SRF2019 - List of Authors (Branlard, J.)

Paper	Title	Page
SATU2	LLRF Controls and RF Operation
	J. Branlard DESY, Hamburg, Germany
	This tutorial presents the challenges and techniques involved in low level radio frequency (LLRF) controls of superconducting (SRF) cavities. The fundamentals of the electro-mechanical model of SRF cavities are recalled; the principles of frequency and bandwidth tuning and its impact on cavity field regulation are presented as well. The basic elements of standard digital LLRF systems are introduced: feed forward, feedback, up and down conversion, sampling, IQ detection and digital processing. The difference between single cavity regulation and vector sum control, pulsed and continuous wave operation are discussed. When applicable, the introduced concepts will be illustrated with real examples, taken from machine operation.
	Slides SATU2 [9.177 MB]
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MOFAA2	Operation of the European XFEL Towards the Maximum Energy	9
	M. Omet, V. Ayvazyan, J. Branlard, S. Choroba, W. Decking, V.V. Katalev, D. Kostin, L. Lilje, P. Morozov, Y. Nachtigal, H. Schlarb, V. Vogel, N. Walker, B. Yildirim DESY, Hamburg, Germany
	After the initial commissioning of the available 25 radio frequency (RF) stations of the European XFEL (RF gun, A1, AH1 and stations A2 through A23) a maximum electron beam energy of 14.5 GeV was achieved, 3 GeV short of the design energy of 17.5 GeV. In order to tackle this problem, the Maximum Gradient Task Force (MGTF) was formed. In the scope of the work of the MGTF, RF stations A6 through A25 (linac L3) were systematically investigated and voltage-limiting factors of the SRF accelerating modules and their RF distribution system were identified and improved. As a result, the design electron beam energy was exceeded at 17.6 GeV on the 18.7.2018. Beside this an overview over the regular RF operation at the European XFEL is given.
	Slides MOFAA2 [5.695 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOFAA2
About •	paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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TUP033	Modal Analysis of the EXFEL 1.3 GHz Cavity and Cryomodule Main Components and Comparison with Measured Data	488
	S. Barbanotti, A. Bellandi, J. Branlard, K. Jensch DESY, Hamburg, Germany
	Future upgrades of the European X-ray Free Electron Laser (EXFEL) may require driving the linac at higher duty factor, possibly extending to Continuous Wave (CW) mode. An R&D program has started at DESY, to prepare for a CW upgrade. Cryomodules are being tested in CW mode in our CryoModule Test Bench (CMTB) to study the performance and main issues for such an operation mode. Sensitivity to vibration causing microphonics is one of the main concerns for the CW operation in mode. Therefore a detailed analysis is being performed to evaluate the frequency spectrum of the EXFEL cryomodule main components: the cavity itself, the cavity string, the cold mass and the vacuum vessel. Finite Element Modal Analyses have been performed and the results compared with data measured at the CMTB. This paper summarizes the main results and conclusions of such a study.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP033
About •	paper received ※ 18 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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THP073	Advanced LLRF System Setup Tool for RF Field Regulation of SRF Cavities	1063
	S. Pfeiffer, J. Branlard, M. Hoffmann, Ch. Schmidt DESY, Hamburg, Germany
	Feedback operation at the European XFEL ensures an amplitude and phase stability of 0.01% and 0.01 deg, respectively. To reach such high RF field stability, model-based approaches for RF field system characterization and RF field controller design are in use. High demand on this system modelling is set especially to the characterization of additional passband modes for small bandwidth SRF cavities operated in pulsed mode and vector-sum regulation. This contribution discusses the developed "Advanced system setup tool" using a graphical user implementation in Matlab® for the RF field system characterization and the multiple-input-multiple-output feedback controller setup. Examples and current limitations will be presented.
	Poster THP073 [0.873 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP073
About •	paper received ※ 19 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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THP092	Status of Cryomodule Testing at CMTB for CW R&D	1129
	J. Branlard, V. Ayvazyan, A. Bellandi, J. Eschke, Ç. Gümüş, D. Kostin, K.P. Przygoda, H. Schlarb, J.K. Sekutowicz DESY, Hamburg, Germany
	Cryo Module Test Bench (CMTB) is a facility to perform tests on European XFEL like superconducting accelerating modules. The 120 kW Inductive Output Tube (IOT) installed in the facility allows driving the eight superconducting cavities inside the module under test in a vector-sum or single cavity control fashion with average Continuous Wave (CW) gradients higher than 20 MV/m. The scope of these tests is to evaluate the feasibility of upgrading European XFEL to CW operation mode. Following the successful tests done on a prototype module XM-3 the initial performance results on the production module XM50 will be presented in this paper. Because of European XFEL requirements, XM50 is equipped with modified couplers that allow a variable Loaded Quality factor(QL) to values higher than 4x10⁷. A cost relevant open question is the maximum QL that can be reached while maintaining the system within the European XFEL field stability specifications of 0.01 % in amplitude and 0.01 deg in phase. Because of this, the LLRF system capability of rejecting microphonic and RF disturbances, as well as Lorentz Force Detuning (LFD) related effects in open and closed loop is of prime interest.
	Poster THP092 [1.514 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP092
About •	paper received ※ 25 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

SATU2

LLRF Controls and RF Operation

J. Branlard
DESY, Hamburg, Germany

This tutorial presents the challenges and techniques involved in low level radio frequency (LLRF) controls of superconducting (SRF) cavities. The fundamentals of the electro-mechanical model of SRF cavities are recalled; the principles of frequency and bandwidth tuning and its impact on cavity field regulation are presented as well. The basic elements of standard digital LLRF systems are introduced: feed forward, feedback, up and down conversion, sampling, IQ detection and digital processing. The difference between single cavity regulation and vector sum control, pulsed and continuous wave operation are discussed. When applicable, the introduced concepts will be illustrated with real examples, taken from machine operation.

Slides SATU2 [9.177 MB]

Export •

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

MOFAA2

Operation of the European XFEL Towards the Maximum Energy

9

M. Omet, V. Ayvazyan, J. Branlard, S. Choroba, W. Decking, V.V. Katalev, D. Kostin, L. Lilje, P. Morozov, Y. Nachtigal, H. Schlarb, V. Vogel, N. Walker, B. Yildirim
DESY, Hamburg, Germany

After the initial commissioning of the available 25 radio frequency (RF) stations of the European XFEL (RF gun, A1, AH1 and stations A2 through A23) a maximum electron beam energy of 14.5 GeV was achieved, 3 GeV short of the design energy of 17.5 GeV. In order to tackle this problem, the Maximum Gradient Task Force (MGTF) was formed. In the scope of the work of the MGTF, RF stations A6 through A25 (linac L3) were systematically investigated and voltage-limiting factors of the SRF accelerating modules and their RF distribution system were identified and improved. As a result, the design electron beam energy was exceeded at 17.6 GeV on the 18.7.2018. Beside this an overview over the regular RF operation at the European XFEL is given.

Slides MOFAA2 [5.695 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOFAA2

About •

paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

Export •

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

TUP033

Modal Analysis of the EXFEL 1.3 GHz Cavity and Cryomodule Main Components and Comparison with Measured Data

488

S. Barbanotti, A. Bellandi, J. Branlard, K. Jensch
DESY, Hamburg, Germany

Future upgrades of the European X-ray Free Electron Laser (EXFEL) may require driving the linac at higher duty factor, possibly extending to Continuous Wave (CW) mode. An R&D program has started at DESY, to prepare for a CW upgrade. Cryomodules are being tested in CW mode in our CryoModule Test Bench (CMTB) to study the performance and main issues for such an operation mode. Sensitivity to vibration causing microphonics is one of the main concerns for the CW operation in mode. Therefore a detailed analysis is being performed to evaluate the frequency spectrum of the EXFEL cryomodule main components: the cavity itself, the cavity string, the cold mass and the vacuum vessel. Finite Element Modal Analyses have been performed and the results compared with data measured at the CMTB. This paper summarizes the main results and conclusions of such a study.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP033

About •

paper received ※ 18 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

Export •

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

THP073

Advanced LLRF System Setup Tool for RF Field Regulation of SRF Cavities

1063

S. Pfeiffer, J. Branlard, M. Hoffmann, Ch. Schmidt
DESY, Hamburg, Germany

Feedback operation at the European XFEL ensures an amplitude and phase stability of 0.01% and 0.01 deg, respectively. To reach such high RF field stability, model-based approaches for RF field system characterization and RF field controller design are in use. High demand on this system modelling is set especially to the characterization of additional passband modes for small bandwidth SRF cavities operated in pulsed mode and vector-sum regulation. This contribution discusses the developed "Advanced system setup tool" using a graphical user implementation in Matlab® for the RF field system characterization and the multiple-input-multiple-output feedback controller setup. Examples and current limitations will be presented.

Poster THP073 [0.873 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP073

About •

paper received ※ 19 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

Export •

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

THP092

Status of Cryomodule Testing at CMTB for CW R&D

1129

J. Branlard, V. Ayvazyan, A. Bellandi, J. Eschke, Ç. Gümüş, D. Kostin, K.P. Przygoda, H. Schlarb, J.K. Sekutowicz
DESY, Hamburg, Germany

Cryo Module Test Bench (CMTB) is a facility to perform tests on European XFEL like superconducting accelerating modules. The 120 kW Inductive Output Tube (IOT) installed in the facility allows driving the eight superconducting cavities inside the module under test in a vector-sum or single cavity control fashion with average Continuous Wave (CW) gradients higher than 20 MV/m. The scope of these tests is to evaluate the feasibility of upgrading European XFEL to CW operation mode. Following the successful tests done on a prototype module XM-3 the initial performance results on the production module XM50 will be presented in this paper. Because of European XFEL requirements, XM50 is equipped with modified couplers that allow a variable Loaded Quality factor(QL) to values higher than 4x10⁷. A cost relevant open question is the maximum QL that can be reached while maintaining the system within the European XFEL field stability specifications of 0.01 % in amplitude and 0.01 deg in phase. Because of this, the LLRF system capability of rejecting microphonic and RF disturbances, as well as Lorentz Force Detuning (LFD) related effects in open and closed loop is of prime interest.

Poster THP092 [1.514 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP092

About •

paper received ※ 25 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

Export •

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