LINAC2016 - List of Keywords (accelerating-gradient)

Paper	Title	Other Keywords	Page
MOOP09	Dielectric and THz Acceleration (Data) Programme at the Cockcroft Institute	acceleration, laser, electron, wakefield	62
	S.P. Jamison, Y.M. Saveliev STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.B. Appleby, H.L. Owen, T.H. Pacey, T.H. Pacey, G.X. Xia UMAN, Manchester, United Kingdom G. Burt, R. Letizia, C. Paoloni Cockcroft Institute, Lancaster University, Lancaster, United Kingdom A.W. Cross USTRAT/SUPA, Glasgow, United Kingdom D.M. Graham The University of Manchester, The Photon Science Institute, Manchester, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work has been funded by STFC Normal conducting RF systems are currently able to pro-vide gradients of around 100 MV/m, limited by break-down on the metallic structures. The breakdown rate is known to scale with pulse length and, in conventional RF systems, this is limited by the filling time of the RF struc-ture. Progressing to higher frequencies, from RF to THz and optical, can utilise higher gradient structures due to the fast filling times. Further increases in gradient may be possible by replacing metallic structures with dielectric structures. The DATA programme at the Cockcroft Insti-tute is investigating concepts for particle acceleration with laser driven THz sources and dielectric structures, beam driven dielectric and metallic structures, and optical and infrared laser acceleration using grating and photonic structures. A cornerstone of the programme is the VELA and CLARA electron accelerator test facility at Daresbury Laboratory which will be used for proof-of-principle experiments demonstrating particle acceleration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP09
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MOPLR005	Design, Manufacturing and Installation of Two Dual-Feed Accelerating Structures for the FERMI Injector	linac, cavity, FEL, emittance	139
	C. Serpico, A. Fabris, G. Penco, M. Svandrlik Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy B. Keune RI Research Instruments GmbH, Bergisch Gladbach, Germany
	FERMI is a seeded Free Electron Laser (FEL) driven by a warm S-band Linac. In the injector region, two 3- meter long Forward Traveling Wave (FTW) accelerating structures, coming from the old Elettra injector, were installed. In order to improve the e-beam quality at higher bunch charge, it was decided to replace the existing ones with two dual-feed accelerating structures. Those structures have been designed and manufactured by RI Research Instruments GmbH and delivered to Elettra in July 2015. The following paper will report about the RF design and the manufacturing of the new structures. Details about the RF conditioning and the installation will also be illustrated.
	Poster MOPLR005 [1.100 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR005
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MOPLR011	Design of a Dielectric-lined Waveguide for Terahertz-driven Linear Electron Acceleration	electron, acceleration, impedance, experiment	158
	A.L. Healy, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom M.J. Cliffe, D.M. Graham The University of Manchester, The Photon Science Institute, Manchester, United Kingdom S.P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom
	A dielectric-lined waveguide has been designed for use as an accelerating structure in terahertz-driven electron acceleration experiments at Daresbury. Experimental verification of acceleration will take place on Versatile Electron Linear Accelerator (VELA). The choice of a rectangular waveguide structure with sidewall dielectric layers enables tuning by varying the spacing between dielectric slabs to account for potential manufacturing errors. Schemes for coupling free-space single cycle THz pulses into the waveguide have been evaluated and optimised through CST simulation. Comparison of simulation with experimental measurements will also be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR011
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MOPLR023	Examination of Cutouts Inner Surfaces from Nb3Sn Coated Cavity	cavity, niobium, SRF, ion	189
	U. Pudasaini, M.J. Kelley The College of William and Mary, Williamsburg, Virginia, USA G.V. Eremeev, C.E. Reece JLab, Newport News, Virginia, USA J. Tuggle Virginia Polytechnic Institute and State University, Blacksburg, USA
	Funding: Supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of High Energy Physics under grant SC00144475. The potential for higher operating temperature and higher gradient have motivated SRF cavity researchers to pursue Nb3Sn as an alternative to Nb for nearly fifty years. Far and away the most common embodiment has been a few micron-thick Nb3Sn layer on the cavity interior surface obtained by vapor diffusion coating, with one or another set of parameters. While many cavities have been made and RF tested, reports of dissecting a cavity in detail to examine the coating and relate it to RF measurements are rare. We coated a BCP-treated single cell cavity in a typical process of tin/tin chloride activation at 500 C followed by tin vapor deposition at 1200 C. After RF-testing, we cut and examined sections from several locations to learn composition, thickness topography of the interior surface. The effect of process variables, such as surface preparation, process temperature and duration, and vapor chemistry needs to be explored.
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MOPLR048	Fabrication and Testing of a Novel S-Band Backward Travelling Wave Accelerating Structure for Proton Therapy Linacs	linac, vacuum, coupling, proton	237
	S. Benedetti, T. Argyropoulos, C. Blanch Gutiérrez, N. Catalán Lasheras, A. Degiovanni, D. Esperante Pereira, M. Garlaschè, J. Giner Navarro, A. Grudiev, G. McMonagle, A. Solodko, M.A. Timmins, R. Wegner, B.J. Woolley, W. Wuensch CERN, Geneva, Switzerland D. Esperante Pereira IFIC, Valencia, Spain
	Compact and more affordable, facilities for proton therapy are now entering the market of commercial medical accelerators. At CERN, a joint collaboration between CLIC and TERA Foundation led to the design, fabrication and testing of a high gradient accelerating structure prototype, capable of halving the length of state-of-art light ion therapy linacs. This paper focuses on the mechanical design, fabrication and testing of a first prototype. CLIC standardized bead-pull measurement setup was used, leading to a quick and successful tuning of the prototype. The high power tests will soon start in order to prove that the structure can withstand a very high accelerating gradient while suffering no more than 10^-6 breakdown per pulse per meter (bpp/m), resulting in less than one breakdown per treatment session.
	Poster MOPLR048 [2.804 MB]
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MOPLR066	ProBE: Proton Boosting Extension for Imaging and Therapy	proton, cavity, septum, linac	283
	S. Pitman, R. Apsimon, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom A.F. Green, H.L. Owen UMAN, Manchester, United Kingdom A. Grudiev, A. Solodko, W. Wuensch CERN, Geneva, Switzerland
	Funding: This work was funded by STFC and IPS Proton beam therapy has been shown to be a promising alternative to traditional radiotherapy, especially for paedi- atric malignancies and radio-resistant tumours. Allowing a highly precise tumour irradiation, it is currently limited by range verification. Several imaging modalities can be utilised for treatment planning, but typically X-ray CT is used. CT scans require conversion from Hounsfield units to estimate the proton stopping power (PSP) of the tissue be- ing treated, and this produces inaccuracy. Proton CT (pCT) measures PSP and is thought to allow an improvement of the treatment accuracy. The Christie Hospital will use a 250 MeV cyclotron for proton therapy, in this paper a pulsed linac upgrade is proposed, to provide 350 MeV protons for pCT within the facility. Space contraints require a compact, high gradient (HG) solution that is reliable and affordable.
	Poster MOPLR066 [0.610 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR066
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MOP106021	Superconducting Traveling Wave Cavity Tuning Studies	cavity, feedback, SRF, acceleration	327
	R.A. Kostin LETI, Saint-Petersburg, Russia P.V. Avrakhov, A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: Work supported by US DOE SBIR # DE-SC0006300 Superconducting traveling wave cavity (SCTW) can provide 1.2-1.4 times larger accelerating gradient than conventional standing wave SRF cavities [1]. Firstly, traveling wave opens the way to use other than Pi-mode phase advance per cell which increase transit time factor. Secondly, traveling wave is not so sensitive to cavity length as standing wave, which length is limited to 1 meter because of field flatness degradation. 3 cell SCTW cavity was proposed [2] and built for high gradient traveling wave demonstration and tuning studies. This paper describes analytical model that was used for cavity development. Tuning properties and requirements are also discussed. ' r.kostin@euclidtechlabs.com
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106021
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TUOP07	High Performance Next-Generation Nb3Sn Cavities for Future High Efficiency SRF Linacs	cavity, niobium, SRF, pulsed-power	398
	D.L. Hall, J.J. Kaufman, M. Liepe, J.T. Maniscalco, R.D. Porter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: DOE A 1.3 GHz ILC-shape single-cell Nb3Sn cavity fabricated at Cornell has shown record performance, exceeding the cryogenic efficiency of niobium cavities at the gradients and quality factors demanded by some contemporary accelerator designs. An optimisation of the coating process has resulted in more cavities of the same design that achieve similar performance, proving the reproducibility of the method. In this paper, we discuss the current limitations on the peak accelerating gradients achieved by these cavities. In particular, high-pulsed-power RF testing, and thermometry mapping of the cavity during CW operation, are used to draw conclusions regarding the nature of the quench limitation. In light of these promising results, the feasibility and utility of applying the current state of the technology to a real-life application is discussed.
	Slides TUOP07 [1.506 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP07
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TUPLR024	Enhancement of the Accelerating Gradient in Superconducting Microwave Resonators	induction, cavity, factory, linac	519
	M. Checchin, A. Grassellino, M. Martinello, S. Posen, A. Romanenko Fermilab, Batavia, Illinois, USA M. Martinello Illinois Institute of Technology, Chicago, Illlinois, USA J. Zasadzinski IIT, Chicago, Illinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DEAC02-07CH11359 with the United States Department of Energy. The accelerating gradient of superconducting resonators can be enhanced by engineering the thickness of a dirty layer grown at the cavity's rf surface. In this paper the description of the physics behind the accelerating gradient enhancement by meaning of the dirty layer is carried out by solving numerically the the Ginzburg-Landau (GL) equations for the layered system. The calculation shows that the presence of the dirty layer stabilizes the Meissner state up to the lower critical field of the bulk, increasing the maximum accelerating gradient.
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WE2A03	Plasma Processing to Improve the Performance of the SNS Superconducting Linac	plasma, cryomodule, linac, cavity	679
	M. Doleans, R. Afanador, J.A. Ball, D.L. Barnhart, W. Blokland, M.T. Crofford, B. DeGraff, S.W. Gold, B.S. Hannah, M.P. Howell, S.-H. Kim, S.W. Lee, J.D. Mammosser, C.J. McMahan, T.S. Neustadt, J. Saunders, S.E. Stewart, W.H. Strong, P.V. Tyagi, D.J. Vandygriff, D.M. Vandygriff ORNL, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. An in-situ plasma processing technique has been developed at the Spallation Neutron Source (SNS) to improve the performance of the superconducting radio-frequency (SRF) cavities in operation. The technique uses a low-density reactive neon-oxygen plasma at room-temperature to improve the surface work function, to help removing adsorbed gases on the RF surface and to reduce its secondary emission yield. Recently, the plasma processing technique has been applied to one offline cryomodule and to two cryomodules in the linac tunnel. Improvement of the accelerating gradient has been observed in all three cryomodules.
	Slides WE2A03 [4.433 MB]
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THOP01	Experimental Study of Nucleation for Nb3Sn Diffusion Coatings on Niobium SRF Cavities	niobium, SRF, experiment, background	740
	U. Pudasaini, M.J. Kelley The College of William and Mary, Williamsburg, Virginia, USA G.V. Eremeev, M.J. Kelley, C.E. Reece JLab, Newport News, Virginia, USA
	Funding: Partially authored by Jefferson Science Associates under Contract No. DE-AC05-06OR23177. Work at William & Mary supported by Office of High Energy Physics under grant SC0014475 Nb3Sn has the potential to achieve superior performance both in terms of operating temperature (4.2 K vs 2 K) and accelerating gradient resulting in significant reduction in both initial and operating costs of SRF linacs. Cavity interior surface coatings are obtained by two-step vapor diffusion: nucleation followed by deposition. To gain more understanding of nucleation and its effect on the subsequent coating, we investigated the effect of varying parameters in a typical tin/tin chloride process. We report findings obtained by SEM/EDS, AFM, SAM and other materials characterization approaches.
	Slides THOP01 [2.784 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP01
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THPLR003	Fabrication and High-Gradient Testing of an Accelerating Structure Made From Milled Halves	shielding, linac, radiation, collider	845
	W. Wuensch, T. Argyropoulos, N. Catalán Lasheras, D. Esperante Pereira, J. Giner Navarro, A. Grudiev, G. McMonagle, I. Syratchev, B.J. Woolley, H. Zha CERN, Geneva, Switzerland T. Argyropoulos, D. Esperante Pereira, J. Giner Navarro IFIC, Valencia, Spain G.B. Bowden, V.A. Dolgashev, A.A. Haase SLAC, Menlo Park, California, USA P.J. Giansiracusa, T.G. Lucas, M. Volpi The University of Melbourne, Melbourne, Victoria, Australia R. Rajamaki Aalto University, School of Science and Technology, Aalto, Finland X.F.D. Stragier TUE, Eindhoven, The Netherlands
	Accelerating structures made from parts which follow symmetry planes offer many potential advantages over traditional disk-based structures: more options for joining (from bonding to welding), following this more options for material state (heat treated or not) and potentially lower cost since structures can be made from fewer parts. An X-band structure made from milled halves, and with a standard benchmarked CLIC test structure design has been fabricated and high-gradient tested in the range of 100 MV/m.
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THPLR004	Development of 1.3 Ghz Single-Cell Superconducting Cavities With Nb Material Developed by Ulba Metallurgical Plant	cavity, niobium, vacuum, radiation	849
	T. Ota, N. Kuroiwa, S. Nomura, Y. Otani, M. Takasaki, M. Yamada Toshiba, Yokohama, Japan H. Hayano, T. Saeki KEK, Ibaraki, Japan Y.V. Krygin, V. Kuznetsov, A.A. Tsorayev Ulba Metallurgical Plant, Ust-Kamenogorak, Kazakhstan Y. Shirota BE International Corporation, Tokyo, Japan T. Tosaka Toshiba Corporation, Power And Industrial Systems Research and Development Center, Yokohama, Japan
	TOSHIBA has been developing high purity niobium (Nb) material for superconducting cavities with ULBA Metallurgical Plant (UMP) since 2008. Recently, we have produced the high purity Nb plates. Two 1.3 GHz single-cell superconducting cavities using UMP's Nb plates have been fabricated by TOSHIBA and RF tested at High Energy Accelerator Research Organization (KEK). One of the cavities has achieved the accelerating gradient of Eacc=31.8 MV/m. The development of high purity Nb plates, details of the fabrication of the cavities and the RF test results are presented in this article.
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THPLR008	3-Cell Superconducting Traveling Wave Cavity Tuning at Room Temperature	cavity, SRF, feedback, factory	858
	R.A. Kostin LETI, Saint-Petersburg, Russia P.V. Avrakhov, A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA T.N. Khabiboulline, A.M. Rowe, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: Work supported by US DOE SBIR # DE-SC0006300 A superconducting traveling wave (SCTW) cavity with a feedback waveguide will support a higher average acceleration gradient compared to conventional SRF standing wave cavities [1]. Euclid Techlabs, in collaboration with Fermilab, previously demonstrated a high accelerating gradient in a single cell cavity with a feedback waveguide [2], and the new waveguide design did not limit the cavity performance. The next step is high gradient traveling wave SRF cavity test. A 3-Cell SCTW cavity was designed and developed [3] to demonstrate the SRF traveling wave regime. Two Nb SCTW cavities were built, characterized and cold tested in 2016. This paper presents the results of cavity inspection, field flatness analysis, along with a discussion of the tuning procedure.
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Paper

Title

Other Keywords

Page

MOOP09

Dielectric and THz Acceleration (Data) Programme at the Cockcroft Institute

acceleration, laser, electron, wakefield

62

S.P. Jamison, Y.M. Saveliev
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.B. Appleby, H.L. Owen, T.H. Pacey, T.H. Pacey, G.X. Xia
UMAN, Manchester, United Kingdom
G. Burt, R. Letizia, C. Paoloni
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A.W. Cross
USTRAT/SUPA, Glasgow, United Kingdom
D.M. Graham
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work has been funded by STFC
Normal conducting RF systems are currently able to pro-vide gradients of around 100 MV/m, limited by break-down on the metallic structures. The breakdown rate is known to scale with pulse length and, in conventional RF systems, this is limited by the filling time of the RF struc-ture. Progressing to higher frequencies, from RF to THz and optical, can utilise higher gradient structures due to the fast filling times. Further increases in gradient may be possible by replacing metallic structures with dielectric structures. The DATA programme at the Cockcroft Insti-tute is investigating concepts for particle acceleration with laser driven THz sources and dielectric structures, beam driven dielectric and metallic structures, and optical and infrared laser acceleration using grating and photonic structures. A cornerstone of the programme is the VELA and CLARA electron accelerator test facility at Daresbury Laboratory which will be used for proof-of-principle experiments demonstrating particle acceleration.

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MOPLR005

Design, Manufacturing and Installation of Two Dual-Feed Accelerating Structures for the FERMI Injector

linac, cavity, FEL, emittance

139

C. Serpico, A. Fabris, G. Penco, M. Svandrlik
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
B. Keune
RI Research Instruments GmbH, Bergisch Gladbach, Germany

FERMI is a seeded Free Electron Laser (FEL) driven by a warm S-band Linac. In the injector region, two 3- meter long Forward Traveling Wave (FTW) accelerating structures, coming from the old Elettra injector, were installed. In order to improve the e-beam quality at higher bunch charge, it was decided to replace the existing ones with two dual-feed accelerating structures. Those structures have been designed and manufactured by RI Research Instruments GmbH and delivered to Elettra in July 2015. The following paper will report about the RF design and the manufacturing of the new structures. Details about the RF conditioning and the installation will also be illustrated.

Poster MOPLR005 [1.100 MB]

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MOPLR011

Design of a Dielectric-lined Waveguide for Terahertz-driven Linear Electron Acceleration

electron, acceleration, impedance, experiment

158

A.L. Healy, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
M.J. Cliffe, D.M. Graham
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
S.P. Jamison
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom

A dielectric-lined waveguide has been designed for use as an accelerating structure in terahertz-driven electron acceleration experiments at Daresbury. Experimental verification of acceleration will take place on Versatile Electron Linear Accelerator (VELA). The choice of a rectangular waveguide structure with sidewall dielectric layers enables tuning by varying the spacing between dielectric slabs to account for potential manufacturing errors. Schemes for coupling free-space single cycle THz pulses into the waveguide have been evaluated and optimised through CST simulation. Comparison of simulation with experimental measurements will also be presented.

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MOPLR023

Examination of Cutouts Inner Surfaces from Nb3Sn Coated Cavity

cavity, niobium, SRF, ion

189

U. Pudasaini, M.J. Kelley
The College of William and Mary, Williamsburg, Virginia, USA
G.V. Eremeev, C.E. Reece
JLab, Newport News, Virginia, USA
J. Tuggle
Virginia Polytechnic Institute and State University, Blacksburg, USA

Funding: Supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of High Energy Physics under grant SC00144475.
The potential for higher operating temperature and higher gradient have motivated SRF cavity researchers to pursue Nb3Sn as an alternative to Nb for nearly fifty years. Far and away the most common embodiment has been a few micron-thick Nb3Sn layer on the cavity interior surface obtained by vapor diffusion coating, with one or another set of parameters. While many cavities have been made and RF tested, reports of dissecting a cavity in detail to examine the coating and relate it to RF measurements are rare. We coated a BCP-treated single cell cavity in a typical process of tin/tin chloride activation at 500 C followed by tin vapor deposition at 1200 C. After RF-testing, we cut and examined sections from several locations to learn composition, thickness topography of the interior surface. The effect of process variables, such as surface preparation, process temperature and duration, and vapor chemistry needs to be explored.

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MOPLR048

Fabrication and Testing of a Novel S-Band Backward Travelling Wave Accelerating Structure for Proton Therapy Linacs

linac, vacuum, coupling, proton

237

S. Benedetti, T. Argyropoulos, C. Blanch Gutiérrez, N. Catalán Lasheras, A. Degiovanni, D. Esperante Pereira, M. Garlaschè, J. Giner Navarro, A. Grudiev, G. McMonagle, A. Solodko, M.A. Timmins, R. Wegner, B.J. Woolley, W. Wuensch
CERN, Geneva, Switzerland
D. Esperante Pereira
IFIC, Valencia, Spain

Compact and more affordable, facilities for proton therapy are now entering the market of commercial medical accelerators. At CERN, a joint collaboration between CLIC and TERA Foundation led to the design, fabrication and testing of a high gradient accelerating structure prototype, capable of halving the length of state-of-art light ion therapy linacs. This paper focuses on the mechanical design, fabrication and testing of a first prototype. CLIC standardized bead-pull measurement setup was used, leading to a quick and successful tuning of the prototype. The high power tests will soon start in order to prove that the structure can withstand a very high accelerating gradient while suffering no more than 10^-6 breakdown per pulse per meter (bpp/m), resulting in less than one breakdown per treatment session.

Poster MOPLR048 [2.804 MB]

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MOPLR066

ProBE: Proton Boosting Extension for Imaging and Therapy

proton, cavity, septum, linac

283

S. Pitman, R. Apsimon, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A.F. Green, H.L. Owen
UMAN, Manchester, United Kingdom
A. Grudiev, A. Solodko, W. Wuensch
CERN, Geneva, Switzerland

Funding: This work was funded by STFC and IPS
Proton beam therapy has been shown to be a promising alternative to traditional radiotherapy, especially for paedi- atric malignancies and radio-resistant tumours. Allowing a highly precise tumour irradiation, it is currently limited by range verification. Several imaging modalities can be utilised for treatment planning, but typically X-ray CT is used. CT scans require conversion from Hounsfield units to estimate the proton stopping power (PSP) of the tissue be- ing treated, and this produces inaccuracy. Proton CT (pCT) measures PSP and is thought to allow an improvement of the treatment accuracy. The Christie Hospital will use a 250 MeV cyclotron for proton therapy, in this paper a pulsed linac upgrade is proposed, to provide 350 MeV protons for pCT within the facility. Space contraints require a compact, high gradient (HG) solution that is reliable and affordable.

Poster MOPLR066 [0.610 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR066

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MOP106021

Superconducting Traveling Wave Cavity Tuning Studies

cavity, feedback, SRF, acceleration

327

R.A. Kostin
LETI, Saint-Petersburg, Russia
P.V. Avrakhov, A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by US DOE SBIR # DE-SC0006300
Superconducting traveling wave cavity (SCTW) can provide 1.2-1.4 times larger accelerating gradient than conventional standing wave SRF cavities [1]. Firstly, traveling wave opens the way to use other than Pi-mode phase advance per cell which increase transit time factor. Secondly, traveling wave is not so sensitive to cavity length as standing wave, which length is limited to 1 meter because of field flatness degradation. 3 cell SCTW cavity was proposed [2] and built for high gradient traveling wave demonstration and tuning studies. This paper describes analytical model that was used for cavity development. Tuning properties and requirements are also discussed.
' r.kostin@euclidtechlabs.com

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106021

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TUOP07

High Performance Next-Generation Nb3Sn Cavities for Future High Efficiency SRF Linacs

cavity, niobium, SRF, pulsed-power

398

D.L. Hall, J.J. Kaufman, M. Liepe, J.T. Maniscalco, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: DOE
A 1.3 GHz ILC-shape single-cell Nb3Sn cavity fabricated at Cornell has shown record performance, exceeding the cryogenic efficiency of niobium cavities at the gradients and quality factors demanded by some contemporary accelerator designs. An optimisation of the coating process has resulted in more cavities of the same design that achieve similar performance, proving the reproducibility of the method. In this paper, we discuss the current limitations on the peak accelerating gradients achieved by these cavities. In particular, high-pulsed-power RF testing, and thermometry mapping of the cavity during CW operation, are used to draw conclusions regarding the nature of the quench limitation. In light of these promising results, the feasibility and utility of applying the current state of the technology to a real-life application is discussed.

Slides TUOP07 [1.506 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP07

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TUPLR024

Enhancement of the Accelerating Gradient in Superconducting Microwave Resonators

induction, cavity, factory, linac

519

M. Checchin, A. Grassellino, M. Martinello, S. Posen, A. Romanenko
Fermilab, Batavia, Illinois, USA
M. Martinello
Illinois Institute of Technology, Chicago, Illlinois, USA
J. Zasadzinski
IIT, Chicago, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DEAC02-07CH11359 with the United States Department of Energy.
The accelerating gradient of superconducting resonators can be enhanced by engineering the thickness of a dirty layer grown at the cavity's rf surface. In this paper the description of the physics behind the accelerating gradient enhancement by meaning of the dirty layer is carried out by solving numerically the the Ginzburg-Landau (GL) equations for the layered system. The calculation shows that the presence of the dirty layer stabilizes the Meissner state up to the lower critical field of the bulk, increasing the maximum accelerating gradient.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR024

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WE2A03

Plasma Processing to Improve the Performance of the SNS Superconducting Linac

plasma, cryomodule, linac, cavity

679

M. Doleans, R. Afanador, J.A. Ball, D.L. Barnhart, W. Blokland, M.T. Crofford, B. DeGraff, S.W. Gold, B.S. Hannah, M.P. Howell, S.-H. Kim, S.W. Lee, J.D. Mammosser, C.J. McMahan, T.S. Neustadt, J. Saunders, S.E. Stewart, W.H. Strong, P.V. Tyagi, D.J. Vandygriff, D.M. Vandygriff
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
An in-situ plasma processing technique has been developed at the Spallation Neutron Source (SNS) to improve the performance of the superconducting radio-frequency (SRF) cavities in operation. The technique uses a low-density reactive neon-oxygen plasma at room-temperature to improve the surface work function, to help removing adsorbed gases on the RF surface and to reduce its secondary emission yield. Recently, the plasma processing technique has been applied to one offline cryomodule and to two cryomodules in the linac tunnel. Improvement of the accelerating gradient has been observed in all three cryomodules.

Slides WE2A03 [4.433 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-WE2A03

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THOP01

Experimental Study of Nucleation for Nb3Sn Diffusion Coatings on Niobium SRF Cavities

niobium, SRF, experiment, background

740

U. Pudasaini, M.J. Kelley
The College of William and Mary, Williamsburg, Virginia, USA
G.V. Eremeev, M.J. Kelley, C.E. Reece
JLab, Newport News, Virginia, USA

Funding: Partially authored by Jefferson Science Associates under Contract No. DE-AC05-06OR23177. Work at William & Mary supported by Office of High Energy Physics under grant SC0014475
Nb3Sn has the potential to achieve superior performance both in terms of operating temperature (4.2 K vs 2 K) and accelerating gradient resulting in significant reduction in both initial and operating costs of SRF linacs. Cavity interior surface coatings are obtained by two-step vapor diffusion: nucleation followed by deposition. To gain more understanding of nucleation and its effect on the subsequent coating, we investigated the effect of varying parameters in a typical tin/tin chloride process. We report findings obtained by SEM/EDS, AFM, SAM and other materials characterization approaches.

Slides THOP01 [2.784 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP01

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THPLR003

Fabrication and High-Gradient Testing of an Accelerating Structure Made From Milled Halves

shielding, linac, radiation, collider

845

W. Wuensch, T. Argyropoulos, N. Catalán Lasheras, D. Esperante Pereira, J. Giner Navarro, A. Grudiev, G. McMonagle, I. Syratchev, B.J. Woolley, H. Zha
CERN, Geneva, Switzerland
T. Argyropoulos, D. Esperante Pereira, J. Giner Navarro
IFIC, Valencia, Spain
G.B. Bowden, V.A. Dolgashev, A.A. Haase
SLAC, Menlo Park, California, USA
P.J. Giansiracusa, T.G. Lucas, M. Volpi
The University of Melbourne, Melbourne, Victoria, Australia
R. Rajamaki
Aalto University, School of Science and Technology, Aalto, Finland
X.F.D. Stragier
TUE, Eindhoven, The Netherlands

Accelerating structures made from parts which follow symmetry planes offer many potential advantages over traditional disk-based structures: more options for joining (from bonding to welding), following this more options for material state (heat treated or not) and potentially lower cost since structures can be made from fewer parts. An X-band structure made from milled halves, and with a standard benchmarked CLIC test structure design has been fabricated and high-gradient tested in the range of 100 MV/m.

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THPLR004

Development of 1.3 Ghz Single-Cell Superconducting Cavities With Nb Material Developed by Ulba Metallurgical Plant

cavity, niobium, vacuum, radiation

849

T. Ota, N. Kuroiwa, S. Nomura, Y. Otani, M. Takasaki, M. Yamada
Toshiba, Yokohama, Japan
H. Hayano, T. Saeki
KEK, Ibaraki, Japan
Y.V. Krygin, V. Kuznetsov, A.A. Tsorayev
Ulba Metallurgical Plant, Ust-Kamenogorak, Kazakhstan
Y. Shirota
BE International Corporation, Tokyo, Japan
T. Tosaka
Toshiba Corporation, Power And Industrial Systems Research and Development Center, Yokohama, Japan

TOSHIBA has been developing high purity niobium (Nb) material for superconducting cavities with ULBA Metallurgical Plant (UMP) since 2008. Recently, we have produced the high purity Nb plates. Two 1.3 GHz single-cell superconducting cavities using UMP's Nb plates have been fabricated by TOSHIBA and RF tested at High Energy Accelerator Research Organization (KEK). One of the cavities has achieved the accelerating gradient of Eacc=31.8 MV/m. The development of high purity Nb plates, details of the fabrication of the cavities and the RF test results are presented in this article.

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THPLR008

3-Cell Superconducting Traveling Wave Cavity Tuning at Room Temperature

cavity, SRF, feedback, factory

858

R.A. Kostin
LETI, Saint-Petersburg, Russia
P.V. Avrakhov, A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
T.N. Khabiboulline, A.M. Rowe, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by US DOE SBIR # DE-SC0006300
A superconducting traveling wave (SCTW) cavity with a feedback waveguide will support a higher average acceleration gradient compared to conventional SRF standing wave cavities [1]. Euclid Techlabs, in collaboration with Fermilab, previously demonstrated a high accelerating gradient in a single cell cavity with a feedback waveguide [2], and the new waveguide design did not limit the cavity performance. The next step is high gradient traveling wave SRF cavity test. A 3-Cell SCTW cavity was designed and developed [3] to demonstrate the SRF traveling wave regime. Two Nb SCTW cavities were built, characterized and cold tested in 2016. This paper presents the results of cavity inspection, field flatness analysis, along with a discussion of the tuning procedure.

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