2011 Particle Accelerator Conference - List of Keywords (superconductivity)

Paper	Title	Other Keywords	Page
TUP099	Design of Superconducting Parallel-bar Deflecting/Crabbing Cavities with Improved Properties	cavity, HOM, damping, higher-order-mode	1021
	J.R. Delayen, S.U. De Silva ODU, Norfolk, Virginia, USA J.R. Delayen JLAB, Newport News, Virginia, USA
	The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. All designs to-date have been based on straight loading elements and rectangular outer conductors. We present new designs of parallel-bar cavities using curved loading elements and circular or elliptical outer conductors, with significantly improved properties such as reduced surface fields and wider higher-order mode separation.

TUP100	Design of Superconducting Spoke Cavities for High-velocity Applications	cavity, HOM, higher-order-mode, linac	1024
	J.R. Delayen, S.U. De Silva, C.S. Hopper ODU, Norfolk, Virginia, USA J.R. Delayen JLAB, Newport News, Virginia, USA
	Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β~0.15 to β~0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of spoke cavities optimized for β=0.8 and β=1.

TUP104	Nb3Sn Block-coil Dipole for High-field Substitution in the LHC Lattice	dipole, lattice, insertion, multipole	1033
	A. Sattarov, E.F. Holik, A.D. McInturff, P.M. McIntyre Texas A&M University, College Station, Texas, USA
	Funding: This work was supported in part by the U.S. Department of Energy under Grant DE-FG02-06ER41405 A design is being developed to prototype for a dipole for this purpose: a block-coil dipole with 13 T short- sample field, 11 T working field, and 6 cm aperture. The dipole is a natural application of the high-field dipole strategy developed at Texas A&M, using simple pancake windings, flux-plate suppression of low-field multipoles, and bladder preloading. A short model dipole is planned.

TUP106	Effect of Surface Flow on Topography in Niobium Electropolishing	niobium, cavity, SRF, cathode	1038
	M.J. Kelley, C.E. Reece JLAB, Newport News, Virginia, USA L. Zhao The College of William and Mary, Williamsburg, USA
	Funding: This work has been supported by U.S. DOE Contract No. DE-AC05-06OR23177 to Jefferson Lab Electropolishing (EP) is reliably delivering improved performance of multi-celled niobium SRF accelerator cavities, attributed to the smoother surface obtained. This superior leveling is a consequence of an etchant concentration gradient layer that arises in the HF-H2SO4 electrolyte adjacent to the niobium surface during polishing. Electrolyte circulation raises the prospect that fluid flow adjacent to the surface might affect the diffusion layer and impair EP performance. In this study, preliminary bench-top experiments with a moving electrode apparatus were conducted. We find that flow conditions approximating cavity EP show no effects attributable to depletion layer disruption.

TUP171	Influence of Proton Irradiation on Angular Dependence of Second Generation (2G) HTS	radiation, proton, quadrupole, target	1145
	Y. Shiroyanagi, G.A. Greene, R.C. Gupta, W. Sampson BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the U.S. DOE under Contract No. DE-AC02-98CH10886 and under Cooperative Agreement DE-SC0000661 from DOE-SC that provides financial assistance to MSU to design and establish FRIB. In the Facility for Rare Isotope Beams (FRIB), superconducting magnets will be exposed to high levels of ionizing radiation. Quadruples in the fragment separator will be exposed to radiation doses as high as ~20 MGy/yr and heat loads as high as ~10 kW/m. High temperature superconducting (HTS) tapes are good candidates for this magnet because they can be operated in the temperature range ~30-50 K to tolerate higher temperatures than low temperature superconductors. Thus, radiation damage studies of HTS tapes are crucial to ensure that they will perform satisfactorily in such a high radiation environment. Therefore, the effects of proton irradiation on second generation HTS tapes from two vendors were studied. Each sample of HTS tape from SuperPower and American Superconductor was irradiated by a 42μA, 142 MeV proton beam at the Brookhaven Linac Isotope Producer. Two of each were irradiated at 5 dose levels: 2.5, 25, 50, 75 and 100μA•hr. The angular dependence of the critical current was measured in a magnetic field at 77K. Based on these measurements, conductors from both vendors appear to satisfy the FRIB radiation-tolerance requirement of 10 years of operation.

TUP172	Studies of High-field Sections of a Muon Helical Cooling Channel with Coil Separation	target, dipole, solenoid, cavity	1148
	M.L. Lopes, V.S. Kashikhin, K. Yonehara, M. Yu, A.V. Zlobin Fermilab, Batavia, USA
	Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. The Helical Cooling Channel (HCC) was proposed for 6D cooling of muon beams required for muon collider and some other applications. HCC uses a continuous absorber inside superconducting magnets which produce solenoidal field superimposed with transverse helical dipole and helical gradient fields. HCC is usually divided into several sections each with progressively stronger fields, smaller aperture and shorter helix period to achieve the optimal muon cooling rate. This paper presents the design issues of the high field section of HCC with coil separation. The effect of coil spacing on the longitudinal and transverse field components is presented and its impact on the muon cooling is evaluated and discussed. The paper also describes methods for field corrections and their practical limits.

Paper

Title

Other Keywords

Page

TUP099

Design of Superconducting Parallel-bar Deflecting/Crabbing Cavities with Improved Properties

cavity, HOM, damping, higher-order-mode

1021

J.R. Delayen, S.U. De Silva
ODU, Norfolk, Virginia, USA
J.R. Delayen
JLAB, Newport News, Virginia, USA

The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. All designs to-date have been based on straight loading elements and rectangular outer conductors. We present new designs of parallel-bar cavities using curved loading elements and circular or elliptical outer conductors, with significantly improved properties such as reduced surface fields and wider higher-order mode separation.

TUP100

Design of Superconducting Spoke Cavities for High-velocity Applications

cavity, HOM, higher-order-mode, linac

1024

J.R. Delayen, S.U. De Silva, C.S. Hopper
ODU, Norfolk, Virginia, USA
J.R. Delayen
JLAB, Newport News, Virginia, USA

Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β~0.15 to β~0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of spoke cavities optimized for β=0.8 and β=1.

TUP104

Nb3Sn Block-coil Dipole for High-field Substitution in the LHC Lattice

dipole, lattice, insertion, multipole

1033

A. Sattarov, E.F. Holik, A.D. McInturff, P.M. McIntyre
Texas A&M University, College Station, Texas, USA

Funding: This work was supported in part by the U.S. Department of Energy under Grant DE-FG02-06ER41405
A design is being developed to prototype for a dipole for this purpose: a block-coil dipole with 13 T short- sample field, 11 T working field, and 6 cm aperture. The dipole is a natural application of the high-field dipole strategy developed at Texas A&M, using simple pancake windings, flux-plate suppression of low-field multipoles, and bladder preloading. A short model dipole is planned.

TUP106

Effect of Surface Flow on Topography in Niobium Electropolishing

niobium, cavity, SRF, cathode

1038

M.J. Kelley, C.E. Reece
JLAB, Newport News, Virginia, USA
L. Zhao
The College of William and Mary, Williamsburg, USA

Funding: This work has been supported by U.S. DOE Contract No. DE-AC05-06OR23177 to Jefferson Lab
Electropolishing (EP) is reliably delivering improved performance of multi-celled niobium SRF accelerator cavities, attributed to the smoother surface obtained. This superior leveling is a consequence of an etchant concentration gradient layer that arises in the HF-H2SO4 electrolyte adjacent to the niobium surface during polishing. Electrolyte circulation raises the prospect that fluid flow adjacent to the surface might affect the diffusion layer and impair EP performance. In this study, preliminary bench-top experiments with a moving electrode apparatus were conducted. We find that flow conditions approximating cavity EP show no effects attributable to depletion layer disruption.

TUP171

Influence of Proton Irradiation on Angular Dependence of Second Generation (2G) HTS

radiation, proton, quadrupole, target

1145

Y. Shiroyanagi, G.A. Greene, R.C. Gupta, W. Sampson
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the U.S. DOE under Contract No. DE-AC02-98CH10886 and under Cooperative Agreement DE-SC0000661 from DOE-SC that provides financial assistance to MSU to design and establish FRIB.
In the Facility for Rare Isotope Beams (FRIB), superconducting magnets will be exposed to high levels of ionizing radiation. Quadruples in the fragment separator will be exposed to radiation doses as high as ~20 MGy/yr and heat loads as high as ~10 kW/m. High temperature superconducting (HTS) tapes are good candidates for this magnet because they can be operated in the temperature range ~30-50 K to tolerate higher temperatures than low temperature superconductors. Thus, radiation damage studies of HTS tapes are crucial to ensure that they will perform satisfactorily in such a high radiation environment. Therefore, the effects of proton irradiation on second generation HTS tapes from two vendors were studied. Each sample of HTS tape from SuperPower and American Superconductor was irradiated by a 42μA, 142 MeV proton beam at the Brookhaven Linac Isotope Producer. Two of each were irradiated at 5 dose levels: 2.5, 25, 50, 75 and 100μA•hr. The angular dependence of the critical current was measured in a magnetic field at 77K. Based on these measurements, conductors from both vendors appear to satisfy the FRIB radiation-tolerance requirement of 10 years of operation.

TUP172

Studies of High-field Sections of a Muon Helical Cooling Channel with Coil Separation

target, dipole, solenoid, cavity

1148

M.L. Lopes, V.S. Kashikhin, K. Yonehara, M. Yu, A.V. Zlobin
Fermilab, Batavia, USA

Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
The Helical Cooling Channel (HCC) was proposed for 6D cooling of muon beams required for muon collider and some other applications. HCC uses a continuous absorber inside superconducting magnets which produce solenoidal field superimposed with transverse helical dipole and helical gradient fields. HCC is usually divided into several sections each with progressively stronger fields, smaller aperture and shorter helix period to achieve the optimal muon cooling rate. This paper presents the design issues of the high field section of HCC with coil separation. The effect of coil spacing on the longitudinal and transverse field components is presented and its impact on the muon cooling is evaluated and discussed. The paper also describes methods for field corrections and their practical limits.