Approximate analytic expressions using Stokes model for tokamak polarimetry and their range of validity

F. P. Orsitto, JET Contributors, Tommy Ahlgren

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The analysis of the polarimetry measurements has the aim of validating models (De Marco and Segre 1972 Plasma Phys. 14 245), with a careful attention to the clarification of their limits of application. In this paper a new approximation method is introduced, the so-called special constant Omega direction (SCOD), which gives an analytical solution to the polarimetry exact Stokes model equations. The available approximate solutions (including SCOD) of the polarimetry propagation equations are presented, compared and their application limits determined, using a reference tokamak configuration, which is a simplified equilibrium for a circular tokamak. The SCOD approximation is compared successfully to the Stokes model in the context also of equilibria evaluated for two JET discharges. The approximation methods are analytical or very simple mathematical expressions which can also be used in equilibrium codes for their optimization.

Original languageEnglish
Article number055008
JournalPlasma Physics and Controlled Fusion
Issue number5
Number of pages11
Publication statusPublished - May 2019
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 114 Physical sciences
  • plasma diagnostics
  • polarimetry
  • equilibrium reconstruction

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