SRF2011 - List of Authors (Chel, S.)

Paper

Title

Page

Optimized RF Design of 704 MHz β=1 Cavity for Pulsed Proton Drivers

157

J. Plouin
CEA/IRFU, Gif-sur-Yvette, France
S. Chel, G. Devanz
CEA/DSM/IRFU, France

The high energy part of the Superconducting Proton Linac (SPL) will be composed of two families of elliptical cavities, β = 0.65 and β = 1. This paper focuses on the β = 1, 5-cell cavity, whose RF design has been developed at CEA-Saclay in the frame of EUCARD (European Coordination for Accelerator Research & Development). These cavities are aimed to work in pulsed mode (50Hz, duty cycle 5%), with a beam current of 40 mA and RF peak power 1MW. Since these cavities should provide a challenging gradient of 25 MV/m, the RF design has been realized to optimize cavity efficiency and peak fields. The position of high power couplers has been determined to achieve the adequate external coupling, and the monopole High Order Modes have been identified and characterized. We have also carried out RF/mechanical simulations in order to optimize the mechanical behavior of cavity, in particular the Lorentz force detuning.

Poster MOPO034 [2.412 MB]

TUPO062

Vertical Electro-Polishing at CEA Saclay: Commissioning of a New Set-Up and Modeling of the Process Applied to Different Cavities

549

F. Eozénou, S. Chel, Y. Gasser, J.P. Poupeau, C. Servouin, Z. Wang
CEA/DSM/IRFU, France

Funding: We acknowledge the support of the EuCARD, ILC HiGrade and ASTRE programs.
High performance required for elliptical low beta cavity makes the electro-polishing desirable for their surface treatment. For large dimension cavities, the EP treatment in vertical configuration (abbreviated as VEP) is more appropriate. A VEP set-up has been designed at Saclay for the electro-polishing of such cavities. The electrolyte will be circulating and the process automated, including several safety procedures. Chosen equipment will make it possible to use a wide range of parameters (voltage, flowrate, temperature, nitrogen inerting) with R&D purpose in mind. R&D will guide the choice of adapted parameters in such configuration. In addition, VEP has been modeled using COMSOL software with 2D axi - symmetry configuration for 2 different cavities: - 9Cell ILC cavity - Proton 5Cell cavity for SPL accelerator. Different cathodes have been designed to optimize the fluid and the electric field distribution during VEP. Respective results will be presented. At last, importance of the size of the cavity will be commented.

Poster TUPO062 [2.067 MB]

THIOA06

Mechanical Design Considerations for β=1 Cavities

650

O. Capatina, G. Arnau-Izquierdo, S. Atieh, I. Aviles Santillana, S. Calatroni, A. D'Elia, R. Garoby, T. Junginger, D. Maciocha, E. Montesinos, V. Parma, T. Renaglia, T. Tardy, N. Valverde Alonso, W. Weingarten
CERN, Geneva, Switzerland
S. Chel, G. Devanz, J. Plouin
CEA/DSM/IRFU, France

The Superconducting Proton Linac (SPL) is an R&D effort coordinated by CERN in partnership with other international laboratories, aimed at developing key technologies for the construction of a multi-megawatt proton linac based on state-of-the-art RF superconducting technology, which would serve as a driver for new physics facilities such as neutrinos and Radioactive Ion Beam (RIB). Amongst the main objectives of this R&D effort, is the development of 704 MHz bulk niobium β=1 elliptical cavities, operating at 2 K with a maximum accelerating field of 25 MV/m, and the testing of a string of cavities integrated in a machine-type cryomodule. The R&D program concerning the elliptical β=1 cavities fabricated from niobium sheets explores new mechanical design and new fabrication methods. The paper presents several opportunities for design optimization that were identified. A comparison between stainless steel helium vessel and titanium helium vessel including Nb to Ti transitions is addressed. Different mechanical design aspects, including cryogenic considerations, and fabrication aspects were analyzed and the results are discussed.

Slides THIOA06 [5.292 MB]

Paper	Title	Page
MOPO034	Optimized RF Design of 704 MHz β=1 Cavity for Pulsed Proton Drivers	157
	J. Plouin CEA/IRFU, Gif-sur-Yvette, France S. Chel, G. Devanz CEA/DSM/IRFU, France
	The high energy part of the Superconducting Proton Linac (SPL) will be composed of two families of elliptical cavities, β = 0.65 and β = 1. This paper focuses on the β = 1, 5-cell cavity, whose RF design has been developed at CEA-Saclay in the frame of EUCARD (European Coordination for Accelerator Research & Development). These cavities are aimed to work in pulsed mode (50Hz, duty cycle 5%), with a beam current of 40 mA and RF peak power 1MW. Since these cavities should provide a challenging gradient of 25 MV/m, the RF design has been realized to optimize cavity efficiency and peak fields. The position of high power couplers has been determined to achieve the adequate external coupling, and the monopole High Order Modes have been identified and characterized. We have also carried out RF/mechanical simulations in order to optimize the mechanical behavior of cavity, in particular the Lorentz force detuning.
	Poster MOPO034 [2.412 MB]

TUPO062	Vertical Electro-Polishing at CEA Saclay: Commissioning of a New Set-Up and Modeling of the Process Applied to Different Cavities	549
	F. Eozénou, S. Chel, Y. Gasser, J.P. Poupeau, C. Servouin, Z. Wang CEA/DSM/IRFU, France
	Funding: We acknowledge the support of the EuCARD, ILC HiGrade and ASTRE programs. High performance required for elliptical low beta cavity makes the electro-polishing desirable for their surface treatment. For large dimension cavities, the EP treatment in vertical configuration (abbreviated as VEP) is more appropriate. A VEP set-up has been designed at Saclay for the electro-polishing of such cavities. The electrolyte will be circulating and the process automated, including several safety procedures. Chosen equipment will make it possible to use a wide range of parameters (voltage, flowrate, temperature, nitrogen inerting) with R&D purpose in mind. R&D will guide the choice of adapted parameters in such configuration. In addition, VEP has been modeled using COMSOL software with 2D axi - symmetry configuration for 2 different cavities: - 9Cell ILC cavity - Proton 5Cell cavity for SPL accelerator. Different cathodes have been designed to optimize the fluid and the electric field distribution during VEP. Respective results will be presented. At last, importance of the size of the cavity will be commented.
	Poster TUPO062 [2.067 MB]

THIOA06	Mechanical Design Considerations for β=1 Cavities	650
	O. Capatina, G. Arnau-Izquierdo, S. Atieh, I. Aviles Santillana, S. Calatroni, A. D'Elia, R. Garoby, T. Junginger, D. Maciocha, E. Montesinos, V. Parma, T. Renaglia, T. Tardy, N. Valverde Alonso, W. Weingarten CERN, Geneva, Switzerland S. Chel, G. Devanz, J. Plouin CEA/DSM/IRFU, France
	The Superconducting Proton Linac (SPL) is an R&D effort coordinated by CERN in partnership with other international laboratories, aimed at developing key technologies for the construction of a multi-megawatt proton linac based on state-of-the-art RF superconducting technology, which would serve as a driver for new physics facilities such as neutrinos and Radioactive Ion Beam (RIB). Amongst the main objectives of this R&D effort, is the development of 704 MHz bulk niobium β=1 elliptical cavities, operating at 2 K with a maximum accelerating field of 25 MV/m, and the testing of a string of cavities integrated in a machine-type cryomodule. The R&D program concerning the elliptical β=1 cavities fabricated from niobium sheets explores new mechanical design and new fabrication methods. The paper presents several opportunities for design optimization that were identified. A comparison between stainless steel helium vessel and titanium helium vessel including Nb to Ti transitions is addressed. Different mechanical design aspects, including cryogenic considerations, and fabrication aspects were analyzed and the results are discussed.
	Slides THIOA06 [5.292 MB]