LINAC2012 - List of Keywords (beam-loading)

Paper	Title	Other Keywords	Page
MOPLB08	Normal Conducting Deflecting Cavity Development at the Cockcroft Institute	cavity, wakefield, damping, electron	159
	G. Burt, P.K. Ambattu, A.C. Dexter, C. Lingwood, B.J. Woolley Cockcroft Institute, Lancaster University, Lancaster, United Kingdom S.R. Buckley, P. Goudket, C. Hill, P.A. McIntosh, J.W. McKenzie, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom V.A. Dolgashev SLAC, Menlo Park, California, USA A. Grudiev CERN, Geneva, Switzerland R.M. Jones UMAN, Manchester, United Kingdom
	Funding: This work has been supported by STFC and the EU through FP7 EUCARD. Two normal conducting deflecting structures are currently being developed at the Cockcroft Institute, one as a crab cavity for CLIC and one for bunch slice diagnostics on low energy electron beams for EBTF at Daresbury. Each has its own challenges that need overcome. For CLIC the phase and amplitude tolerances are very stringent and hence beamloading effects and wakefields must be minimised. Significant work has been undertook to understand the effect of the couplers on beamloading and the effect of the couplers on the wakefields. For EBTF the difficulty is avoiding the large beam offset caused by the cavities internal deflecting voltage at the low beam energy. Propotypes for both cavities have been manufactured and results will be presented.
	Slides MOPLB08 [1.572 MB]

MOPB021	Bunch-by-bunch Phase Modulation for Linac Beam-loading Compensation	linac, impedance, injection, bunching	216
	G. Huang, D. Jia, K. Jin, H. Lin, Weishi, Zhou. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China Y. Liu USTC, Hefei, Anhui, People's Republic of China
	Funding: supported by NSFC-CAS Joint Fund, contract no. 11079034 If the linac is loaded by a high current, long pulse multi-bunch beam, the energy of the beam drops with time during the pulse. The bunch phase modulation method is introduced to compensate the beam loading. In this method the beam phase in the RF accelerating filed is changed bunch-by-bunch, the beam energy gain in the RF filed gradually grows up, which cancels the drop due to beam loading. The relationship between the beam phase distribution and the linac parameters is calculated in this paper.

MOPB031	Vibration Response Testing of the CEBAF 12 GeV Upgrade Cryomodules	cryomodule, cavity, damping, controls	240
	G.K. Davis, J. Matalevich, T. Powers, M. Wiseman JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 The CEBAF 12 GeV upgrade project includes 80 new 7-cell cavities assembled into 10 cryomodules. These cryomodules were tested during production to characterize their microphonic response in situ. For several early cryomodules, detailed (vibration) modal studies of the cryomodule string were performed during the assembly process to identify the structural contributors to the measured cryomodule microphonic response. Structural modifications were then modeled, implemented, and verified by subsequent modal testing and in-situ microphonic response testing. Interim and final results from this multi-stage process will be reviewed.

MOPB079	Normal Conducting Deflecting Cavity Development at the Cockcroft Institute	cavity, wakefield, damping, electron	357
	G. Burt, P.K. Ambattu, A.C. Dexter, C. Lingwood, B.J. Woolley Cockcroft Institute, Lancaster University, Lancaster, United Kingdom S.R. Buckley, P. Goudket, C. Hill, P.A. McIntosh, J.W. McKenzie, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom V.A. Dolgashev SLAC, Menlo Park, California, USA A. Grudiev CERN, Geneva, Switzerland R.M. Jones UMAN, Manchester, United Kingdom
	Funding: This work has been supported by STFC and the EU through FP7 EUCARD. Two normal conducting deflecting structures are currently being developed at the Cockcroft Institute, one as a crab cavity for CLIC and one for bunch slice diagnostics on low energy electron beams for EBTF at Daresbury. Each has its own challenges that need overcome. For CLIC the phase and amplitude tolerances are very stringent and hence beamloading effects and wakefields must be minimised. Significant work has been undertook to understand the effect of the couplers on beamloading and the effect of the couplers on the wakefields. For EBTF the difficulty is avoiding the large beam offset caused by the cavities internal deflecting voltage at the low beam energy. Propotypes for both cavities have been manufactured and results will be presented.

TUPB061	ADRC Control for Beam Loading and Microphonics	controls, cavity, LLRF, simulation	615
	Z. Zheng, Z. Liu, J. Wei, Y. Zhang, S. Zhao FRIB, East Lansing, Michigan, USA Z. Zheng TUB, Beijing, People's Republic of China
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 Superconducting RF (SRF) cavities are subject to many disturbances such as beam loading and microphonics. Although we implemented Proportional Integral (PI) control and Active Disturbance Rejection Control (ADRC) in the Low Level RF (LLRF) system at FRIB to stabilize the RF field, the control loop gains are inadequate in the presence of beam loading and microphonics. An improved scheme is proposed and simulated with much higher gains are achieved. The feasibility to include piezo tuner in ADRC and PI circuit is also presented in this paper.

TUPB107	Amplitude and Phase Control of the Accelerating Field in the ESS Spoke Cavity	cavity, controls, feedback, simulation	708
	V.A. Goryashko, R.J.M.Y. Ruber, R.A. Yogi, V.G. Ziemann Uppsala University, Uppsala, Sweden
	We report about numerical simulations of the accelerating field dynamics in the ESS spoke cavity in the presence of the beam loading and Lorentz detuning. A slow feedforward is used to cure the Lorentz detuning whereas a fast feedback through a signal oscillator and cavity pre-detuning technique are applied to eliminate the beam loading effect. An analysis performed with a Simulink model shows that a combination of feedforward, feedback and cavity pre-detuning result in a substantially shorter stabilization time of the field voltage and phase on a required level as compared to a control method using only the feedforward and feedback. The latter allows one to obtain smaller magnitude but longer duration of deviations of the instantaneous voltage and phase from the required nominal values. As a result, a series of cavities only with feedforward and feedback needs an extra control technique to mitigate a cumulative systematic error rising in each cavity. In addition, a technique of adiabatic turning off of the RF power in order to prevent a high reflected power in the case of a sudden beam loss is studied.

THPB064	Beam Dynamics Tools for Linacs Design	electron, simulation, linac, synchrotron	987
	A.S. Setty THALES, Colombes, France
	In the last 25 years, we have been using our in house 3D code PRODYN * for electron beam simulations. We have also been using our in house code SECTION for the design of the travelling wave accelerating structures and the beam loading compensation. PRODYN follows in time, the most complicated electron trajectories with relativistic space-charge effects. This code includes backward as well as forwards movements. This paper will describe those two codes and will give some simulations and measurements results. * D. Tronc and A. Setty, Electrons RF auto-focusing and capture in bunchers, Linear Accelerator Conference 1988, Virginia.

THPB085	LLRF Automation for the 9mA ILC Tests at FLASH	cavity, controls, feedback, cryomodule	1023
	J. Branlard, V. Ayvazyan, O. Hensler, H. Schlarb, Ch. Schmidt, N.J. Walker, M. Walla DESY, Hamburg, Germany G.I. Cancelo, B. Chase Fermilab, Batavia, USA J. Carwardine ANL, Argonne, USA W. Cichalewski, W. Jałmużna TUL-DMCS, Łódź, Poland S. Michizono KEK, Ibaraki, Japan
	Since 2009 and under the scope of the International Linear Collider (ILC) R&D, a series of studies takes place twice a year at the Free electron Laser accelerator in Hamburg, (FLASH) DESY, in order to investigate technical challenges related to the high-gradient, high-beam-current design of the ILC. Such issues as operating cavities near their quench limit with high beam loading or in klystron saturation regime are investigated, always pushing the limits of FLASH nominal operational conditions. To support these studies, a series of automation algorithms have been developed and implemented at DESY. These include automatic detection of cavity quenches, automatic adjustment of the superconducting cavity quality factor, and automatic compensation of detuning due to Lorentz forces. This paper explains the functionality of these automation tools, details about their implementation, and shows the experience acquired during the last 9mA ILC test which took place at DESY in February 2012. The benefit of these algorithms and the R&D results these automation tools have permitted will be clearly explained.

Paper

Title

Other Keywords

Page

MOPLB08

Normal Conducting Deflecting Cavity Development at the Cockcroft Institute

cavity, wakefield, damping, electron

159

G. Burt, P.K. Ambattu, A.C. Dexter, C. Lingwood, B.J. Woolley
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
S.R. Buckley, P. Goudket, C. Hill, P.A. McIntosh, J.W. McKenzie, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
V.A. Dolgashev
SLAC, Menlo Park, California, USA
A. Grudiev
CERN, Geneva, Switzerland
R.M. Jones
UMAN, Manchester, United Kingdom

Funding: This work has been supported by STFC and the EU through FP7 EUCARD.
Two normal conducting deflecting structures are currently being developed at the Cockcroft Institute, one as a crab cavity for CLIC and one for bunch slice diagnostics on low energy electron beams for EBTF at Daresbury. Each has its own challenges that need overcome. For CLIC the phase and amplitude tolerances are very stringent and hence beamloading effects and wakefields must be minimised. Significant work has been undertook to understand the effect of the couplers on beamloading and the effect of the couplers on the wakefields. For EBTF the difficulty is avoiding the large beam offset caused by the cavities internal deflecting voltage at the low beam energy. Propotypes for both cavities have been manufactured and results will be presented.

Slides MOPLB08 [1.572 MB]

MOPB021

Bunch-by-bunch Phase Modulation for Linac Beam-loading Compensation

linac, impedance, injection, bunching

216

G. Huang, D. Jia, K. Jin, H. Lin, Weishi, Zhou. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China
Y. Liu
USTC, Hefei, Anhui, People's Republic of China

Funding: supported by NSFC-CAS Joint Fund, contract no. 11079034
If the linac is loaded by a high current, long pulse multi-bunch beam, the energy of the beam drops with time during the pulse. The bunch phase modulation method is introduced to compensate the beam loading. In this method the beam phase in the RF accelerating filed is changed bunch-by-bunch, the beam energy gain in the RF filed gradually grows up, which cancels the drop due to beam loading. The relationship between the beam phase distribution and the linac parameters is calculated in this paper.

MOPB031

Vibration Response Testing of the CEBAF 12 GeV Upgrade Cryomodules

cryomodule, cavity, damping, controls

240

G.K. Davis, J. Matalevich, T. Powers, M. Wiseman
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
The CEBAF 12 GeV upgrade project includes 80 new 7-cell cavities assembled into 10 cryomodules. These cryomodules were tested during production to characterize their microphonic response in situ. For several early cryomodules, detailed (vibration) modal studies of the cryomodule string were performed during the assembly process to identify the structural contributors to the measured cryomodule microphonic response. Structural modifications were then modeled, implemented, and verified by subsequent modal testing and in-situ microphonic response testing. Interim and final results from this multi-stage process will be reviewed.

MOPB079

Normal Conducting Deflecting Cavity Development at the Cockcroft Institute

cavity, wakefield, damping, electron

357

G. Burt, P.K. Ambattu, A.C. Dexter, C. Lingwood, B.J. Woolley
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
S.R. Buckley, P. Goudket, C. Hill, P.A. McIntosh, J.W. McKenzie, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
V.A. Dolgashev
SLAC, Menlo Park, California, USA
A. Grudiev
CERN, Geneva, Switzerland
R.M. Jones
UMAN, Manchester, United Kingdom

Funding: This work has been supported by STFC and the EU through FP7 EUCARD.
Two normal conducting deflecting structures are currently being developed at the Cockcroft Institute, one as a crab cavity for CLIC and one for bunch slice diagnostics on low energy electron beams for EBTF at Daresbury. Each has its own challenges that need overcome. For CLIC the phase and amplitude tolerances are very stringent and hence beamloading effects and wakefields must be minimised. Significant work has been undertook to understand the effect of the couplers on beamloading and the effect of the couplers on the wakefields. For EBTF the difficulty is avoiding the large beam offset caused by the cavities internal deflecting voltage at the low beam energy. Propotypes for both cavities have been manufactured and results will be presented.

TUPB061

ADRC Control for Beam Loading and Microphonics

controls, cavity, LLRF, simulation

615

Z. Zheng, Z. Liu, J. Wei, Y. Zhang, S. Zhao
FRIB, East Lansing, Michigan, USA
Z. Zheng
TUB, Beijing, People's Republic of China

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Superconducting RF (SRF) cavities are subject to many disturbances such as beam loading and microphonics. Although we implemented Proportional Integral (PI) control and Active Disturbance Rejection Control (ADRC) in the Low Level RF (LLRF) system at FRIB to stabilize the RF field, the control loop gains are inadequate in the presence of beam loading and microphonics. An improved scheme is proposed and simulated with much higher gains are achieved. The feasibility to include piezo tuner in ADRC and PI circuit is also presented in this paper.

TUPB107

Amplitude and Phase Control of the Accelerating Field in the ESS Spoke Cavity

cavity, controls, feedback, simulation

708

V.A. Goryashko, R.J.M.Y. Ruber, R.A. Yogi, V.G. Ziemann
Uppsala University, Uppsala, Sweden

We report about numerical simulations of the accelerating field dynamics in the ESS spoke cavity in the presence of the beam loading and Lorentz detuning. A slow feedforward is used to cure the Lorentz detuning whereas a fast feedback through a signal oscillator and cavity pre-detuning technique are applied to eliminate the beam loading effect. An analysis performed with a Simulink model shows that a combination of feedforward, feedback and cavity pre-detuning result in a substantially shorter stabilization time of the field voltage and phase on a required level as compared to a control method using only the feedforward and feedback. The latter allows one to obtain smaller magnitude but longer duration of deviations of the instantaneous voltage and phase from the required nominal values. As a result, a series of cavities only with feedforward and feedback needs an extra control technique to mitigate a cumulative systematic error rising in each cavity. In addition, a technique of adiabatic turning off of the RF power in order to prevent a high reflected power in the case of a sudden beam loss is studied.

THPB064

Beam Dynamics Tools for Linacs Design

electron, simulation, linac, synchrotron

987

A.S. Setty
THALES, Colombes, France

In the last 25 years, we have been using our in house 3D code PRODYN * for electron beam simulations. We have also been using our in house code SECTION for the design of the travelling wave accelerating structures and the beam loading compensation. PRODYN follows in time, the most complicated electron trajectories with relativistic space-charge effects. This code includes backward as well as forwards movements. This paper will describe those two codes and will give some simulations and measurements results.
* D. Tronc and A. Setty, Electrons RF auto-focusing and capture in bunchers, Linear Accelerator Conference 1988, Virginia.

THPB085

LLRF Automation for the 9mA ILC Tests at FLASH

cavity, controls, feedback, cryomodule

1023

J. Branlard, V. Ayvazyan, O. Hensler, H. Schlarb, Ch. Schmidt, N.J. Walker, M. Walla
DESY, Hamburg, Germany
G.I. Cancelo, B. Chase
Fermilab, Batavia, USA
J. Carwardine
ANL, Argonne, USA
W. Cichalewski, W. Jałmużna
TUL-DMCS, Łódź, Poland
S. Michizono
KEK, Ibaraki, Japan

Since 2009 and under the scope of the International Linear Collider (ILC) R&D, a series of studies takes place twice a year at the Free electron Laser accelerator in Hamburg, (FLASH) DESY, in order to investigate technical challenges related to the high-gradient, high-beam-current design of the ILC. Such issues as operating cavities near their quench limit with high beam loading or in klystron saturation regime are investigated, always pushing the limits of FLASH nominal operational conditions. To support these studies, a series of automation algorithms have been developed and implemented at DESY. These include automatic detection of cavity quenches, automatic adjustment of the superconducting cavity quality factor, and automatic compensation of detuning due to Lorentz forces. This paper explains the functionality of these automation tools, details about their implementation, and shows the experience acquired during the last 9mA ILC test which took place at DESY in February 2012. The benefit of these algorithms and the R&D results these automation tools have permitted will be clearly explained.