IPAC2015 - List of Keywords (radio-frequency)

Paper	Title	Other Keywords	Page
MOPJE033	Coupled Orbit Response Coefficients with Constant Revolution Time	storage-ring, optics, closed-orbit, diagnostics	354
	V.G. Ziemann Uppsala University, Uppsala, Sweden
	We calculate orbit response coefficients for arbitrarily coupled lattice which keep the orbit length constant as is needed to maintain synchronicity with a radio-frequency system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE033
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WEPHA059	Physical Vapour Deposition of Thin Films for Use in Superconducting RF Cavities	SRF, superconductivity, plasma, power-supply	3249
	S. Wilde, B. Chesca Loughborough University, Loughborough, Leicestershire, United Kingdom A.N. Hannah, D.O. Malyshev, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G.B.G. Stenning STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The production of superconducting coatings for radio frequency cavities is a rapidly developing field that should ultimately lead to acceleration gradients greater than those obtained by bulk Nb RF cavities. Optimizing superconducting properties of Nb thin-films is therefore essential. Nb films were deposited by magnetron sputtering in pulsed DC mode onto Si (100) and MgO (100) substrates and also by high impulse magnetron sputtering (HiPIMS) onto Si (100), MgO (100) and polycrystalline Cu. The films were characterised using scanning electron microscopy, x-ray diffraction and DC SQUID magnetometry.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA059
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WEPTY050	Low Powered RF Measurements of Dielectric Materials for use in High Pressure Gas Filled RF Cavities	cavity, simulation, factory, collider	3387
	B.T. Freemire IIT, Chicago, Illinois, USA G. Arriaga Northern Illinois Univerity, Dekalb, Illinois, USA D.L. Bowring, A.V. Kochemirovskiy, A. Moretti, A.V. Tollestrup, Y. Torun, K. Yonehara Fermilab, Batavia, Illinois, USA H.D. Phan McDaniel College, Westminster, USA Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA
	The Helical Cooling Channel scheme envisioned for a Muon Collider or Neutrino Factory requires high pressure gas filled radio frequency cavities to operate in superconducting magnets. One method to shrink the radii of the cavities is to load them with a dielectric material. The dielectric constant, loss tangent, and dielectric strength are important in determining the most suitable material. Low powered RF measurements of the dielectric constant and loss tangent were taken for multiple purities of alumina and magnesium calcium titanate, as well as cordierite, forsterite, and aluminum nitride. Measurements of alumina were consistent with previously reported results. The results were used to design an insert for a high powered RF test that included sending beam through the cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY050
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WEPTY075	Hc2 Measurements of Nb3Sn and Nitrogen-doped Niobium using Physical Property Measurement System	niobium, SRF, controls, superconductivity	3458
	J.T. Maniscalco, D. Gonnella, D.L. Hall, M. Liepe, S. Posen Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The measurement of the upper critical field of a type-2 superconductor, Hc2, is an important step in determining its superconducting properties, and therefore its suitability as a material in SRF cavities. However, measuring Hc2 directly can be challenging, as performing electrical measurements causes changes in the very properties one seeks to measure. We present a method for extracting Hc2 from resistivity measurements made near the transition temperature for varied applied fields and excitation currents. We also present results of these measurements made on Nb3Sn and nitrogen-doped niobium.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY075
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WEPTY077	On Quench Propagation, Quench Detection, and Second Sound in SRF Cavities	niobium, cavity, simulation, SRF	3464
	S.R. Markham, R.G. Eichhorn Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The detection of a second sound wave, excited by a quench, has become a valuable tool in diagnosing hot spots and performance limitations of superconducting cavities. Several years ago, Cornell developed an oscillating super-leak transducer (OST) for these waves that nowadays are used world-wide. In a usual set-up, several OSTs surround the cavity, and the quench location is determined by triangulation of the different OST signals. Convenient as the method is there is a small remaining mystery: taking the well-known velocity of the second sound wave, the quench seems to come from a place slightly above the cavity’s outer surface. We will present a model based on numerical quench propagation simulations and analytic geometrical calculations that help explain the discrepancy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY077
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WEPWI009	Nitrogen Doping Study in Ingot Niobium Cavities	cavity, niobium, SRF, accelerating-gradient	3506
	P. Dhakal, G. Ciovati, P. Kneisel, G.R. Myneni JLab, Newport News, Virginia, USA J. Makita ODU, Norfolk, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 Thermal diffusion of nitrogen in superconducting radio frequency cavities at temperatures around 800C has resulted in the increase in quality factor with a low-field Q-rise. However, the maximum accelerating gradients of these doped cavities often reduces below the values achieved by standard treatments. In this contribution, we present the results of the nitrogen diffusion into ingot niobium cavities subjected to successive material removal from the inner cavity surface by electropolishing in an effort to explore the underlying cause for the gradient degradation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI009
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WEPWI016	Investigation of Differential Surface Removal due to Electropolishing at JLab	cavity, simulation, cathode, SRF	3525
	F. Marhauser, J. Follkie, C.E. Reece JLab, Newport News, Virginia, USA
	Surface chemistry carried out for Superconducting Radio Frequency (SRF) cavities such as Buffered Chemical Polishing (BCP) and Electropolishing (EP) aims to uniformly remove the internal surface of a cavity along the entire structure and within each cell from equator to iris in order to obtain an equally etched surface. A uniform removal however is not readily achievable due to the complex fluid flow and varying temperatures of the acid mixture, which can lead to differential etching. This needs to be considered when envisaging a certain surface damage removal throughout the interior. The process-specific differential etching influences the target frequency set at the manufacturing stage as well as the field flatness and length of the as-built cavity. We report on analyses of JLab's present EP system using experimental data for six nine-cell cavities that have been processed recently in the frame of the LCLS-II high-Q development plan. In conjunction with numerical simulations, the differential etching and the impact on field flatness is assessed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI016
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WEPWI038	Temperature Mapping of Nitrogen-doped Niobium Superconducting Radiofrequency Cavities	cavity, niobium, SRF, cryogenics	3575
	J. Makita ODU, Norfolk, Virginia, USA G. Ciovati, P. Dhakal JLab, Newport News, Virginia, USA
	It was recently shown that diffusing nitrogen on the inner surface of superconducting radiofrequency (SRF) cavities at high temperature can improve the quality factor of the niobium cavity. However, a reduction of the quench field is also typically found. To better understand the location of rf losses and quench, we used a thermometry system to map the temperature of the outer surface of ingot Nb cavities after nitrogen doping and electropolishing. Surface temperature of the cavities was recorded while increasing the rf power and also during the quenching. The results of thermal mapping showed no precursor heating on the cavities and quenching to be ignited near the equator where the surface magnetic field is maximum. Hot-spots at the equator area during multipacting were also detected by thermal mapping.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI038
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOPJE033

Coupled Orbit Response Coefficients with Constant Revolution Time

storage-ring, optics, closed-orbit, diagnostics

354

V.G. Ziemann
Uppsala University, Uppsala, Sweden

We calculate orbit response coefficients for arbitrarily coupled lattice which keep the orbit length constant as is needed to maintain synchronicity with a radio-frequency system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE033

Export •

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

WEPHA059

Physical Vapour Deposition of Thin Films for Use in Superconducting RF Cavities

SRF, superconductivity, plasma, power-supply

3249

S. Wilde, B. Chesca
Loughborough University, Loughborough, Leicestershire, United Kingdom
A.N. Hannah, D.O. Malyshev, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G.B.G. Stenning
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The production of superconducting coatings for radio frequency cavities is a rapidly developing field that should ultimately lead to acceleration gradients greater than those obtained by bulk Nb RF cavities. Optimizing superconducting properties of Nb thin-films is therefore essential. Nb films were deposited by magnetron sputtering in pulsed DC mode onto Si (100) and MgO (100) substrates and also by high impulse magnetron sputtering (HiPIMS) onto Si (100), MgO (100) and polycrystalline Cu. The films were characterised using scanning electron microscopy, x-ray diffraction and DC SQUID magnetometry.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA059

Export •

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

WEPTY050

Low Powered RF Measurements of Dielectric Materials for use in High Pressure Gas Filled RF Cavities

cavity, simulation, factory, collider

3387

B.T. Freemire
IIT, Chicago, Illinois, USA
G. Arriaga
Northern Illinois Univerity, Dekalb, Illinois, USA
D.L. Bowring, A.V. Kochemirovskiy, A. Moretti, A.V. Tollestrup, Y. Torun, K. Yonehara
Fermilab, Batavia, Illinois, USA
H.D. Phan
McDaniel College, Westminster, USA
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

The Helical Cooling Channel scheme envisioned for a Muon Collider or Neutrino Factory requires high pressure gas filled radio frequency cavities to operate in superconducting magnets. One method to shrink the radii of the cavities is to load them with a dielectric material. The dielectric constant, loss tangent, and dielectric strength are important in determining the most suitable material. Low powered RF measurements of the dielectric constant and loss tangent were taken for multiple purities of alumina and magnesium calcium titanate, as well as cordierite, forsterite, and aluminum nitride. Measurements of alumina were consistent with previously reported results. The results were used to design an insert for a high powered RF test that included sending beam through the cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY050

Export •

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

WEPTY075

Hc2 Measurements of Nb3Sn and Nitrogen-doped Niobium using Physical Property Measurement System

niobium, SRF, controls, superconductivity

3458

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

The measurement of the upper critical field of a type-2 superconductor, Hc2, is an important step in determining its superconducting properties, and therefore its suitability as a material in SRF cavities. However, measuring Hc2 directly can be challenging, as performing electrical measurements causes changes in the very properties one seeks to measure. We present a method for extracting Hc2 from resistivity measurements made near the transition temperature for varied applied fields and excitation currents. We also present results of these measurements made on Nb3Sn and nitrogen-doped niobium.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY075

Export •

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

WEPTY077

On Quench Propagation, Quench Detection, and Second Sound in SRF Cavities

niobium, cavity, simulation, SRF

3464

S.R. Markham, R.G. Eichhorn
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The detection of a second sound wave, excited by a quench, has become a valuable tool in diagnosing hot spots and performance limitations of superconducting cavities. Several years ago, Cornell developed an oscillating super-leak transducer (OST) for these waves that nowadays are used world-wide. In a usual set-up, several OSTs surround the cavity, and the quench location is determined by triangulation of the different OST signals. Convenient as the method is there is a small remaining mystery: taking the well-known velocity of the second sound wave, the quench seems to come from a place slightly above the cavity’s outer surface. We will present a model based on numerical quench propagation simulations and analytic geometrical calculations that help explain the discrepancy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY077

Export •

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

WEPWI009

Nitrogen Doping Study in Ingot Niobium Cavities

cavity, niobium, SRF, accelerating-gradient

3506

P. Dhakal, G. Ciovati, P. Kneisel, G.R. Myneni
JLab, Newport News, Virginia, USA
J. Makita
ODU, Norfolk, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Thermal diffusion of nitrogen in superconducting radio frequency cavities at temperatures around 800C has resulted in the increase in quality factor with a low-field Q-rise. However, the maximum accelerating gradients of these doped cavities often reduces below the values achieved by standard treatments. In this contribution, we present the results of the nitrogen diffusion into ingot niobium cavities subjected to successive material removal from the inner cavity surface by electropolishing in an effort to explore the underlying cause for the gradient degradation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI009

Export •

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

WEPWI016

Investigation of Differential Surface Removal due to Electropolishing at JLab

cavity, simulation, cathode, SRF

3525

F. Marhauser, J. Follkie, C.E. Reece
JLab, Newport News, Virginia, USA

Surface chemistry carried out for Superconducting Radio Frequency (SRF) cavities such as Buffered Chemical Polishing (BCP) and Electropolishing (EP) aims to uniformly remove the internal surface of a cavity along the entire structure and within each cell from equator to iris in order to obtain an equally etched surface. A uniform removal however is not readily achievable due to the complex fluid flow and varying temperatures of the acid mixture, which can lead to differential etching. This needs to be considered when envisaging a certain surface damage removal throughout the interior. The process-specific differential etching influences the target frequency set at the manufacturing stage as well as the field flatness and length of the as-built cavity. We report on analyses of JLab's present EP system using experimental data for six nine-cell cavities that have been processed recently in the frame of the LCLS-II high-Q development plan. In conjunction with numerical simulations, the differential etching and the impact on field flatness is assessed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI016

Export •

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

WEPWI038

Temperature Mapping of Nitrogen-doped Niobium Superconducting Radiofrequency Cavities

cavity, niobium, SRF, cryogenics

3575

J. Makita
ODU, Norfolk, Virginia, USA
G. Ciovati, P. Dhakal
JLab, Newport News, Virginia, USA

It was recently shown that diffusing nitrogen on the inner surface of superconducting radiofrequency (SRF) cavities at high temperature can improve the quality factor of the niobium cavity. However, a reduction of the quench field is also typically found. To better understand the location of rf losses and quench, we used a thermometry system to map the temperature of the outer surface of ingot Nb cavities after nitrogen doping and electropolishing. Surface temperature of the cavities was recorded while increasing the rf power and also during the quenching. The results of thermal mapping showed no precursor heating on the cavities and quenching to be ignited near the equator where the surface magnetic field is maximum. Hot-spots at the equator area during multipacting were also detected by thermal mapping.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI038

Export •

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