The localization of low order rational surfaces based on the intermittence parameter in the TJ-II stellarator Articles uri icon

authors

  • VAN MILLIGEN, B. PH.
  • CARRERAS VERDAGUER, BENJAMIN A.
  • GARCIA GONZALO, LUIS
  • GARCIA GONZALEZ, LEANDRO
  • HIDALGO, C.

publication date

  • April 2020

start page

  • 1

end page

  • 10

issue

  • 5

volume

  • 60

International Standard Serial Number (ISSN)

  • 0029-5515

Electronic International Standard Serial Number (EISSN)

  • 1741-4326

abstract

  • This work intends to show that the multifractal concept of intermittence can be fruitfully applied to the identification of the radial location of low order rational surfaces inside a magnetically confined plasma. To do so, we make use of Langmuir probe data from a set of experiments in which the rotational transform was scanned dynamically in the TJ-II stellarator. It is shown that up to five rational surfaces can be identified from the data, which is a first in plasma physics, to the best of our knowledge. The effect of the radial electric field on intermittence was also studied using a specific subset of experiments in which the electron density was raised on a shot by shot basis. The observations are contrasted with results from numerical calculations using a resistive magneto-hydrodynamic model to facilitate interpretation.

keywords

  • magnetic confinement; rational surfaces; stellarator; turbulence