Feasibility and Features of a Staggered Undulator Constructed With HTS YBCO Bulks

Section: Lt01)mentioning

confidence: 99%

Superconducting undulators: permanent magnets after all

Hänisch

2023

“…In 2013, NSRRC reported the experiment on a 5-period staggered-array BHTSU model with 5 mm period and 4 mm magnetic gap, but the measurement on-axis field profile was quite far from expectation possibly due to the saturation or J c inhomogeneity in ReBCO bulks [108]. Further experiments on mapping the field profile above different field-trapped ReBCO bulks showed inconsistent results and the necessity to improve the bulk's quality [109].…”

Section: Staggered-array Bulk Hts Planarmentioning

confidence: 99%

“…In 2000, Rossmanith et al first adopted the boundary integral method-based RADIA code (implemented in Mathematica) for the magnetic field calculation of an in-vacuum planar SCU [141]. Further studies based on RADIA code were reported for the magnetic design or field optimization of planar SCU [59,[142][143][144], hybrid planar-tilted SCU [117,120], staggered-array BHTSU [108], Delta-like SCAPE undulator [125] and NbTi helical SCU [13]. In 2002, Caspi et al first adopted the finite element method (FEM) software TOSCA/OPERA 2D for the magnetic design of helical windings based planar SCU [145].…”

Section: Modelling Toolsmentioning

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.

“…In a few reports, the placement of several trapped field superconductors in close proximity was investigated [37]. A DC field varying sinusoidally in space was generated through the use of two staggered rows of stationary samples with parallel magnetizations [38][39][40]. A magnetic concentration effect was successfully demonstrated by exploiting flux trapping together with flux exclusion with samples having different critical temperatures [41,42].…”

Section: Introductionmentioning

confidence: 99%

Trapped magnetic field distribution above a superconducting linear Halbach array

Houbart

Fagnard

Dular

et al. 2022

In applications requiring a large magnetic force, permanent magnets with non-parallel magnetization directions can be assembled in a Halbach array to generate a large gradient of magnetic flux density. The saturation magnetization of permanent magnets, however, brings a fundamental limit on the performance of this configuration. In the present work, we investigate experimentally the assembly of cuboid bulk, large grain melt-textured YBa2Cu3O7−x superconductors (∼14×14×14 mm3) with orthogonal c-axes so as to form a basic unit of Halbach array. The experiments are carried out at 77 K. The experimental distribution of the magnetic flux density above the array of trapped-field superconductors is compared to a similar array made of permanent magnets. A simple analytical model is developed and is shown to accurately reproduce the main experimental observations. The results suggest that a redistribution occurs in the current flowing in the central sample when the distance between the superconductors is reduced, whereas the neighbouring superconductors are unaffected. It is shown that this current redistribution yields a reduced contribution of the central sample to the magnetic flux density above the centre of the array and a new negative contribution associated with stray fields to the magnetic flux density at this location. This interpretation is confirmed by modelling of the distribution of transport currents in the superconductor using a 3D finite element model.