ERL2019 - Table of Session: TUCOZBS (WG4: Superconducting RF)

Paper	Title	Page
TUCOZBS02	A Ferroelectric Fast Reactive Tuner (FE-FRT) to Combat Microphonics	42
	N.C. Shipman, J. Bastard, M.R. Coly, F. Gerigk, A. Macphersonpresenter, N. Stapley CERN, Geneva, Switzerland I. Ben-Zvi BNL, Upton, New York, USA G. Burt, A. Castilla Lancaster University, Lancaster, United Kingdom C.-J. Jing, A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA E. Nenasheva Ceramics Ltd., St. Petersburg, Russia
	A prototype Fast Reactive Tuner (FRT) for superconducting cavities has been developed, which allows the frequency to be controlled by application of a potential difference across a newly developed ultra-low loss ferro-electric material residing within the tuner. The tuner operates at room temperature, outside of the cryostat and coupled to the cavity via an antenna and co-axial cable. This technique allows for active compensation of microphonics, eliminating the need to design over-coupled fundamental power couplers and thus significantly reducing RF power particularly for low beam current applications. Modelling; simulation; and stability analysis, of the tuner; cavity; measurement system; and feedback loop, have been performed in the frequency and time domain, and are compared to the latest experimental results. The potential benefits of applying this techniques to ERLs, which are seen as one of the major use cases, are detailed both in general and with regards to specific projects. Ideas and designs for an improved next generation FRT are also discussed.
	Slides TUCOZBS02 [5.607 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-TUCOZBS02
About •	paper received ※ 17 September 2019 paper accepted ※ 06 November 2019 issue date ※ 24 June 2020
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TUCOZBS04	Characterization of Microphonics in the cERL Main Linac Superconducting Cavities	48
	F. Qiu, D.A. Arakawa, M. Egi, E. Kako, H. Katagiri, T. Konomi, T. Matsumoto, S. Michizono, T. Miura, H. Sakai, K. Umemori KEK, Ibaraki, Japan M. Egi, S. Michizono Sokendai - Hayama, Hayama, Japan E. Kako, T. Konomi, T. Matsumoto, T. Miura, F. Qiu, H. Sakai, K. Umemori Sokendai, Ibaraki, Japan
	In the main linac (ML) of the KEK-cERL, two superconducting cavities with high loaded Q (QL ¿ 1×107) are operated in continuous wave (CW) mode. It is important to control and suppress the microphonics detuning owing to the low bandwidth of the cavities. We evaluated the background microphonics detuning by the low level radio frequency system during the beam operation. Interestingly, a ¿field level dependence microphonics¿ phenomenon was observed on one of the cavities in the ML. Several frequency components were suddenly excited if the cavity field is above a threshold field (~3 MV/m). We found that this threshold field is probably related with the cavity quench limits despite the unclear inherent physical mechanism. Furthermore, in order to optimize the cavity resonance control system for better microphonics rejection, we have measured the mechanical transfer function between the fast piezo tuner and cavity detuning. Finally, we validated this model by comparing the model response with actual system response.
	Slides TUCOZBS04 [7.564 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-TUCOZBS04
About •	paper received ※ 13 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020
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TUCOZBS05	Low Level RF ERL Experience at the S-DALINAC*	52
	M. Steinhorst, M. Arnold, T. Bahlo, R. Grewe, L.E. Jürgensen, J. Pforr, N. Pietralla, F. Schließmann, S. Weih TU Darmstadt, Darmstadt, Germany
	Funding: Supported by the DFG through GRK 2128. The recirculating superconducting Darmstadt linear accelerator S-DALINAC [1] is one of the main research instruments at the institute for nuclear physics at the TU Darmstadt. It is operating in cw mode at beam currents of up to 20 uA with energies of up to 130 MeV using a thrice recirculating scheme. In 2010 the present digital low-level rf (LLRF) control system was set into operation. Since 2017 the S-DALINAC can be used as an energy recovery linac (ERL). The ERL mode is adjusted by shifting the phase of the beam by 180° in the second recirculation. The current setup of the LLRF control system is not optimized for the usage in an ERL operation. Therefore investigations in regard of the rf control performance have to be done. The first successful one turn ERL operation was set up in August 2017 where the rf control performance was investigated the first time in this new mode. In this talk the LLRF control system of the S-DALINAC is presented and its perfomance during an ERL operation is discussed. [1] N. Pietralla, Nucl. Phys. News 28 No. 2, 4 (2018).
	Slides TUCOZBS05 [26.760 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-TUCOZBS05
About •	paper received ※ 13 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020
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TUCOZBS06	Cryomodules for the Mainz Energy-Recovering Superconducting Accelerator (MESA)	56
	T. Stengler, K. Aulenbacher, F. Hugpresenter, D. Simon, C.P. Stoll, S.D.W. Thomas KPH, Mainz, Germany K. Aulenbacher HIM, Mainz, Germany K. Aulenbacher GSI, Darmstadt, Germany
	Funding: This work is supported by the German Research Foundation (DFG) under the Cluster of Excellence "PRISMA+" EXC 2118/2019} The Mainz Energy-recovering Superconducting Accelerator (MESA) will be an electron accelerator allowing c.w. operation in energy-recovery (ER) mode. The energy gain of 50 MeV will be provided by two modified ELBE/Rossendorf-type cryomodules. The MESA-cryomodules are delivered and tested. The test results will be discussed.
	Slides TUCOZBS06 [10.644 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-TUCOZBS06
About •	paper received ※ 16 September 2019 paper accepted ※ 11 November 2019 issue date ※ 24 June 2020
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

A Ferroelectric Fast Reactive Tuner (FE-FRT) to Combat Microphonics

42

N.C. Shipman, J. Bastard, M.R. Coly, F. Gerigk, A. Macphersonpresenter, N. Stapley
CERN, Geneva, Switzerland
I. Ben-Zvi
BNL, Upton, New York, USA
G. Burt, A. Castilla
Lancaster University, Lancaster, United Kingdom
C.-J. Jing, A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
E. Nenasheva
Ceramics Ltd., St. Petersburg, Russia

A prototype Fast Reactive Tuner (FRT) for superconducting cavities has been developed, which allows the frequency to be controlled by application of a potential difference across a newly developed ultra-low loss ferro-electric material residing within the tuner. The tuner operates at room temperature, outside of the cryostat and coupled to the cavity via an antenna and co-axial cable. This technique allows for active compensation of microphonics, eliminating the need to design over-coupled fundamental power couplers and thus significantly reducing RF power particularly for low beam current applications. Modelling; simulation; and stability analysis, of the tuner; cavity; measurement system; and feedback loop, have been performed in the frequency and time domain, and are compared to the latest experimental results. The potential benefits of applying this techniques to ERLs, which are seen as one of the major use cases, are detailed both in general and with regards to specific projects. Ideas and designs for an improved next generation FRT are also discussed.

Slides TUCOZBS02 [5.607 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-TUCOZBS02

About •

paper received ※ 17 September 2019 paper accepted ※ 06 November 2019 issue date ※ 24 June 2020

Export •

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

TUCOZBS04

Characterization of Microphonics in the cERL Main Linac Superconducting Cavities

48

F. Qiu, D.A. Arakawa, M. Egi, E. Kako, H. Katagiri, T. Konomi, T. Matsumoto, S. Michizono, T. Miura, H. Sakai, K. Umemori
KEK, Ibaraki, Japan
M. Egi, S. Michizono
Sokendai - Hayama, Hayama, Japan
E. Kako, T. Konomi, T. Matsumoto, T. Miura, F. Qiu, H. Sakai, K. Umemori
Sokendai, Ibaraki, Japan

In the main linac (ML) of the KEK-cERL, two superconducting cavities with high loaded Q (QL ¿ 1×107) are operated in continuous wave (CW) mode. It is important to control and suppress the microphonics detuning owing to the low bandwidth of the cavities. We evaluated the background microphonics detuning by the low level radio frequency system during the beam operation. Interestingly, a ¿field level dependence microphonics¿ phenomenon was observed on one of the cavities in the ML. Several frequency components were suddenly excited if the cavity field is above a threshold field (~3 MV/m). We found that this threshold field is probably related with the cavity quench limits despite the unclear inherent physical mechanism. Furthermore, in order to optimize the cavity resonance control system for better microphonics rejection, we have measured the mechanical transfer function between the fast piezo tuner and cavity detuning. Finally, we validated this model by comparing the model response with actual system response.

Slides TUCOZBS04 [7.564 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-TUCOZBS04

About •

paper received ※ 13 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020

Export •

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

TUCOZBS05

Low Level RF ERL Experience at the S-DALINAC*

52

M. Steinhorst, M. Arnold, T. Bahlo, R. Grewe, L.E. Jürgensen, J. Pforr, N. Pietralla, F. Schließmann, S. Weih
TU Darmstadt, Darmstadt, Germany

Funding: *Supported by the DFG through GRK 2128.
The recirculating superconducting Darmstadt linear accelerator S-DALINAC [1] is one of the main research instruments at the institute for nuclear physics at the TU Darmstadt. It is operating in cw mode at beam currents of up to 20 uA with energies of up to 130 MeV using a thrice recirculating scheme. In 2010 the present digital low-level rf (LLRF) control system was set into operation. Since 2017 the S-DALINAC can be used as an energy recovery linac (ERL). The ERL mode is adjusted by shifting the phase of the beam by 180° in the second recirculation. The current setup of the LLRF control system is not optimized for the usage in an ERL operation. Therefore investigations in regard of the rf control performance have to be done. The first successful one turn ERL operation was set up in August 2017 where the rf control performance was investigated the first time in this new mode. In this talk the LLRF control system of the S-DALINAC is presented and its perfomance during an ERL operation is discussed.
*[1] N. Pietralla, Nucl. Phys. News 28 No. 2, 4 (2018).

Slides TUCOZBS05 [26.760 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-TUCOZBS05

About •

paper received ※ 13 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020

Export •

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

TUCOZBS06

Cryomodules for the Mainz Energy-Recovering Superconducting Accelerator (MESA)

56

T. Stengler, K. Aulenbacher, F. Hugpresenter, D. Simon, C.P. Stoll, S.D.W. Thomas
KPH, Mainz, Germany
K. Aulenbacher
HIM, Mainz, Germany
K. Aulenbacher
GSI, Darmstadt, Germany

Funding: This work is supported by the German Research Foundation (DFG) under the Cluster of Excellence "PRISMA+" EXC 2118/2019}
The Mainz Energy-recovering Superconducting Accelerator (MESA) will be an electron accelerator allowing c.w. operation in energy-recovery (ER) mode. The energy gain of 50 MeV will be provided by two modified ELBE/Rossendorf-type cryomodules. The MESA-cryomodules are delivered and tested. The test results will be discussed.

Slides TUCOZBS06 [10.644 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-TUCOZBS06

About •

paper received ※ 16 September 2019 paper accepted ※ 11 November 2019 issue date ※ 24 June 2020

Export •

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