LINAC2012 - List of Keywords (HOM)

Paper	Title	Other Keywords	Page
SUPB025	Development of Superconducting Radio-Frequency (SRF) Deflecting Mode Cavities and Associated Waveguide Dampers for the APS Upgrade Short Pulse X-Ray Project	cavity, photon, cryomodule, damping	65
	J.P. Holzbauer, A. Nassiri, G.J. Waldschmidt, G. Wu ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357. The Advanced Photon Source Upgrade (APS-U) is a Department of Energy (DoE) funded project to increase the available x-ray beam brightness and add capability to enhance time-resolved experiments on few-ps-scale at APS. A centerpiece of the upgrade is the generation of short pulse x-rays (SPXs) for pump-probe time-resolved capability using SRF deflecting cavities[1]. The SPX project is designed to produce 1-2 ps x-ray pulses for some users compared to the standard 100 ps pulses currently produced. SPX calls for using superconducting rf (SRF) deflecting cavities to give the electrons a correlation between longitudinal position in the bunch and vertical momentum [2]. The light produced by this bunch can be passed through a slit to produce a pulse of light much shorter than the bunch length at reduced flux. The ongoing work of designing these cavities and associated technologies will be presented. This includes the design and prototyping of higher-order (HOM) and lower-order mode (LOM) couplers and dampers as well as the fundamental power coupler (FPC). This work will be given in the context of SPX0, a demonstration cryomodule with two deflecting cavities to be installed in APS in early 2014. [1] A. Zholents, et al., NIM A 425, 385 (1999) [2] A. Nassiri, et al., “ Status of the Short-Pulse X-Ray Project at the Advanced Photon Source,” IPAC 2012, New Orleans, LA, May 2012.

SUPB027	Mechanical Study of the First Superconducting Half-wave Resonator for Injector II of CADS Project	cavity, simulation, controls, cryomodule	71
	S. He, Y. He, S.C. Huang, F.F. Wang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: This work is Supported by the National Natural Science Foundation of China (Grant Agreement 91026001) Within the framework of the China Accelerator-Driven Sub-critical Systems (CADS) project, Institute of Modern Physics (IMP) Chinese Academic of Sciences has proposed a 162.5 MHz Half-Wave Resonator (HWR) Superconducting cavity for low energy section (β=0.09) of high power proton linear accelerators as a new injector II for CIADS. For the geometrical design of superconducting cavities structure mechanical simulations are essential to predict mechanical eigenmodes and the deformation of the cavity walls due to bath pressure effects and the cavity cool-down. Additionally, the tuning analysis has been investigated to control the frequency against microphonics and Lorentz force detuning. Therefore, several RF, static structure, thermal and modal analysis with a three-dimensional Finite-Element Method (FEM) code Traditional ANSYS have been performed.

SUPB039	Compact Superconducting Crabbing and Deflecting Cavities	cavity, dipole, damping, collider	95
	S.U. De Silva ODU, Norfolk, Virginia, USA S.U. De Silva JLAB, Newport News, Virginia, USA
	Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM110 cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities.

MOPB012	First RF Measurement Results for the European XFEL SC Cavity Production	cavity, controls, factory, higher-order-mode	195
	A.A. Sulimov, P.B. Borowiec, V. Gubarev, J. Iversen, D. Kostin, G. Kreps, K. Krzysik, A. Matheisen, W.-D. Möller, D. Reschke, W. Singer DESY, Hamburg, Germany
	The first reference cavities (RCV) for the European XFEL Project are being tested within the collaboration of Research Instruments (RI), E. ZANON, IFJ-PAN and DESY: - production and warm RF measurements of cavities and their components at RI and ZANON; - surface preparation at DESY; - cold RF tests at DESY by IFJ-PAN. Purpose of the RCV is to establish a stable cavity fabrication and qualification of the surface preparation infrastructure at industry. All necessary RF measurements were done, starting with mechanical fabrication in 2011, till the tuning and cold cavity RF tests in 2012. We present the first results of RF measurements within RCV production for the European XFEL.
	Poster MOPB012 [1.843 MB]

MOPB017	Integration of the European XFEL Accelerating Modules	cavity, controls, linac, vacuum	207
	E. Vogel, S. Barbanotti, J. Branlard, H. Brueck, S. Choroba, L. Hagge, K. Jensch, V.V. Katalev, D. Kostin, D. Käfer, L. Lilje, A. Matheisen, W.-D. Möller, D. Nölle, B. Petersen, J. Prenting, D. Reschke, H. Schlarb, M. Schmökel, J.K. Sekutowicz, W. Singer, H. Weise DESY, Hamburg, Germany J. Świerbleski, P.B. Borowiec IFJ-PAN, Kraków, Poland S. Berry, O. Napoly, B. Visentin CEA/DSM/IRFU, France A. Bosotti, P. Michelato INFN/LASA, Segrate (MI), Italy W. Kaabi LAL, Orsay, France C. Madec CEA/IRFU, Gif-sur-Yvette, France E.P. Plawski NCBJ, Świerk/Otwock, Poland F. Toral CIEMAT, Madrid, Spain
	The production of the 103 superconducting accelerating modules for the European XFEL is an international effort. Institutes and companies from seven different countries (China, France, Germany, Italy, Poland, Russia and Spain), organized in 12 different work packages contribute with parts, capacity for work and facilities to the production of the modules. Currently the series production of the individual parts started or is approaching. Personnel are trained for the assembly and testing of parts and as well for the complete modules. Here we present an overview and the status of all these activities.

MOPB034	Novel Technique of Suppressing TBBU in High-energy ERLs	linac, SRF, electron, lattice	249
	V. Litvinenko BNL, Upton, Long Island, New York, USA
	Energy recovery linacs (ERLs) is emerging generation of accelerators promising revolutionize the fields of high-energy physics and photon sciences. One potential weakness of these devices is transverse beam-breakup instability, which may severely limit available beam current. In this paper I am presenting new idea [1] developed for high-energy ERL which could be used for eRHIC, LHeC and, potentially, ILC: a concept of using main ERL linacs and natural chromaticity to suppressing TBBU instabilities by simplifying an ERL lattice. As demonstration of this method, I present tow specific example of eRHIC and LHeC ERLs. [1] V.N. Litvinenko, Chromaticity of the lattice and beam stability in energy recovery linacs, submitted to PR ST-AB

MOPB043	Detailed Analysis of the Long-Range Wakefield in the Baseline Design of the CLIC Main Linac	wakefield, damping, factory, impedance	270
	V.F. Khan, A. Grudiev CERN, Geneva, Switzerland
	The baseline design for the accelerating structure of the CLIC main linac relies on strong damping of transverse higher order modes (HOMs). Each accelerating cell is equipped with four damping waveguides that enables HOM energy to propagate to damping loads. Most of the HOMs decay exponentially with a Q-factor of about 10 however, there are modes with higher Q-factors. Though the amplitude of the high Q modes is nearly two orders of magnitude smaller than the dominating lowest dipole mode, their cumulative effect over the entire bunch train may be significant and dilute the beam emittance to unacceptable level. In this paper we report on an accurate calculation of the long-range wakefield and its overall effect on beam dynamics. We also discuss possible measures to minimise its effect in a tapered structure.

MOPB055	Development of Superconducting Radio-Frequency (SRF) Deflecting Mode Cavities and Associated Waveguide Dampers for the APS Upgrade Short Pulse X-Ray Project	cavity, photon, cryomodule, damping	300
	J.P. Holzbauer, A. Nassiri, G.J. Waldschmidt, G. Wu ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357. The Advanced Photon Source Upgrade (APS-U) is a Department of Energy (DoE) funded project to increase the available x-ray beam brightness and add capability to enhance time-resolved experiments on few-ps-scale at APS. A centerpiece of the upgrade is the generation of short pulse x-rays (SPXs) for pump-probe time-resolved capability using SRF deflecting cavities[1]. The SPX project is designed to produce 1-2 ps x-ray pulses for some users compared to the standard 100 ps pulses currently produced. SPX calls for using superconducting rf (SRF) deflecting cavities to give the electrons a correlation between longitudinal position in the bunch and vertical momentum [2]. The light produced by this bunch can be passed through a slit to produce a pulse of light much shorter than the bunch length at reduced flux. The ongoing work of designing these cavities and associated technologies will be presented. This includes the design and prototyping of higher-order (HOM) and lower-order mode (LOM) couplers and dampers as well as the fundamental power coupler (FPC). This work will be given in the context of SPX0, a demonstration cryomodule with two deflecting cavities to be installed in APS in early 2014. [1] A. Zholents, et al., NIM A 425, 385 (1999) [2] A. Nassiri, et al., “ Status of the Short-Pulse X-Ray Project at the Advanced Photon Source,” IPAC 2012, New Orleans, LA, May 2012.

MOPB057	Mechanical Study of the First Superconducting Half-wave Resonator for Injector II of CADS Project	cavity, simulation, controls, cryomodule	306
	S. He, Y. He, S.C. Huang, F.F. Wang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: This work is Supported by the National Natural Science Foundation of China (Grant Agreement 91026001) Within the framework of the China Accelerator-Driven Sub-critical Systems (CADS) project, Institute of Modern Physics (IMP) Chinese Academic of Sciences has proposed a 162.5 MHz Half-Wave Resonator (HWR) Superconducting cavity for low energy section (β=0.09) of high power proton linear accelerators as a new injector II for CIADS. For the geometrical design of superconducting cavities structure mechanical simulations are essential to predict mechanical eigenmodes and the deformation of the cavity walls due to bath pressure effects and the cavity cool-down. Additionally, the tuning analysis has been investigated to control the frequency against microphonics and Lorentz force detuning. Therefore, several RF, static structure, thermal and modal analysis with a three-dimensional Finite-Element Method (FEM) code Traditional ANSYS have been performed.

MOPB063	Superconducting RF Linac for eRHIC	cavity, linac, SRF, electron	321
	S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, H. Hahn, D. Kayran, V. Litvinenko, G.J. Mahler, G.T. McIntyre, V. Ptitsyn, R. Than, J.E. Tuozzolo, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh Stony Brook University, Stony Brook, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. eRHIC will collide high-intensity hadron beams from RHIC with 50-mA electron beam from a six-pass 30-GeV Energy Recovery Linac (ERL), which will utilize 704 MHz superconducting RF accelerating structures. This presentation describes the eRHIC SRF linac requirements, layout and parameters, 5-cell SRF cavity with a new HOM damping scheme, project status and plans.

MOPB066	Alternative Approaches for HOM-Damped Cavities	multipole, cavity, acceleration, linac	330
	B. Riemann, T. Weis DELTA, Dortmund, Germany A. Neumann HZB, Berlin, Germany
	Funding: this work is partly funded by BMBF contract no. 05K10PEA Elliptical cavities have been a standard in SRF linac technology for 30 years. We present another approach to base cell geometry based on Bezier splines, that leads to equal performance levels and is much more flexible in terms of optimization. Using the BERLinPro main linac as an example, a spline multicell cavity is designed with equal performance goals. For the damping of higher order modes (HOMs), the installation of waveguides at the ends of a multicell cavity is a common approach.

MOPB067	Results and Performance Simulations of the Main Linac Design for BERLinPro	cavity, linac, quadrupole, dipole	333
	A. Neumann, W. Anders, J. Knobloch HZB, Berlin, Germany K. Brackebusch, T. Flisgen, T. Galek, K. Papke, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany B. Riemann, T. Weis DELTA, Dortmund, Germany
	Funding: this work is partly funded by BMBF contract no. 05K10PEA and 05K10HRC The Berlin Energy Recovery Linac Project (BERLinPro) is designed to develop and demonstrate CW LINAC technology for 100-mA-class ERLs. High-current operation requires an effective damping of higher-order modes (HOMs) of the 1.3 GHz main-linac cavities. We have studied elliptical 7-cell cavities damped by on the whole five waveguides at both ends. Eigenmode computations for geometrical figures of merit show that the present design should allow successful CW linac operation at the maximum beam current of 100 mA/77 pC bunch charge. To verify the results, the external Q factors are compared to the results of S-Parameter simulations that are postprocessed by a pole-fitting technique. First results of scattering parameter measurement on a room-temperature aluminium model are discussed. An outlook presenting the possibilities of combined multi-cavity simulations is included.

TUPB019	Second CW and LP Operation Test of XFEL Prototype Cryomodule	cryomodule, feedback, cavity, LLRF	516
	J.K. Sekutowicz, V. Ayvazyan, J. Branlard, M. Ebert, J. Eschke, A. Gössel, D. Kostin, W. Merz, F. Mittag, R. Onken DESY, Hamburg, Germany W. Cichalewski, W. Jałmużna, A. Piotrowski, K.P. Przygoda TUL-DMCS, Łódź, Poland K. Czuba, L. Zembala Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland I.M. Kudla, J. Szewiński NCBJ, Świerk/Otwock, Poland
	In summer 2011, we have performed the first test of continuous wave (cw) and long pulse (lp) operation of the XFEL prototype cryomodule, which originally has been designed for short pulse operation. In April and June 2012, the second test took place, with the next cryomodule prototype. For that test cooling in the cryomodule was improved and new LLRF system has been implemented. In this contribution we discuss results of the second RF test of these new types of operation, which can in the future extend flexibility in the time beam structure of the European XFEL facility

TUPB020	Status of the European XFEL 3.9 GHz system	cavity, status, cryomodule, coupling	519
	E. Vogel DESY, Hamburg, Germany A. Bosotti, P. Michelato, L. Monaco, C. Pagani, R. Paparella, P. Pierini, D. Sertore INFN/LASA, Segrate (MI), Italy E.R. Harms Fermilab, Batavia, USA
	The third harmonic system at 3.9 GHz of the European XFEL injector section will linearize the bunch RF curvature, induced by first accelerating module, before the first compression stage. This paper presents qualification tests on cavity prototypes and the on-going activities towards the realization of the third harmonic section of the European XFEL in view of its commissioning in 2014.

TUPB054	Coherent Effects of High Current Beam in Project-X Linac	linac, cavity, emittance, cryogenics	597
	A.I. Sukhanov, I.V. Gonin, T.N. Khabiboulline, A. Lunin, A. Saini, N. Solyak, A. Vostrikov, V.P. Yakovlev Fermilab, Batavia, USA
	Resonance excitation of longitudinal high order modes in superconducting RF structures of Project X CW linac is studied. We analyze regimes of operation of the linac with high beam current, which can be used to provide an intense muon source for the future Neutrino Factory or Muon Collider, and also important for the Accelerator-Driven Subcritical (ADS) systems. We calculate power loss and associated heat load to the cryogenic system. Longitudinal emittance growth is estimated. We consider an alternative design of the elliptical cavity for the high energy part of linac, which is more suitable for high current operation.

TH1A02	Compact Superconducting Crabbing and Deflecting Cavities	cavity, dipole, damping, collider	753
	S.U. De Silva ODU, Norfolk, Virginia, USA S.U. De Silva JLAB, Newport News, Virginia, USA
	Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM110 cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities.
	Slides TH1A02 [3.811 MB]

THPLB12	Photoinjector SRF Cavity Development for BERLinPro	cavity, cathode, gun, emittance	837
	A. Neumann, W. Anders, T. Kamps, J. Knobloch HZB, Berlin, Germany E.N. Zaplatin FZJ, Jülich, Germany
	In 2010 HZB has received approval to build BERLinPro, an ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.5 MeV kinetic energy while limited by fundamental power coupler performance to about 200 kW forward power. In oder to achieve these goals the injector cavity is being developed in a three stage approach. The current design studies focus on implementing a normal conducting cathode insert into a newly developed superconducting photoinjector cavity. In this paper the fundamental RF design calculations concerning cell shape for optimized beam dynamics as well as SRF performance will be presented. Further studies concentrate on the HZDR based choke cell design to implement the high quantum efficiency normal conducting cathode with the SRF cavity.
	Slides THPLB12 [1.431 MB]

THPB066	Photoinjector SRF Cavity Development for BERLinPro	cavity, cathode, gun, emittance	993
	A. Neumann, W. Anders, T. Kamps, J. Knobloch HZB, Berlin, Germany E.N. Zaplatin FZJ, Jülich, Germany
	In 2010 HZB has received approval to build BERLinPro, an ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.5 MeV kinetic energy while limited by fundamental power coupler performance to about 200 kW forward power. In oder to achieve these goals the injector cavity is being developed in a three stage approach. The current design studies focus on implementing a normal conducting cathode insert into a newly developed superconducting photoinjector cavity. In this paper the fundamental RF design calculations concerning cell shape for optimized beam dynamics as well as SRF performance will be presented. Further studies concentrate on the HZDR based choke cell design to implement the high quantum efficiency normal conducting cathode with the SRF cavity.

Paper

Title

Other Keywords

Page

Development of Superconducting Radio-Frequency (SRF) Deflecting Mode Cavities and Associated Waveguide Dampers for the APS Upgrade Short Pulse X-Ray Project

cavity, photon, cryomodule, damping

65

J.P. Holzbauer, A. Nassiri, G.J. Waldschmidt, G. Wu
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357.
The Advanced Photon Source Upgrade (APS-U) is a Department of Energy (DoE) funded project to increase the available x-ray beam brightness and add capability to enhance time-resolved experiments on few-ps-scale at APS. A centerpiece of the upgrade is the generation of short pulse x-rays (SPXs) for pump-probe time-resolved capability using SRF deflecting cavities[1]. The SPX project is designed to produce 1-2 ps x-ray pulses for some users compared to the standard 100 ps pulses currently produced. SPX calls for using superconducting rf (SRF) deflecting cavities to give the electrons a correlation between longitudinal position in the bunch and vertical momentum [2]. The light produced by this bunch can be passed through a slit to produce a pulse of light much shorter than the bunch length at reduced flux. The ongoing work of designing these cavities and associated technologies will be presented. This includes the design and prototyping of higher-order (HOM) and lower-order mode (LOM) couplers and dampers as well as the fundamental power coupler (FPC). This work will be given in the context of SPX0, a demonstration cryomodule with two deflecting cavities to be installed in APS in early 2014.
[1] A. Zholents, et al., NIM A 425, 385 (1999)
[2] A. Nassiri, et al., “ Status of the Short-Pulse X-Ray Project at the Advanced Photon Source,” IPAC 2012, New Orleans, LA, May 2012.

SUPB027

Mechanical Study of the First Superconducting Half-wave Resonator for Injector II of CADS Project

cavity, simulation, controls, cryomodule

71

S. He, Y. He, S.C. Huang, F.F. Wang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: This work is Supported by the National Natural Science Foundation of China (Grant Agreement 91026001)
Within the framework of the China Accelerator-Driven Sub-critical Systems (CADS) project, Institute of Modern Physics (IMP) Chinese Academic of Sciences has proposed a 162.5 MHz Half-Wave Resonator (HWR) Superconducting cavity for low energy section (β=0.09) of high power proton linear accelerators as a new injector II for CIADS. For the geometrical design of superconducting cavities structure mechanical simulations are essential to predict mechanical eigenmodes and the deformation of the cavity walls due to bath pressure effects and the cavity cool-down. Additionally, the tuning analysis has been investigated to control the frequency against microphonics and Lorentz force detuning. Therefore, several RF, static structure, thermal and modal analysis with a three-dimensional Finite-Element Method (FEM) code Traditional ANSYS have been performed.

SUPB039

Compact Superconducting Crabbing and Deflecting Cavities

cavity, dipole, damping, collider

95

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

Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM110 cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities.

MOPB012

First RF Measurement Results for the European XFEL SC Cavity Production

cavity, controls, factory, higher-order-mode

195

A.A. Sulimov, P.B. Borowiec, V. Gubarev, J. Iversen, D. Kostin, G. Kreps, K. Krzysik, A. Matheisen, W.-D. Möller, D. Reschke, W. Singer
DESY, Hamburg, Germany

The first reference cavities (RCV) for the European XFEL Project are being tested within the collaboration of Research Instruments (RI), E. ZANON, IFJ-PAN and DESY: - production and warm RF measurements of cavities and their components at RI and ZANON; - surface preparation at DESY; - cold RF tests at DESY by IFJ-PAN. Purpose of the RCV is to establish a stable cavity fabrication and qualification of the surface preparation infrastructure at industry. All necessary RF measurements were done, starting with mechanical fabrication in 2011, till the tuning and cold cavity RF tests in 2012. We present the first results of RF measurements within RCV production for the European XFEL.

Poster MOPB012 [1.843 MB]

MOPB017

Integration of the European XFEL Accelerating Modules

cavity, controls, linac, vacuum

207

E. Vogel, S. Barbanotti, J. Branlard, H. Brueck, S. Choroba, L. Hagge, K. Jensch, V.V. Katalev, D. Kostin, D. Käfer, L. Lilje, A. Matheisen, W.-D. Möller, D. Nölle, B. Petersen, J. Prenting, D. Reschke, H. Schlarb, M. Schmökel, J.K. Sekutowicz, W. Singer, H. Weise
DESY, Hamburg, Germany
J. Świerbleski, P.B. Borowiec
IFJ-PAN, Kraków, Poland
S. Berry, O. Napoly, B. Visentin
CEA/DSM/IRFU, France
A. Bosotti, P. Michelato
INFN/LASA, Segrate (MI), Italy
W. Kaabi
LAL, Orsay, France
C. Madec
CEA/IRFU, Gif-sur-Yvette, France
E.P. Plawski
NCBJ, Świerk/Otwock, Poland
F. Toral
CIEMAT, Madrid, Spain

The production of the 103 superconducting accelerating modules for the European XFEL is an international effort. Institutes and companies from seven different countries (China, France, Germany, Italy, Poland, Russia and Spain), organized in 12 different work packages contribute with parts, capacity for work and facilities to the production of the modules. Currently the series production of the individual parts started or is approaching. Personnel are trained for the assembly and testing of parts and as well for the complete modules. Here we present an overview and the status of all these activities.

MOPB034

Novel Technique of Suppressing TBBU in High-energy ERLs

linac, SRF, electron, lattice

249

V. Litvinenko
BNL, Upton, Long Island, New York, USA

Energy recovery linacs (ERLs) is emerging generation of accelerators promising revolutionize the fields of high-energy physics and photon sciences. One potential weakness of these devices is transverse beam-breakup instability, which may severely limit available beam current. In this paper I am presenting new idea [1] developed for high-energy ERL which could be used for eRHIC, LHeC and, potentially, ILC: a concept of using main ERL linacs and natural chromaticity to suppressing TBBU instabilities by simplifying an ERL lattice. As demonstration of this method, I present tow specific example of eRHIC and LHeC ERLs.
[1] V.N. Litvinenko, Chromaticity of the lattice and beam stability in energy recovery linacs, submitted to PR ST-AB

MOPB043

Detailed Analysis of the Long-Range Wakefield in the Baseline Design of the CLIC Main Linac

wakefield, damping, factory, impedance

270

V.F. Khan, A. Grudiev
CERN, Geneva, Switzerland

The baseline design for the accelerating structure of the CLIC main linac relies on strong damping of transverse higher order modes (HOMs). Each accelerating cell is equipped with four damping waveguides that enables HOM energy to propagate to damping loads. Most of the HOMs decay exponentially with a Q-factor of about 10 however, there are modes with higher Q-factors. Though the amplitude of the high Q modes is nearly two orders of magnitude smaller than the dominating lowest dipole mode, their cumulative effect over the entire bunch train may be significant and dilute the beam emittance to unacceptable level. In this paper we report on an accurate calculation of the long-range wakefield and its overall effect on beam dynamics. We also discuss possible measures to minimise its effect in a tapered structure.

MOPB055

Development of Superconducting Radio-Frequency (SRF) Deflecting Mode Cavities and Associated Waveguide Dampers for the APS Upgrade Short Pulse X-Ray Project

cavity, photon, cryomodule, damping

300

J.P. Holzbauer, A. Nassiri, G.J. Waldschmidt, G. Wu
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357.
The Advanced Photon Source Upgrade (APS-U) is a Department of Energy (DoE) funded project to increase the available x-ray beam brightness and add capability to enhance time-resolved experiments on few-ps-scale at APS. A centerpiece of the upgrade is the generation of short pulse x-rays (SPXs) for pump-probe time-resolved capability using SRF deflecting cavities[1]. The SPX project is designed to produce 1-2 ps x-ray pulses for some users compared to the standard 100 ps pulses currently produced. SPX calls for using superconducting rf (SRF) deflecting cavities to give the electrons a correlation between longitudinal position in the bunch and vertical momentum [2]. The light produced by this bunch can be passed through a slit to produce a pulse of light much shorter than the bunch length at reduced flux. The ongoing work of designing these cavities and associated technologies will be presented. This includes the design and prototyping of higher-order (HOM) and lower-order mode (LOM) couplers and dampers as well as the fundamental power coupler (FPC). This work will be given in the context of SPX0, a demonstration cryomodule with two deflecting cavities to be installed in APS in early 2014.
[1] A. Zholents, et al., NIM A 425, 385 (1999)
[2] A. Nassiri, et al., “ Status of the Short-Pulse X-Ray Project at the Advanced Photon Source,” IPAC 2012, New Orleans, LA, May 2012.

MOPB057

Mechanical Study of the First Superconducting Half-wave Resonator for Injector II of CADS Project

cavity, simulation, controls, cryomodule

306

S. He, Y. He, S.C. Huang, F.F. Wang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: This work is Supported by the National Natural Science Foundation of China (Grant Agreement 91026001)
Within the framework of the China Accelerator-Driven Sub-critical Systems (CADS) project, Institute of Modern Physics (IMP) Chinese Academic of Sciences has proposed a 162.5 MHz Half-Wave Resonator (HWR) Superconducting cavity for low energy section (β=0.09) of high power proton linear accelerators as a new injector II for CIADS. For the geometrical design of superconducting cavities structure mechanical simulations are essential to predict mechanical eigenmodes and the deformation of the cavity walls due to bath pressure effects and the cavity cool-down. Additionally, the tuning analysis has been investigated to control the frequency against microphonics and Lorentz force detuning. Therefore, several RF, static structure, thermal and modal analysis with a three-dimensional Finite-Element Method (FEM) code Traditional ANSYS have been performed.

MOPB063

Superconducting RF Linac for eRHIC

cavity, linac, SRF, electron

321

S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, H. Hahn, D. Kayran, V. Litvinenko, G.J. Mahler, G.T. McIntyre, V. Ptitsyn, R. Than, J.E. Tuozzolo, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh
Stony Brook University, Stony Brook, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
eRHIC will collide high-intensity hadron beams from RHIC with 50-mA electron beam from a six-pass 30-GeV Energy Recovery Linac (ERL), which will utilize 704 MHz superconducting RF accelerating structures. This presentation describes the eRHIC SRF linac requirements, layout and parameters, 5-cell SRF cavity with a new HOM damping scheme, project status and plans.

MOPB066

Alternative Approaches for HOM-Damped Cavities

multipole, cavity, acceleration, linac

330

B. Riemann, T. Weis
DELTA, Dortmund, Germany
A. Neumann
HZB, Berlin, Germany

Funding: this work is partly funded by BMBF contract no. 05K10PEA
Elliptical cavities have been a standard in SRF linac technology for 30 years. We present another approach to base cell geometry based on Bezier splines, that leads to equal performance levels and is much more flexible in terms of optimization. Using the BERLinPro main linac as an example, a spline multicell cavity is designed with equal performance goals. For the damping of higher order modes (HOMs), the installation of waveguides at the ends of a multicell cavity is a common approach.

MOPB067

Results and Performance Simulations of the Main Linac Design for BERLinPro

cavity, linac, quadrupole, dipole

333

A. Neumann, W. Anders, J. Knobloch
HZB, Berlin, Germany
K. Brackebusch, T. Flisgen, T. Galek, K. Papke, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
B. Riemann, T. Weis
DELTA, Dortmund, Germany

Funding: this work is partly funded by BMBF contract no. 05K10PEA and 05K10HRC
The Berlin Energy Recovery Linac Project (BERLinPro) is designed to develop and demonstrate CW LINAC technology for 100-mA-class ERLs. High-current operation requires an effective damping of higher-order modes (HOMs) of the 1.3 GHz main-linac cavities. We have studied elliptical 7-cell cavities damped by on the whole five waveguides at both ends. Eigenmode computations for geometrical figures of merit show that the present design should allow successful CW linac operation at the maximum beam current of 100 mA/77 pC bunch charge. To verify the results, the external Q factors are compared to the results of S-Parameter simulations that are postprocessed by a pole-fitting technique. First results of scattering parameter measurement on a room-temperature aluminium model are discussed. An outlook presenting the possibilities of combined multi-cavity simulations is included.

TUPB019

Second CW and LP Operation Test of XFEL Prototype Cryomodule

cryomodule, feedback, cavity, LLRF

516

J.K. Sekutowicz, V. Ayvazyan, J. Branlard, M. Ebert, J. Eschke, A. Gössel, D. Kostin, W. Merz, F. Mittag, R. Onken
DESY, Hamburg, Germany
W. Cichalewski, W. Jałmużna, A. Piotrowski, K.P. Przygoda
TUL-DMCS, Łódź, Poland
K. Czuba, L. Zembala
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
I.M. Kudla, J. Szewiński
NCBJ, Świerk/Otwock, Poland

In summer 2011, we have performed the first test of continuous wave (cw) and long pulse (lp) operation of the XFEL prototype cryomodule, which originally has been designed for short pulse operation. In April and June 2012, the second test took place, with the next cryomodule prototype. For that test cooling in the cryomodule was improved and new LLRF system has been implemented. In this contribution we discuss results of the second RF test of these new types of operation, which can in the future extend flexibility in the time beam structure of the European XFEL facility

TUPB020

Status of the European XFEL 3.9 GHz system

cavity, status, cryomodule, coupling

519

E. Vogel
DESY, Hamburg, Germany
A. Bosotti, P. Michelato, L. Monaco, C. Pagani, R. Paparella, P. Pierini, D. Sertore
INFN/LASA, Segrate (MI), Italy
E.R. Harms
Fermilab, Batavia, USA

The third harmonic system at 3.9 GHz of the European XFEL injector section will linearize the bunch RF curvature, induced by first accelerating module, before the first compression stage. This paper presents qualification tests on cavity prototypes and the on-going activities towards the realization of the third harmonic section of the European XFEL in view of its commissioning in 2014.

TUPB054

Coherent Effects of High Current Beam in Project-X Linac

linac, cavity, emittance, cryogenics

597

A.I. Sukhanov, I.V. Gonin, T.N. Khabiboulline, A. Lunin, A. Saini, N. Solyak, A. Vostrikov, V.P. Yakovlev
Fermilab, Batavia, USA

Resonance excitation of longitudinal high order modes in superconducting RF structures of Project X CW linac is studied. We analyze regimes of operation of the linac with high beam current, which can be used to provide an intense muon source for the future Neutrino Factory or Muon Collider, and also important for the Accelerator-Driven Subcritical (ADS) systems. We calculate power loss and associated heat load to the cryogenic system. Longitudinal emittance growth is estimated. We consider an alternative design of the elliptical cavity for the high energy part of linac, which is more suitable for high current operation.

TH1A02

Compact Superconducting Crabbing and Deflecting Cavities

cavity, dipole, damping, collider

753

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

Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM110 cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities.

Slides TH1A02 [3.811 MB]

THPLB12

Photoinjector SRF Cavity Development for BERLinPro

cavity, cathode, gun, emittance

837

A. Neumann, W. Anders, T. Kamps, J. Knobloch
HZB, Berlin, Germany
E.N. Zaplatin
FZJ, Jülich, Germany

In 2010 HZB has received approval to build BERLinPro, an ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.5 MeV kinetic energy while limited by fundamental power coupler performance to about 200 kW forward power. In oder to achieve these goals the injector cavity is being developed in a three stage approach. The current design studies focus on implementing a normal conducting cathode insert into a newly developed superconducting photoinjector cavity. In this paper the fundamental RF design calculations concerning cell shape for optimized beam dynamics as well as SRF performance will be presented. Further studies concentrate on the HZDR based choke cell design to implement the high quantum efficiency normal conducting cathode with the SRF cavity.

Slides THPLB12 [1.431 MB]

THPB066

Photoinjector SRF Cavity Development for BERLinPro

cavity, cathode, gun, emittance

993

A. Neumann, W. Anders, T. Kamps, J. Knobloch
HZB, Berlin, Germany
E.N. Zaplatin
FZJ, Jülich, Germany

In 2010 HZB has received approval to build BERLinPro, an ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.5 MeV kinetic energy while limited by fundamental power coupler performance to about 200 kW forward power. In oder to achieve these goals the injector cavity is being developed in a three stage approach. The current design studies focus on implementing a normal conducting cathode insert into a newly developed superconducting photoinjector cavity. In this paper the fundamental RF design calculations concerning cell shape for optimized beam dynamics as well as SRF performance will be presented. Further studies concentrate on the HZDR based choke cell design to implement the high quantum efficiency normal conducting cathode with the SRF cavity.