LINAC2016 - List of Keywords (LLRF)

Paper	Title	Other Keywords	Page
MOPLR072	The Effect of DTL Cavity Field Errors on Beam Spill at LANSCE	DTL, cavity, linac, target	301
	L. Rybarcyk, R.C. McCrady LANL, Los Alamos, New Mexico, USA
	The Los Alamos Neutron Science Center (LANSCE) accelerator comprises two (H⁺ and H⁻) 750-keV Cockcroft-Walton style injectors, a 201.25-MHz, 100-MeV drift-tube linac (DTL) and an 805-MHz, 800-MeV coupled-cavity linac (CCL). As part of the LANSCE Risk Mitigation project a new digital low-level radio frequency (LLRF) control system is being deployed across the linac, starting with the DTL. Related to this upgrade, a study was performed where specific cavity field errors were simultaneously introduced in all DTL tanks about the nominal stable, low-spill, production set points to mimic LLRF control errors. The impact of these errors on the resultant beam spill was quantified for the nominal 100 μA, 800-MeV Lujan beam. We present the details of the measurement approach and results that show a rapid increase in total linac beam spill as DTL cavity field phase and amplitude errors are increased.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR072
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TUPLR010	Measurements and Analysis of Cavity Microphonics and Frequency Control in the Cornell ERL Main Linac Prototype Cryomodule	cavity, linac, cryomodule, vacuum	488
	M. Ge, N. Banerjee, J. Dobbins, R.G. Eichhorn, F. Furuta, G.H. Hoffstaetter, M. Liepe, P. Quigley, J. Sears, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The Cornell Main Linac cryomodule (MLC) is a key component in the CBETA project. The SRF cavities with high loaded-Q in the MLC are very sensitive to microphonics from mechanical vibrations. Poor frequency stability of the cavities would dramatically increase the input RF power required to maintain stable accelerating fields in the SRF cavities. In this paper, we present detailed results from microphonics measurement for the cavities in the MLC, discuss dominant vibration sources, and show vibration damping results. The current microphonics level meets the CBETA requirement of a 36MeV energy gain without applying fast tuner compensation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR010
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TUPLR047	Commissioning of XBox-3: A Very High Capacity X-band Test Stand	klystron, controls, detector, FPGA	568
	N. Catalán Lasheras, C.F. Eymin, J. Giner Navarro, G. McMonagle, S.F. Rey, A. Solodko, I. Syratchev, B.J. Woolley, W. Wuensch CERN, Geneva, Switzerland T. Argyropoulos, D. Esperante Pereira IFIC, Valencia, Spain M. Volpi The University of Melbourne, Melbourne, Victoria, Australia
	The Compact Linear Collider (CLIC) beam-based acceleration baseline uses high-gradient travelling wave accelerating structures at a frequency of 12 GHz. In order to prove the performance of these structures at high peak power and short pulse width RF, two klystron-based test facilities have been put in operation in the last years. The third X-band testing facility at CERN (Xbox3) has recently been commissioned and has tripled the number of testing slots available. Xbox3 uses a novel way of combining relatively low peak power (6 MW) but high average power klystron units whose power is steered to feed four testing slots with RF to the required power with a repetition rate of up to 400 Hz. Besides the repetition rate, peak power, pulse length and pulse shape can be customized to fit the test requirements. This novel way of combining pulsed RF high power can eventually be used for many other applications where multiple test slots are required.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR047
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THPRC009	IF-Mixture Performance During Cavity Conditioning at STF-KEK	cavity, controls, feedback, flattop	785
	S.B. Wibowo Sokendai, Ibaraki, Japan T. Matsumoto, S. Michizono, T. Miura, F. Qiu KEK, Ibaraki, Japan
	The Superconducting rf Test Facility (STF) at High Energy Accelerator Research Organization (KEK) was built for research and development of the International Linear Collider (ILC). In order to satisfy the stability requirement of the accelerating field, a digital low-level RF (LLRF) control system is employed. In this control system, signal from a cavity is down-converted into intermediate frequency (IF) signal before being digitized by analog-to-digital converter (ADC). In order to reduce the required number of ADCs, we proposed a technique that combines several IFs and to be read by a single ADC. Signal reconstruction of each IF is performed by digital signal processing. The performance of this technique, which is named IF-mixture, is reported in this paper.
	Poster THPRC009 [0.992 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC009
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THPRC011	Single LLRF for Multi-Harmonic Buncher	controls, pick-up, experiment, radio-frequency	789
	N.R. Usher, D.M. Alt, J.F. Brandon, D.G. Morris, S. Zhao FRIB, East Lansing, Michigan, USA D.M. Alt NSCL, East Lansing, Michigan, USA
	Funding: Work supported by Michigan State University, National Science Foundation: NSF Award Number PHY-1102511. In this paper, a unique low level radio frequency (LLRF) controller designed for a multi-harmonic buncher (MHB) is presented. Different than conventional designs, the single LLRF output contains three RF frequencies (f1, f2 = 2f1, f3 = 3f1) and is fed to a wide band amplifier driving the MHB. The challenge is while driving f1, due to the non-linearity of the amplifier, the f2 and f3 terms will also be generated and will couple into the control of these two modes. Hence an active cancellation algorithm is used to suppress the nonlinear effect of the amplifier. It is demonstrated in a test that the designed LLRF is able to control the amplitude and phase of the three modes in-dependently.
	Poster THPRC011 [1.944 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC011
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THPRC012	Resonance Control System for the CEBAF Separator Upgrade	cavity, controls, resonance, extraction	792
	T. E. Plawski, R. Bachimanchi, B. Bevins, L. Farrish, C. Hovater, G.E. Lahti, M.J. Wissmann JLab, Newport News, Virgina, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of four new 748.5 MHz normal conducting deflecting cavities in the 5th pass extraction region. The RF system employs two digital LLRF systems controlling four normal conducting cavities in a vector sum setting. Cavity tune information of the individual cavities is obtained using a multiplexing scheme of the forward and reflected RF signals. Water skids equipped with heaters and valves are used to control resonance. A new FPGA-based hardware and EPICS-based predictive control algorithm has been developed to support reliable operation of the beam extraction process. This paper presents the architecture design of the existing hardware and software as well as a plan to develop a model predictive control system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC012
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THPLR025	Modernisation of the 10⁸ MHz RF Systems at the GSI UNILAC	controls, cavity, operation, PLC	898
	B. Schlitt, G. Eichler, S. Hermann, M. Hoerr, M. Mueh, S. Petit, A. Schnase, G. Schreiber, W. Vinzenz, J. Zappai GSI, Darmstadt, Germany
	A substantial modernisation of the RF systems at the 10⁸ MHz Alvarez type post-stripper section of the GSI heavy ion linac UNILAC was launched in 2014 to prepare the existing facility for the future FAIR operation. A new 1.8 MW RF cavity amplifier prototype for low duty-cycle operation (2 ms pulse length at 10 Hz repetition rate) based on the widely-used tetrode TH558SC was designed and built by THALES and is under commissioning. A call for tenders was started for a 150 kW solid state driver amplifier. An RF test bench for the amplifier prototypes is in preparation at GSI including new control racks, commercial grid power supplies, and a modern PLC system for amplifier control. The existing powerful 1 MVA anode power supplies will be reused and are also being equipped with new PLC systems. The development of a digital low-level RF system based on the MTCA.4 standard and commercial vector modulator and FPGA boards was started. Status and details of the modernisation as well as first commissioning results of the new high power amplifier prototype will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR025
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THPLR048	Development of a Digital LLRF Control System at LNL	FPGA, controls, cavity, radio-frequency	966
	S. Pavinato, M. Betti, D. Bortolato, F. Gelain, D. Marcato, D. Pedretti INFN/LNL, Legnaro (PD), Italy M.A. Bellato, R. Isocrate INFN- Sez. di Padova, Padova, Italy M. Bertocco UNIPD, Padova (PD), Italy
	The new Low-Level Radio Frequency (LLRF) control system for linear accelerator at Legnaro National Laboratories (LNL) of INFN is presently being commissioned. A digital Radio Frequency (RF) controller was implemented. Its goal is to stabilize the amplitude, the phase and the frequency of the superconducting cavities of the Linac. The resonance frequency of the low beta cavities is 80 MHz, while medium and high beta cavities resonate at 160 MHz. Each RF controller controls at the same time eight different cavities. The hardware complexity of the RF controller (RF IOC) is reduced by adopting direct RF sampling and the RF to baseband conversion method. The main hardware components are RF ADCs for the direct undersampling of the signals picked up from cavities, a Xilinx Kintek 7 FPGA for the signal processing and DACs for driving the power amplifiers and hence the cavities. In the RF IOC the serial communication between FPGA and ADCs and between FPGA and DACs is based on JESD204b standard. An RF front-end board (RFFE) is placed between cavities and the RF IOC. This is used to adapt the power level of the RF signal from the cavities to the ADCs and from the DACs to the power amplifiers. This paper addresses the LLRF control system focusing on the hardware design of the RF IOC and RFFE boards and on the first test results carried out with the new controller.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR048
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOPLR072

The Effect of DTL Cavity Field Errors on Beam Spill at LANSCE

DTL, cavity, linac, target

301

L. Rybarcyk, R.C. McCrady
LANL, Los Alamos, New Mexico, USA

The Los Alamos Neutron Science Center (LANSCE) accelerator comprises two (H⁺ and H⁻) 750-keV Cockcroft-Walton style injectors, a 201.25-MHz, 100-MeV drift-tube linac (DTL) and an 805-MHz, 800-MeV coupled-cavity linac (CCL). As part of the LANSCE Risk Mitigation project a new digital low-level radio frequency (LLRF) control system is being deployed across the linac, starting with the DTL. Related to this upgrade, a study was performed where specific cavity field errors were simultaneously introduced in all DTL tanks about the nominal stable, low-spill, production set points to mimic LLRF control errors. The impact of these errors on the resultant beam spill was quantified for the nominal 100 μA, 800-MeV Lujan beam. We present the details of the measurement approach and results that show a rapid increase in total linac beam spill as DTL cavity field phase and amplitude errors are increased.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR072

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPLR010

Measurements and Analysis of Cavity Microphonics and Frequency Control in the Cornell ERL Main Linac Prototype Cryomodule

cavity, linac, cryomodule, vacuum

488

M. Ge, N. Banerjee, J. Dobbins, R.G. Eichhorn, F. Furuta, G.H. Hoffstaetter, M. Liepe, P. Quigley, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The Cornell Main Linac cryomodule (MLC) is a key component in the CBETA project. The SRF cavities with high loaded-Q in the MLC are very sensitive to microphonics from mechanical vibrations. Poor frequency stability of the cavities would dramatically increase the input RF power required to maintain stable accelerating fields in the SRF cavities. In this paper, we present detailed results from microphonics measurement for the cavities in the MLC, discuss dominant vibration sources, and show vibration damping results. The current microphonics level meets the CBETA requirement of a 36MeV energy gain without applying fast tuner compensation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR010

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPLR047

Commissioning of XBox-3: A Very High Capacity X-band Test Stand

klystron, controls, detector, FPGA

568

N. Catalán Lasheras, C.F. Eymin, J. Giner Navarro, G. McMonagle, S.F. Rey, A. Solodko, I. Syratchev, B.J. Woolley, W. Wuensch
CERN, Geneva, Switzerland
T. Argyropoulos, D. Esperante Pereira
IFIC, Valencia, Spain
M. Volpi
The University of Melbourne, Melbourne, Victoria, Australia

The Compact Linear Collider (CLIC) beam-based acceleration baseline uses high-gradient travelling wave accelerating structures at a frequency of 12 GHz. In order to prove the performance of these structures at high peak power and short pulse width RF, two klystron-based test facilities have been put in operation in the last years. The third X-band testing facility at CERN (Xbox3) has recently been commissioned and has tripled the number of testing slots available. Xbox3 uses a novel way of combining relatively low peak power (6 MW) but high average power klystron units whose power is steered to feed four testing slots with RF to the required power with a repetition rate of up to 400 Hz. Besides the repetition rate, peak power, pulse length and pulse shape can be customized to fit the test requirements. This novel way of combining pulsed RF high power can eventually be used for many other applications where multiple test slots are required.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR047

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRC009

IF-Mixture Performance During Cavity Conditioning at STF-KEK

cavity, controls, feedback, flattop

785

S.B. Wibowo
Sokendai, Ibaraki, Japan
T. Matsumoto, S. Michizono, T. Miura, F. Qiu
KEK, Ibaraki, Japan

The Superconducting rf Test Facility (STF) at High Energy Accelerator Research Organization (KEK) was built for research and development of the International Linear Collider (ILC). In order to satisfy the stability requirement of the accelerating field, a digital low-level RF (LLRF) control system is employed. In this control system, signal from a cavity is down-converted into intermediate frequency (IF) signal before being digitized by analog-to-digital converter (ADC). In order to reduce the required number of ADCs, we proposed a technique that combines several IFs and to be read by a single ADC. Signal reconstruction of each IF is performed by digital signal processing. The performance of this technique, which is named IF-mixture, is reported in this paper.

Poster THPRC009 [0.992 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC009

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRC011

Single LLRF for Multi-Harmonic Buncher

controls, pick-up, experiment, radio-frequency

789

N.R. Usher, D.M. Alt, J.F. Brandon, D.G. Morris, S. Zhao
FRIB, East Lansing, Michigan, USA
D.M. Alt
NSCL, East Lansing, Michigan, USA

Funding: Work supported by Michigan State University, National Science Foundation: NSF Award Number PHY-1102511.
In this paper, a unique low level radio frequency (LLRF) controller designed for a multi-harmonic buncher (MHB) is presented. Different than conventional designs, the single LLRF output contains three RF frequencies (f1, f2 = 2*f1, f3 = 3*f1) and is fed to a wide band amplifier driving the MHB. The challenge is while driving f1, due to the non-linearity of the amplifier, the f2 and f3 terms will also be generated and will couple into the control of these two modes. Hence an active cancellation algorithm is used to suppress the nonlinear effect of the amplifier. It is demonstrated in a test that the designed LLRF is able to control the amplitude and phase of the three modes in-dependently.

Poster THPRC011 [1.944 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRC012

Resonance Control System for the CEBAF Separator Upgrade

cavity, controls, resonance, extraction

792

T. E. Plawski, R. Bachimanchi, B. Bevins, L. Farrish, C. Hovater, G.E. Lahti, M.J. Wissmann
JLab, Newport News, Virgina, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of four new 748.5 MHz normal conducting deflecting cavities in the 5th pass extraction region. The RF system employs two digital LLRF systems controlling four normal conducting cavities in a vector sum setting. Cavity tune information of the individual cavities is obtained using a multiplexing scheme of the forward and reflected RF signals. Water skids equipped with heaters and valves are used to control resonance. A new FPGA-based hardware and EPICS-based predictive control algorithm has been developed to support reliable operation of the beam extraction process. This paper presents the architecture design of the existing hardware and software as well as a plan to develop a model predictive control system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPLR025

Modernisation of the 10⁸ MHz RF Systems at the GSI UNILAC

controls, cavity, operation, PLC

898

B. Schlitt, G. Eichler, S. Hermann, M. Hoerr, M. Mueh, S. Petit, A. Schnase, G. Schreiber, W. Vinzenz, J. Zappai
GSI, Darmstadt, Germany

A substantial modernisation of the RF systems at the 10⁸ MHz Alvarez type post-stripper section of the GSI heavy ion linac UNILAC was launched in 2014 to prepare the existing facility for the future FAIR operation. A new 1.8 MW RF cavity amplifier prototype for low duty-cycle operation (2 ms pulse length at 10 Hz repetition rate) based on the widely-used tetrode TH558SC was designed and built by THALES and is under commissioning. A call for tenders was started for a 150 kW solid state driver amplifier. An RF test bench for the amplifier prototypes is in preparation at GSI including new control racks, commercial grid power supplies, and a modern PLC system for amplifier control. The existing powerful 1 MVA anode power supplies will be reused and are also being equipped with new PLC systems. The development of a digital low-level RF system based on the MTCA.4 standard and commercial vector modulator and FPGA boards was started. Status and details of the modernisation as well as first commissioning results of the new high power amplifier prototype will be reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR025

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPLR048

Development of a Digital LLRF Control System at LNL

FPGA, controls, cavity, radio-frequency

966

S. Pavinato, M. Betti, D. Bortolato, F. Gelain, D. Marcato, D. Pedretti
INFN/LNL, Legnaro (PD), Italy
M.A. Bellato, R. Isocrate
INFN- Sez. di Padova, Padova, Italy
M. Bertocco
UNIPD, Padova (PD), Italy

The new Low-Level Radio Frequency (LLRF) control system for linear accelerator at Legnaro National Laboratories (LNL) of INFN is presently being commissioned. A digital Radio Frequency (RF) controller was implemented. Its goal is to stabilize the amplitude, the phase and the frequency of the superconducting cavities of the Linac. The resonance frequency of the low beta cavities is 80 MHz, while medium and high beta cavities resonate at 160 MHz. Each RF controller controls at the same time eight different cavities. The hardware complexity of the RF controller (RF IOC) is reduced by adopting direct RF sampling and the RF to baseband conversion method. The main hardware components are RF ADCs for the direct undersampling of the signals picked up from cavities, a Xilinx Kintek 7 FPGA for the signal processing and DACs for driving the power amplifiers and hence the cavities. In the RF IOC the serial communication between FPGA and ADCs and between FPGA and DACs is based on JESD204b standard. An RF front-end board (RFFE) is placed between cavities and the RF IOC. This is used to adapt the power level of the RF signal from the cavities to the ADCs and from the DACs to the power amplifiers. This paper addresses the LLRF control system focusing on the hardware design of the RF IOC and RFFE boards and on the first test results carried out with the new controller.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR048

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)