PAC2013 - List of Authors (Xu, Y.)

Paper	Title	Page
WEPAC03	Electro-Magnetic Optimization and Analysis of a Quarter Wave Resonator	790
	Z. Zheng, Z.Q. He TUB, Beijing, People's Republic of China A. Facco INFN/LNL, Legnaro (PD), Italy A. Facco, Z.Q. He, Z. Liu, J. Wei, Y. Xu, Y. Zhang, Z. Zheng FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 A β=0.085 quarter wave resonator (QWR) with resonant frequency=80.5 MHz is used in the Facility of Rare Isotope Beam (FRIB). Its baseline structure is designed to achieve the FRIB specifications with optimum cost to performance ratio. Electro-magnetic optimization is introduced in this paper to modify its internal geometry to reach instead maximum accelerating gradient, while preserving the original flange to flange length. Reduced peak magnetic field and increased shunt impedance are well achieved in the optimization while keeping the same stored energy. The maximum accelerating voltage is raised accordingly. Multipacting and steering are also analyzed for the optimized cavity. This resonator could be used in the ReA linac at MSU and in all applications where the maximum accelerating voltage should be achieved in a limited space, or where the accelerator cost is mainly driven by the resonator gradient.

WEPAC20	Magnetic Shield Optimization for the FRIB Superconducting Quarter-Wave Resonator Cryomodule	829
	Y. Xu, A.D. Fox, M.J. Johnson, M. Leitner, S.J. Miller, K. Saito FRIB, East Lansing, Michigan, USA
	The Facility for Rare Isotope Beams (FRIB) requires 49 cryomodules containing 330 superconducting low-beta cavities, which have to be shielded from the earth magnetic field. Comprehensive magnetic shielding simulations have been conducted for 80.5 MHz β=0.085 cryomodules exposed to earth fields of 0.5 Gauss in different coordinate directions. The magnetic shield has to attenuate the earth magnetic field by a minimum factor of 33 (to less than 15 milli Gauss) in order to limit flux trapping in the cavities during cool-down. In the reported optimization studies, the permeability of the magnetic shielding material, shield thickness, and number of magnetic shield layers have been varied. Different design concepts including global and local magnetic shielding have been evaluated. In addition, the design concepts are compared based on the cost of material, fabrication and assembly, the design complexity and compatibility with the overall cryomodule design to obtain an optimum solution.

THPBA13	Mechanical Design of the Cryogenic Sub-Systems for ReA6 Quarter Wave Resonator Cryomodule	1256
	M. Shuptar, F. Casagrande, A.D. Fox, M.J. Johnson, M. Leitner, S.J. Miller, T. Nellis, M.S. Patil, T. Xu, Y. Xu FRIB, East Lansing, Michigan, USA
	Funding: Work supported by US DOE Cooperative Agreement DE-SC000061 The driver linac for the Facility for Rare Isotope Beams (FRIB) consists of 49 cryomodules operated at 2 K utilizing 4 different types of superconducting resonators and 2 solenoid lengths which in turn requires 7 individual cryomodule configurations. The mechanical design requirements of the internal cryogenics of an FRIB cryomodule are determined by the piping and instrumentation diagram, which is discussed in the paper based on the FRIB quarter wave cryomodule type. In addition, heat load requirements and spatial constraints of other cryomodule sub-systems influence the cryomodule cryogenics design. The paper describes detailed design choices for the cryogenic headers and piping, a 2 K heat exchanger inside the cryomodule, solenoid current leads, and the bayonet connections to the cryogenic distribution system inside the accelerator tunnel. Different operating modes, which influence the cryogenic design, are summarized.

Paper

Title

Page

Electro-Magnetic Optimization and Analysis of a Quarter Wave Resonator

790

Z. Zheng, Z.Q. He
TUB, Beijing, People's Republic of China
A. Facco
INFN/LNL, Legnaro (PD), Italy
A. Facco, Z.Q. He, Z. Liu, J. Wei, Y. Xu, Y. Zhang, Z. Zheng
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
A β=0.085 quarter wave resonator (QWR) with resonant frequency=80.5 MHz is used in the Facility of Rare Isotope Beam (FRIB). Its baseline structure is designed to achieve the FRIB specifications with optimum cost to performance ratio. Electro-magnetic optimization is introduced in this paper to modify its internal geometry to reach instead maximum accelerating gradient, while preserving the original flange to flange length. Reduced peak magnetic field and increased shunt impedance are well achieved in the optimization while keeping the same stored energy. The maximum accelerating voltage is raised accordingly. Multipacting and steering are also analyzed for the optimized cavity. This resonator could be used in the ReA linac at MSU and in all applications where the maximum accelerating voltage should be achieved in a limited space, or where the accelerator cost is mainly driven by the resonator gradient.

WEPAC20

Magnetic Shield Optimization for the FRIB Superconducting Quarter-Wave Resonator Cryomodule

829

Y. Xu, A.D. Fox, M.J. Johnson, M. Leitner, S.J. Miller, K. Saito
FRIB, East Lansing, Michigan, USA

The Facility for Rare Isotope Beams (FRIB) requires 49 cryomodules containing 330 superconducting low-beta cavities, which have to be shielded from the earth magnetic field. Comprehensive magnetic shielding simulations have been conducted for 80.5 MHz β=0.085 cryomodules exposed to earth fields of 0.5 Gauss in different coordinate directions. The magnetic shield has to attenuate the earth magnetic field by a minimum factor of 33 (to less than 15 milli Gauss) in order to limit flux trapping in the cavities during cool-down. In the reported optimization studies, the permeability of the magnetic shielding material, shield thickness, and number of magnetic shield layers have been varied. Different design concepts including global and local magnetic shielding have been evaluated. In addition, the design concepts are compared based on the cost of material, fabrication and assembly, the design complexity and compatibility with the overall cryomodule design to obtain an optimum solution.

THPBA13

Mechanical Design of the Cryogenic Sub-Systems for ReA6 Quarter Wave Resonator Cryomodule

1256

M. Shuptar, F. Casagrande, A.D. Fox, M.J. Johnson, M. Leitner, S.J. Miller, T. Nellis, M.S. Patil, T. Xu, Y. Xu
FRIB, East Lansing, Michigan, USA

Funding: Work supported by US DOE Cooperative Agreement DE-SC000061
The driver linac for the Facility for Rare Isotope Beams (FRIB) consists of 49 cryomodules operated at 2 K utilizing 4 different types of superconducting resonators and 2 solenoid lengths which in turn requires 7 individual cryomodule configurations. The mechanical design requirements of the internal cryogenics of an FRIB cryomodule are determined by the piping and instrumentation diagram, which is discussed in the paper based on the FRIB quarter wave cryomodule type. In addition, heat load requirements and spatial constraints of other cryomodule sub-systems influence the cryomodule cryogenics design. The paper describes detailed design choices for the cryogenic headers and piping, a 2 K heat exchanger inside the cryomodule, solenoid current leads, and the bayonet connections to the cryogenic distribution system inside the accelerator tunnel. Different operating modes, which influence the cryogenic design, are summarized.