TY - JOUR
T1 - Fully-staggered-array bulk Re-Ba-Cu-O short-period undulator: large-scale 3D electromagnetic modelling and design optimization using A-V and H-formulation methods
AU - Zhang, Kai
AU - Ainslie, Mark
AU - Calvi, Marco
AU - Kinjo, Ryota
AU - Schmidt, Thomas
N1 - Funding Information:
The authors would like to thank Dr Sebastian Hellmann for his helpful discussions regarding the 3D BHTSU modelling. This work is supported by the European Union’s Horizon2020 research and innovation program under Grant Agreement No. 777431 and by the Swiss Accelerator Research and Technology (CHART) program. Dr Mark Ainslie would like to acknowledge financial support from an Engineering and Physical Sciences Research Council (EPSRC) Early Career Fellowship EP/P020313/1. M A would also like to thank Alexandre Arsenault and Frederic Sirois for helpful discussions regarding the implementation of the H-φ formulation. The ANSYS APDL codes and COMSOL models in this article will be shared on the website of HTS Modelling Workgroup www.htsmodelling.com.
Publisher Copyright:
© 2021 The Author(s).
PY - 2021/8/18
Y1 - 2021/8/18
N2 - The development of a new hard x-ray beamline I-TOMCAT equipped with a 1 m long short-period bulk high-temperature superconductor undulator (BHTSU) has been scheduled for the upgrade of the Swiss Light Source at the Paul Scherrer Institute. The very hard x-ray source generated by the BHTSU will increase the brilliance at the beamline by over one order of magnitude in comparison to other state-of-the-art undulator technologies and allow experiments to be carried out with photon energies in excess of 60 keV. One of the key challenges for designing a 1 m long (100 periods) BHTSU is the large-scale simulation of the magnetization currents inside 200 staggered-array bulk superconductors. A feasible approach to simplify the electromagnetic model is to retain five periods from both ends of the 1 m long BHTSU, reducing the number of degrees of freedom to the scale of millions. In this paper, the theory of the recently-proposed 2D A-V formulation-based backward computation method is extended to calculate the critical state magnetization currents in the ten-period staggered-array BHTSU in 3D. The simulation results of the magnetization currents and the associated undulator field along the electron beam axis are compared with the well-known 3D H-formulation and the highly efficient 3D H-φ formulation method, all methods showing excellent agreement with each other as well as with experimental results. The mixed H-φ formulation avoids computing the eddy currents in the air subdomain and is significantly faster than the full H-formulation method, but is slower in comparison to the A-V formulation-based backward computation. Finally, the fastest and the most efficient A-V formulation, implemented in ANSYS 2020R1 Academic, is adopted to optimize the integrals of the undulator field along the electron beam axis by optimizing the sizes of the end bulks.
AB - The development of a new hard x-ray beamline I-TOMCAT equipped with a 1 m long short-period bulk high-temperature superconductor undulator (BHTSU) has been scheduled for the upgrade of the Swiss Light Source at the Paul Scherrer Institute. The very hard x-ray source generated by the BHTSU will increase the brilliance at the beamline by over one order of magnitude in comparison to other state-of-the-art undulator technologies and allow experiments to be carried out with photon energies in excess of 60 keV. One of the key challenges for designing a 1 m long (100 periods) BHTSU is the large-scale simulation of the magnetization currents inside 200 staggered-array bulk superconductors. A feasible approach to simplify the electromagnetic model is to retain five periods from both ends of the 1 m long BHTSU, reducing the number of degrees of freedom to the scale of millions. In this paper, the theory of the recently-proposed 2D A-V formulation-based backward computation method is extended to calculate the critical state magnetization currents in the ten-period staggered-array BHTSU in 3D. The simulation results of the magnetization currents and the associated undulator field along the electron beam axis are compared with the well-known 3D H-formulation and the highly efficient 3D H-φ formulation method, all methods showing excellent agreement with each other as well as with experimental results. The mixed H-φ formulation avoids computing the eddy currents in the air subdomain and is significantly faster than the full H-formulation method, but is slower in comparison to the A-V formulation-based backward computation. Finally, the fastest and the most efficient A-V formulation, implemented in ANSYS 2020R1 Academic, is adopted to optimize the integrals of the undulator field along the electron beam axis by optimizing the sizes of the end bulks.
KW - Backward computation
KW - Bulk superconductors
KW - Critical state model
KW - Finite element method
KW - H-formulation
KW - HTS modelling
KW - Undulator
UR - http://www.scopus.com/inward/record.url?scp=85114512697&partnerID=8YFLogxK
U2 - 10.1088/1361-6668/ac1c14
DO - 10.1088/1361-6668/ac1c14
M3 - Article
AN - SCOPUS:85114512697
SN - 0953-2048
VL - 34
JO - Superconductor Science and Technology
JF - Superconductor Science and Technology
IS - 9
M1 - 094002
ER -