A versatile method for the real time determination of the safety factor and density profiles in JET

L. Zabeo, A. Murari, E. Joffrin, D. Mazon, C. Taliercio

Research output: Contribution to journalArticle

24 Citations (Scopus)


In this paper, the algorithms to determine the safety factor q and density profiles in real time are presented. They have been designed to be implemented in JET, in the framework of the real time enhancements for the control of the internal transport barriers. In this method, only the signals of the magnetic diagnostics and of the interferometer polarimeter are used. Instead of solving the equilibrium equation, which at the moment does not seem fully compatible with real time requirements, the topology of the magnetic surfaces is determined on the basis of the external magnetic measurements. Then the density and poloidal field profiles are found inverting the interferometric and polarimetric measurements, respectively. Once the poloidal field has been obtained, the q profile is inferred. The density profiles obtained have been checked against the JET LIDAR diagnostic, showing very good agreement. On the other hand, the q profiles have been compared with the results of several versions of the equilibrium code EFIT, proving that the algorithms developed can identify with good precision both monotonic and reversed shear profiles. An optimized version of the code has also been written and it has been verified that the computing time is compatible with the requirements of JET real time system. The present algorithm is being implemented and is used during JET experimental campaigns.
Original languageEnglish
Pages (from-to)2483 - 2494
Number of pages12
JournalPlasma Physics and Controlled Fusion
Issue number11
Publication statusPublished - Nov 2002
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

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