Undulators Consisting of Magnetized Helices

Eyal Magory, Nezah Balal, Vladimir L. Bratman

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


A ferromagnetic helix magnetized axially or radially is apparently the simplest helical undulator. Four helices with alternating magnetization can provide a stronger helical field than a pair of conventional planar Halbach arrays. Such undulators and microundulators seem promising for various powerful high frequency sources. The fields of infinite helices uniformly magnetized in the longitudinal and radial directions are found analytically by integration of contributions from elementary dipoles. The analytical values of the field magnitudes are close to the numerically calculated ones for a helix with a relatively small number of periods five-ten. According to simulation, a magnitude of about 1 T can be obtained on the axis of a system of helices with small inner radii.

Original languageEnglish
Pages (from-to)798-801
Number of pages4
JournalIEEE Transactions on Electron Devices
Issue number2
StatePublished - 1 Feb 2022


  • Free electron laser (FEL)
  • Halbach array
  • planar and helical undulator
  • rare-earth magnets


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