SRF2013 - List of Authors (Martinet, G.)

Paper

Title

Page

Study of NbTi Welded Parts

659

N. Bazin, C.Z. Antoine
CEA/DSM/IRFU, France
C. B. Baumier, G. Martinet
IPN, Orsay, France
F. F. Fortuna
CSNSM, ORSAY CAMPUS, France
J.-B. Sirven
Commisariat à l'Energie Atomique (CEA/DEN/DPC), Direction de l'Energie Nucléaire, Gif-sur-Yvette, France

Due to its properties, niobium-titanium alloy is widely used to manufacture the flanges of superconducting niobium accelerating cavities. The material hardness is compliant to provide UHV-tight connections with aluminum gaskets or spring-type gaskets (Helicoflex). And the alloy can be directly welded to the niobium. The paper will present the surface analysis made on NbTi samples after the chemical treatment and on a Nb / NbTi weld.

TUP092

MUSICC3D: a Code for Modeling the Multipacting

683

T. Hamelin, M. Chabot, J.-L. Coacolo, J. Lesrel, G. Martinet
IPN, Orsay, France

IPNO has conducted an effort to develop a 3D code for modeling multipacting in RF structures. The MUSICC3D program is using particle in cell method. Based on Runge Kutta method and using relativistic equation of motion, it solves the trajectory of a particle (e-) in the RF field. The integrations over the multi differential Secondary Emission Yield (SEY) (E_in, Alpha_in ,E_out, Alpha_out)) is made with Montecarlo method. Two running modes are available. The first one is using a model of virtual particle (i.e. the charge of a unique particle “rebounding” in the interior of the cavity is made by the product of SEYs occurring at each interaction with the walls). The other one makes generation of a full cascade of individual electrons. Benchmarking calculations have been done with analytical calculations and 2D particle in cell code (MULTIPAC). In all these cases the effects of the different inputs for the multi differential SEY have been investigated. Its intend is to give a guide to determine which precision on the SEY is needed to perform accurate multipacting calculations. Benchmarking with real cavity has been recently started and results with QWR Spiral2 cavities are presented.
Hatch, Multipacting Modes etc., Physical Review.
Wood, Investigations into Multipactor Breakdown etc., ESA Journal.
Geng, Multipacting Simulations etc., Particule Accelerator Conference.

WEIOC02

Multilayers Activities at Saclay / Orsay

789

C. B. Baumier, G. Martinet
IPN, Orsay, France
C.Z. Antoine
CEA/IRFU, Gif-sur-Yvette, France
F. F. Fortuna
CSNSM, ORSAY CAMPUS, France
J.C. Villegier
CEA/INAC, Grenoble Cedex 9, France

In the investigations on the high gradient SRF cavities, the superconducting multilayer is a promising alternative. The predictions show that an SIS (Superconductor/Isolator/Superconductor) nano-composite could improve the efficiency limited by the bulk Nb it-self used today for accelerating cavities. We start, at the IPNO lab in collaboration with the CSNSM lab (CNRS) and Irfu lab (CEA), an experimental study to test the screening effect on multilayer assemblies. Based on 3rd harmonic magnetometer and a TE011 SRF cavity, measurements of first critical magnetic field HC1 and surface resistance of samples have been performed. Along with these first results, we are starting the development of a MBE deposition. This set-up is devoted to optimise the best organisation of the multilayer to produce the model sample, and to find, in a close future, a realistic solution to apply this technique on an accelerating SRF cavity.
Labex P2IO funding

Slides WEIOC02 [3.035 MB]

THIOD04

A Cold Tuner System With Mobile Plunger

884

D. Longuevergne, S. Blivet, S. Bousson, N. Gandolfo, G. Martinet, G. Olry, H. Saugnac
IPN, Orsay, France

Tuner systems for accelerating cavities are required to compensate static and dynamic frequency perturbations during beam operation. In the case of superconducting cavities, these are commonly tuned by deforming the cavity wall in specific places of the geometry. Nevertheless, considering the mechanical properties and frequency versus displacement sensitivity of some structures, tuning by deformation doesn’t allow to meet the requirements. In these specific cases, inspired from the “room temperature technology”, an alternative tuning technique by insertion of a helium-cooled superconducting plunger can be considered and has been studied for several projects (IFMIF, ESS-BILBAO). Advantages and drawbacks of such solution will be discussed and the successful results on SPIRAL2 cryomodule developed at IPNO will be presented.

Slides THIOD04 [4.938 MB]

Paper	Title	Page
TUP085	Study of NbTi Welded Parts	659
	N. Bazin, C.Z. Antoine CEA/DSM/IRFU, France C. B. Baumier, G. Martinet IPN, Orsay, France F. F. Fortuna CSNSM, ORSAY CAMPUS, France J.-B. Sirven Commisariat à l'Energie Atomique (CEA/DEN/DPC), Direction de l'Energie Nucléaire, Gif-sur-Yvette, France
	Due to its properties, niobium-titanium alloy is widely used to manufacture the flanges of superconducting niobium accelerating cavities. The material hardness is compliant to provide UHV-tight connections with aluminum gaskets or spring-type gaskets (Helicoflex). And the alloy can be directly welded to the niobium. The paper will present the surface analysis made on NbTi samples after the chemical treatment and on a Nb / NbTi weld.

TUP092	MUSICC3D: a Code for Modeling the Multipacting	683
	T. Hamelin, M. Chabot, J.-L. Coacolo, J. Lesrel, G. Martinet IPN, Orsay, France
	IPNO has conducted an effort to develop a 3D code for modeling multipacting in RF structures. The MUSICC3D program is using particle in cell method. Based on Runge Kutta method and using relativistic equation of motion, it solves the trajectory of a particle (e-) in the RF field. The integrations over the multi differential Secondary Emission Yield (SEY) (E_in, Alpha_in ,E_out, Alpha_out)) is made with Montecarlo method. Two running modes are available. The first one is using a model of virtual particle (i.e. the charge of a unique particle “rebounding” in the interior of the cavity is made by the product of SEYs occurring at each interaction with the walls). The other one makes generation of a full cascade of individual electrons. Benchmarking calculations have been done with analytical calculations and 2D particle in cell code (MULTIPAC). In all these cases the effects of the different inputs for the multi differential SEY have been investigated. Its intend is to give a guide to determine which precision on the SEY is needed to perform accurate multipacting calculations. Benchmarking with real cavity has been recently started and results with QWR Spiral2 cavities are presented. Hatch, Multipacting Modes etc., Physical Review. Wood, Investigations into Multipactor Breakdown etc., ESA Journal. Geng, Multipacting Simulations etc., Particule Accelerator Conference.

WEIOC02	Multilayers Activities at Saclay / Orsay	789
	C. B. Baumier, G. Martinet IPN, Orsay, France C.Z. Antoine CEA/IRFU, Gif-sur-Yvette, France F. F. Fortuna CSNSM, ORSAY CAMPUS, France J.C. Villegier CEA/INAC, Grenoble Cedex 9, France
	In the investigations on the high gradient SRF cavities, the superconducting multilayer is a promising alternative. The predictions show that an SIS (Superconductor/Isolator/Superconductor) nano-composite could improve the efficiency limited by the bulk Nb it-self used today for accelerating cavities. We start, at the IPNO lab in collaboration with the CSNSM lab (CNRS) and Irfu lab (CEA), an experimental study to test the screening effect on multilayer assemblies. Based on 3rd harmonic magnetometer and a TE011 SRF cavity, measurements of first critical magnetic field HC1 and surface resistance of samples have been performed. Along with these first results, we are starting the development of a MBE deposition. This set-up is devoted to optimise the best organisation of the multilayer to produce the model sample, and to find, in a close future, a realistic solution to apply this technique on an accelerating SRF cavity. Labex P2IO funding
	Slides WEIOC02 [3.035 MB]

THIOD04	A Cold Tuner System With Mobile Plunger	884
	D. Longuevergne, S. Blivet, S. Bousson, N. Gandolfo, G. Martinet, G. Olry, H. Saugnac IPN, Orsay, France
	Tuner systems for accelerating cavities are required to compensate static and dynamic frequency perturbations during beam operation. In the case of superconducting cavities, these are commonly tuned by deforming the cavity wall in specific places of the geometry. Nevertheless, considering the mechanical properties and frequency versus displacement sensitivity of some structures, tuning by deformation doesn’t allow to meet the requirements. In these specific cases, inspired from the “room temperature technology”, an alternative tuning technique by insertion of a helium-cooled superconducting plunger can be considered and has been studied for several projects (IFMIF, ESS-BILBAO). Advantages and drawbacks of such solution will be discussed and the successful results on SPIRAL2 cryomodule developed at IPNO will be presented.
	Slides THIOD04 [4.938 MB]