IPAC2014 - List of Keywords (accelerating-gradient)

Paper	Title	Other Keywords	Page
MOOCA01	High Power Test Results of the SPARC C-Band Accelerating Structures	controls, klystron, vacuum, operation	39
	D. Alesini, M. Bellaveglia, M.E. Biagini, R. Boni, P. Chimenti, R. Clementi, G. Di Pirro, R. D. Di Raddo, M. Ferrario, A. Gallo, V.L. Lollo INFN/LNF, Frascati (Roma), Italy M. Brönnimann, R. Kalt, T. Schilcher PSI, Villigen PSI, Switzerland L. Ficcadenti INFN-Roma, Roma, Italy L. Palumbo URLS, Rome, Italy
	The energy upgrade of the SPARC photo-injector at LNF-INFN (Italy) from 150 to more than 240 MeV will be done by replacing a low gradient S-Band accelerating structure with two C-band structures. The structures are Traveling Wave (TW) and Constant Impedance (CI), have symmetric axial input couplers and have been optimized to work with a SLED RF input pulse. In the paper we present the results of the low and high power RF tests on the two final fabricated structures that shown the feasibility of the operation at accelerating gradients larger than 35 MV/m.
	Slides MOOCA01 [6.242 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOOCA01
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TUPME081	Plasma Wakefield Acceleration at CLARA PARS	plasma, simulation, wakefield, electron	1544
	K. Hanahoe, O. Mete, G.X. Xia UMAN, Manchester, United Kingdom D. Angal-Kalinin, J.A. Clarke, J.K. Jones, J.W. McKenzie, B.L. Militsyn, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom D. Angal-Kalinin, J.A. Clarke, J.K. Jones, J.W. McKenzie, Y. Wei, C.P. Welsch, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom B. Hidding USTRAT/SUPA, Glasgow, United Kingdom J.D.A. Smith TXUK, Warrington, United Kingdom Y. Wei, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	PARS is a proposed Plasma Accelerator Research Station using the planned CLARA (Compact Linear Accelerator for Research and Applications) electron linear accelerator at Daresbury Laboratory in the UK. In this paper, two- dimensional particle-in-cell simulations based on realistic CLARA beam parameters are presented. The results show that an accelerating gradient of 2.0 GV/m can be achieved over an accelerating length of at least 13 cm. Preliminary simulation results for a two bunch scheme show an energy gain of 70% over a length of 13 cm, giving an average accelerating gradient of 1.2 GeV/m.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME081
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WEOCA02	Recent Results from CTF3 Two Beam Test Stand	HOM, wakefield, experiment, diagnostics	1880
	W. Farabolini, F. Peauger CEA/DSM/IRFU, France Ch. Borgmann, J. Ögren, R.J.M.Y. Ruber Uppsala University, Uppsala, Sweden R. Corsini, D. Gamba, A. Grudiev, M.A. Khan, S. Mazzoni, J.L. Navarro Quirante, R. Pan, J.R. Towler, N. Vitoratou, K. Yaqub CERN, Geneva, Switzerland
	From mid-2012, the Two Beam Test Stand (TBTS) in the CTF3 Experimental Facility is hosting 2 high gradient accelerating structures powered by a single power extraction and transfer structure in a scheme very close to the CLIC basic cell. We report here about the results obtained with this configuration as: energy gain and energy spread in relation with RF phases and power, octupolar transverse beam effects compared with modeling predictions, breakdown rate and breakdown locations within the structures. These structures are the first to be fitted with Wake Field Monitors (WFM) that have been extensively tested and used to further improve the structures alignment on the beam line. These results show the unique capabilities of this test stand to conduct experiments with real beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEOCA02
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WEOAB03	Linear Electron Acceleration in THz Waveguides	electron, linac, acceleration, laser	1896
	E.A. Nanni, W.S. Graves, K.-H. Hong, W.R. Huang, F.X. Kärtner, KR. Ravi, L.J. Wong MIT, Cambridge, Massachusetts, USA A. Fallahi, F.X. Kärtner CFEL, Hamburg, Germany R.J.D. Miller DESY, Hamburg, Germany G. Moriena University of Toronto, Toronto, Ontario, Canada
	Funding: Supported by DARPA N66001-11-1-4192, CFEL DESY, DOE DEFG02-10ER46745, DOE DE-FG02-08ER41532, ERC Synergy Grant 609920 and NSF DMR-1042342. We report the first experimental demonstration of linear electron acceleration using an optically generated single cycle THz pulse centered at 0.45 THz. 7 keV of acceleration is achieved using 10 microJ THz pulses in a 3 mm interaction length. The THz pulse is produced via optical rectification of a 1.2 mJ, 1 micron laser pulse with a 1 kHz repetition rate. The THz pulse is coupled into a dielectric-loaded circular waveguide with 10 MeV/m on-axis accelerating gradient. A 25 fC input electron bunch is produced with a 60 keV DC photo-emitting cathode. The achievable accelerating gradient in the THz structures being investigated will scale rapidly by increasing the IR pulse energy (100 mJ - 1 J) and correspondingly the THz pulse energy. Additionally, with recent advances in the generation of THz pulses via optical rectification, in particular improvements to efficiency and generation of multi-cycle pulses, GeV/m accelerating gradients could be achieved. An ultra-compact high-gradient THz accelerator would be of interest for a wide variety of applications.
	Slides WEOAB03 [7.185 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEOAB03
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WEPME015	High-gradient Test Results from a CLIC Prototype Accelerating Structure: TD26CC	damping, linac, target, vacuum	2285
	W. Wuensch, A. Degiovanni, S. Döbert, W. Farabolini, A. Grudiev, J.W. Kovermann, E. Montesinos, G. Riddone, I. Syratchev, R. Wegner CERN, Geneva, Switzerland A. Solodko JINR, Dubna, Moscow Region, Russia B.J. Woolley Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	The CLIC study has progressively tested prototype accelerating structures which incorporate an ever increasing number of features which are needed for a final version installed in a linear collider. The most recent high power test made in the CERN X-band test stand, Xbox-1, is a of a CERN-built prototype which includes damping features but also compact input and output power couplers, which maximize the overall length to active gradient ratio of the structure. The structure’s high-gradient performance, 100 MV/m and low breakdown rate, matches previously tested structures validating both CERN fabrication and the compact coupler design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME015
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WEPRI002	Status and First Results of Two High Beta Prototype Elliptical Cavities for ESS	cavity, cryomodule, operation, niobium	2477
	F. Peauger, P. Bosland, P. Carbonnier, G. Devanz, F. Éozénou, X. Hanus, P. Hardy, V.M. Hennion, J. Plouin, D. Roudier, C. Servouin CEA/DSM/IRFU, France C. Darve, S. Molloy ESS, Lund, Sweden L. Maurice CEA/IRFU, Gif-sur-Yvette, France G. Olivier IPN, Orsay, France
	Two prototypes of elliptical superconducting cavities have been designed and manufactured in the frame of the French-Swedish agreement for ESS. These 5-cell cavities have a beta value of 0.86 and their frequency is 704.42 MHz. The nominal accelerating gradient on the ESS accelerator is 19.9 MV/m at 2K. We present the manufacturing status of the cavities by two different vendors as well as the specific means which have been developed for the cavity treatments performed at CEA after delivery. We emphasis the activities performed on the first bare cavities recently received at CEA such as the RF measurement and tuning operations, the cleaning and chemical treatments and the clean room assembly including high pressure rinsing. Finally, first test results at 2K in vertical cryostat are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI002
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WEPRI011	Progress of R&D on SRF Cavities at DESY towards the ILC Performance Goal	cavity, SRF, factory, electron	2499
	A. Navitski DESY, Hamburg, Germany A. Prudnikava, Y. Tamashevich Uni HH, Hamburg, Germany
	Funding: BMBF project 05H12GU9, Alexander von Humboldt Foundation, CRISP (No. 283745) and ”Construction of New Infrastructures-Preparatory Phase” ILC-HiGrade (No. 206711) of the EU 7th FP7/2007-2013 Programme. The R&D program of the ILC-HiGrade group at DESY aims at a solid understanding and control of the industrial mass-production process of the superconducting radio-frequency accelerating cavities that are being manufactured for the European X-ray Free Electron Laser (EXFEL). This accelerator is currently under construction at DESY. As well as the main production cavities for XFEL, 24 additional cavities are being constructed as part of the ILC-HiGrade program. The goal is to identify the gradient-limiting factors and further refine the cavity-treatment technique to understand how to achieve gradients above 35 MV/m at >90% production yield in an industrial context. Techniques such as 2nd sound and temperature mapping for the quench detection, OBACHT optical inspections, as well as Centrifugal Barrel Polishing (CBP) and Local Grinding repair are foreseen as tools. Actual status, details, and achievements will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI011
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WEPRI022	In-house Production of a Large-Grain Single-Cell Cavity at Cavity Fabrication Facility and Results of Performance Tests	cavity, SRF, radio-frequency, vacuum	2519
	T. Kubo, Y. Ajima, H. Inoue, K. Umemori, Y. Watanabe, M. Yamanaka KEK, Ibaraki, Japan
	We studied electron beam welding (EBW) conditions for large grain Nb, and fabricated a single cell cavity in Cavity Fabrication Facility (CFF), KEK. Vertical-test results of the cavity made from large grain Nb are also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI022
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WEPRI066	Recent Progress in Nb3Sn SRF Cavity Development at Cornell	cavity, niobium, SRF, cryogenics	2641
	S. Posen, D. Gonnella, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Nb₃Sn coatings on niobium SRF cavities have the potential to significantly reduce cryogenic costs due to their extremely small surface resistance (R_s). In this paper, we present new results showing the repeatability of Cornell's fabrication process, which produces high Q₀ cavities that reach medium fields with minimal Q-slope. We also show the results of attempts to smooth RF surfaces and reduce defects via material removal. However, both HF rinsing and centrifugal barrel polishing resulted in strong performance degradation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI066
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THPME021	Designs of High-intensity Proton Linacs with Non-equipartitioning	linac, emittance, cavity, proton	3262
	C. Meng, Z. Li, S. Pei, B. Sun, J.Y. Tang, F. Yan IHEP, Beijing, People's Republic of China R. Garoby, F. Gerigk, A.M. Lombardi CERN, Geneva, Switzerland
	Superconducting technology is playing more and more important roles in high-power proton linacs. Periodic phase advance less than 90 degrees and equipartitioning design are considered very important principles in linac design. Due to the very high construction and operation costs, it is very important in optimizing the design to lower the costs. In usual, the longitudinal emittance is larger from the front-end, thus the transverse phase advance is designed to have a larger value. However, with the technical advancement, higher accelerating field can be obtained. In order to take this advantage, it is of much interest in increasing the longitudinal phase advance to shorten the linac or reduce the cost. In this paper, we present the design method that keeping the longitudinal phase advance as large as possible but smaller than 90 degree to maximize the use of the available accelerating gradient. Even though this method does not observe the equipartitioning condition, we can also obtain very good beam dynamics results by placing the tunes in resonant-free regions. In this paper, the design and simulation results by applying this method to the SPL and China-ADS linac will be present.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME021
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Paper

Title

Other Keywords

Page

MOOCA01

High Power Test Results of the SPARC C-Band Accelerating Structures

controls, klystron, vacuum, operation

39

D. Alesini, M. Bellaveglia, M.E. Biagini, R. Boni, P. Chimenti, R. Clementi, G. Di Pirro, R. D. Di Raddo, M. Ferrario, A. Gallo, V.L. Lollo
INFN/LNF, Frascati (Roma), Italy
M. Brönnimann, R. Kalt, T. Schilcher
PSI, Villigen PSI, Switzerland
L. Ficcadenti
INFN-Roma, Roma, Italy
L. Palumbo
URLS, Rome, Italy

The energy upgrade of the SPARC photo-injector at LNF-INFN (Italy) from 150 to more than 240 MeV will be done by replacing a low gradient S-Band accelerating structure with two C-band structures. The structures are Traveling Wave (TW) and Constant Impedance (CI), have symmetric axial input couplers and have been optimized to work with a SLED RF input pulse. In the paper we present the results of the low and high power RF tests on the two final fabricated structures that shown the feasibility of the operation at accelerating gradients larger than 35 MV/m.

Slides MOOCA01 [6.242 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOOCA01

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TUPME081

Plasma Wakefield Acceleration at CLARA PARS

plasma, simulation, wakefield, electron

1544

K. Hanahoe, O. Mete, G.X. Xia
UMAN, Manchester, United Kingdom
D. Angal-Kalinin, J.A. Clarke, J.K. Jones, J.W. McKenzie, B.L. Militsyn, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
D. Angal-Kalinin, J.A. Clarke, J.K. Jones, J.W. McKenzie, Y. Wei, C.P. Welsch, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B. Hidding
USTRAT/SUPA, Glasgow, United Kingdom
J.D.A. Smith
TXUK, Warrington, United Kingdom
Y. Wei, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

PARS is a proposed Plasma Accelerator Research Station using the planned CLARA (Compact Linear Accelerator for Research and Applications) electron linear accelerator at Daresbury Laboratory in the UK. In this paper, two- dimensional particle-in-cell simulations based on realistic CLARA beam parameters are presented. The results show that an accelerating gradient of 2.0 GV/m can be achieved over an accelerating length of at least 13 cm. Preliminary simulation results for a two bunch scheme show an energy gain of 70% over a length of 13 cm, giving an average accelerating gradient of 1.2 GeV/m.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME081

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WEOCA02

Recent Results from CTF3 Two Beam Test Stand

HOM, wakefield, experiment, diagnostics

1880

W. Farabolini, F. Peauger
CEA/DSM/IRFU, France
Ch. Borgmann, J. Ögren, R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden
R. Corsini, D. Gamba, A. Grudiev, M.A. Khan, S. Mazzoni, J.L. Navarro Quirante, R. Pan, J.R. Towler, N. Vitoratou, K. Yaqub
CERN, Geneva, Switzerland

From mid-2012, the Two Beam Test Stand (TBTS) in the CTF3 Experimental Facility is hosting 2 high gradient accelerating structures powered by a single power extraction and transfer structure in a scheme very close to the CLIC basic cell. We report here about the results obtained with this configuration as: energy gain and energy spread in relation with RF phases and power, octupolar transverse beam effects compared with modeling predictions, breakdown rate and breakdown locations within the structures. These structures are the first to be fitted with Wake Field Monitors (WFM) that have been extensively tested and used to further improve the structures alignment on the beam line. These results show the unique capabilities of this test stand to conduct experiments with real beams.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEOCA02

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WEOAB03

Linear Electron Acceleration in THz Waveguides

electron, linac, acceleration, laser

1896

E.A. Nanni, W.S. Graves, K.-H. Hong, W.R. Huang, F.X. Kärtner, KR. Ravi, L.J. Wong
MIT, Cambridge, Massachusetts, USA
A. Fallahi, F.X. Kärtner
CFEL, Hamburg, Germany
R.J.D. Miller
DESY, Hamburg, Germany
G. Moriena
University of Toronto, Toronto, Ontario, Canada

Funding: Supported by DARPA N66001-11-1-4192, CFEL DESY, DOE DEFG02-10ER46745, DOE DE-FG02-08ER41532, ERC Synergy Grant 609920 and NSF DMR-1042342.
We report the first experimental demonstration of linear electron acceleration using an optically generated single cycle THz pulse centered at 0.45 THz. 7 keV of acceleration is achieved using 10 microJ THz pulses in a 3 mm interaction length. The THz pulse is produced via optical rectification of a 1.2 mJ, 1 micron laser pulse with a 1 kHz repetition rate. The THz pulse is coupled into a dielectric-loaded circular waveguide with 10 MeV/m on-axis accelerating gradient. A 25 fC input electron bunch is produced with a 60 keV DC photo-emitting cathode. The achievable accelerating gradient in the THz structures being investigated will scale rapidly by increasing the IR pulse energy (100 mJ - 1 J) and correspondingly the THz pulse energy. Additionally, with recent advances in the generation of THz pulses via optical rectification, in particular improvements to efficiency and generation of multi-cycle pulses, GeV/m accelerating gradients could be achieved. An ultra-compact high-gradient THz accelerator would be of interest for a wide variety of applications.

Slides WEOAB03 [7.185 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEOAB03

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WEPME015

High-gradient Test Results from a CLIC Prototype Accelerating Structure: TD26CC

damping, linac, target, vacuum

2285

W. Wuensch, A. Degiovanni, S. Döbert, W. Farabolini, A. Grudiev, J.W. Kovermann, E. Montesinos, G. Riddone, I. Syratchev, R. Wegner
CERN, Geneva, Switzerland
A. Solodko
JINR, Dubna, Moscow Region, Russia
B.J. Woolley
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

The CLIC study has progressively tested prototype accelerating structures which incorporate an ever increasing number of features which are needed for a final version installed in a linear collider. The most recent high power test made in the CERN X-band test stand, Xbox-1, is a of a CERN-built prototype which includes damping features but also compact input and output power couplers, which maximize the overall length to active gradient ratio of the structure. The structure’s high-gradient performance, 100 MV/m and low breakdown rate, matches previously tested structures validating both CERN fabrication and the compact coupler design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME015

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WEPRI002

Status and First Results of Two High Beta Prototype Elliptical Cavities for ESS

cavity, cryomodule, operation, niobium

2477

F. Peauger, P. Bosland, P. Carbonnier, G. Devanz, F. Éozénou, X. Hanus, P. Hardy, V.M. Hennion, J. Plouin, D. Roudier, C. Servouin
CEA/DSM/IRFU, France
C. Darve, S. Molloy
ESS, Lund, Sweden
L. Maurice
CEA/IRFU, Gif-sur-Yvette, France
G. Olivier
IPN, Orsay, France

Two prototypes of elliptical superconducting cavities have been designed and manufactured in the frame of the French-Swedish agreement for ESS. These 5-cell cavities have a beta value of 0.86 and their frequency is 704.42 MHz. The nominal accelerating gradient on the ESS accelerator is 19.9 MV/m at 2K. We present the manufacturing status of the cavities by two different vendors as well as the specific means which have been developed for the cavity treatments performed at CEA after delivery. We emphasis the activities performed on the first bare cavities recently received at CEA such as the RF measurement and tuning operations, the cleaning and chemical treatments and the clean room assembly including high pressure rinsing. Finally, first test results at 2K in vertical cryostat are reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI002

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WEPRI011

Progress of R&D on SRF Cavities at DESY towards the ILC Performance Goal

cavity, SRF, factory, electron

2499

A. Navitski
DESY, Hamburg, Germany
A. Prudnikava, Y. Tamashevich
Uni HH, Hamburg, Germany

Funding: BMBF project 05H12GU9, Alexander von Humboldt Foundation, CRISP (No. 283745) and ”Construction of New Infrastructures-Preparatory Phase” ILC-HiGrade (No. 206711) of the EU 7th FP7/2007-2013 Programme.
The R&D program of the ILC-HiGrade group at DESY aims at a solid understanding and control of the industrial mass-production process of the superconducting radio-frequency accelerating cavities that are being manufactured for the European X-ray Free Electron Laser (EXFEL). This accelerator is currently under construction at DESY. As well as the main production cavities for XFEL, 24 additional cavities are being constructed as part of the ILC-HiGrade program. The goal is to identify the gradient-limiting factors and further refine the cavity-treatment technique to understand how to achieve gradients above 35 MV/m at >90% production yield in an industrial context. Techniques such as 2nd sound and temperature mapping for the quench detection, OBACHT optical inspections, as well as Centrifugal Barrel Polishing (CBP) and Local Grinding repair are foreseen as tools. Actual status, details, and achievements will be reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI011

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WEPRI022

In-house Production of a Large-Grain Single-Cell Cavity at Cavity Fabrication Facility and Results of Performance Tests

cavity, SRF, radio-frequency, vacuum

2519

T. Kubo, Y. Ajima, H. Inoue, K. Umemori, Y. Watanabe, M. Yamanaka
KEK, Ibaraki, Japan

We studied electron beam welding (EBW) conditions for large grain Nb, and fabricated a single cell cavity in Cavity Fabrication Facility (CFF), KEK. Vertical-test results of the cavity made from large grain Nb are also presented.

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WEPRI066

Recent Progress in Nb3Sn SRF Cavity Development at Cornell

cavity, niobium, SRF, cryogenics

2641

S. Posen, D. Gonnella, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Nb₃Sn coatings on niobium SRF cavities have the potential to significantly reduce cryogenic costs due to their extremely small surface resistance (R_s). In this paper, we present new results showing the repeatability of Cornell's fabrication process, which produces high Q₀ cavities that reach medium fields with minimal Q-slope. We also show the results of attempts to smooth RF surfaces and reduce defects via material removal. However, both HF rinsing and centrifugal barrel polishing resulted in strong performance degradation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI066

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THPME021

Designs of High-intensity Proton Linacs with Non-equipartitioning

linac, emittance, cavity, proton

3262

C. Meng, Z. Li, S. Pei, B. Sun, J.Y. Tang, F. Yan
IHEP, Beijing, People's Republic of China
R. Garoby, F. Gerigk, A.M. Lombardi
CERN, Geneva, Switzerland

Superconducting technology is playing more and more important roles in high-power proton linacs. Periodic phase advance less than 90 degrees and equipartitioning design are considered very important principles in linac design. Due to the very high construction and operation costs, it is very important in optimizing the design to lower the costs. In usual, the longitudinal emittance is larger from the front-end, thus the transverse phase advance is designed to have a larger value. However, with the technical advancement, higher accelerating field can be obtained. In order to take this advantage, it is of much interest in increasing the longitudinal phase advance to shorten the linac or reduce the cost. In this paper, we present the design method that keeping the longitudinal phase advance as large as possible but smaller than 90 degree to maximize the use of the available accelerating gradient. Even though this method does not observe the equipartitioning condition, we can also obtain very good beam dynamics results by placing the tunes in resonant-free regions. In this paper, the design and simulation results by applying this method to the SPL and China-ADS linac will be present.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME021

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