2011 Particle Accelerator Conference - List of Authors (Delayen, J.R.)

Paper

Title

Page

Beam Dynamics Studies of Parallel-Bar Deflecting Cavities

790

S. Ahmed, J.R. Delayen, A.S. Hofler, G.A. Krafft, M. Spata, M.G. Tiefenback
JLAB, Newport News, Virginia, USA
K.B. Beard
Muons, Inc, Batavia, USA
K.A. Deitrick
RPI, Troy, New York, USA
S.D. Silva
ODU, Norfolk, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We have performed three-dimensional simulations of beam dynamics for parallel-bar transverse electromagnetic mode (TEM) type RF separators: normal- and superconducting. The compact size of these cavities as compared to conventional TM₁₁₀ type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of eight 2-cell normal conducting cavities or a one- or two-cell superconducting structure are enough to produce the required vertical displacement at the Lambertson magnet. Both the normal and superconducting structures show very small emittance dilution due to the vertical kick of the beam.

Slides TUODN3 [1.558 MB]

TUP099

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

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

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.

TUP097

Fundamental and HOM Coupler Design for the Superconducting Parallel-Bar Cavity

1015

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

The superconducting parallel-bar cavity is currently being considered as a deflecting system for the Jefferson Lab 12 GeV upgrade and as a crabbing cavity for a possible LHC luminosity upgrade. Currently the designs are optimized to achieve lower surface fields within the dimensional constraints for the above applications. A detailed analysis of the fundamental input power coupler design for the parallel-bar cavity is performed considering beam loading and the effects of microphonics. For higher beam loading the damping of the HOMs is vital to reduce beam instabilities generated due to the wake fields. An analysis of threshold impedances for each application and impedances of the modes that requires damping are presented in this paper with the design of HOM couplers.

TUP098

Multipacting Analysis of the Superconducting Parallel-bar Cavity

1018

S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA
S.U. De Silva
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. Multipacting can be a limiting factor to the performance of in any superconducting structure. In the parallel-bar cavity the main contribution to the deflection is due to the transverse deflecting voltage, between the parallel bars, making the design potentially prone to multipacting. This paper presents the results of analytical calculations and numerical simulations of multipacting in the parallel-bar cavity with resonant voltage, impact energies and corresponding particle trajectories.

TUP099

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

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

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.

WEP082

Crab Crossing Consideration for MEIC

1627

S. Ahmed, Y.S. Derbenev, G.A. Krafft, Y. Zhang
JLAB, Newport News, Virginia, USA
A. Castilla, J.R. Delayen, S.D. Silva
ODU, Norfolk, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Crab crossing of colliding electron and ion beams is essential for accommodating the ultra high bunch repetition frequency in the conceptual design of MEIC – a high luminosity polarized electron-ion collider at Jefferson Lab. The scheme eliminates parasitic beam-beam interactions and avoids luminosity reduction by restoring head-on collisions at interaction points. In this paper, we report simulation studies of beam dynamics with crab cavities for MEIC design. The detailed study involves full 3-D simulations of particle tracking through the various configurations of crab cavities for evaluating the performance. To gain insight, beam and RF dominated fields with other parametric studies will be presented in the paper.

Paper	Title	Page
TUODN3	Beam Dynamics Studies of Parallel-Bar Deflecting Cavities	790
	S. Ahmed, J.R. Delayen, A.S. Hofler, G.A. Krafft, M. Spata, M.G. Tiefenback JLAB, Newport News, Virginia, USA K.B. Beard Muons, Inc, Batavia, USA K.A. Deitrick RPI, Troy, New York, USA S.D. Silva ODU, Norfolk, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. We have performed three-dimensional simulations of beam dynamics for parallel-bar transverse electromagnetic mode (TEM) type RF separators: normal- and superconducting. The compact size of these cavities as compared to conventional TM₁₁₀ type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of eight 2-cell normal conducting cavities or a one- or two-cell superconducting structure are enough to produce the required vertical displacement at the Lambertson magnet. Both the normal and superconducting structures show very small emittance dilution due to the vertical kick of the beam.
	Slides TUODN3 [1.558 MB]

TUP099	Design of Superconducting Parallel-bar Deflecting/Crabbing Cavities with Improved Properties	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	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.

TUP097	Fundamental and HOM Coupler Design for the Superconducting Parallel-Bar Cavity	1015
	S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA S.U. De Silva JLAB, Newport News, Virginia, USA
	The superconducting parallel-bar cavity is currently being considered as a deflecting system for the Jefferson Lab 12 GeV upgrade and as a crabbing cavity for a possible LHC luminosity upgrade. Currently the designs are optimized to achieve lower surface fields within the dimensional constraints for the above applications. A detailed analysis of the fundamental input power coupler design for the parallel-bar cavity is performed considering beam loading and the effects of microphonics. For higher beam loading the damping of the HOMs is vital to reduce beam instabilities generated due to the wake fields. An analysis of threshold impedances for each application and impedances of the modes that requires damping are presented in this paper with the design of HOM couplers.

TUP098	Multipacting Analysis of the Superconducting Parallel-bar Cavity	1018
	S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA S.U. De Silva 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. Multipacting can be a limiting factor to the performance of in any superconducting structure. In the parallel-bar cavity the main contribution to the deflection is due to the transverse deflecting voltage, between the parallel bars, making the design potentially prone to multipacting. This paper presents the results of analytical calculations and numerical simulations of multipacting in the parallel-bar cavity with resonant voltage, impact energies and corresponding particle trajectories.

TUP099	Design of Superconducting Parallel-bar Deflecting/Crabbing Cavities with Improved Properties	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	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.

WEP082	Crab Crossing Consideration for MEIC	1627
	S. Ahmed, Y.S. Derbenev, G.A. Krafft, Y. Zhang JLAB, Newport News, Virginia, USA A. Castilla, J.R. Delayen, S.D. Silva ODU, Norfolk, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Crab crossing of colliding electron and ion beams is essential for accommodating the ultra high bunch repetition frequency in the conceptual design of MEIC – a high luminosity polarized electron-ion collider at Jefferson Lab. The scheme eliminates parasitic beam-beam interactions and avoids luminosity reduction by restoring head-on collisions at interaction points. In this paper, we report simulation studies of beam dynamics with crab cavities for MEIC design. The detailed study involves full 3-D simulations of particle tracking through the various configurations of crab cavities for evaluating the performance. To gain insight, beam and RF dominated fields with other parametric studies will be presented in the paper.