizes at the ID source points will be essential to ensure the absence of degradation of brilliance and transverse coherence of radiation at the beamlines. The XFD observes a double-lobed diffraction pattern that emerges by optimizing the single slit width. The principle is based on a correlation between the depth of a median dip in the double-lobed pattern and the light source size at the ID. The validity of the new technique was theoretically and experimentally studied. The achievable resolution of the XFD will be also discussed. * M. Masaki, et al.,"X-ray Fresnel Diffractometry for Ultra-Low Emittance Diagnostics of Next Generation Synchrotron Light Sources", submitted to Phys. Rev.ST-AB.
	Slides TUCZB1 [5.456 MB]
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WEPF16	Algorithm to Improve the Beta-Function Measurement and its Evaluation in Storage Rings Lattices	lattice, storage-ring, optics, collider	574
	A.C. García-Bonilla UNAL, Bogota D.C, Colombia
	In any beam-line, one of the basic measurements during the beam-diagnostics is the measurement of the Beta-Function along the beam-line. This can be achieved in Storage Ring by taking the tune change obtained when varing the intensity of quadrupoles, or by using the matrix response to fit the corresponding parameters, or by shaking the beam to obtain a betatron motion. In accelerators like the LHC, the Beta-Function measurement is done from the Phase Advance Measurement using the Transfer Matrix. In this paper, a study of a new algorithm or numerically approximation for this measurement is presented, as well as the results of the simulations for the LHC and CLIC damping ring. The deduced and implemented algorithm takes into account a fraction of the both transverse planes measurements. A random (uniform) deviation of the MAD-X phase values is studied, by comparison of the proposed algorithm with the traditional one. An improvement close to 30% and 50% on the global error compare to the traditional way to measure the Beta Function is observed; this is for the studied cases using closed-orbits and phase advance values with deviations of 10 or 20 degrees. Postgraduate Student at Universidad Nacional de Colombia
	Poster WEPF16 [0.742 MB]
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WEPD24	New Features and Measurements using the Upgraded Transverse Multibunch Feedback at Diamond	feedback, damping, experiment, FPGA	696
	G. Rehm, M.G. Abbott, A.F.D. Morgan DLS, Oxfordshire, United Kingdom
	A Transverse Multi-Bunch Feedback has been used in the Diamond Storage Ring for the stabilization of instabilities since 2007. Following a recent upgrade of the FPGA code and EPICS layer, a set of new features is now available to support operation and machine development: Firstly, a bunch by bunch choice of feedback filter allows for better stabilization of a single high charge bunch in a hybrid fill pattern. Secondly, complex grow-damp experiments are now possible using a sequencer of internal states allowing precise measurements of the damping rates on a mode by mode basis. Thirdly, a phase locked loop excitation and detection has been implemented to allow both extremely fast (kHz update rates) and extremely precise tracking of the betatron tune frequencies. Finally, short FIR filters on the ADC input and DAC output enable a fine tuning of the impulse response to provide maximum bunch to bunch isolation, as for instance required for efficient bunch cleaning.
	Poster WEPD24 [1.977 MB]
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WEPD27	Commissioning of Bunch-by-Bunch Feedback System for NSLS2 Storage Ring	ion, feedback, storage-ring, kicker	707
	W.X. Cheng, B. Bacha, Y. Hu, O. Singh, H. Xu BNL, Upton, Long Island, New York, USA D. Teytelman Dimtel, San Jose, USA
	NSLS2 Storage Ring transverse bunch by bunch feedback system has been designed to cure the coupled bunch instabilities, caused by HOM, resistive wall or ions. The system has been constructed, tested and commissioned with beam. Preliminary studies show that the feedback system can suppress single bunch instability. Mode analysis of the unstable coupled bunch motion reveals fast ion instability exist even at relative low current. The bunch by bunch feedback system performance will be presented in this paper.
	Poster WEPD27 [0.623 MB]
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THCXB2	Performance Evaluation of the Intra-Bunch Feedback System at J-PARC Main Ring	feedback, simulation, damping, experiment	727
	K.G. Nakamura Kyoto University, Kyoto, Japan Y.H. Chin, T. Koseki, H. Kuboki, M. Okada, M. Tobiyama KEK, Ibaraki, Japan Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Intra-bunch feedback system in J-PARC (Japan Proton Accelerator Complex) Main Ring(MR) has been developed for suppression of head-tail motion and reduction of beam loss. This system consists of mainly BPM, signal processing circuit (iGp12), power amplifiers, and stripline kickers. These components were fabricated and installed in April of 2014. This system succeeded in suppressing the internal bunch motion caused by injection kicker error in the 3GeV constant-energy operation, and showed shorter damping time compared to the bunch by bunch feedback system, which is currently working in the normal operation. In this paper, we will report the performance of the system by comparison with simulations.
	Slides THCXB2 [6.430 MB]
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Paper

Title

Other Keywords

Page

MOPD04

Synchronisation of the LHC Betatron Coupling and Phase Advance Measurement System

timing, detector, FPGA, controls

139

J. Olexa, M. Gąsior
CERN, Geneva, Switzerland

The new LHC Diode ORbit and OScillation (DOROS) system will provide beam position readings with sub-micrometre resolution and at the same time will be able to perform measurements of local betatron coupling and beam phase advance with micrometre beam excitation. The oscillation sub-system employs gain-controlled RF amplifiers, shared with the orbit system, and followed by dedicated diode detectors to demodulate the beam oscillation signals into the kHz frequency range, subsequently digitized by multi-channel 24-bit ADCs. The digital signals are processed in each front-end with an FPGA and the results of reduced throughput are sent using an Ethernet protocol to a common concentrator, together with the orbit data. The phase advance calculation between multiple Beam Position Monitors (BPMs) requires that all DOROS front-ends have a common phase reference. This paper presents methods used to generate such a reference and to maintain a stable synchronous sampling on all system front-ends. The performance of the DOROS prototype synchronisation is presented based upon laboratory measurements.

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reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

TUCZB1

Novel Emittance Diagnostics for Diffraction Limited Light Sources Based on X-ray Fresnel Diffractometry

emittance, electron, radiation, diagnostics

274

M. Masaki, Y. Shimosaki, S. Takano, M. Takao
JASRI/SPring-8, Hyogo-ken, Japan

A novel emittance diagnostics technique with high sensitivity using X-ray Fresnel diffraction by a single slit has been developed to measure micron-order electron beam sizes at insertion devices (IDs) of photon beamlines. The X-ray Fresnel diffractometry (XFD)* is promising for diagnostics especially of a so-called diffraction limited storage ring (DLSR) with ultra-low emittance. In the DLSR, due to inevitable field errors of strong quadrupole and sextupole magnets, unwanted distortion of lattice functions and local betatron coupling will result in a different light source size at each beamline. Therefore, measurements of electron beam sizes at the ID source points will be essential to ensure the absence of degradation of brilliance and transverse coherence of radiation at the beamlines. The XFD observes a double-lobed diffraction pattern that emerges by optimizing the single slit width. The principle is based on a correlation between the depth of a median dip in the double-lobed pattern and the light source size at the ID. The validity of the new technique was theoretically and experimentally studied. The achievable resolution of the XFD will be also discussed.
* M. Masaki, et al.,"X-ray Fresnel Diffractometry for Ultra-Low Emittance Diagnostics of Next Generation Synchrotron Light Sources", submitted to Phys. Rev.ST-AB.

Slides TUCZB1 [5.456 MB]

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WEPF16

Algorithm to Improve the Beta-Function Measurement and its Evaluation in Storage Rings Lattices

lattice, storage-ring, optics, collider

574

A.C. García-Bonilla
UNAL, Bogota D.C, Colombia

In any beam-line, one of the basic measurements during the beam-diagnostics is the measurement of the Beta-Function along the beam-line. This can be achieved in Storage Ring by taking the tune change obtained when varing the intensity of quadrupoles, or by using the matrix response to fit the corresponding parameters, or by shaking the beam to obtain a betatron motion. In accelerators like the LHC, the Beta-Function measurement is done from the Phase Advance Measurement using the Transfer Matrix. In this paper, a study of a new algorithm or numerically approximation for this measurement is presented, as well as the results of the simulations for the LHC and CLIC damping ring. The deduced and implemented algorithm takes into account a fraction of the both transverse planes measurements. A random (uniform) deviation of the MAD-X phase values is studied, by comparison of the proposed algorithm with the traditional one. An improvement close to 30% and 50% on the global error compare to the traditional way to measure the Beta Function is observed; this is for the studied cases using closed-orbits and phase advance values with deviations of 10 or 20 degrees.
Postgraduate Student at Universidad Nacional de Colombia

Poster WEPF16 [0.742 MB]

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WEPD24

New Features and Measurements using the Upgraded Transverse Multibunch Feedback at Diamond

feedback, damping, experiment, FPGA

696

G. Rehm, M.G. Abbott, A.F.D. Morgan
DLS, Oxfordshire, United Kingdom

A Transverse Multi-Bunch Feedback has been used in the Diamond Storage Ring for the stabilization of instabilities since 2007. Following a recent upgrade of the FPGA code and EPICS layer, a set of new features is now available to support operation and machine development: Firstly, a bunch by bunch choice of feedback filter allows for better stabilization of a single high charge bunch in a hybrid fill pattern. Secondly, complex grow-damp experiments are now possible using a sequencer of internal states allowing precise measurements of the damping rates on a mode by mode basis. Thirdly, a phase locked loop excitation and detection has been implemented to allow both extremely fast (kHz update rates) and extremely precise tracking of the betatron tune frequencies. Finally, short FIR filters on the ADC input and DAC output enable a fine tuning of the impulse response to provide maximum bunch to bunch isolation, as for instance required for efficient bunch cleaning.

Poster WEPD24 [1.977 MB]

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WEPD27

Commissioning of Bunch-by-Bunch Feedback System for NSLS2 Storage Ring

ion, feedback, storage-ring, kicker

707

W.X. Cheng, B. Bacha, Y. Hu, O. Singh, H. Xu
BNL, Upton, Long Island, New York, USA
D. Teytelman
Dimtel, San Jose, USA

NSLS2 Storage Ring transverse bunch by bunch feedback system has been designed to cure the coupled bunch instabilities, caused by HOM, resistive wall or ions. The system has been constructed, tested and commissioned with beam. Preliminary studies show that the feedback system can suppress single bunch instability. Mode analysis of the unstable coupled bunch motion reveals fast ion instability exist even at relative low current. The bunch by bunch feedback system performance will be presented in this paper.

Poster WEPD27 [0.623 MB]

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reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

THCXB2

Performance Evaluation of the Intra-Bunch Feedback System at J-PARC Main Ring

feedback, simulation, damping, experiment

727

K.G. Nakamura
Kyoto University, Kyoto, Japan
Y.H. Chin, T. Koseki, H. Kuboki, M. Okada, M. Tobiyama
KEK, Ibaraki, Japan
Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Intra-bunch feedback system in J-PARC (Japan Proton Accelerator Complex) Main Ring(MR) has been developed for suppression of head-tail motion and reduction of beam loss. This system consists of mainly BPM, signal processing circuit (iGp12), power amplifiers, and stripline kickers. These components were fabricated and installed in April of 2014. This system succeeded in suppressing the internal bunch motion caused by injection kicker error in the 3GeV constant-energy operation, and showed shorter damping time compared to the bunch by bunch feedback system, which is currently working in the normal operation. In this paper, we will report the performance of the system by comparison with simulations.

Slides THCXB2 [6.430 MB]

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reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)