A 2.5-T, 1.25-m Free Bore Superconducting Magnet for the Magnum-PSI Linear Plasma Generator

Hans J.N. van Eck*, Herman H.J. ten Kate, Alexey V. Dudarev, Tim Mulder, Alain Hervé

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

4 Citations (Scopus)


DIFFER's main experiment, Magnum-PSI, is the only laboratory setup in the world capable of exposing materials to plasma conditions similar to those of future fusion reactors. The success of the Magnum-PSI experiment depends on the generation of a 2.5-T magnetic field without restricting the diagnostic access and operational aspects of the experiment. This has been achieved with a magnet consisting of five superconducting solenoids wound on a 2.5-m-long stainless steel coil former positioned in a cryostat offering a 1.25-m warm bore. A copper stabilized multifilamentary NbTi conductor with a 3.48-mm2 cross section has been used; thus the magnet exhibits a total inductance of 500 H and a stored energy of 16 MJ. This presents quite a challenge for the protection scheme that has been implemented using a mix of back-to-back cold diodes and external dump resistors. The coils generate a plateau-shaped magnetic field adjustable up to 2.5 T while the distance between the coils allows for 16 room temperature view-ports. The coils are cooled with liquid helium using a recondensing system operated with cryocoolers, while the magnet system cycles between zero and full field up to once per day. The magnetic stray field is shielded down to 1 mT outside the experimental area by iron walls that flank the magnet.

Original languageEnglish
Article number4203305
JournalIEEE transactions on applied superconductivity
Issue number3
Publication statusPublished - 1 Apr 2018
Externally publishedYes


  • Fusion reactors
  • linear plasma generators
  • plasma-surface interaction
  • superconducting magnets


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