Measurement of disruption forces in JET using fiber-optic sensors

C. Lescure, S. Hotchin, E. Ivings, M. F. Johnson, V. Riccardo, M. Walsh, A. West, G. Fusiek, P. Niewczas

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

2 Citations (Scopus)
215 Downloads (Pure)


Monitoring the forces induced on the vacuum vessel when a disruption occurs is essential for the protection of the machine. Since divertor coils have been installed in JET, during disruptions a significant difference between the forces measured on the top and the bottom of the machine has been observed. In order to investigate these further, optical fiber transducers FBGs (Fiber Bragg Gratings) were installed in addition to the currently used strain gauges. During VDE (Vertical Displacement Event) tests, these new transducers were used to measure different level of disruptions ranging from 80T up to 230T vertical forces. The results were then compared with the strain gauges. The FBG measurement was carried out using a broadband light source illuminating an array of 4 FBGs through a combination of directional couplers, connectors and fiber-optic cable. The forces measured both by FBG and by the strain gauges are within the same range, except for the initial swing where large random differences are observed. The tests have demonstrated that the FBG-based force measurement system has adequate resolution (±1.52strain corresponding to a force of 4kN due to the geometry of the leg) and measurement range (50002strain or 13000kN) for this application.
Original languageEnglish
Title of host publication2009 23rd IEEE/NPSS Symposium on Fusion Engineering
Place of PublicationNew York
Number of pages4
ISBN (Print)9781424426355
Publication statusPublished - 28 Aug 2009
Event2009 23rd IEEE/NPSS Symposium on Fusion Engineering - San Diego, United States
Duration: 1 Jun 20095 Sept 2009

Publication series

NameIEEE/NPSS Symposium on Fusion Engineering
ISSN (Print)1078-8891
ISSN (Electronic)2155-9953


Conference2009 23rd IEEE/NPSS Symposium on Fusion Engineering
Abbreviated titleICOPS-SOFE 2009
Country/TerritoryUnited States
CitySan Diego


  • fiber-optic sensors
  • fusion energy
  • electrical engineering
  • JET


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