LINAC2014 - List of Authors (Delayen, J.R.)

Paper	Title	Page
MOPP117	Multipole and Field Uniformity Tailoring of a 750 MHz RF Dipole	326
SUPG020	use link to see paper's listing under its alternate paper code
	A. Castilla, J.R. Delayen ODU, Norfolk, Virginia, USA A. Castilla DCI-UG, León, Mexico A. Castilla, J.R. Delayen JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. In recent years great interest has been shown in developing rf structures for beam separation, correction of geometrical degradation on luminosity, and diagnostic applications in both lepton and hadron machines. The rf dipole being a very promising one among all of them. The rf dipole has been tested and proven to have attractive properties that include high shunt impedance, low and balance surface fields, absence of lower order modes and far-spaced higher order modes that simplify their damping scheme. As well as to be a compact and versatile design in a considerable range of frequencies, its fairly simple geometry dependency is suitable both for fabrication and surface treatment. The rf dipole geometry can also be optimized for lowering multipacting risk and multipole tailoring to meet machine specific field uniformity tolerances. In the present work a survey of field uniformities, and multipole contents for a set of 750 MHz rf dipole designs is presented as both a qualitative and quantitative analysis of the inherent flexibility of the structure and its limitations.

MOPP138	Fabrication and Measurements of 500 MHz Double Spoke Cavity	385
SUPG025	use link to see paper's listing under its alternate paper code
	H. Park, J.R. Delayen JLab, Newport News, Virginia, USA J.R. Delayen, C.S. Hopper, H. Park ODU, Norfolk, Virginia, USA
	The 500 MHz double spoke cavity has been designed for a high velocity application such as a compact electron accelerator at Center for Accelerator Science at Old Dominion University and is being built at Jefferson Lab. The geometry specific to the double spoke cavity requires a variety of tooling and fixtures. Also a number of joints are expected to make it difficult to maintain the geometric deviation from the design minimal. This paper will report the fabrication technique, resulting tolerance from the design, and comparison between the measurements and simulations.
	Poster MOPP138 [2.144 MB]

TUPP109	Cryogenic Testing of High-Velocity Spoke Cavities	677
SUPG023	use link to see paper's listing under its alternate paper code
	C.S. Hopper, J.R. Delayen, H. Park ODU, Norfolk, Virginia, USA J.R. Delayen, H. Park JLab, Newport News, Virginia, USA
	Spoke-loaded cavities are being investigated for the high-velocity regime. The relative compactness at low-frequency makes them attractive for applications requiring, or benefiting from, 4 K operation. Additionally, the large velocity acceptance makes them good candidates for the acceleration of high-velocity protons and ions. Here we present the results of cryogenic testing of a 325 MHz, β0 = 0.82 single-spoke cavity and a 500 MHz, β0 = 1 double-spoke cavity.

THPP112	Multipacting Optimization of a 750 MHz RF Dipole	1111
SUPG021	use link to see paper's listing under its alternate paper code
	A. Castilla, J.R. Delayen ODU, Norfolk, Virginia, USA A. Castilla DCI-UG, León, Mexico A. Castilla, J.R. Delayen JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Crab crossing schemes have been proposed to re-instate luminosity degradation due to crossing angles at the interaction points in next generation colliders to avoid the use of sharp bending magnets and their resulting large synchrotron radiation generation, highly undessirable in the detector region. The rf dipole has been considered for a different set of applications in several machines, both rings and linear colliders. We present in this paper a study of the effects on the multipacting levels and location depending on geometrical variations on the design for a crabbing/deflecting application in a high current (3/0.5 A), high repetition (750 MHz) electron/proton collider, as a matter to provide a comparison point for similar applications of rf dipoles.

MOPP117	Multipole and Field Uniformity Tailoring of a 750 MHz RF Dipole	326
SUPG020	use link to see paper's listing under its alternate paper code
	A. Castilla, J.R. Delayen ODU, Norfolk, Virginia, USA A. Castilla DCI-UG, León, Mexico A. Castilla, J.R. Delayen JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. In recent years great interest has been shown in developing rf structures for beam separation, correction of geometrical degradation on luminosity, and diagnostic applications in both lepton and hadron machines. The rf dipole being a very promising one among all of them. The rf dipole has been tested and proven to have attractive properties that include high shunt impedance, low and balance surface fields, absence of lower order modes and far-spaced higher order modes that simplify their damping scheme. As well as to be a compact and versatile design in a considerable range of frequencies, its fairly simple geometry dependency is suitable both for fabrication and surface treatment. The rf dipole geometry can also be optimized for lowering multipacting risk and multipole tailoring to meet machine specific field uniformity tolerances. In the present work a survey of field uniformities, and multipole contents for a set of 750 MHz rf dipole designs is presented as both a qualitative and quantitative analysis of the inherent flexibility of the structure and its limitations.

MOPP134	Superconducting Accelerating Cavity Pressure Sensitivity Analysis and Stiffening	373
	J. Rodnizki, Y. Ben Aliz, A. Grin, Z. Horvitz, A. Perry, L. Weissman Soreq NRC, Yavne, Israel G.K. Davis JLab, Newport News, Virginia, USA J.R. Delayen ODU, Norfolk, Virginia, USA
	The SARAF Prototype Superconducting Module (PSM) houses six 176 MHz Half Wave Resonators(HWR). The PSM accelerates protons and deuterons from 1.5 MeV/u to 4 and 5.6 MeV. The HWRs are highly sensitive to the coolant liquid Helium pressure fluctuations which limit the available beam power to 2kW per cavity out of 4kW RF amplifier and coupler and so might limit the available beam current to 2mA depending on the output energy. The flat shape of the cavity along the beam line in the area of the high electric field generates the high sensitivity of the Eigen mode frequency to helium pressure. The evaluated cavity sensitivity is full consistent with the measured values. It was explored that the tuning system (the fog structure) has a significant contribution to the cavity sensitivity. By using ribs or by modifying the rigidity of the fog we may reduce the HWR sensitivity by a factor of 3. This analysis is applied to study the stresses on the cavity during cool down and warm up to avoid plastic deformation as the Niobium yield is an order of magnitude lower in room temperature.

MOPP138	Fabrication and Measurements of 500 MHz Double Spoke Cavity	385
SUPG025	use link to see paper's listing under its alternate paper code
	H. Park, J.R. Delayen JLab, Newport News, Virginia, USA J.R. Delayen, C.S. Hopper, H. Park ODU, Norfolk, Virginia, USA
	The 500 MHz double spoke cavity has been designed for a high velocity application such as a compact electron accelerator at Center for Accelerator Science at Old Dominion University and is being built at Jefferson Lab. The geometry specific to the double spoke cavity requires a variety of tooling and fixtures. Also a number of joints are expected to make it difficult to maintain the geometric deviation from the design minimal. This paper will report the fabrication technique, resulting tolerance from the design, and comparison between the measurements and simulations.
	Poster MOPP138 [2.144 MB]

TUPP108	HOM and Impedance Study of RF Separators for LCLS II	674
SUPG022	use link to see paper's listing under its alternate paper code
	S.U. De Silva, J.R. Delayen, B.R.P. Gamage, G.A. Krafft, T. Satogata ODU, Norfolk, Virginia, USA R.G. Olave Old Dominion University, Norfolk, Virginia, USA
	The LCLS-II upgrade requires an rf spreader system to guide bunches into a switchyard delivering beam to two undulators and the primary beam dump. The beam pattern therefore needs a 3-way beam spreader. An rf deflecting cavity concept was proposed that includes both superconducting and normal conducting options. We characterize the higher order modes (HOM) of these rf separator cavities and evaluate beam dynamics effects due to potential HOM excitation. This study includes both short term wake and multi-bunch effects.
	Poster TUPP108 [1.032 MB]

TUPP109	Cryogenic Testing of High-Velocity Spoke Cavities	677
SUPG023	use link to see paper's listing under its alternate paper code
	C.S. Hopper, J.R. Delayen, H. Park ODU, Norfolk, Virginia, USA J.R. Delayen, H. Park JLab, Newport News, Virginia, USA
	Spoke-loaded cavities are being investigated for the high-velocity regime. The relative compactness at low-frequency makes them attractive for applications requiring, or benefiting from, 4 K operation. Additionally, the large velocity acceptance makes them good candidates for the acceleration of high-velocity protons and ions. Here we present the results of cryogenic testing of a 325 MHz, β0 = 0.82 single-spoke cavity and a 500 MHz, β0 = 1 double-spoke cavity.

THPP112	Multipacting Optimization of a 750 MHz RF Dipole	1111
SUPG021	use link to see paper's listing under its alternate paper code
	A. Castilla, J.R. Delayen ODU, Norfolk, Virginia, USA A. Castilla DCI-UG, León, Mexico A. Castilla, J.R. Delayen JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Crab crossing schemes have been proposed to re-instate luminosity degradation due to crossing angles at the interaction points in next generation colliders to avoid the use of sharp bending magnets and their resulting large synchrotron radiation generation, highly undessirable in the detector region. The rf dipole has been considered for a different set of applications in several machines, both rings and linear colliders. We present in this paper a study of the effects on the multipacting levels and location depending on geometrical variations on the design for a crabbing/deflecting application in a high current (3/0.5 A), high repetition (750 MHz) electron/proton collider, as a matter to provide a comparison point for similar applications of rf dipoles.

Paper

Title

Page

MOPP117

Multipole and Field Uniformity Tailoring of a 750 MHz RF Dipole

326

SUPG020

use link to see paper's listing under its alternate paper code

A. Castilla, J.R. Delayen
ODU, Norfolk, Virginia, USA
A. Castilla
DCI-UG, León, Mexico
A. Castilla, J.R. Delayen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In recent years great interest has been shown in developing rf structures for beam separation, correction of geometrical degradation on luminosity, and diagnostic applications in both lepton and hadron machines. The rf dipole being a very promising one among all of them. The rf dipole has been tested and proven to have attractive properties that include high shunt impedance, low and balance surface fields, absence of lower order modes and far-spaced higher order modes that simplify their damping scheme. As well as to be a compact and versatile design in a considerable range of frequencies, its fairly simple geometry dependency is suitable both for fabrication and surface treatment. The rf dipole geometry can also be optimized for lowering multipacting risk and multipole tailoring to meet machine specific field uniformity tolerances. In the present work a survey of field uniformities, and multipole contents for a set of 750 MHz rf dipole designs is presented as both a qualitative and quantitative analysis of the inherent flexibility of the structure and its limitations.

MOPP138

Fabrication and Measurements of 500 MHz Double Spoke Cavity

385

SUPG025

use link to see paper's listing under its alternate paper code

H. Park, J.R. Delayen
JLab, Newport News, Virginia, USA
J.R. Delayen, C.S. Hopper, H. Park
ODU, Norfolk, Virginia, USA

The 500 MHz double spoke cavity has been designed for a high velocity application such as a compact electron accelerator at Center for Accelerator Science at Old Dominion University and is being built at Jefferson Lab. The geometry specific to the double spoke cavity requires a variety of tooling and fixtures. Also a number of joints are expected to make it difficult to maintain the geometric deviation from the design minimal. This paper will report the fabrication technique, resulting tolerance from the design, and comparison between the measurements and simulations.

Poster MOPP138 [2.144 MB]

TUPP109

Cryogenic Testing of High-Velocity Spoke Cavities

677

SUPG023

use link to see paper's listing under its alternate paper code

C.S. Hopper, J.R. Delayen, H. Park
ODU, Norfolk, Virginia, USA
J.R. Delayen, H. Park
JLab, Newport News, Virginia, USA

Spoke-loaded cavities are being investigated for the high-velocity regime. The relative compactness at low-frequency makes them attractive for applications requiring, or benefiting from, 4 K operation. Additionally, the large velocity acceptance makes them good candidates for the acceleration of high-velocity protons and ions. Here we present the results of cryogenic testing of a 325 MHz, β0 = 0.82 single-spoke cavity and a 500 MHz, β0 = 1 double-spoke cavity.

THPP112

Multipacting Optimization of a 750 MHz RF Dipole

1111

SUPG021

use link to see paper's listing under its alternate paper code

A. Castilla, J.R. Delayen
ODU, Norfolk, Virginia, USA
A. Castilla
DCI-UG, León, Mexico
A. Castilla, J.R. Delayen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Crab crossing schemes have been proposed to re-instate luminosity degradation due to crossing angles at the interaction points in next generation colliders to avoid the use of sharp bending magnets and their resulting large synchrotron radiation generation, highly undessirable in the detector region. The rf dipole has been considered for a different set of applications in several machines, both rings and linear colliders. We present in this paper a study of the effects on the multipacting levels and location depending on geometrical variations on the design for a crabbing/deflecting application in a high current (3/0.5 A), high repetition (750 MHz) electron/proton collider, as a matter to provide a comparison point for similar applications of rf dipoles.

MOPP117

Multipole and Field Uniformity Tailoring of a 750 MHz RF Dipole

326

SUPG020

use link to see paper's listing under its alternate paper code

A. Castilla, J.R. Delayen
ODU, Norfolk, Virginia, USA
A. Castilla
DCI-UG, León, Mexico
A. Castilla, J.R. Delayen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In recent years great interest has been shown in developing rf structures for beam separation, correction of geometrical degradation on luminosity, and diagnostic applications in both lepton and hadron machines. The rf dipole being a very promising one among all of them. The rf dipole has been tested and proven to have attractive properties that include high shunt impedance, low and balance surface fields, absence of lower order modes and far-spaced higher order modes that simplify their damping scheme. As well as to be a compact and versatile design in a considerable range of frequencies, its fairly simple geometry dependency is suitable both for fabrication and surface treatment. The rf dipole geometry can also be optimized for lowering multipacting risk and multipole tailoring to meet machine specific field uniformity tolerances. In the present work a survey of field uniformities, and multipole contents for a set of 750 MHz rf dipole designs is presented as both a qualitative and quantitative analysis of the inherent flexibility of the structure and its limitations.

MOPP134

Superconducting Accelerating Cavity Pressure Sensitivity Analysis and Stiffening

373

J. Rodnizki, Y. Ben Aliz, A. Grin, Z. Horvitz, A. Perry, L. Weissman
Soreq NRC, Yavne, Israel
G.K. Davis
JLab, Newport News, Virginia, USA
J.R. Delayen
ODU, Norfolk, Virginia, USA

The SARAF Prototype Superconducting Module (PSM) houses six 176 MHz Half Wave Resonators(HWR). The PSM accelerates protons and deuterons from 1.5 MeV/u to 4 and 5.6 MeV. The HWRs are highly sensitive to the coolant liquid Helium pressure fluctuations which limit the available beam power to 2kW per cavity out of 4kW RF amplifier and coupler and so might limit the available beam current to 2mA depending on the output energy. The flat shape of the cavity along the beam line in the area of the high electric field generates the high sensitivity of the Eigen mode frequency to helium pressure. The evaluated cavity sensitivity is full consistent with the measured values. It was explored that the tuning system (the fog structure) has a significant contribution to the cavity sensitivity. By using ribs or by modifying the rigidity of the fog we may reduce the HWR sensitivity by a factor of 3. This analysis is applied to study the stresses on the cavity during cool down and warm up to avoid plastic deformation as the Niobium yield is an order of magnitude lower in room temperature.

MOPP138

Fabrication and Measurements of 500 MHz Double Spoke Cavity

385

SUPG025

use link to see paper's listing under its alternate paper code

H. Park, J.R. Delayen
JLab, Newport News, Virginia, USA
J.R. Delayen, C.S. Hopper, H. Park
ODU, Norfolk, Virginia, USA

The 500 MHz double spoke cavity has been designed for a high velocity application such as a compact electron accelerator at Center for Accelerator Science at Old Dominion University and is being built at Jefferson Lab. The geometry specific to the double spoke cavity requires a variety of tooling and fixtures. Also a number of joints are expected to make it difficult to maintain the geometric deviation from the design minimal. This paper will report the fabrication technique, resulting tolerance from the design, and comparison between the measurements and simulations.

Poster MOPP138 [2.144 MB]

TUPP108

HOM and Impedance Study of RF Separators for LCLS II

674

SUPG022

use link to see paper's listing under its alternate paper code

S.U. De Silva, J.R. Delayen, B.R.P. Gamage, G.A. Krafft, T. Satogata
ODU, Norfolk, Virginia, USA
R.G. Olave
Old Dominion University, Norfolk, Virginia, USA

The LCLS-II upgrade requires an rf spreader system to guide bunches into a switchyard delivering beam to two undulators and the primary beam dump. The beam pattern therefore needs a 3-way beam spreader. An rf deflecting cavity concept was proposed that includes both superconducting and normal conducting options. We characterize the higher order modes (HOM) of these rf separator cavities and evaluate beam dynamics effects due to potential HOM excitation. This study includes both short term wake and multi-bunch effects.

Poster TUPP108 [1.032 MB]

TUPP109

Cryogenic Testing of High-Velocity Spoke Cavities

677

SUPG023

use link to see paper's listing under its alternate paper code

C.S. Hopper, J.R. Delayen, H. Park
ODU, Norfolk, Virginia, USA
J.R. Delayen, H. Park
JLab, Newport News, Virginia, USA

Spoke-loaded cavities are being investigated for the high-velocity regime. The relative compactness at low-frequency makes them attractive for applications requiring, or benefiting from, 4 K operation. Additionally, the large velocity acceptance makes them good candidates for the acceleration of high-velocity protons and ions. Here we present the results of cryogenic testing of a 325 MHz, β0 = 0.82 single-spoke cavity and a 500 MHz, β0 = 1 double-spoke cavity.

THPP112

Multipacting Optimization of a 750 MHz RF Dipole

1111

SUPG021

use link to see paper's listing under its alternate paper code

A. Castilla, J.R. Delayen
ODU, Norfolk, Virginia, USA
A. Castilla
DCI-UG, León, Mexico
A. Castilla, J.R. Delayen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Crab crossing schemes have been proposed to re-instate luminosity degradation due to crossing angles at the interaction points in next generation colliders to avoid the use of sharp bending magnets and their resulting large synchrotron radiation generation, highly undessirable in the detector region. The rf dipole has been considered for a different set of applications in several machines, both rings and linear colliders. We present in this paper a study of the effects on the multipacting levels and location depending on geometrical variations on the design for a crabbing/deflecting application in a high current (3/0.5 A), high repetition (750 MHz) electron/proton collider, as a matter to provide a comparison point for similar applications of rf dipoles.