Inverse analysis of critical current density in a bulk high-temperature superconducting undulator

Section: Lt01)mentioning

confidence: 99%

Superconducting undulators: permanent magnets after all

Hänisch

2023

“…Recent experiments on staggered-array BHTSU prototypes reached high undulator field at short period length [3,107], but the field uniformity was quite poor possibly due to the difference of superconducting performances between ReBCO bulks. One possible shimming approach was to first inversely calculating the J e in each ReBCO bulk according to the measured on-axis undulator field and then swapping or sorting the ReBCO bulks shown in figure 34 to minimize the RMS phase error [183].…”

Section: Swapping and Sortingmentioning

confidence: 99%

Review and prospects of world-wide superconducting undulator development for synchrotrons and FELs

Zhang

Calvi²

2022

Superconducting undulators (SCUs) with period >15 mm can offer much higher on-axis undulator field B0 than state-of-the-art cryogenic permanent magnet undulators (CPMUs) with the same period and vacuum gap. The commissioned NbTi planar SCUs for user operation in the Karlsruhe Institute of Technology (KIT) synchrotron and the Advanced Photon Source (APS) storage ring are operated stably without quenches, producing outperformed photon flux in the high energy part of the hard X-ray spectrum. Another potential advantage of deploying SCU is its radiation hardness, a crucial characteristic for being used in free electron lasers (FELs) driven by high repetition rate superconducting linear accelerators (LINACs) and diffraction limited storage rings (DLSRs) with small vacuum gap and large averaged beam current. Development of shorter period but high field SCU is an important mission in an EU founded CompactLight project as this technology would reduce both the length of undulators and the length of LINACs. This review paper first overviews the research and development of SCUs worldwide from late 1970s to 2021, then presents the SCU design requirements and compares the theory limits of different types of planar and helical SCUs, and finally reviews the technical challenges including the SCU cryostat, the magnetic field measurement, the integral/local field correction and the high-temperature superconductor (HTS) challenges and prospects the research needs for SCUs.

“…The material properties often differ between different HTS bulks, as demonstrated in [4], even within the same batch. In such a case, to improve the accuracy of the models even further, we need to first evaluate the J c of each HTS bulk by referring to the measured undulator field B y and then tune the amplitude of B y and the associated phase errors through moving the HTS bulks up and down [93].…”

Section: Optimal Design Of the Bhtsumentioning

confidence: 99%

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

Zhang

Ainslie

Calvi

et al. 2021

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