SRF2011 - List of Authors (Devanz, G.)

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]

MOPO041

Conceptual Design of the β = 0.86 Cavities for the Superconducting Linac of ESS

180

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

CEA-Saclay is in charge of the design, the fabrication and the tests of the superconducting high beta cavities for the high energy part of the ESS (European Spallation Source) linac. This paper reports the actual status of the RF and mechanical design of these cavities. According to ESS specifications, these cavities will be 5-cells elliptical, with frequency 704 MHz and β=0.86. They will work in the pulsed mode, with a beam current initially equal to 50 mA. The target accelerating gradient is 18 MV/m on the linac, and 20 MV/m in vertical tests. For the RF design, the cavity efficiency and the peak fields were optimized, while the feasibility of the external coupling with RF power was taken into account. Attention was also paid to the HOM frequencies and impedances and to their future extraction. Coupled RF/mechanical FEM calculations have been carried out and the Lorentz detuning, critical for a pulsed mode cavity, is lowered by the insertion of stiffening rings.

Poster MOPO041 [1.676 MB]

TUPO002

High Power Pulsed Tests of a β=0.5 5-Cell 704 MHz Superconducting Cavity

345

J. Plouin, D. Braud, M. Desmons, G. Devanz, Y. Gasser, E. Jacques, O. Piquet, J.P. Poupeau, D. Roudier, P. Sahuquet
CEA/DSM/IRFU, France
W. Höfle, D. Valuch
CERN, Geneva, Switzerland

A β=0.5 5-cell 704 MHz cavity was developed in the framework of european R&D programs on high intensity pulsed proton injectors. Medium beta elliptical cavities are known to be sensitive to Lorentz detuning, which can become difficult to deal with in pulsed operation. The cavity was optimized to reduce the Lorentz detuning by means of two series of rings welded around the irises, and equipped with a piezo tuning system . In order to test the cavity in pulsed mode, a power coupler with 1 MW capability was connected to the cavity. We report here on the fully equipped cavity tests at 1.8 K carried out in the horizontal cryostat Cryholab at Saclay to study its Rf and mechanical behavior in pulsed mode, mostly with 2 ms pulses at a 50 Hz repetition rate. The compensation of Lorentz force detuning has been achieved at an accelerating gradient of 13 MV/m (44 MV/m peak surface electric field).

Poster TUPO002 [1.917 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]

MOPO041	Conceptual Design of the β = 0.86 Cavities for the Superconducting Linac of ESS	180
	J. Plouin CEA/IRFU, Gif-sur-Yvette, France G. Devanz CEA/DSM/IRFU, France
	CEA-Saclay is in charge of the design, the fabrication and the tests of the superconducting high beta cavities for the high energy part of the ESS (European Spallation Source) linac. This paper reports the actual status of the RF and mechanical design of these cavities. According to ESS specifications, these cavities will be 5-cells elliptical, with frequency 704 MHz and β=0.86. They will work in the pulsed mode, with a beam current initially equal to 50 mA. The target accelerating gradient is 18 MV/m on the linac, and 20 MV/m in vertical tests. For the RF design, the cavity efficiency and the peak fields were optimized, while the feasibility of the external coupling with RF power was taken into account. Attention was also paid to the HOM frequencies and impedances and to their future extraction. Coupled RF/mechanical FEM calculations have been carried out and the Lorentz detuning, critical for a pulsed mode cavity, is lowered by the insertion of stiffening rings.
	Poster MOPO041 [1.676 MB]

TUPO002	High Power Pulsed Tests of a β=0.5 5-Cell 704 MHz Superconducting Cavity	345
	J. Plouin, D. Braud, M. Desmons, G. Devanz, Y. Gasser, E. Jacques, O. Piquet, J.P. Poupeau, D. Roudier, P. Sahuquet CEA/DSM/IRFU, France W. Höfle, D. Valuch CERN, Geneva, Switzerland
	A β=0.5 5-cell 704 MHz cavity was developed in the framework of european R&D programs on high intensity pulsed proton injectors. Medium beta elliptical cavities are known to be sensitive to Lorentz detuning, which can become difficult to deal with in pulsed operation. The cavity was optimized to reduce the Lorentz detuning by means of two series of rings welded around the irises, and equipped with a piezo tuning system . In order to test the cavity in pulsed mode, a power coupler with 1 MW capability was connected to the cavity. We report here on the fully equipped cavity tests at 1.8 K carried out in the horizontal cryostat Cryholab at Saclay to study its Rf and mechanical behavior in pulsed mode, mostly with 2 ms pulses at a 50 Hz repetition rate. The compensation of Lorentz force detuning has been achieved at an accelerating gradient of 13 MV/m (44 MV/m peak surface electric field).
	Poster TUPO002 [1.917 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]