LINAC2016 - Classification: 3 Technology / 3B Room Temperature RF

Paper	Title	Page
MOOP04	Traveling Wave Linear Accelerator With RF Power Flow Outside of Accelerating Cavities	48
MOPRC030	use link to see paper's listing under its alternate paper code
	V.A. Dolgashev SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. DOE under Contract No. DE-AC02-76-SF00515. An accelerating structure is a critical component of particle accelerators for medical, security, industrial and scientific applications. Standing-wave side-coupled accelerating structures are used where available RF power is at a premium, while average current and average RF power lost in the structure are high. These structures are expensive to manufacture and typically require a circulator to divert structure-reflected power away from RF source, klystron or magnetron. In this report a traveling wave accelerating structure is presented which combines high shunt impedance of the side-coupled standing wave structure with such advantages as simpler tuning and manufacturing. In addition, the structure is matched to the RF source so no circulator is needed. This paper presents the motivation for this structure and shows a practical example.
	Slides MOOP04 [5.459 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP04
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MOOP05	Dry-Ice Cleaning of RF-Structures at DESY	52
MOPRC032	use link to see paper's listing under its alternate paper code
	A. Brinkmann, J. Ziegler DESY, Hamburg, Germany
	Dry-Ice cleaning is today a well established cleaning method in matters of reducing harmful dark current and field emission in copper RF-structures like RF-Guns such as for the European XFEL, FLASH and REGAE. This led to the idea to clean longer RF-structures, in particular 3GHz transverse deflecting structures for the European XFEL. We developed a cleaning device with the possibility to clean up to 2 m long structures in horizontal position with an inner diameter of not more than 40 mm. Furthermore this device also allows to clean 9-cell TESLA-type Nb-cavities as well. A report of the technical layout and results of RF-tests will be given.
	Slides MOOP05 [0.969 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP05
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TU2A04	High-Gradient RF Development and Applications	368
	W. Wuensch CERN, Geneva, Switzerland
	Significant progress has been made by the CLIC collaboration to understand the phenomena which limit gradient in normal-conducting accelerating structures and to increase achievable gradient in excess of 100 MV/m. Scientific and technological highlights from the CLIC high-gradient program are presented along with on-going developments and future plans. The talk will also give an overview of the range of applications that potentially benefit from high-frequency and high-gradient accelerating technology.
	Slides TU2A04 [14.317 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TU2A04
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TUPLR035	RF Analysis of Electropolishing for EXFEL Cavities Production at Ettore Zanon Spa	544
	A.A. Sulimov DESY, Hamburg, Germany M. Giaretta, A. Gresele, A. Visentin Ettore Zanon S.p.A., Nuclear Division, Schio, Italy
	After successful finishing of superconducting cavities mass production at Ettore Zanon S.p.A. (EZ) for the European XFEL (EXFEL), the authors had the possibility to provide a detailed analysis of the electropolishing (EP) process. The analysis of EP material removal is based on specified RF measurements and was used for the determination of both, the ratio between cavity's iris and equator and uniformity in different cells. A comparison of the RF measurements results with mechanical measurements is presented.
	Poster TUPLR035 [0.195 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR035
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TUPLR038	The DTL Post Coupler - An Ingenious Invention Turns 50	547
	S. Ramberger CERN, Geneva, Switzerland M.R. Khalvati IPM, Tehran, Iran
	In September 1967, the patent for "A method and device for stabilization of the field distribution in drift tube linac" has been filed by Edward A. Knapp, Donald A. Swenson, and James M. Potter of Los Alamos National Laboratory. It is this invention which to a good part led to the success of highly efficient Alvarez drift tube linacs (DTLs) in that it considerably reduces field errors. The explanation for why the post coupler when tuned correctly has such a strong stabilizing effect has been given at the time in an accompanying paper by describing the modal confluence of the accelerating mode band with the post-coupler mode band, turning a comparatively sensitive 0-mode structure into a stable pi/2-mode like structure. As ingenious as the invention of the post-coupler appears, as poor has been the way of finding its optimum length by relying mainly on trial and error. With the design of the Linac4 DTL at CERN, a new technique has been derived by a DTL equivalent circuit model. Understanding stabilization on an almost cell by cell level provides a new way of optimizing post-couplers of an entire structure with few measurements and even without the extraction of the circuit model itself. Previous approaches to post-coupler stabilization are reviewed and the new, straightforward and accurate technique is described and demonstrated in the stabilization of the Linac4 DTL structures.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR038
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TUPLR040	The RF System of Thomx	551
	M. El Khaldi, R. Marie, H. Monard, F. Wicek LAL, Orsay, France M. Diop, L.R. Lopes, A. Loulergue, M. Louvet, P. Marchand, F. Ribeiro, R. Sreedharan SOLEIL, Gif-sur-Yvette, France
	The RF system of the ThomX electron storage ring consists in a 500 MHz single cell copper cavity of the ELETTRA type, powered with a 50 kW CW solid state power amplifier (SSPA), and the associated Low Level RF feedback and control loops. The low operating energy of 50/70 MeV makes the impedances of the cavity higher order modes (HOMs) particularly critical for the beam stability. Their parasitic effects on the beam can be cured by HOM frequency shifting techniques, based on a fine temperature tuning and a dedicated plunger. A typical cavity temperature stability of ± 0.05°C within a range from 30 up to 70 °C can be achieved by a precise control of its water cooling temperature. On the other hand, the tuning of the cavity fundamental mode is achieved by changing its axial length by means of a motor-driven mechanism. A general description of the system and the state of its progress are reported together with some considerations of the effects of beam cavity interactions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR040
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TUPLR041	Manufacturing, Assembly and Tests of the LIPAc Medium Energy Beam Transport Line (MEBT)	554
	I. Podadera, P. Abramian, B. Brañas, J. Calero, J. Castellanos, J.M. García, D. Gavela, A. Guirao, J.L. Gutiérrez, D. Jiménez-Rey, M. Lafoz, D. López, L.M. Martínez, E. Molina Marinas, J. Mollá, C. Oliver, A. Soleto, F. Toral, R. Varela, V. Villamayor CIEMAT, Madrid, Spain J. Castellanos UNED, Madrid, Spain O. Nomen IREC, Sant Adria del Besos, Spain
	Funding: This work has been funded by the Spanish Ministry of Economy and Competitiveness under the Agreement as published in BOE, 16/01/2013, page 1988 and the project FIS2013-40860-R. LIPAc* will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF-DONES accelerator. The acceleration of the beam will be carried out in two stages. An RFQ will increase the energy up to 5 MeV before a Superconducting RF (SRF) linac made of a chain of eight Half Wave Resonators bring the particles to the final energy. Between both stages, a Medium Energy Beam Transport line (MEBT)* is in charge of transporting and matching the beam between the RFQ and the SRF. The transverse focusing of the beam is controlled by five quadrupole magnets with integrated steerers, grouped in one triplet and one doublet. Two buncher cavities surrounding the doublet handle the longitudinal dynamics. Two movable collimators are also included to purify the beam optics coming out the RFQ and avoid losses in the SRF. In this contribution, the final integrated design of the beamline will be shown, together with the auxiliaries. The manufacturing of all the components and the integration in the beamline will be depicted. The final tests carried out to the beamline prior to the installation in the accelerator will be also reported. * P. Cara et al., IPAC16, to be published, Busan, Korea (2016). A. Ibarra et al., Fus. Sci. Tech., 66, 1, p. 252-259 (2014). * I. Podadera et al., IPAC11, San Sebastian, Spain (2011).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR041
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TH1A06	High-Frequency Compact RFQs for Medical and Industrial Applications	704
	M. Vretenar, V.A. Dimov, M. Garlaschè, A. Grudiev, B. Koubek, A.M. Lombardi, S.J. Mathot, D. Mazur, E. Montesinos, M.A. Timmins CERN, Geneva, Switzerland
	CERN has completed the construction of a 750 MHz RFQ reaching 5 MeV proton energy in a length of only 2 meters, to be used as injector for a compact proton therapy linac. Beyond proton therapy, this compact and lightweight design can be used for several applications, ranging from the production of radioisotopes in hospitals to ion beam analysis of industrial components or of artworks. The ex-perience with the construction of the first unit will be pre-sented together with the design and plans for other appli-cations.
	Slides TH1A06 [9.369 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH1A06
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

MOOP04

Traveling Wave Linear Accelerator With RF Power Flow Outside of Accelerating Cavities

48

MOPRC030

use link to see paper's listing under its alternate paper code

V.A. Dolgashev
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. DOE under Contract No. DE-AC02-76-SF00515.
An accelerating structure is a critical component of particle accelerators for medical, security, industrial and scientific applications. Standing-wave side-coupled accelerating structures are used where available RF power is at a premium, while average current and average RF power lost in the structure are high. These structures are expensive to manufacture and typically require a circulator to divert structure-reflected power away from RF source, klystron or magnetron. In this report a traveling wave accelerating structure is presented which combines high shunt impedance of the side-coupled standing wave structure with such advantages as simpler tuning and manufacturing. In addition, the structure is matched to the RF source so no circulator is needed. This paper presents the motivation for this structure and shows a practical example.

Slides MOOP04 [5.459 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP04

Export •

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

MOOP05

Dry-Ice Cleaning of RF-Structures at DESY

52

MOPRC032

use link to see paper's listing under its alternate paper code

A. Brinkmann, J. Ziegler
DESY, Hamburg, Germany

Dry-Ice cleaning is today a well established cleaning method in matters of reducing harmful dark current and field emission in copper RF-structures like RF-Guns such as for the European XFEL, FLASH and REGAE. This led to the idea to clean longer RF-structures, in particular 3GHz transverse deflecting structures for the European XFEL. We developed a cleaning device with the possibility to clean up to 2 m long structures in horizontal position with an inner diameter of not more than 40 mm. Furthermore this device also allows to clean 9-cell TESLA-type Nb-cavities as well. A report of the technical layout and results of RF-tests will be given.

Slides MOOP05 [0.969 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP05

Export •

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

TU2A04

High-Gradient RF Development and Applications

368

W. Wuensch
CERN, Geneva, Switzerland

Significant progress has been made by the CLIC collaboration to understand the phenomena which limit gradient in normal-conducting accelerating structures and to increase achievable gradient in excess of 100 MV/m. Scientific and technological highlights from the CLIC high-gradient program are presented along with on-going developments and future plans. The talk will also give an overview of the range of applications that potentially benefit from high-frequency and high-gradient accelerating technology.

Slides TU2A04 [14.317 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TU2A04

Export •

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

TUPLR035

RF Analysis of Electropolishing for EXFEL Cavities Production at Ettore Zanon Spa

544

A.A. Sulimov
DESY, Hamburg, Germany
M. Giaretta, A. Gresele, A. Visentin
Ettore Zanon S.p.A., Nuclear Division, Schio, Italy

After successful finishing of superconducting cavities mass production at Ettore Zanon S.p.A. (EZ) for the European XFEL (EXFEL), the authors had the possibility to provide a detailed analysis of the electropolishing (EP) process. The analysis of EP material removal is based on specified RF measurements and was used for the determination of both, the ratio between cavity's iris and equator and uniformity in different cells. A comparison of the RF measurements results with mechanical measurements is presented.

Poster TUPLR035 [0.195 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR035

Export •

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

TUPLR038

The DTL Post Coupler - An Ingenious Invention Turns 50

547

S. Ramberger
CERN, Geneva, Switzerland
M.R. Khalvati
IPM, Tehran, Iran

In September 1967, the patent for "A method and device for stabilization of the field distribution in drift tube linac" has been filed by Edward A. Knapp, Donald A. Swenson, and James M. Potter of Los Alamos National Laboratory. It is this invention which to a good part led to the success of highly efficient Alvarez drift tube linacs (DTLs) in that it considerably reduces field errors. The explanation for why the post coupler when tuned correctly has such a strong stabilizing effect has been given at the time in an accompanying paper by describing the modal confluence of the accelerating mode band with the post-coupler mode band, turning a comparatively sensitive 0-mode structure into a stable pi/2-mode like structure. As ingenious as the invention of the post-coupler appears, as poor has been the way of finding its optimum length by relying mainly on trial and error. With the design of the Linac4 DTL at CERN, a new technique has been derived by a DTL equivalent circuit model. Understanding stabilization on an almost cell by cell level provides a new way of optimizing post-couplers of an entire structure with few measurements and even without the extraction of the circuit model itself. Previous approaches to post-coupler stabilization are reviewed and the new, straightforward and accurate technique is described and demonstrated in the stabilization of the Linac4 DTL structures.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR038

Export •

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

TUPLR040

The RF System of Thomx

551

M. El Khaldi, R. Marie, H. Monard, F. Wicek
LAL, Orsay, France
M. Diop, L.R. Lopes, A. Loulergue, M. Louvet, P. Marchand, F. Ribeiro, R. Sreedharan
SOLEIL, Gif-sur-Yvette, France

The RF system of the ThomX electron storage ring consists in a 500 MHz single cell copper cavity of the ELETTRA type, powered with a 50 kW CW solid state power amplifier (SSPA), and the associated Low Level RF feedback and control loops. The low operating energy of 50/70 MeV makes the impedances of the cavity higher order modes (HOMs) particularly critical for the beam stability. Their parasitic effects on the beam can be cured by HOM frequency shifting techniques, based on a fine temperature tuning and a dedicated plunger. A typical cavity temperature stability of ± 0.05°C within a range from 30 up to 70 °C can be achieved by a precise control of its water cooling temperature. On the other hand, the tuning of the cavity fundamental mode is achieved by changing its axial length by means of a motor-driven mechanism. A general description of the system and the state of its progress are reported together with some considerations of the effects of beam cavity interactions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR040

Export •

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

TUPLR041

Manufacturing, Assembly and Tests of the LIPAc Medium Energy Beam Transport Line (MEBT)

554

I. Podadera, P. Abramian, B. Brañas, J. Calero, J. Castellanos, J.M. García, D. Gavela, A. Guirao, J.L. Gutiérrez, D. Jiménez-Rey, M. Lafoz, D. López, L.M. Martínez, E. Molina Marinas, J. Mollá, C. Oliver, A. Soleto, F. Toral, R. Varela, V. Villamayor
CIEMAT, Madrid, Spain
J. Castellanos
UNED, Madrid, Spain
O. Nomen
IREC, Sant Adria del Besos, Spain

Funding: This work has been funded by the Spanish Ministry of Economy and Competitiveness under the Agreement as published in BOE, 16/01/2013, page 1988 and the project FIS2013-40860-R.
LIPAc* will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF-DONES accelerator**. The acceleration of the beam will be carried out in two stages. An RFQ will increase the energy up to 5 MeV before a Superconducting RF (SRF) linac made of a chain of eight Half Wave Resonators bring the particles to the final energy. Between both stages, a Medium Energy Beam Transport line (MEBT)*** is in charge of transporting and matching the beam between the RFQ and the SRF. The transverse focusing of the beam is controlled by five quadrupole magnets with integrated steerers, grouped in one triplet and one doublet. Two buncher cavities surrounding the doublet handle the longitudinal dynamics. Two movable collimators are also included to purify the beam optics coming out the RFQ and avoid losses in the SRF. In this contribution, the final integrated design of the beamline will be shown, together with the auxiliaries. The manufacturing of all the components and the integration in the beamline will be depicted. The final tests carried out to the beamline prior to the installation in the accelerator will be also reported.
* P. Cara et al., IPAC16, to be published, Busan, Korea (2016).
** A. Ibarra et al., Fus. Sci. Tech., 66, 1, p. 252-259 (2014).
*** I. Podadera et al., IPAC11, San Sebastian, Spain (2011).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR041

Export •

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

TH1A06

High-Frequency Compact RFQs for Medical and Industrial Applications

704

M. Vretenar, V.A. Dimov, M. Garlaschè, A. Grudiev, B. Koubek, A.M. Lombardi, S.J. Mathot, D. Mazur, E. Montesinos, M.A. Timmins
CERN, Geneva, Switzerland

CERN has completed the construction of a 750 MHz RFQ reaching 5 MeV proton energy in a length of only 2 meters, to be used as injector for a compact proton therapy linac. Beyond proton therapy, this compact and lightweight design can be used for several applications, ranging from the production of radioisotopes in hospitals to ion beam analysis of industrial components or of artworks. The ex-perience with the construction of the first unit will be pre-sented together with the design and plans for other appli-cations.

Slides TH1A06 [9.369 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH1A06

Export •

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